Cargoify servo

14 files changed, 2653 insertions, 0 deletions

diff --git a/components/net/Cargo.toml b/components/net/Cargo.toml
new file mode 100644
index 00000000000..17560f4aa5c
--- /dev/null
+++ b/components/net/Cargo.toml
@@ -0,0 +1,27 @@
+[package]
+name = "net"
+version = "0.0.1"
+authors = ["The Servo Project Developers"]
+
+[lib]
+name = "net"
+path = "lib.rs"
+
+[dependencies.util]
+path = "../util"
+
+[dependencies.geom]
+git = "https://github.com/servo/rust-geom"
+
+[dependencies.http]
+git = "https://github.com/servo/rust-http"
+branch = "servo"
+
+[dependencies.png]
+git = "https://github.com/servo/rust-png"
+
+[dependencies.stb_image]
+git = "https://github.com/servo/rust-stb-image"
+
+[dependencies.url]
+git = "https://github.com/servo/rust-url"
diff --git a/components/net/data_loader.rs b/components/net/data_loader.rs
new file mode 100644
index 00000000000..5d9fb776674
--- /dev/null
+++ b/components/net/data_loader.rs
@@ -0,0 +1,154 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use std::str;
+
+use resource_task::{Done, Payload, Metadata, LoadData, LoadResponse, LoaderTask, start_sending};
+
+use serialize::base64::FromBase64;
+
+use http::headers::test_utils::from_stream_with_str;
+use http::headers::content_type::MediaType;
+use url::{percent_decode, NonRelativeSchemeData};
+
+
+pub fn factory() -> LoaderTask {
+    proc(url, start_chan) {
+        // NB: we don't spawn a new task.
+        // Hypothesis: data URLs are too small for parallel base64 etc. to be worth it.
+        // Should be tested at some point.
+        load(url, start_chan)
+    }
+}
+
+fn load(load_data: LoadData, start_chan: Sender<LoadResponse>) {
+    let url = load_data.url;
+    assert!("data" == url.scheme.as_slice());
+
+    let mut metadata = Metadata::default(url.clone());
+
+    // Split out content type and data.
+    let mut scheme_data = match url.scheme_data {
+        NonRelativeSchemeData(scheme_data) => scheme_data,
+        _ => fail!("Expected a non-relative scheme URL.")
+    };
+    match url.query {
+        Some(query) => {
+            scheme_data.push_str("?");
+            scheme_data.push_str(query.as_slice());
+        },
+        None => ()
+    }
+    let parts: Vec<&str> = scheme_data.as_slice().splitn(',', 1).collect();
+    if parts.len() != 2 {
+        start_sending(start_chan, metadata).send(Done(Err("invalid data uri".to_string())));
+        return;
+    }
+
+    // ";base64" must come at the end of the content type, per RFC 2397.
+    // rust-http will fail to parse it because there's no =value part.
+    let mut is_base64 = false;
+    let mut ct_str = parts[0];
+    if ct_str.ends_with(";base64") {
+        is_base64 = true;
+        ct_str = ct_str.slice_to(ct_str.as_bytes().len() - 7);
+    }
+
+    // Parse the content type using rust-http.
+    // FIXME: this can go into an infinite loop! (rust-http #25)
+    let content_type: Option<MediaType> = from_stream_with_str(ct_str);
+    metadata.set_content_type(&content_type);
+
+    let progress_chan = start_sending(start_chan, metadata);
+    let bytes = percent_decode(parts[1].as_bytes());
+
+    if is_base64 {
+        // FIXME(#2909): It’s unclear what to do with non-alphabet characters,
+        // but Acid 3 apparently depends on spaces being ignored.
+        let bytes = bytes.move_iter().filter(|&b| b != ' ' as u8).collect::<Vec<u8>>();
+        // FIXME(#2877): use bytes.as_slice().from_base64() when we upgrade to a Rust version
+        // that includes https://github.com/rust-lang/rust/pull/15810
+        let fake_utf8 = unsafe { str::raw::from_utf8(bytes.as_slice()) };
+        match fake_utf8.from_base64() {
+            Err(..) => {
+                progress_chan.send(Done(Err("non-base64 data uri".to_string())));
+            }
+            Ok(data) => {
+                progress_chan.send(Payload(data));
+                progress_chan.send(Done(Ok(())));
+            }
+        }
+    } else {
+        progress_chan.send(Payload(bytes));
+        progress_chan.send(Done(Ok(())));
+    }
+}
+
+#[cfg(test)]
+fn assert_parse(url:          &'static str,
+                content_type: Option<(String, String)>,
+                charset:      Option<String>,
+                data:         Option<Vec<u8>>) {
+    use std::comm;
+    use url::Url;
+
+    let (start_chan, start_port) = comm::channel();
+    load(LoadData::new(Url::parse(url).unwrap()), start_chan);
+
+    let response = start_port.recv();
+    assert_eq!(&response.metadata.content_type, &content_type);
+    assert_eq!(&response.metadata.charset,      &charset);
+
+    let progress = response.progress_port.recv();
+
+    match data {
+        None => {
+            assert_eq!(progress, Done(Err("invalid data uri".to_string())));
+        }
+        Some(dat) => {
+            assert_eq!(progress, Payload(dat));
+            assert_eq!(response.progress_port.recv(), Done(Ok(())));
+        }
+    }
+}
+
+#[test]
+fn empty_invalid() {
+    assert_parse("data:", None, None, None);
+}
+
+#[test]
+fn plain() {
+    assert_parse("data:,hello%20world", None, None, Some(b"hello world".iter().map(|&x| x).collect()));
+}
+
+#[test]
+fn plain_ct() {
+    assert_parse("data:text/plain,hello",
+        Some(("text".to_string(), "plain".to_string())), None, Some(b"hello".iter().map(|&x| x).collect()));
+}
+
+#[test]
+fn plain_charset() {
+    assert_parse("data:text/plain;charset=latin1,hello",
+        Some(("text".to_string(), "plain".to_string())), Some("latin1".to_string()), Some(b"hello".iter().map(|&x| x).collect()));
+}
+
+#[test]
+fn base64() {
+    assert_parse("data:;base64,C62+7w==", None, None, Some(vec!(0x0B, 0xAD, 0xBE, 0xEF)));
+}
+
+#[test]
+fn base64_ct() {
+    assert_parse("data:application/octet-stream;base64,C62+7w==",
+        Some(("application".to_string(), "octet-stream".to_string())), None, Some(vec!(0x0B, 0xAD, 0xBE, 0xEF)));
+}
+
+#[test]
+fn base64_charset() {
+    assert_parse("data:text/plain;charset=koi8-r;base64,8PLl9+XkIO3l5Pfl5A==",
+        Some(("text".to_string(), "plain".to_string())), Some("koi8-r".to_string()),
+        Some(vec!(0xF0, 0xF2, 0xE5, 0xF7, 0xE5, 0xE4, 0x20, 0xED, 0xE5, 0xE4, 0xF7, 0xE5, 0xE4)));
+}
diff --git a/components/net/fetch/cors_cache.rs b/components/net/fetch/cors_cache.rs
new file mode 100644
index 00000000000..fb6676e8064
--- /dev/null
+++ b/components/net/fetch/cors_cache.rs
@@ -0,0 +1,316 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! An implementation of the [CORS preflight cache](http://fetch.spec.whatwg.org/#cors-preflight-cache)
+//! For now this library is XHR-specific.
+//! For stuff involving `<img>`, `<iframe>`, `<form>`, etc please check what
+//! the request mode should be and compare with the fetch spec
+//! This library will eventually become the core of the Fetch crate
+//! with CORSRequest being expanded into FetchRequest (etc)
+
+use http::method::Method;
+use std::ascii::StrAsciiExt;
+use std::comm::{Sender, Receiver, channel};
+use time;
+use time::{now, Timespec};
+use url::Url;
+
+/// Union type for CORS cache entries
+///
+/// Each entry might pertain to a header or method
+#[deriving(Clone)]
+pub enum HeaderOrMethod {
+    HeaderData(String),
+    MethodData(Method)
+}
+
+impl HeaderOrMethod {
+    fn match_header(&self, header_name: &str) -> bool {
+        match *self {
+            HeaderData(ref s) => s.as_slice().eq_ignore_ascii_case(header_name),
+            _ => false
+        }
+    }
+
+    fn match_method(&self, method: &Method) -> bool {
+        match *self {
+            MethodData(ref m) => m == method,
+            _ => false
+        }
+    }
+}
+
+/// An entry in the CORS cache
+#[deriving(Clone)]
+pub struct CORSCacheEntry {
+    pub origin: Url,
+    pub url: Url,
+    pub max_age: uint,
+    pub credentials: bool,
+    pub header_or_method: HeaderOrMethod,
+    created: Timespec
+}
+
+impl CORSCacheEntry {
+    fn new (origin:Url, url: Url, max_age: uint, credentials: bool, header_or_method: HeaderOrMethod) -> CORSCacheEntry {
+        CORSCacheEntry {
+            origin: origin,
+            url: url,
+            max_age: max_age,
+            credentials: credentials,
+            header_or_method: header_or_method,
+            created: time::now().to_timespec()
+        }
+    }
+}
+
+/// Properties of Request required to cache match.
+pub struct CacheRequestDetails {
+    pub origin: Url,
+    pub destination: Url,
+    pub credentials: bool
+}
+
+/// Trait for a generic CORS Cache
+pub trait CORSCache {
+    /// [Clear the cache](http://fetch.spec.whatwg.org/#concept-cache-clear)
+    fn clear (&mut self, request: CacheRequestDetails);
+
+    /// Remove old entries
+    fn cleanup(&mut self);
+
+    /// Returns true if an entry with a [matching header](http://fetch.spec.whatwg.org/#concept-cache-match-header) is found
+    fn match_header(&mut self, request: CacheRequestDetails, header_name: &str) -> bool;
+
+    /// Updates max age if an entry for a [matching header](http://fetch.spec.whatwg.org/#concept-cache-match-header) is found.
+    ///
+    /// If not, it will insert an equivalent entry
+    fn match_header_and_update(&mut self, request: CacheRequestDetails, header_name: &str, new_max_age: uint) -> bool;
+
+    /// Returns true if an entry with a [matching method](http://fetch.spec.whatwg.org/#concept-cache-match-method) is found
+    fn match_method(&mut self, request: CacheRequestDetails, method: Method) -> bool;
+
+    /// Updates max age if an entry for [a matching method](http://fetch.spec.whatwg.org/#concept-cache-match-method) is found.
+    ///
+    /// If not, it will insert an equivalent entry
+    fn match_method_and_update(&mut self, request: CacheRequestDetails, method: Method, new_max_age: uint) -> bool;
+    /// Insert an entry
+    fn insert(&mut self, entry: CORSCacheEntry);
+}
+
+/// A simple, vector-based CORS Cache
+#[deriving(Clone)]
+#[unstable = "This might later be replaced with a HashMap-like entity, though that requires a separate Origin struct"]
+pub struct BasicCORSCache(Vec<CORSCacheEntry>);
+
+impl BasicCORSCache {
+    fn find_entry_by_header<'a>(&'a mut self, request: &CacheRequestDetails, header_name: &str) -> Option<&'a mut CORSCacheEntry> {
+        self.cleanup();
+        let BasicCORSCache(ref mut buf) = *self;
+        let entry = buf.mut_iter().find(|e| e.origin.scheme == request.origin.scheme &&
+                            e.origin.host() == request.origin.host() &&
+                            e.origin.port() == request.origin.port() &&
+                            e.url == request.destination &&
+                            e.credentials == request.credentials &&
+                            e.header_or_method.match_header(header_name));
+        entry
+    }
+
+    fn find_entry_by_method<'a>(&'a mut self, request: &CacheRequestDetails, method: Method) -> Option<&'a mut CORSCacheEntry> {
+        // we can take the method from CORSRequest itself
+        self.cleanup();
+        let BasicCORSCache(ref mut buf) = *self;
+        let entry = buf.mut_iter().find(|e| e.origin.scheme == request.origin.scheme &&
+                            e.origin.host() == request.origin.host() &&
+                            e.origin.port() == request.origin.port() &&
+                            e.url == request.destination &&
+                            e.credentials == request.credentials &&
+                            e.header_or_method.match_method(&method));
+        entry
+    }
+}
+
+impl CORSCache for BasicCORSCache {
+    /// http://fetch.spec.whatwg.org/#concept-cache-clear
+    #[allow(dead_code)]
+    fn clear (&mut self, request: CacheRequestDetails) {
+        let BasicCORSCache(buf) = self.clone();
+        let new_buf: Vec<CORSCacheEntry> = buf.move_iter().filter(|e| e.origin == request.origin && request.destination == e.url).collect();
+        *self = BasicCORSCache(new_buf);
+    }
+
+    // Remove old entries
+    fn cleanup(&mut self) {
+        let BasicCORSCache(buf) = self.clone();
+        let now = time::now().to_timespec();
+        let new_buf: Vec<CORSCacheEntry> = buf.move_iter().filter(|e| now.sec > e.created.sec + e.max_age as i64).collect();
+        *self = BasicCORSCache(new_buf);
+    }
+
+    fn match_header(&mut self, request: CacheRequestDetails, header_name: &str) -> bool {
+        self.find_entry_by_header(&request, header_name).is_some()
+    }
+
+    fn match_header_and_update(&mut self, request: CacheRequestDetails, header_name: &str, new_max_age: uint) -> bool {
+        match self.find_entry_by_header(&request, header_name).map(|e| e.max_age = new_max_age) {
+            Some(_) => true,
+            None => {
+                self.insert(CORSCacheEntry::new(request.origin, request.destination, new_max_age,
+                                                request.credentials, HeaderData(header_name.to_string())));
+                false
+            }
+        }
+    }
+
+    fn match_method(&mut self, request: CacheRequestDetails, method: Method) -> bool {
+        self.find_entry_by_method(&request, method).is_some()
+    }
+
+    fn match_method_and_update(&mut self, request: CacheRequestDetails, method: Method, new_max_age: uint) -> bool {
+        match self.find_entry_by_method(&request, method.clone()).map(|e| e.max_age = new_max_age) {
+            Some(_) => true,
+            None => {
+                self.insert(CORSCacheEntry::new(request.origin, request.destination, new_max_age,
+                                                request.credentials, MethodData(method)));
+                false
+            }
+        }
+    }
+
+    fn insert(&mut self, entry: CORSCacheEntry) {
+        self.cleanup();
+        let BasicCORSCache(ref mut buf) = *self;
+        buf.push(entry);
+    }
+}
+
+/// Various messages that can be sent to a CORSCacheTask
+pub enum CORSCacheTaskMsg {
+    Clear(CacheRequestDetails, Sender<()>),
+    Cleanup(Sender<()>),
+    MatchHeader(CacheRequestDetails, String, Sender<bool>),
+    MatchHeaderUpdate(CacheRequestDetails, String, uint, Sender<bool>),
+    MatchMethod(CacheRequestDetails, Method, Sender<bool>),
+    MatchMethodUpdate(CacheRequestDetails, Method, uint, Sender<bool>),
+    Insert(CORSCacheEntry, Sender<()>),
+    ExitMsg
+}
+
+/// A Sender to a CORSCacheTask
+///
+/// This can be used as a CORS Cache.
+/// The methods on this type block until they can run, and it behaves similar to a mutex
+pub type CORSCacheSender = Sender<CORSCacheTaskMsg>;
+
+impl CORSCache for CORSCacheSender {
+    fn clear (&mut self, request: CacheRequestDetails) {
+        let (tx, rx) = channel();
+        self.send(Clear(request, tx));
+        let _ = rx.recv_opt();
+    }
+
+    fn cleanup(&mut self) {
+        let (tx, rx) = channel();
+        self.send(Cleanup(tx));
+        let _ = rx.recv_opt();
+    }
+
+    fn match_header(&mut self, request: CacheRequestDetails, header_name: &str) -> bool {
+        let (tx, rx) = channel();
+        self.send(MatchHeader(request, header_name.to_string(), tx));
+        rx.recv_opt().unwrap_or(false)
+    }
+
+    fn match_header_and_update(&mut self, request: CacheRequestDetails, header_name: &str, new_max_age: uint) -> bool {
+        let (tx, rx) = channel();
+        self.send(MatchHeaderUpdate(request, header_name.to_string(), new_max_age, tx));
+        rx.recv_opt().unwrap_or(false)
+    }
+
+    fn match_method(&mut self, request: CacheRequestDetails, method: Method) -> bool {
+        let (tx, rx) = channel();
+        self.send(MatchMethod(request, method, tx));
+        rx.recv_opt().unwrap_or(false)
+    }
+
+    fn match_method_and_update(&mut self, request: CacheRequestDetails, method: Method, new_max_age: uint) -> bool {
+        let (tx, rx) = channel();
+        self.send(MatchMethodUpdate(request, method, new_max_age, tx));
+        rx.recv_opt().unwrap_or(false)
+    }
+
+    fn insert(&mut self, entry: CORSCacheEntry) {
+        let (tx, rx) = channel();
+        self.send(Insert(entry, tx));
+        let _ = rx.recv_opt();
+    }
+}
+
+/// A simple task-based CORS Cache that can be sent messages
+///
+/// #Example
+/// ```
+/// let task = CORSCacheTask::new();
+/// let builder = TaskBuilder::new().named("XHRTask");
+/// let mut sender = task.get_sender();
+/// builder.spawn(proc() { task.run() });
+/// sender.insert(CORSCacheEntry::new(/* parameters here */));
+/// ```
+pub struct CORSCacheTask {
+    receiver: Receiver<CORSCacheTaskMsg>,
+    cache: BasicCORSCache,
+    sender: CORSCacheSender
+}
+
+impl CORSCacheTask {
+    pub fn new() -> CORSCacheTask {
+        let (tx, rx) = channel();
+        CORSCacheTask {
+            receiver: rx,
+            cache: BasicCORSCache(vec![]),
+            sender: tx
+        }
+    }
+
+    /// Provides a sender to the cache task
+    pub fn get_sender(&self) -> CORSCacheSender {
+        self.sender.clone()
+    }
+
+    /// Runs the cache task
+    /// This blocks the current task, so it is advised
+    /// to spawn a new task for this
+    /// Send ExitMsg to the associated Sender to exit
+    pub fn run(&mut self) {
+        loop {
+            match self.receiver.recv() {
+                Clear(request, tx) => {
+                    self.cache.clear(request);
+                    tx.send(());
+                },
+                Cleanup(tx) => {
+                    self.cache.cleanup();
+                    tx.send(());
+                },
+                MatchHeader(request, header, tx) => {
+                    tx.send(self.cache.match_header(request, header.as_slice()));
+                },
+                MatchHeaderUpdate(request, header, new_max_age, tx) => {
+                    tx.send(self.cache.match_header_and_update(request, header.as_slice(), new_max_age));
+                },
+                MatchMethod(request, method, tx) => {
+                    tx.send(self.cache.match_method(request, method));
+                },
+                MatchMethodUpdate(request, method, new_max_age, tx) => {
+                    tx.send(self.cache.match_method_and_update(request, method, new_max_age));
+                },
+                Insert(entry, tx) => {
+                    self.cache.insert(entry);
+                    tx.send(());
+                },
+                ExitMsg => break
+            }
+        }
+    }
+}
diff --git a/components/net/fetch/request.rs b/components/net/fetch/request.rs
new file mode 100644
index 00000000000..c14efe9c59e
--- /dev/null
+++ b/components/net/fetch/request.rs
@@ -0,0 +1,149 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use url::Url;
+use http::method::{Get, Method};
+use http::headers::request::HeaderCollection;
+use fetch::cors_cache::CORSCache;
+use fetch::response::Response;
+
+/// A [request context](http://fetch.spec.whatwg.org/#concept-request-context)
+pub enum Context {
+    Audio, Beacon, CSPreport, Download, Embed, Eventsource,
+    Favicon, Fetch, Font, Form, Frame, Hyperlink, IFrame, Image,
+    ImageSet, Import, Internal, Location, Manifest, Object, Ping,
+    Plugin, Prefetch, Script, ServiceWorker, SharedWorker, Subresource,
+    Style, Track, Video, Worker, XMLHttpRequest, XSLT
+}
+
+/// A [request context frame type](http://fetch.spec.whatwg.org/#concept-request-context-frame-type)
+pub enum ContextFrameType {
+    Auxiliary,
+    TopLevel,
+    Nested,
+    ContextNone
+}
+
+/// A [referer](http://fetch.spec.whatwg.org/#concept-request-referrer)
+pub enum Referer {
+    RefererNone,
+    Client,
+    RefererUrl(Url)
+}
+
+/// A [request mode](http://fetch.spec.whatwg.org/#concept-request-mode)
+pub enum RequestMode {
+    SameOrigin,
+    NoCORS,
+    CORSMode,
+    ForcedPreflightMode
+}
+
+/// Request [credentials mode](http://fetch.spec.whatwg.org/#concept-request-credentials-mode)
+pub enum CredentialsMode {
+    Omit,
+    CredentialsSameOrigin,
+    Include
+}
+
+/// [Response tainting](http://fetch.spec.whatwg.org/#concept-request-response-tainting)
+pub enum ResponseTainting {
+    Basic,
+    CORSTainting,
+    Opaque
+}
+
+/// A [Request](http://fetch.spec.whatwg.org/#requests) as defined by the Fetch spec
+pub struct Request {
+    pub method: Method,
+    pub url: Url,
+    pub headers: HeaderCollection,
+    pub unsafe_request: bool,
+    pub body: Option<Vec<u8>>,
+    pub preserve_content_codings: bool,
+    // pub client: GlobalRef, // XXXManishearth copy over only the relevant fields of the global scope,
+                              // not the entire scope to avoid the libscript dependency
+    pub skip_service_worker: bool,
+    pub context: Context,
+    pub context_frame_type: ContextFrameType,
+    pub origin: Option<Url>,
+    pub force_origin_header: bool,
+    pub same_origin_data: bool,
+    pub referer: Referer,
+    pub authentication: bool,
+    pub sync: bool,
+    pub mode: RequestMode,
+    pub credentials_mode: CredentialsMode,
+    pub use_url_credentials: bool,
+    pub manual_redirect: bool,
+    pub redirect_count: uint,
+    pub response_tainting: ResponseTainting,
+    pub cache: Option<Box<CORSCache>>
+}
+
+impl Request {
+    pub fn new(url: Url, context: Context) -> Request {
+         Request {
+            method: Get,
+            url: url,
+            headers: HeaderCollection::new(),
+            unsafe_request: false,
+            body: None,
+            preserve_content_codings: false,
+            skip_service_worker: false,
+            context: context,
+            context_frame_type: ContextNone,
+            origin: None,
+            force_origin_header: false,
+            same_origin_data: false,
+            referer: Client,
+            authentication: false,
+            sync: false,
+            mode: NoCORS,
+            credentials_mode: Omit,
+            use_url_credentials: false,
+            manual_redirect: false,
+            redirect_count: 0,
+            response_tainting: Basic,
+            cache: None
+        }
+    }
+
+    /// [Basic fetch](http://fetch.spec.whatwg.org#basic-fetch)
+    pub fn basic_fetch(&mut self) -> Response {
+        match self.url.scheme.as_slice() {
+            "about" => match self.url.non_relative_scheme_data() {
+                Some(s) if s.as_slice() == "blank" => {
+                    let mut response = Response::new();
+                    let _ = response.headers.insert_raw("Content-Type".to_string(), b"text/html;charset=utf-8");
+                    response
+                },
+                _ => Response::network_error()
+            },
+            "http" | "https" => {
+                self.http_fetch(false, false, false)
+            },
+            "blob" | "data" | "file" | "ftp" => {
+                // XXXManishearth handle these
+                fail!("Unimplemented scheme for Fetch")
+            },
+
+            _ => Response::network_error()
+        }
+    }
+
+    // [HTTP fetch](http://fetch.spec.whatwg.org#http-fetch)
+    pub fn http_fetch(&mut self, _cors_flag: bool, cors_preflight_flag: bool, _authentication_fetch_flag: bool) -> Response {
+        let response = Response::new();
+        // TODO: Service worker fetch
+        // Step 3
+        // Substep 1
+        self.skip_service_worker = true;
+        // Substep 2
+        if cors_preflight_flag {
+            // XXXManishearth stuff goes here
+        }
+        response
+    }
+}
diff --git a/components/net/fetch/response.rs b/components/net/fetch/response.rs
new file mode 100644
index 00000000000..359ec6aa394
--- /dev/null
+++ b/components/net/fetch/response.rs
@@ -0,0 +1,144 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use url::Url;
+use http::status::{Status, UnregisteredStatus};
+use StatusOk = http::status::Ok;
+use http::headers::HeaderEnum;
+use http::headers::response::HeaderCollection;
+use std::ascii::OwnedStrAsciiExt;
+use std::comm::Receiver;
+
+/// [Response type](http://fetch.spec.whatwg.org/#concept-response-type)
+#[deriving(Clone, PartialEq)]
+pub enum ResponseType {
+    Basic,
+    CORS,
+    Default,
+    Error,
+    Opaque
+}
+
+/// [Response termination reason](http://fetch.spec.whatwg.org/#concept-response-termination-reason)
+#[deriving(Clone)]
+pub enum TerminationReason {
+    EndUserAbort,
+    Fatal,
+    Timeout
+}
+
+/// The response body can still be pushed to after fetch
+/// This provides a way to store unfinished response bodies
+#[unstable = "I haven't yet decided exactly how the interface for this will be"]
+#[deriving(Clone)]
+pub enum ResponseBody {
+    Empty, // XXXManishearth is this necessary, or is Done(vec![]) enough?
+    Receiving(Vec<u8>),
+    Done(Vec<u8>),
+}
+
+#[unstable = "I haven't yet decided exactly how the interface for this will be"]
+pub enum ResponseMsg {
+    Chunk(Vec<u8>),
+    Finished,
+    Errored
+}
+
+#[unstable = "I haven't yet decided exactly how the interface for this will be"]
+pub struct ResponseLoader {
+    response: Response,
+    chan: Receiver<ResponseMsg>
+}
+
+/// A [Response](http://fetch.spec.whatwg.org/#concept-response) as defined by the Fetch spec
+#[deriving(Clone)]
+pub struct Response {
+    pub response_type: ResponseType,
+    pub termination_reason: Option<TerminationReason>,
+    pub url: Option<Url>,
+    pub status: Status,
+    pub headers: HeaderCollection,
+    pub body: ResponseBody,
+    /// [Internal response](http://fetch.spec.whatwg.org/#concept-internal-response), only used if the Response is a filtered response
+    pub internal_response: Option<Box<Response>>,
+}
+
+impl Response {
+    pub fn new() -> Response {
+        Response {
+            response_type: Default,
+            termination_reason: None,
+            url: None,
+            status: StatusOk,
+            headers: HeaderCollection::new(),
+            body: Empty,
+            internal_response: None
+        }
+    }
+
+    pub fn network_error() -> Response {
+        Response {
+            response_type: Error,
+            termination_reason: None,
+            url: None,
+            status: UnregisteredStatus(0, "".to_string()),
+            headers: HeaderCollection::new(),
+            body: Empty,
+            internal_response: None
+        }
+    }
+
+    pub fn is_network_error(&self) -> bool {
+        match self.response_type {
+            Error => true,
+            _ => false
+        }
+    }
+
+    /// Convert to a filtered response, of type `filter_type`.
+    /// Do not use with type Error or Default
+    pub fn to_filtered(self, filter_type: ResponseType) -> Response {
+        assert!(filter_type != Error);
+        assert!(filter_type != Default);
+        if self.is_network_error() {
+            return self;
+        }
+        let old_headers = self.headers.clone();
+        let mut response = self.clone();
+        response.internal_response = Some(box self);
+        match filter_type {
+            Default | Error => unreachable!(),
+            Basic => {
+                let mut headers = HeaderCollection::new();
+                for h in old_headers.iter() {
+                    match h.header_name().into_ascii_lower().as_slice() {
+                        "set-cookie" | "set-cookie2" => {},
+                        _ => headers.insert(h)
+                    }
+                }
+                response.headers = headers;
+                response.response_type = filter_type;
+            },
+            CORS => {
+                let mut headers = HeaderCollection::new();
+                for h in old_headers.iter() {
+                    match h.header_name().into_ascii_lower().as_slice() {
+                        "cache-control" | "content-language" |
+                        "content-type" | "expires" | "last-modified" | "Pragma" => {},
+                        // XXXManishearth handle Access-Control-Expose-Headers
+                        _ => headers.insert(h)
+                    }
+                }
+                response.headers = headers;
+                response.response_type = filter_type;
+            },
+            Opaque => {
+                response.headers = HeaderCollection::new();
+                response.status = UnregisteredStatus(0, "".to_string());
+                response.body = Empty;
+            }
+        }
+        response
+    }
+}
diff --git a/components/net/file_loader.rs b/components/net/file_loader.rs
new file mode 100644
index 00000000000..43c3191c600
--- /dev/null
+++ b/components/net/file_loader.rs
@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use resource_task::{ProgressMsg, Metadata, Payload, Done, LoaderTask, start_sending};
+
+use std::io;
+use std::io::File;
+use servo_util::task::spawn_named;
+
+static READ_SIZE: uint = 8192;
+
+fn read_all(reader: &mut io::Stream, progress_chan: &Sender<ProgressMsg>)
+        -> Result<(), String> {
+    loop {
+        let mut buf = vec!();
+        match reader.push_at_least(READ_SIZE, READ_SIZE, &mut buf) {
+            Ok(_) => progress_chan.send(Payload(buf)),
+            Err(e) => match e.kind {
+                io::EndOfFile => {
+                    if buf.len() > 0 {
+                        progress_chan.send(Payload(buf));
+                    }
+                    return Ok(());
+                }
+                _ => return Err(e.desc.to_string()),
+            }
+        }
+    }
+}
+
+pub fn factory() -> LoaderTask {
+    let f: LoaderTask = proc(load_data, start_chan) {
+        let url = load_data.url;
+        assert!("file" == url.scheme.as_slice());
+        let progress_chan = start_sending(start_chan, Metadata::default(url.clone()));
+        spawn_named("file_loader", proc() {
+            match File::open_mode(&Path::new(url.serialize_path().unwrap()), io::Open, io::Read) {
+                Ok(ref mut reader) => {
+                    let res = read_all(reader as &mut io::Stream, &progress_chan);
+                    progress_chan.send(Done(res));
+                }
+                Err(e) => {
+                    progress_chan.send(Done(Err(e.desc.to_string())));
+                }
+            };
+        });
+    };
+    f
+}
diff --git a/components/net/http_loader.rs b/components/net/http_loader.rs
new file mode 100644
index 00000000000..c7cb56d4231
--- /dev/null
+++ b/components/net/http_loader.rs
@@ -0,0 +1,167 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use resource_task::{Metadata, Payload, Done, LoadResponse, LoadData, LoaderTask, start_sending_opt};
+
+use std::collections::hashmap::HashSet;
+use http::client::{RequestWriter, NetworkStream};
+use http::headers::HeaderEnum;
+use std::io::Reader;
+use servo_util::task::spawn_named;
+use url::Url;
+
+pub fn factory() -> LoaderTask {
+    let f: LoaderTask = proc(url, start_chan) {
+        spawn_named("http_loader", proc() load(url, start_chan))
+    };
+    f
+}
+
+fn send_error(url: Url, err: String, start_chan: Sender<LoadResponse>) {
+    match start_sending_opt(start_chan, Metadata::default(url)) {
+        Ok(p) => p.send(Done(Err(err))),
+        _ => {}
+    };
+}
+
+fn load(load_data: LoadData, start_chan: Sender<LoadResponse>) {
+    // FIXME: At the time of writing this FIXME, servo didn't have any central
+    //        location for configuration. If you're reading this and such a
+    //        repository DOES exist, please update this constant to use it.
+    let max_redirects = 50u;
+    let mut iters = 0u;
+    let mut url = load_data.url.clone();
+    let mut redirected_to = HashSet::new();
+
+    // Loop to handle redirects.
+    loop {
+        iters = iters + 1;
+
+        if iters > max_redirects {
+            send_error(url, "too many redirects".to_string(), start_chan);
+            return;
+        }
+
+        if redirected_to.contains(&url) {
+            send_error(url, "redirect loop".to_string(), start_chan);
+            return;
+        }
+
+        redirected_to.insert(url.clone());
+
+        match url.scheme.as_slice() {
+            "http" | "https" => {}
+            _ => {
+                let s = format!("{:s} request, but we don't support that scheme", url.scheme);
+                send_error(url, s, start_chan);
+                return;
+            }
+        }
+
+        info!("requesting {:s}", url.serialize());
+
+        let request = RequestWriter::<NetworkStream>::new(load_data.method.clone(), url.clone());
+        let mut writer = match request {
+            Ok(w) => box w,
+            Err(e) => {
+                send_error(url, e.desc.to_string(), start_chan);
+                return;
+            }
+        };
+
+        // Preserve the `host` header set automatically by RequestWriter.
+        let host = writer.headers.host.clone();
+        writer.headers = box load_data.headers.clone();
+        writer.headers.host = host;
+        if writer.headers.accept_encoding.is_none() {
+            // We currently don't support HTTP Compression (FIXME #2587)
+            writer.headers.accept_encoding = Some(String::from_str("identity".as_slice()))
+        }
+        match load_data.data {
+            Some(ref data) => {
+                writer.headers.content_length = Some(data.len());
+                match writer.write(data.as_slice()) {
+                    Err(e) => {
+                        send_error(url, e.desc.to_string(), start_chan);
+                        return;
+                    }
+                    _ => {}
+                }
+            },
+            _ => {}
+        }
+        let mut response = match writer.read_response() {
+            Ok(r) => r,
+            Err((_, e)) => {
+                send_error(url, e.desc.to_string(), start_chan);
+                return;
+            }
+        };
+
+        // Dump headers, but only do the iteration if info!() is enabled.
+        info!("got HTTP response {:s}, headers:", response.status.to_string());
+        info!("{:?}",
+            for header in response.headers.iter() {
+                info!(" - {:s}: {:s}", header.header_name(), header.header_value());
+            });
+
+        if 3 == (response.status.code() / 100) {
+            match response.headers.location {
+                Some(new_url) => {
+                    // CORS (http://fetch.spec.whatwg.org/#http-fetch, status section, point 9, 10)
+                    match load_data.cors {
+                        Some(ref c) => {
+                            if c.preflight {
+                                // The preflight lied
+                                send_error(url, "Preflight fetch inconsistent with main fetch".to_string(), start_chan);
+                                return;
+                            } else {
+                                // XXXManishearth There are some CORS-related steps here,
+                                // but they don't seem necessary until credentials are implemented
+                            }
+                        }
+                        _ => {}
+                    }
+                    info!("redirecting to {:s}", new_url.serialize());
+                    url = new_url;
+                    continue;
+                }
+                None => ()
+            }
+        }
+
+        let mut metadata = Metadata::default(url);
+        metadata.set_content_type(&response.headers.content_type);
+        metadata.headers = Some(*response.headers.clone());
+        metadata.status = response.status.clone();
+
+        let progress_chan = match start_sending_opt(start_chan, metadata) {
+            Ok(p) => p,
+            _ => return
+        };
+        loop {
+            let mut buf = Vec::with_capacity(1024);
+
+            unsafe { buf.set_len(1024); }
+            match response.read(buf.as_mut_slice()) {
+                Ok(len) => {
+                    unsafe { buf.set_len(len); }
+                    if progress_chan.send_opt(Payload(buf)).is_err() {
+                        // The send errors when the receiver is out of scope,
+                        // which will happen if the fetch has timed out (or has been aborted)
+                        // so we don't need to continue with the loading of the file here.
+                        return;
+                    }
+                }
+                Err(_) => {
+                    let _ = progress_chan.send_opt(Done(Ok(())));
+                    break;
+                }
+            }
+        }
+
+        // We didn't get redirected.
+        break;
+    }
+}
diff --git a/components/net/image/base.rs b/components/net/image/base.rs
new file mode 100644
index 00000000000..deda4ee8556
--- /dev/null
+++ b/components/net/image/base.rs
@@ -0,0 +1,67 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use std::iter::range_step;
+use stb_image = stb_image::image;
+use png;
+
+// FIXME: Images must not be copied every frame. Instead we should atomically
+// reference count them.
+pub type Image = png::Image;
+
+
+static TEST_IMAGE: &'static [u8] = include_bin!("test.jpeg");
+
+pub fn test_image_bin() -> Vec<u8> {
+    TEST_IMAGE.iter().map(|&x| x).collect()
+}
+
+// TODO(pcwalton): Speed up with SIMD, or better yet, find some way to not do this.
+fn byte_swap(data: &mut [u8]) {
+    let length = data.len();
+    for i in range_step(0, length, 4) {
+        let r = data[i + 2];
+        data[i + 2] = data[i + 0];
+        data[i + 0] = r;
+    }
+}
+
+pub fn load_from_memory(buffer: &[u8]) -> Option<Image> {
+    if buffer.len() == 0 {
+        return None;
+    }
+
+    if png::is_png(buffer) {
+        match png::load_png_from_memory(buffer) {
+            Ok(mut png_image) => {
+                match png_image.pixels {
+                    png::RGB8(ref mut data) | png::RGBA8(ref mut data) => {
+                        byte_swap(data.as_mut_slice());
+                    }
+                    _ => {}
+                }
+                Some(png_image)
+            }
+            Err(_err) => None,
+        }
+    } else {
+        // For non-png images, we use stb_image
+        // Can't remember why we do this. Maybe it's what cairo wants
+        static FORCE_DEPTH: uint = 4;
+
+        match stb_image::load_from_memory_with_depth(buffer, FORCE_DEPTH, true) {
+            stb_image::ImageU8(mut image) => {
+                assert!(image.depth == 4);
+                byte_swap(image.data.as_mut_slice());
+                Some(png::Image {
+                    width: image.width as u32,
+                    height: image.height as u32,
+                    pixels: png::RGBA8(image.data)
+                })
+            }
+            stb_image::ImageF32(_image) => fail!("HDR images not implemented"),
+            stb_image::Error(_) => None
+        }
+    }
+}
diff --git a/components/net/image/holder.rs b/components/net/image/holder.rs
new file mode 100644
index 00000000000..11f055aad9d
--- /dev/null
+++ b/components/net/image/holder.rs
@@ -0,0 +1,109 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use image::base::Image;
+use image_cache_task::{ImageReady, ImageNotReady, ImageFailed};
+use local_image_cache::LocalImageCache;
+
+use geom::size::Size2D;
+use std::mem;
+use sync::{Arc, Mutex};
+use url::Url;
+
+// FIXME: Nasty coupling here This will be a problem if we want to factor out image handling from
+// the network stack. This should probably be factored out into an interface and use dependency
+// injection.
+
+/// A struct to store image data. The image will be loaded once the first time it is requested,
+/// and an Arc will be stored.  Clones of this Arc are given out on demand.
+#[deriving(Clone)]
+pub struct ImageHolder {
+    url: Url,
+    image: Option<Arc<Box<Image>>>,
+    cached_size: Size2D<int>,
+    local_image_cache: Arc<Mutex<LocalImageCache>>,
+}
+
+impl ImageHolder {
+    pub fn new(url: Url, local_image_cache: Arc<Mutex<LocalImageCache>>) -> ImageHolder {
+        debug!("ImageHolder::new() {}", url.serialize());
+        let holder = ImageHolder {
+            url: url,
+            image: None,
+            cached_size: Size2D(0,0),
+            local_image_cache: local_image_cache.clone(),
+        };
+
+        // Tell the image cache we're going to be interested in this url
+        // FIXME: These two messages must be sent to prep an image for use
+        // but they are intended to be spread out in time. Ideally prefetch
+        // should be done as early as possible and decode only once we
+        // are sure that the image will be used.
+        {
+            let val = holder.local_image_cache.lock();
+            let mut local_image_cache = val;
+            local_image_cache.prefetch(&holder.url);
+            local_image_cache.decode(&holder.url);
+        }
+
+        holder
+    }
+
+    /// This version doesn't perform any computation, but may be stale w.r.t. newly-available image
+    /// data that determines size.
+    ///
+    /// The intent is that the impure version is used during layout when dimensions are used for
+    /// computing layout.
+    pub fn size(&self) -> Size2D<int> {
+        self.cached_size
+    }
+
+    /// Query and update the current image size.
+    pub fn get_size(&mut self) -> Option<Size2D<int>> {
+        debug!("get_size() {}", self.url.serialize());
+        self.get_image().map(|img| {
+            self.cached_size = Size2D(img.width as int,
+                                      img.height as int);
+            self.cached_size.clone()
+        })
+    }
+
+    pub fn get_image_if_present(&self) -> Option<Arc<Box<Image>>> {
+        debug!("get_image_if_present() {}", self.url.serialize());
+        self.image.clone()
+    }
+
+    pub fn get_image(&mut self) -> Option<Arc<Box<Image>>> {
+        debug!("get_image() {}", self.url.serialize());
+
+        // If this is the first time we've called this function, load
+        // the image and store it for the future
+        if self.image.is_none() {
+            let port = {
+                let val = self.local_image_cache.lock();
+                let mut local_image_cache = val;
+                local_image_cache.get_image(&self.url)
+            };
+            match port.recv() {
+                ImageReady(image) => {
+                    self.image = Some(image);
+                }
+                ImageNotReady => {
+                    debug!("image not ready for {:s}", self.url.serialize());
+                }
+                ImageFailed => {
+                    debug!("image decoding failed for {:s}", self.url.serialize());
+                }
+            }
+        }
+
+        // Clone isn't pure so we have to swap out the mutable image option
+        let image = mem::replace(&mut self.image, None);
+        let result = image.clone();
+        mem::replace(&mut self.image, image);
+
+        return result;
+    }
+}
+
diff --git a/components/net/image/test.jpeg b/components/net/image/test.jpeg
new file mode 100644
index 00000000000..1a0bdb7acd1
--- /dev/null
+++ b/components/net/image/test.jpeg
diff --git a/components/net/image_cache_task.rs b/components/net/image_cache_task.rs
new file mode 100644
index 00000000000..de0c978c3cf
--- /dev/null
+++ b/components/net/image_cache_task.rs
@@ -0,0 +1,993 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use image::base::{Image, load_from_memory};
+use resource_task;
+use resource_task::{LoadData, ResourceTask};
+
+use std::comm::{channel, Receiver, Sender};
+use std::collections::hashmap::HashMap;
+use std::mem::replace;
+use std::task::spawn;
+use std::result;
+use sync::{Arc, Mutex};
+use serialize::{Encoder, Encodable};
+use url::Url;
+
+pub enum Msg {
+    /// Tell the cache that we may need a particular image soon. Must be posted
+    /// before Decode
+    Prefetch(Url),
+
+    /// Tell the cache to decode an image. Must be posted before GetImage/WaitForImage
+    Decode(Url),
+
+    /// Request an Image object for a URL. If the image is not is not immediately
+    /// available then ImageNotReady is returned.
+    GetImage(Url, Sender<ImageResponseMsg>),
+
+    /// Wait for an image to become available (or fail to load).
+    WaitForImage(Url, Sender<ImageResponseMsg>),
+
+    /// Clients must wait for a response before shutting down the ResourceTask
+    Exit(Sender<()>),
+
+    /// Used by the prefetch tasks to post back image binaries
+    StorePrefetchedImageData(Url, Result<Vec<u8>, ()>),
+
+    /// Used by the decoder tasks to post decoded images back to the cache
+    StoreImage(Url, Option<Arc<Box<Image>>>),
+
+    /// For testing
+    WaitForStore(Sender<()>),
+
+    /// For testing
+    WaitForStorePrefetched(Sender<()>),
+}
+
+#[deriving(Clone)]
+pub enum ImageResponseMsg {
+    ImageReady(Arc<Box<Image>>),
+    ImageNotReady,
+    ImageFailed
+}
+
+impl PartialEq for ImageResponseMsg {
+    fn eq(&self, other: &ImageResponseMsg) -> bool {
+        match (self, other) {
+            (&ImageReady(..), &ImageReady(..)) => fail!("unimplemented comparison"),
+            (&ImageNotReady, &ImageNotReady) => true,
+            (&ImageFailed, &ImageFailed) => true,
+
+            (&ImageReady(..), _) | (&ImageNotReady, _) | (&ImageFailed, _) => false
+        }
+    }
+}
+
+#[deriving(Clone)]
+pub struct ImageCacheTask {
+    chan: Sender<Msg>,
+}
+
+impl<E, S: Encoder<E>> Encodable<S, E> for ImageCacheTask {
+    fn encode(&self, _: &mut S) -> Result<(), E> {
+        Ok(())
+    }
+}
+
+type DecoderFactory = fn() -> proc(&[u8]) -> Option<Image>;
+
+impl ImageCacheTask {
+    pub fn new(resource_task: ResourceTask) -> ImageCacheTask {
+        let (chan, port) = channel();
+        let chan_clone = chan.clone();
+
+        spawn(proc() {
+            let mut cache = ImageCache {
+                resource_task: resource_task,
+                port: port,
+                chan: chan_clone,
+                state_map: HashMap::new(),
+                wait_map: HashMap::new(),
+                need_exit: None
+            };
+            cache.run();
+        });
+
+        ImageCacheTask {
+            chan: chan,
+        }
+    }
+
+    pub fn new_sync(resource_task: ResourceTask) -> ImageCacheTask {
+        let (chan, port) = channel();
+
+        spawn(proc() {
+            let inner_cache = ImageCacheTask::new(resource_task);
+
+            loop {
+                let msg: Msg = port.recv();
+
+                match msg {
+                    GetImage(url, response) => {
+                        inner_cache.send(WaitForImage(url, response));
+                    }
+                    Exit(response) => {
+                        inner_cache.send(Exit(response));
+                        break;
+                    }
+                    msg => inner_cache.send(msg)
+                }
+            }
+        });
+
+        ImageCacheTask {
+            chan: chan,
+        }
+    }
+}
+
+struct ImageCache {
+    /// A handle to the resource task for fetching the image binaries
+    resource_task: ResourceTask,
+    /// The port on which we'll receive client requests
+    port: Receiver<Msg>,
+    /// A copy of the shared chan to give to child tasks
+    chan: Sender<Msg>,
+    /// The state of processsing an image for a URL
+    state_map: HashMap<Url, ImageState>,
+    /// List of clients waiting on a WaitForImage response
+    wait_map: HashMap<Url, Arc<Mutex<Vec<Sender<ImageResponseMsg>>>>>,
+    need_exit: Option<Sender<()>>,
+}
+
+#[deriving(Clone)]
+enum ImageState {
+    Init,
+    Prefetching(AfterPrefetch),
+    Prefetched(Vec<u8>),
+    Decoding,
+    Decoded(Arc<Box<Image>>),
+    Failed
+}
+
+#[deriving(Clone)]
+enum AfterPrefetch {
+    DoDecode,
+    DoNotDecode
+}
+
+impl ImageCache {
+    pub fn run(&mut self) {
+        let mut store_chan: Option<Sender<()>> = None;
+        let mut store_prefetched_chan: Option<Sender<()>> = None;
+
+        loop {
+            let msg = self.port.recv();
+
+            debug!("image_cache_task: received: {:?}", msg);
+
+            match msg {
+                Prefetch(url) => self.prefetch(url),
+                StorePrefetchedImageData(url, data) => {
+                    store_prefetched_chan.map(|chan| {
+                        chan.send(());
+                    });
+                    store_prefetched_chan = None;
+
+                    self.store_prefetched_image_data(url, data);
+                }
+                Decode(url) => self.decode(url),
+                StoreImage(url, image) => {
+                    store_chan.map(|chan| {
+                        chan.send(());
+                    });
+                    store_chan = None;
+
+                    self.store_image(url, image)
+                }
+                GetImage(url, response) => self.get_image(url, response),
+                WaitForImage(url, response) => {
+                    self.wait_for_image(url, response)
+                }
+                WaitForStore(chan) => store_chan = Some(chan),
+                WaitForStorePrefetched(chan) => store_prefetched_chan = Some(chan),
+                Exit(response) => {
+                    assert!(self.need_exit.is_none());
+                    self.need_exit = Some(response);
+                }
+            }
+
+            let need_exit = replace(&mut self.need_exit, None);
+
+            match need_exit {
+              Some(response) => {
+                // Wait until we have no outstanding requests and subtasks
+                // before exiting
+                let mut can_exit = true;
+                for (_, state) in self.state_map.iter() {
+                    match *state {
+                        Prefetching(..) => can_exit = false,
+                        Decoding => can_exit = false,
+
+                        Init | Prefetched(..) | Decoded(..) | Failed => ()
+                    }
+                }
+
+                if can_exit {
+                    response.send(());
+                    break;
+                } else {
+                    self.need_exit = Some(response);
+                }
+              }
+              None => ()
+            }
+        }
+    }
+
+    fn get_state(&self, url: Url) -> ImageState {
+        match self.state_map.find(&url) {
+            Some(state) => state.clone(),
+            None => Init
+        }
+    }
+
+    fn set_state(&mut self, url: Url, state: ImageState) {
+        self.state_map.insert(url, state);
+    }
+
+    fn prefetch(&mut self, url: Url) {
+        match self.get_state(url.clone()) {
+            Init => {
+                let to_cache = self.chan.clone();
+                let resource_task = self.resource_task.clone();
+                let url_clone = url.clone();
+
+                spawn(proc() {
+                    let url = url_clone;
+                    debug!("image_cache_task: started fetch for {:s}", url.serialize());
+
+                    let image = load_image_data(url.clone(), resource_task.clone());
+
+                    let result = if image.is_ok() {
+                        Ok(image.unwrap())
+                    } else {
+                        Err(())
+                    };
+                    to_cache.send(StorePrefetchedImageData(url.clone(), result));
+                    debug!("image_cache_task: ended fetch for {:s}", url.serialize());
+                });
+
+                self.set_state(url, Prefetching(DoNotDecode));
+            }
+
+            Prefetching(..) | Prefetched(..) | Decoding | Decoded(..) | Failed => {
+                // We've already begun working on this image
+            }
+        }
+    }
+
+    fn store_prefetched_image_data(&mut self, url: Url, data: Result<Vec<u8>, ()>) {
+        match self.get_state(url.clone()) {
+          Prefetching(next_step) => {
+            match data {
+              Ok(data) => {
+                self.set_state(url.clone(), Prefetched(data));
+                match next_step {
+                  DoDecode => self.decode(url),
+                  _ => ()
+                }
+              }
+              Err(..) => {
+                self.set_state(url.clone(), Failed);
+                self.purge_waiters(url, || ImageFailed);
+              }
+            }
+          }
+
+          Init
+          | Prefetched(..)
+          | Decoding
+          | Decoded(..)
+          | Failed => {
+            fail!("wrong state for storing prefetched image")
+          }
+        }
+    }
+
+    fn decode(&mut self, url: Url) {
+        match self.get_state(url.clone()) {
+            Init => fail!("decoding image before prefetch"),
+
+            Prefetching(DoNotDecode) => {
+                // We don't have the data yet, queue up the decode
+                self.set_state(url, Prefetching(DoDecode))
+            }
+
+            Prefetching(DoDecode) => {
+                // We don't have the data yet, but the decode request is queued up
+            }
+
+            Prefetched(data) => {
+                let to_cache = self.chan.clone();
+                let url_clone = url.clone();
+
+                spawn(proc() {
+                    let url = url_clone;
+                    debug!("image_cache_task: started image decode for {:s}", url.serialize());
+                    let image = load_from_memory(data.as_slice());
+                    let image = if image.is_some() {
+                        Some(Arc::new(box image.unwrap()))
+                    } else {
+                        None
+                    };
+                    to_cache.send(StoreImage(url.clone(), image));
+                    debug!("image_cache_task: ended image decode for {:s}", url.serialize());
+                });
+
+                self.set_state(url, Decoding);
+            }
+
+            Decoding | Decoded(..) | Failed => {
+                // We've already begun decoding
+            }
+        }
+    }
+
+    fn store_image(&mut self, url: Url, image: Option<Arc<Box<Image>>>) {
+
+        match self.get_state(url.clone()) {
+          Decoding => {
+            match image {
+              Some(image) => {
+                self.set_state(url.clone(), Decoded(image.clone()));
+                self.purge_waiters(url, || ImageReady(image.clone()) );
+              }
+              None => {
+                self.set_state(url.clone(), Failed);
+                self.purge_waiters(url, || ImageFailed );
+              }
+            }
+          }
+
+          Init
+          | Prefetching(..)
+          | Prefetched(..)
+          | Decoded(..)
+          | Failed => {
+            fail!("incorrect state in store_image")
+          }
+        }
+
+    }
+
+    fn purge_waiters(&mut self, url: Url, f: || -> ImageResponseMsg) {
+        match self.wait_map.pop(&url) {
+            Some(waiters) => {
+                let mut items = waiters.lock();
+                for response in items.iter() {
+                    response.send(f());
+                }
+            }
+            None => ()
+        }
+    }
+
+    fn get_image(&self, url: Url, response: Sender<ImageResponseMsg>) {
+        match self.get_state(url.clone()) {
+            Init => fail!("request for image before prefetch"),
+            Prefetching(DoDecode) => response.send(ImageNotReady),
+            Prefetching(DoNotDecode) | Prefetched(..) => fail!("request for image before decode"),
+            Decoding => response.send(ImageNotReady),
+            Decoded(image) => response.send(ImageReady(image.clone())),
+            Failed => response.send(ImageFailed),
+        }
+    }
+
+    fn wait_for_image(&mut self, url: Url, response: Sender<ImageResponseMsg>) {
+        match self.get_state(url.clone()) {
+            Init => fail!("request for image before prefetch"),
+
+            Prefetching(DoNotDecode) | Prefetched(..) => fail!("request for image before decode"),
+
+            Prefetching(DoDecode) | Decoding => {
+                // We don't have this image yet
+                if self.wait_map.contains_key(&url) {
+                    let waiters = self.wait_map.find_mut(&url).unwrap();
+                    let mut response = Some(response);
+                    let mut items = waiters.lock();
+                    items.push(response.take().unwrap());
+                } else {
+                    let response = vec!(response);
+                    let wrapped = Arc::new(Mutex::new(response));
+                    self.wait_map.insert(url, wrapped);
+                }
+            }
+
+            Decoded(image) => {
+                response.send(ImageReady(image.clone()));
+            }
+
+            Failed => {
+                response.send(ImageFailed);
+            }
+        }
+    }
+
+}
+
+
+pub trait ImageCacheTaskClient {
+    fn exit(&self);
+}
+
+impl ImageCacheTaskClient for ImageCacheTask {
+    fn exit(&self) {
+        let (response_chan, response_port) = channel();
+        self.send(Exit(response_chan));
+        response_port.recv();
+    }
+}
+
+impl ImageCacheTask {
+    pub fn send(&self, msg: Msg) {
+        self.chan.send(msg);
+    }
+
+    #[cfg(test)]
+    fn wait_for_store(&self) -> Receiver<()> {
+        let (chan, port) = channel();
+        self.send(WaitForStore(chan));
+        port
+    }
+
+    #[cfg(test)]
+    fn wait_for_store_prefetched(&self) -> Receiver<()> {
+        let (chan, port) = channel();
+        self.send(WaitForStorePrefetched(chan));
+        port
+    }
+}
+
+fn load_image_data(url: Url, resource_task: ResourceTask) -> Result<Vec<u8>, ()> {
+    let (response_chan, response_port) = channel();
+    resource_task.send(resource_task::Load(LoadData::new(url), response_chan));
+
+    let mut image_data = vec!();
+
+    let progress_port = response_port.recv().progress_port;
+    loop {
+        match progress_port.recv() {
+            resource_task::Payload(data) => {
+                image_data.push_all(data.as_slice());
+            }
+            resource_task::Done(result::Ok(..)) => {
+                return Ok(image_data.move_iter().collect());
+            }
+            resource_task::Done(result::Err(..)) => {
+                return Err(());
+            }
+        }
+    }
+}
+
+
+pub fn spawn_listener<A: Send>(f: proc(Receiver<A>):Send) -> Sender<A> {
+    let (setup_chan, setup_port) = channel();
+
+    spawn(proc() {
+        let (chan, port) = channel();
+        setup_chan.send(chan);
+        f(port);
+    });
+    setup_port.recv()
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use resource_task;
+    use resource_task::{ResourceTask, Metadata, start_sending};
+    use image::base::test_image_bin;
+    use std::comm;
+    use url::Url;
+
+    trait Closure {
+        fn invoke(&self, _response: Sender<resource_task::ProgressMsg>) { }
+    }
+    struct DoesNothing;
+    impl Closure for DoesNothing { }
+
+    struct JustSendOK {
+        url_requested_chan: Sender<()>,
+    }
+    impl Closure for JustSendOK {
+        fn invoke(&self, response: Sender<resource_task::ProgressMsg>) {
+            self.url_requested_chan.send(());
+            response.send(resource_task::Done(Ok(())));
+        }
+    }
+
+    struct SendTestImage;
+    impl Closure for SendTestImage {
+        fn invoke(&self, response: Sender<resource_task::ProgressMsg>) {
+            response.send(resource_task::Payload(test_image_bin()));
+            response.send(resource_task::Done(Ok(())));
+        }
+    }
+
+    struct SendBogusImage;
+    impl Closure for SendBogusImage {
+        fn invoke(&self, response: Sender<resource_task::ProgressMsg>) {
+            response.send(resource_task::Payload(vec!()));
+            response.send(resource_task::Done(Ok(())));
+        }
+    }
+
+    struct SendTestImageErr;
+    impl Closure for SendTestImageErr {
+        fn invoke(&self, response: Sender<resource_task::ProgressMsg>) {
+            response.send(resource_task::Payload(test_image_bin()));
+            response.send(resource_task::Done(Err("".to_string())));
+        }
+    }
+
+    struct WaitSendTestImage {
+        wait_port: Receiver<()>,
+    }
+    impl Closure for WaitSendTestImage {
+        fn invoke(&self, response: Sender<resource_task::ProgressMsg>) {
+            // Don't send the data until after the client requests
+            // the image
+            self.wait_port.recv();
+            response.send(resource_task::Payload(test_image_bin()));
+            response.send(resource_task::Done(Ok(())));
+        }
+    }
+
+    struct WaitSendTestImageErr {
+        wait_port: Receiver<()>,
+    }
+    impl Closure for WaitSendTestImageErr {
+        fn invoke(&self, response: Sender<resource_task::ProgressMsg>) {
+            // Don't send the data until after the client requests
+            // the image
+            self.wait_port.recv();
+            response.send(resource_task::Payload(test_image_bin()));
+            response.send(resource_task::Done(Err("".to_string())));
+        }
+    }
+
+    fn mock_resource_task<T: Closure+Send>(on_load: Box<T>) -> ResourceTask {
+        spawn_listener(proc(port: Receiver<resource_task::ControlMsg>) {
+            loop {
+                match port.recv() {
+                    resource_task::Load(_, response) => {
+                        let chan = start_sending(response, Metadata::default(
+                            Url::parse("file:///fake").unwrap()));
+                        on_load.invoke(chan);
+                    }
+                    resource_task::Exit => break
+                }
+            }
+        })
+    }
+
+    #[test]
+    fn should_exit_on_request() {
+        let mock_resource_task = mock_resource_task(box DoesNothing);
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+    }
+
+    #[test]
+    #[should_fail]
+    fn should_fail_if_unprefetched_image_is_requested() {
+        let mock_resource_task = mock_resource_task(box DoesNothing);
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        let (chan, port) = channel();
+        image_cache_task.send(GetImage(url, chan));
+        port.recv();
+    }
+
+    #[test]
+    fn should_request_url_from_resource_task_on_prefetch() {
+        let (url_requested_chan, url_requested) = channel();
+
+        let mock_resource_task = mock_resource_task(box JustSendOK { url_requested_chan: url_requested_chan});
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        image_cache_task.send(Prefetch(url));
+        url_requested.recv();
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+    }
+
+    #[test]
+    fn should_not_request_url_from_resource_task_on_multiple_prefetches() {
+        let (url_requested_chan, url_requested) = comm::channel();
+
+        let mock_resource_task = mock_resource_task(box JustSendOK { url_requested_chan: url_requested_chan});
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        image_cache_task.send(Prefetch(url.clone()));
+        image_cache_task.send(Prefetch(url));
+        url_requested.recv();
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+        match url_requested.try_recv() {
+            Err(_) => (),
+            Ok(_) => fail!(),
+        };
+    }
+
+    #[test]
+    fn should_return_image_not_ready_if_data_has_not_arrived() {
+        let (wait_chan, wait_port) = comm::channel();
+
+        let mock_resource_task = mock_resource_task(box WaitSendTestImage{wait_port: wait_port});
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        image_cache_task.send(Prefetch(url.clone()));
+        image_cache_task.send(Decode(url.clone()));
+        let (response_chan, response_port) = comm::channel();
+        image_cache_task.send(GetImage(url, response_chan));
+        assert!(response_port.recv() == ImageNotReady);
+        wait_chan.send(());
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+    }
+
+    #[test]
+    fn should_return_decoded_image_data_if_data_has_arrived() {
+        let mock_resource_task = mock_resource_task(box SendTestImage);
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        let join_port = image_cache_task.wait_for_store();
+
+        image_cache_task.send(Prefetch(url.clone()));
+        image_cache_task.send(Decode(url.clone()));
+
+        // Wait until our mock resource task has sent the image to the image cache
+        join_port.recv();
+
+        let (response_chan, response_port) = comm::channel();
+        image_cache_task.send(GetImage(url, response_chan));
+        match response_port.recv() {
+          ImageReady(_) => (),
+          _ => fail!("bleh")
+        }
+
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+    }
+
+    #[test]
+    fn should_return_decoded_image_data_for_multiple_requests() {
+        let mock_resource_task = mock_resource_task(box SendTestImage);
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        let join_port = image_cache_task.wait_for_store();
+
+        image_cache_task.send(Prefetch(url.clone()));
+        image_cache_task.send(Decode(url.clone()));
+
+        // Wait until our mock resource task has sent the image to the image cache
+        join_port.recv();
+
+        for _ in range(0u32, 2u32) {
+            let (response_chan, response_port) = comm::channel();
+            image_cache_task.send(GetImage(url.clone(), response_chan));
+            match response_port.recv() {
+              ImageReady(_) => (),
+              _ => fail!("bleh")
+            }
+        }
+
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+    }
+
+    #[test]
+    fn should_not_request_image_from_resource_task_if_image_is_already_available() {
+        let (image_bin_sent_chan, image_bin_sent) = comm::channel();
+
+        let (resource_task_exited_chan, resource_task_exited) = comm::channel();
+
+        let mock_resource_task = spawn_listener(proc(port: Receiver<resource_task::ControlMsg>) {
+            loop {
+                match port.recv() {
+                    resource_task::Load(_, response) => {
+                        let chan = start_sending(response, Metadata::default(
+                            Url::parse("file:///fake").unwrap()));
+                        chan.send(resource_task::Payload(test_image_bin()));
+                        chan.send(resource_task::Done(Ok(())));
+                        image_bin_sent_chan.send(());
+                    }
+                    resource_task::Exit => {
+                        resource_task_exited_chan.send(());
+                        break
+                    }
+                }
+            }
+        });
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        image_cache_task.send(Prefetch(url.clone()));
+
+        // Wait until our mock resource task has sent the image to the image cache
+        image_bin_sent.recv();
+
+        image_cache_task.send(Prefetch(url.clone()));
+
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+
+        resource_task_exited.recv();
+
+        // Our resource task should not have received another request for the image
+        // because it's already cached
+        match image_bin_sent.try_recv() {
+            Err(_) => (),
+            Ok(_) => fail!(),
+        }
+    }
+
+    #[test]
+    fn should_not_request_image_from_resource_task_if_image_fetch_already_failed() {
+        let (image_bin_sent_chan, image_bin_sent) = comm::channel();
+
+        let (resource_task_exited_chan, resource_task_exited) = comm::channel();
+
+        let mock_resource_task = spawn_listener(proc(port: Receiver<resource_task::ControlMsg>) {
+            loop {
+                match port.recv() {
+                    resource_task::Load(_, response) => {
+                        let chan = start_sending(response, Metadata::default(
+                            Url::parse("file:///fake").unwrap()));
+                        chan.send(resource_task::Payload(test_image_bin()));
+                        chan.send(resource_task::Done(Err("".to_string())));
+                        image_bin_sent_chan.send(());
+                    }
+                    resource_task::Exit => {
+                        resource_task_exited_chan.send(());
+                        break
+                    }
+                }
+            }
+        });
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        image_cache_task.send(Prefetch(url.clone()));
+        image_cache_task.send(Decode(url.clone()));
+
+        // Wait until our mock resource task has sent the image to the image cache
+        image_bin_sent.recv();
+
+        image_cache_task.send(Prefetch(url.clone()));
+        image_cache_task.send(Decode(url.clone()));
+
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+
+        resource_task_exited.recv();
+
+        // Our resource task should not have received another request for the image
+        // because it's already cached
+        match image_bin_sent.try_recv() {
+            Err(_) => (),
+            Ok(_) => fail!(),
+        }
+    }
+
+    #[test]
+    fn should_return_failed_if_image_bin_cannot_be_fetched() {
+        let mock_resource_task = mock_resource_task(box SendTestImageErr);
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        let join_port = image_cache_task.wait_for_store_prefetched();
+
+        image_cache_task.send(Prefetch(url.clone()));
+        image_cache_task.send(Decode(url.clone()));
+
+        // Wait until our mock resource task has sent the image to the image cache
+        join_port.recv();
+
+        let (response_chan, response_port) = comm::channel();
+        image_cache_task.send(GetImage(url, response_chan));
+        match response_port.recv() {
+          ImageFailed => (),
+          _ => fail!("bleh")
+        }
+
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+    }
+
+    #[test]
+    fn should_return_failed_for_multiple_get_image_requests_if_image_bin_cannot_be_fetched() {
+        let mock_resource_task = mock_resource_task(box SendTestImageErr);
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        let join_port = image_cache_task.wait_for_store_prefetched();
+
+        image_cache_task.send(Prefetch(url.clone()));
+        image_cache_task.send(Decode(url.clone()));
+
+        // Wait until our mock resource task has sent the image to the image cache
+        join_port.recv();
+
+        let (response_chan, response_port) = comm::channel();
+        image_cache_task.send(GetImage(url.clone(), response_chan));
+        match response_port.recv() {
+          ImageFailed => (),
+          _ => fail!("bleh")
+        }
+
+        // And ask again, we should get the same response
+        let (response_chan, response_port) = comm::channel();
+        image_cache_task.send(GetImage(url, response_chan));
+        match response_port.recv() {
+          ImageFailed => (),
+          _ => fail!("bleh")
+        }
+
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+    }
+
+    #[test]
+    fn should_return_failed_if_image_decode_fails() {
+        let mock_resource_task = mock_resource_task(box SendBogusImage);
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        let join_port = image_cache_task.wait_for_store();
+
+        image_cache_task.send(Prefetch(url.clone()));
+        image_cache_task.send(Decode(url.clone()));
+
+        // Wait until our mock resource task has sent the image to the image cache
+        join_port.recv();
+
+        // Make the request
+        let (response_chan, response_port) = comm::channel();
+        image_cache_task.send(GetImage(url, response_chan));
+
+        match response_port.recv() {
+          ImageFailed => (),
+          _ => fail!("bleh")
+        }
+
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+    }
+
+    #[test]
+    fn should_return_image_on_wait_if_image_is_already_loaded() {
+        let mock_resource_task = mock_resource_task(box SendTestImage);
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        let join_port = image_cache_task.wait_for_store();
+
+        image_cache_task.send(Prefetch(url.clone()));
+        image_cache_task.send(Decode(url.clone()));
+
+        // Wait until our mock resource task has sent the image to the image cache
+        join_port.recv();
+
+        let (response_chan, response_port) = comm::channel();
+        image_cache_task.send(WaitForImage(url, response_chan));
+        match response_port.recv() {
+          ImageReady(..) => (),
+          _ => fail!("bleh")
+        }
+
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+    }
+
+    #[test]
+    fn should_return_image_on_wait_if_image_is_not_yet_loaded() {
+        let (wait_chan, wait_port) = comm::channel();
+
+        let mock_resource_task = mock_resource_task(box WaitSendTestImage {wait_port: wait_port});
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        image_cache_task.send(Prefetch(url.clone()));
+        image_cache_task.send(Decode(url.clone()));
+
+        let (response_chan, response_port) = comm::channel();
+        image_cache_task.send(WaitForImage(url, response_chan));
+
+        wait_chan.send(());
+
+        match response_port.recv() {
+          ImageReady(..) => (),
+          _ => fail!("bleh")
+        }
+
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+    }
+
+    #[test]
+    fn should_return_image_failed_on_wait_if_image_fails_to_load() {
+        let (wait_chan, wait_port) = comm::channel();
+
+        let mock_resource_task = mock_resource_task(box WaitSendTestImageErr{wait_port: wait_port});
+
+        let image_cache_task = ImageCacheTask::new(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        image_cache_task.send(Prefetch(url.clone()));
+        image_cache_task.send(Decode(url.clone()));
+
+        let (response_chan, response_port) = comm::channel();
+        image_cache_task.send(WaitForImage(url, response_chan));
+
+        wait_chan.send(());
+
+        match response_port.recv() {
+          ImageFailed => (),
+          _ => fail!("bleh")
+        }
+
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+    }
+
+    #[test]
+    fn sync_cache_should_wait_for_images() {
+        let mock_resource_task = mock_resource_task(box SendTestImage);
+
+        let image_cache_task = ImageCacheTask::new_sync(mock_resource_task.clone());
+        let url = Url::parse("file:///").unwrap();
+
+        image_cache_task.send(Prefetch(url.clone()));
+        image_cache_task.send(Decode(url.clone()));
+
+        let (response_chan, response_port) = comm::channel();
+        image_cache_task.send(GetImage(url, response_chan));
+        match response_port.recv() {
+          ImageReady(_) => (),
+          _ => fail!("bleh")
+        }
+
+        image_cache_task.exit();
+        mock_resource_task.send(resource_task::Exit);
+    }
+}
diff --git a/components/net/lib.rs b/components/net/lib.rs
new file mode 100644
index 00000000000..bb1c5d47b1a
--- /dev/null
+++ b/components/net/lib.rs
@@ -0,0 +1,44 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#![feature(default_type_params, globs, managed_boxes, phase)]
+
+extern crate debug;
+extern crate collections;
+extern crate geom;
+extern crate http;
+extern crate png;
+#[phase(plugin, link)]
+extern crate log;
+extern crate serialize;
+extern crate servo_util = "util";
+extern crate stb_image;
+extern crate sync;
+extern crate time;
+extern crate url;
+
+/// Image handling.
+///
+/// It may be surprising that this goes in the network crate as opposed to the graphics crate.
+/// However, image handling is generally very integrated with the network stack (especially where
+/// caching is involved) and as a result it must live in here.
+pub mod image {
+    pub mod base;
+    pub mod holder;
+}
+
+pub mod file_loader;
+pub mod http_loader;
+pub mod data_loader;
+pub mod image_cache_task;
+pub mod local_image_cache;
+pub mod resource_task;
+
+/// An implementation of the [Fetch spec](http://fetch.spec.whatwg.org/)
+pub mod fetch {
+    #![allow(dead_code)] // XXXManishearth this is only temporary until the Fetch mod starts being used
+    pub mod request;
+    pub mod response;
+    pub mod cors_cache;
+}
diff --git a/components/net/local_image_cache.rs b/components/net/local_image_cache.rs
new file mode 100644
index 00000000000..1427c831654
--- /dev/null
+++ b/components/net/local_image_cache.rs
@@ -0,0 +1,166 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*!
+An adapter for ImageCacheTask that does local caching to avoid
+extra message traffic, it also avoids waiting on the same image
+multiple times and thus triggering reflows multiple times.
+*/
+
+use image_cache_task::{Decode, GetImage, ImageCacheTask, ImageFailed, ImageNotReady, ImageReady};
+use image_cache_task::{ImageResponseMsg, Prefetch, WaitForImage};
+
+use std::comm::{Receiver, channel};
+use std::collections::hashmap::HashMap;
+use servo_util::task::spawn_named;
+use url::Url;
+
+pub trait ImageResponder {
+    fn respond(&self) -> proc(ImageResponseMsg):Send;
+}
+
+pub struct LocalImageCache {
+    image_cache_task: ImageCacheTask,
+    round_number: uint,
+    on_image_available: Option<Box<ImageResponder+Send>>,
+    state_map: HashMap<Url, ImageState>
+}
+
+impl LocalImageCache {
+    pub fn new(image_cache_task: ImageCacheTask) -> LocalImageCache {
+        LocalImageCache {
+            image_cache_task: image_cache_task,
+            round_number: 1,
+            on_image_available: None,
+            state_map: HashMap::new()
+        }
+    }
+}
+
+#[deriving(Clone)]
+struct ImageState {
+    prefetched: bool,
+    decoded: bool,
+    last_request_round: uint,
+    last_response: ImageResponseMsg
+}
+
+impl LocalImageCache {
+    /// The local cache will only do a single remote request for a given
+    /// URL in each 'round'. Layout should call this each time it begins
+    pub fn next_round(&mut self, on_image_available: Box<ImageResponder+Send>) {
+        self.round_number += 1;
+        self.on_image_available = Some(on_image_available);
+    }
+
+    pub fn prefetch(&mut self, url: &Url) {
+        {
+            let state = self.get_state(url);
+            if state.prefetched {
+                return
+            }
+
+            state.prefetched = true;
+        }
+
+        self.image_cache_task.send(Prefetch((*url).clone()));
+    }
+
+    pub fn decode(&mut self, url: &Url) {
+        {
+            let state = self.get_state(url);
+            if state.decoded {
+                return
+            }
+            state.decoded = true;
+        }
+
+        self.image_cache_task.send(Decode((*url).clone()));
+    }
+
+    // FIXME: Should return a Future
+    pub fn get_image(&mut self, url: &Url) -> Receiver<ImageResponseMsg> {
+        {
+            let round_number = self.round_number;
+            let state = self.get_state(url);
+
+            // Save the previous round number for comparison
+            let last_round = state.last_request_round;
+            // Set the current round number for this image
+            state.last_request_round = round_number;
+
+            match state.last_response {
+                ImageReady(ref image) => {
+                    let (chan, port) = channel();
+                    chan.send(ImageReady(image.clone()));
+                    return port;
+                }
+                ImageNotReady => {
+                    if last_round == round_number {
+                        let (chan, port) = channel();
+                        chan.send(ImageNotReady);
+                        return port;
+                    } else {
+                        // We haven't requested the image from the
+                        // remote cache this round
+                    }
+                }
+                ImageFailed => {
+                    let (chan, port) = channel();
+                    chan.send(ImageFailed);
+                    return port;
+                }
+            }
+        }
+
+        let (response_chan, response_port) = channel();
+        self.image_cache_task.send(GetImage((*url).clone(), response_chan));
+
+        let response = response_port.recv();
+        match response {
+            ImageNotReady => {
+                // Need to reflow when the image is available
+                // FIXME: Instead we should be just passing a Future
+                // to the caller, then to the display list. Finally,
+                // the compositor should be resonsible for waiting
+                // on the image to load and triggering layout
+                let image_cache_task = self.image_cache_task.clone();
+                assert!(self.on_image_available.is_some());
+                let on_image_available: proc(ImageResponseMsg):Send = self.on_image_available.as_ref().unwrap().respond();
+                let url = (*url).clone();
+                spawn_named("LocalImageCache", proc() {
+                    let (response_chan, response_port) = channel();
+                    image_cache_task.send(WaitForImage(url.clone(), response_chan));
+                    on_image_available(response_port.recv());
+                });
+            }
+            _ => ()
+        }
+
+        // Put a copy of the response in the cache
+        let response_copy = match response {
+            ImageReady(ref image) => ImageReady(image.clone()),
+            ImageNotReady => ImageNotReady,
+            ImageFailed => ImageFailed
+        };
+        self.get_state(url).last_response = response_copy;
+
+        let (chan, port) = channel();
+        chan.send(response);
+        return port;
+    }
+
+    fn get_state<'a>(&'a mut self, url: &Url) -> &'a mut ImageState {
+        let state = self.state_map.find_or_insert_with(url.clone(), |_| {
+            let new_state = ImageState {
+                prefetched: false,
+                decoded: false,
+                last_request_round: 0,
+                last_response: ImageNotReady
+            };
+            new_state
+        });
+        state
+    }
+}
diff --git a/components/net/resource_task.rs b/components/net/resource_task.rs
new file mode 100644
index 00000000000..bdc1c3f2339
--- /dev/null
+++ b/components/net/resource_task.rs
@@ -0,0 +1,267 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! A task that takes a URL and streams back the binary data.
+
+use file_loader;
+use http_loader;
+use data_loader;
+
+use std::comm::{channel, Receiver, Sender};
+use std::task::TaskBuilder;
+use std::os;
+use http::headers::content_type::MediaType;
+use ResponseHeaderCollection = http::headers::response::HeaderCollection;
+use RequestHeaderCollection = http::headers::request::HeaderCollection;
+use http::method::{Method, Get};
+use url::Url;
+
+use StatusOk = http::status::Ok;
+use http::status::Status;
+
+
+pub enum ControlMsg {
+    /// Request the data associated with a particular URL
+    Load(LoadData, Sender<LoadResponse>),
+    Exit
+}
+
+#[deriving(Clone)]
+pub struct LoadData {
+    pub url: Url,
+    pub method: Method,
+    pub headers: RequestHeaderCollection,
+    pub data: Option<Vec<u8>>,
+    pub cors: Option<ResourceCORSData>
+}
+
+impl LoadData {
+    pub fn new(url: Url) -> LoadData {
+        LoadData {
+            url: url,
+            method: Get,
+            headers: RequestHeaderCollection::new(),
+            data: None,
+            cors: None
+        }
+    }
+}
+
+#[deriving(Clone)]
+pub struct ResourceCORSData {
+    /// CORS Preflight flag
+    pub preflight: bool,
+    /// Origin of CORS Request
+    pub origin: Url
+}
+
+/// Metadata about a loaded resource, such as is obtained from HTTP headers.
+pub struct Metadata {
+    /// Final URL after redirects.
+    pub final_url: Url,
+
+    /// MIME type / subtype.
+    pub content_type: Option<(String, String)>,
+
+    /// Character set.
+    pub charset: Option<String>,
+
+    /// Headers
+    pub headers: Option<ResponseHeaderCollection>,
+
+    /// HTTP Status
+    pub status: Status
+}
+
+impl Metadata {
+    /// Metadata with defaults for everything optional.
+    pub fn default(url: Url) -> Metadata {
+        Metadata {
+            final_url:    url,
+            content_type: None,
+            charset:      None,
+            headers: None,
+            status: StatusOk // http://fetch.spec.whatwg.org/#concept-response-status-message
+        }
+    }
+
+    /// Extract the parts of a MediaType that we care about.
+    pub fn set_content_type(&mut self, content_type: &Option<MediaType>) {
+        match *content_type {
+            None => (),
+            Some(MediaType { type_:      ref type_,
+                             subtype:    ref subtype,
+                             parameters: ref parameters }) => {
+                self.content_type = Some((type_.clone(), subtype.clone()));
+                for &(ref k, ref v) in parameters.iter() {
+                    if "charset" == k.as_slice() {
+                        self.charset = Some(v.clone());
+                    }
+                }
+            }
+        }
+    }
+}
+
+/// Message sent in response to `Load`.  Contains metadata, and a port
+/// for receiving the data.
+///
+/// Even if loading fails immediately, we send one of these and the
+/// progress_port will provide the error.
+pub struct LoadResponse {
+    /// Metadata, such as from HTTP headers.
+    pub metadata: Metadata,
+    /// Port for reading data.
+    pub progress_port: Receiver<ProgressMsg>,
+}
+
+/// Messages sent in response to a `Load` message
+#[deriving(PartialEq,Show)]
+pub enum ProgressMsg {
+    /// Binary data - there may be multiple of these
+    Payload(Vec<u8>),
+    /// Indicates loading is complete, either successfully or not
+    Done(Result<(), String>)
+}
+
+/// For use by loaders in responding to a Load message.
+pub fn start_sending(start_chan: Sender<LoadResponse>, metadata: Metadata) -> Sender<ProgressMsg> {
+    start_sending_opt(start_chan, metadata).ok().unwrap()
+}
+
+/// For use by loaders in responding to a Load message.
+pub fn start_sending_opt(start_chan: Sender<LoadResponse>, metadata: Metadata) -> Result<Sender<ProgressMsg>, ()> {
+    let (progress_chan, progress_port) = channel();
+    let result = start_chan.send_opt(LoadResponse {
+        metadata:      metadata,
+        progress_port: progress_port,
+    });
+    match result {
+        Ok(_) => Ok(progress_chan),
+        Err(_) => Err(())
+    }
+}
+
+/// Convenience function for synchronously loading a whole resource.
+pub fn load_whole_resource(resource_task: &ResourceTask, url: Url)
+        -> Result<(Metadata, Vec<u8>), String> {
+    let (start_chan, start_port) = channel();
+    resource_task.send(Load(LoadData::new(url), start_chan));
+    let response = start_port.recv();
+
+    let mut buf = vec!();
+    loop {
+        match response.progress_port.recv() {
+            Payload(data) => buf.push_all(data.as_slice()),
+            Done(Ok(()))  => return Ok((response.metadata, buf)),
+            Done(Err(e))  => return Err(e)
+        }
+    }
+}
+
+/// Handle to a resource task
+pub type ResourceTask = Sender<ControlMsg>;
+
+pub type LoaderTask = proc(load_data: LoadData, Sender<LoadResponse>);
+
+/**
+Creates a task to load a specific resource
+
+The ResourceManager delegates loading to a different type of loader task for
+each URL scheme
+*/
+type LoaderTaskFactory = extern "Rust" fn() -> LoaderTask;
+
+/// Create a ResourceTask
+pub fn new_resource_task() -> ResourceTask {
+    let (setup_chan, setup_port) = channel();
+    let builder = TaskBuilder::new().named("ResourceManager");
+    builder.spawn(proc() {
+        ResourceManager::new(setup_port).start();
+    });
+    setup_chan
+}
+
+struct ResourceManager {
+    from_client: Receiver<ControlMsg>,
+}
+
+
+impl ResourceManager {
+    fn new(from_client: Receiver<ControlMsg>) -> ResourceManager {
+        ResourceManager {
+            from_client : from_client,
+        }
+    }
+}
+
+
+impl ResourceManager {
+    fn start(&self) {
+        loop {
+            match self.from_client.recv() {
+              Load(load_data, start_chan) => {
+                self.load(load_data, start_chan)
+              }
+              Exit => {
+                break
+              }
+            }
+        }
+    }
+
+    fn load(&self, mut load_data: LoadData, start_chan: Sender<LoadResponse>) {
+        let loader = match load_data.url.scheme.as_slice() {
+            "file" => file_loader::factory(),
+            "http" | "https" => http_loader::factory(),
+            "data" => data_loader::factory(),
+            "about" => {
+                match load_data.url.non_relative_scheme_data().unwrap() {
+                    "crash" => fail!("Loading the about:crash URL."),
+                    "failure" => {
+                        // FIXME: Find a way to load this without relying on the `../src` directory.
+                        let mut path = os::self_exe_path().expect("can't get exe path");
+                        path.pop();
+                        path.push_many(["src", "test", "html", "failure.html"]);
+                        load_data.url = Url::from_file_path(&path).unwrap();
+                        file_loader::factory()
+                    }
+                    _ => {
+                        start_sending(start_chan, Metadata::default(load_data.url))
+                            .send(Done(Err("Unknown about: URL.".to_string())));
+                        return
+                    }
+                }
+            },
+            _ => {
+                debug!("resource_task: no loader for scheme {:s}", load_data.url.scheme);
+                start_sending(start_chan, Metadata::default(load_data.url))
+                    .send(Done(Err("no loader for scheme".to_string())));
+                return
+            }
+        };
+        debug!("resource_task: loading url: {:s}", load_data.url.serialize());
+        loader(load_data, start_chan);
+    }
+}
+
+#[test]
+fn test_exit() {
+    let resource_task = new_resource_task();
+    resource_task.send(Exit);
+}
+
+#[test]
+fn test_bad_scheme() {
+    let resource_task = new_resource_task();
+    let (start_chan, start) = channel();
+    let url = Url::parse("bogus://whatever").unwrap();
+    resource_task.send(Load(LoadData::new(url), start_chan));
+    let response = start.recv();
+    match response.progress_port.recv() {
+      Done(result) => { assert!(result.is_err()) }
+      _ => fail!("bleh")
+    }
+    resource_task.send(Exit);
+}