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/* 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 https://mozilla.org/MPL/2.0/. */
//! Low-level wire protocol implementation. Currently only supports
//! [JSON packets](https://firefox-source-docs.mozilla.org/devtools/backend/protocol.html#json-packets).
use std::error::Error;
use std::io::{Read, Write};
use std::net::TcpStream;
use log::debug;
use serde::Serialize;
use serde_json::{self, Value};
#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
pub struct ActorDescription {
pub category: &'static str,
pub type_name: &'static str,
pub methods: Vec<Method>,
}
#[derive(Serialize)]
pub struct Method {
pub name: &'static str,
pub request: Value,
pub response: Value,
}
pub trait JsonPacketStream {
fn write_json_packet<T: Serialize>(&mut self, obj: &T) -> Result<(), Box<dyn Error>>;
fn write_merged_json_packet<T: Serialize, U: Serialize>(
&mut self,
base: &T,
extra: &U,
) -> Result<(), Box<dyn Error>>;
fn read_json_packet(&mut self) -> Result<Option<Value>, String>;
}
impl JsonPacketStream for TcpStream {
fn write_json_packet<T: Serialize>(&mut self, obj: &T) -> Result<(), Box<dyn Error>> {
let s = serde_json::to_string(obj)?;
debug!("<- {}", s);
write!(self, "{}:{}", s.len(), s)?;
Ok(())
}
fn write_merged_json_packet<T: Serialize, U: Serialize>(
&mut self,
base: &T,
extra: &U,
) -> Result<(), Box<dyn Error>> {
let mut obj = serde_json::to_value(base)?;
let obj = obj.as_object_mut().unwrap();
let extra = serde_json::to_value(extra)?;
let extra = extra.as_object().unwrap();
for (key, value) in extra {
obj.insert(key.to_owned(), value.to_owned());
}
self.write_json_packet(obj)
}
fn read_json_packet(&mut self) -> Result<Option<Value>, String> {
// https://firefox-source-docs.mozilla.org/devtools/backend/protocol.html#stream-transport
// In short, each JSON packet is [ascii length]:[JSON data of given length]
let mut buffer = vec![];
loop {
let mut buf = [0];
let byte = match self.read(&mut buf) {
Ok(0) => return Ok(None), // EOF
Ok(1) => buf[0],
Ok(_) => unreachable!(),
Err(e) => return Err(e.to_string()),
};
match byte {
b':' => {
let packet_len_str = match String::from_utf8(buffer) {
Ok(packet_len) => packet_len,
Err(_) => return Err("nonvalid UTF8 in packet length".to_owned()),
};
let packet_len = match packet_len_str.parse::<u64>() {
Ok(packet_len) => packet_len,
Err(_) => return Err("packet length missing / not parsable".to_owned()),
};
let mut packet = String::new();
self.take(packet_len)
.read_to_string(&mut packet)
.map_err(|e| e.to_string())?;
debug!("{}", packet);
return match serde_json::from_str(&packet) {
Ok(json) => Ok(Some(json)),
Err(err) => Err(err.to_string()),
};
},
c => buffer.push(c),
}
}
}
}
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