subtlecrypto: Don't throw exceptions twice when converting to Algorithm object (#34239)

* Don't throw exceptions twice when converting to Algorithm object

Removes match statements like
```rust
let Ok(ConversionResult::Success(algorithm)) = Algorithm::new(cx, value.handle())
else {
    return Err(Error::Syntax);
};
```
These don't cause issues if `Algorithm::new` returns `Ok(ConversionResult::Failure`,
but in the case of `Err(())` the implementation already called `throw_type_error`
and we must not throw an additional Syntax error, otherwise we'll crash.

Luckily, this case is already handled elsewhere by the
`value_from_js_object` macro.

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Test that calling subtlecrypto methods with empty algorithm objects throws a TypeError

The WebCryptoAPI spec does not tell us which error to throw exactly, but
according to https://webidl.spec.whatwg.org/ it should be a TypeError.

This previously crashed servo.

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

---------

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

1 files changed, 7 insertions, 25 deletions

diff --git a/components/script/dom/subtlecrypto.rs b/components/script/dom/subtlecrypto.rs
index efb3009a831..26c415b04c7 100644
--- a/components/script/dom/subtlecrypto.rs
+++ b/components/script/dom/subtlecrypto.rs
@@ -1126,10 +1126,7 @@ fn normalize_algorithm_for_get_key_length(
     match algorithm {
         AlgorithmIdentifier::Object(obj) => {
             rooted!(in(*cx) let value = ObjectValue(obj.get()));
-            let Ok(ConversionResult::Success(algorithm)) = Algorithm::new(cx, value.handle())
-            else {
-                return Err(Error::Syntax);
-            };
+            let algorithm = value_from_js_object!(Algorithm, cx, value);
 
             let name = algorithm.name.str();
             let normalized_algorithm = if name.eq_ignore_ascii_case(ALG_AES_CBC) ||
@@ -1162,10 +1159,7 @@ fn normalize_algorithm_for_digest(
     let name = match algorithm {
         AlgorithmIdentifier::Object(obj) => {
             rooted!(in(*cx) let value = ObjectValue(obj.get()));
-            let Ok(ConversionResult::Success(algorithm)) = Algorithm::new(cx, value.handle())
-            else {
-                return Err(Error::Syntax);
-            };
+            let algorithm = value_from_js_object!(Algorithm, cx, value);
 
             algorithm.name.str().to_uppercase()
         },
@@ -1191,10 +1185,7 @@ fn normalize_algorithm_for_import_key(
     let name = match algorithm {
         AlgorithmIdentifier::Object(obj) => {
             rooted!(in(*cx) let value = ObjectValue(obj.get()));
-            let Ok(ConversionResult::Success(algorithm)) = Algorithm::new(cx, value.handle())
-            else {
-                return Err(Error::Syntax);
-            };
+            let algorithm = value_from_js_object!(Algorithm, cx, value);
 
             let name = algorithm.name.str().to_uppercase();
             if name == ALG_HMAC {
@@ -1230,9 +1221,7 @@ fn normalize_algorithm_for_derive_bits(
     };
 
     rooted!(in(*cx) let value = ObjectValue(obj.get()));
-    let Ok(ConversionResult::Success(algorithm)) = Algorithm::new(cx, value.handle()) else {
-        return Err(Error::Syntax);
-    };
+    let algorithm = value_from_js_object!(Algorithm, cx, value);
 
     let normalized_algorithm = if algorithm.name.str().eq_ignore_ascii_case(ALG_PBKDF2) {
         let params = value_from_js_object!(Pbkdf2Params, cx, value);
@@ -1260,9 +1249,7 @@ fn normalize_algorithm_for_encrypt_or_decrypt(
     };
 
     rooted!(in(*cx) let value = ObjectValue(obj.get()));
-    let Ok(ConversionResult::Success(algorithm)) = Algorithm::new(cx, value.handle()) else {
-        return Err(Error::Syntax);
-    };
+    let algorithm = value_from_js_object!(Algorithm, cx, value);
 
     let name = algorithm.name.str();
     let normalized_algorithm = if name.eq_ignore_ascii_case(ALG_AES_CBC) {
@@ -1287,10 +1274,7 @@ fn normalize_algorithm_for_sign_or_verify(
     let name = match algorithm {
         AlgorithmIdentifier::Object(obj) => {
             rooted!(in(*cx) let value = ObjectValue(obj.get()));
-            let Ok(ConversionResult::Success(algorithm)) = Algorithm::new(cx, value.handle())
-            else {
-                return Err(Error::Syntax);
-            };
+            let algorithm = value_from_js_object!(Algorithm, cx, value);
 
             algorithm.name.str().to_uppercase()
         },
@@ -1316,9 +1300,7 @@ fn normalize_algorithm_for_generate_key(
     };
 
     rooted!(in(*cx) let value = ObjectValue(obj.get()));
-    let Ok(ConversionResult::Success(algorithm)) = Algorithm::new(cx, value.handle()) else {
-        return Err(Error::Syntax);
-    };
+    let algorithm = value_from_js_object!(Algorithm, cx, value);
 
     let name = algorithm.name.str();
     let normalized_algorithm =