ffi: Update Client::get_url to return raw data and to throw on HTTP errors

Client::get_url is there for SDK consumers to be able to use the
existing HTTP stack (configuration and all) however in practice it was a
bit weird:
- Responses came back as strings limiting the types of resource that
could be fetched (as well as requiring the string to be converted back
to data before handed to a JSON decoder).
- HTTP errors weren't being raised and instead you would find the (e.g.
404) error response in the Ok case.

This patch fixes both of these issues.

Author: pixlwave

bindings/matrix-sdk-ffi/CHANGELOG.md

@@ -25,6 +25,9 @@ All notable changes to this project will be documented in this file.
 
 ### Breaking changes:
 
+- `Client::get_url` now returns a `Vec<u8>` instead of a `String`. It also throws an error when the
+  response isn't status code 200 OK, instead of providing the error in the response body.
+  ([#5438](https://github.com/matrix-org/matrix-rust-sdk/pull/5438))
 - `RoomPreview::info()` doesn't return a result anymore. All unknown join rules are handled in the
   `JoinRule::Custom` variant.
   ([#5337](https://github.com/matrix-org/matrix-rust-sdk/pull/5337))
@@ -48,7 +51,6 @@ All notable changes to this project will be documented in this file.
 - The MSRV has been bumped to Rust 1.88.
   ([#5431](https://github.com/matrix-org/matrix-rust-sdk/pull/5431))
 
-
 ## [0.13.0] - 2025-07-10
 
 ### Features
@@ -115,7 +117,8 @@ Additions:
   we can automatically update the UI.
 - `Client::get_max_media_upload_size` to get the max size of a request sent to the homeserver so we can tweak our media
   uploads by compressing/transcoding the media.
-- Add `ClientBuilder::enable_share_history_on_invite` to enable experimental support for sharing encrypted room history on invite, per [MSC4268](https://github.com/matrix-org/matrix-spec-proposals/pull/4268).
+- Add `ClientBuilder::enable_share_history_on_invite` to enable experimental support for sharing encrypted room history
+  on invite, per [MSC4268](https://github.com/matrix-org/matrix-spec-proposals/pull/4268).
   ([#5141](https://github.com/matrix-org/matrix-rust-sdk/pull/5141))
 - Support for adding a Sentry layer to the FFI bindings has been added. Only `tracing` statements with
   the field `sentry=true` will be forwarded to Sentry, in addition to default Sentry filters.
@@ -208,7 +211,8 @@ Breaking changes:
 - The `dynamic_registrations_file` field of `OidcConfiguration` was removed.
   Clients are supposed to re-register with the homeserver for every login.
 
-- `RoomPreview::own_membership_details` is now `RoomPreview::member_with_sender_info`, takes any user id and returns an `Option<RoomMemberWithSenderInfo>`.
+- `RoomPreview::own_membership_details` is now `RoomPreview::member_with_sender_info`, takes any user id and returns an
+  `Option<RoomMemberWithSenderInfo>`.
 
 Additions:
 
@@ -223,9 +227,11 @@ Additions:
 - Add `Timeline::send_thread_reply` for clients that need to start threads
   themselves.
   ([4819](https://github.com/matrix-org/matrix-rust-sdk/pull/4819))
-- Add `ClientBuilder::session_pool_max_size`, `::session_cache_size` and `::session_journal_size_limit` to control the stores configuration, especially their memory consumption
+- Add `ClientBuilder::session_pool_max_size`, `::session_cache_size` and `::session_journal_size_limit` to control the
+  stores configuration, especially their memory consumption
   ([#4870](https://github.com/matrix-org/matrix-rust-sdk/pull/4870/))
 - Add `ClientBuilder::system_is_memory_constrained` to indicate that the system
   has less memory available than the current standard
   ([#4894](https://github.com/matrix-org/matrix-rust-sdk/pull/4894))
-- Add `Room::member_with_sender_info` to get both a room member's info and for the user who sent the `m.room.member` event the `RoomMember` is based on.
+- Add `Room::member_with_sender_info` to get both a room member's info and for the user who sent the `m.room.member`
+  event the `RoomMember` is based on.

bindings/matrix-sdk-ffi/src/client.rs

@@ -775,11 +775,24 @@ impl Client {
         }
     }
 
-    /// Allows generic GET requests to be made through the SDKs internal HTTP
-    /// client
-    pub async fn get_url(&self, url: String) -> Result<String, ClientError> {
-        let http_client = self.inner.http_client();
-        Ok(http_client.get(url).send().await?.text().await?)
+    /// Allows generic GET requests to be made through the SDK's internal HTTP
+    /// client. This is useful when the caller's native HTTP client wouldn't
+    /// have the same configuration (such as certificates, proxies, etc.) This
+    /// method returns the raw bytes of the response, so that any kind of
+    /// resource can be fetched including images, files, etc.
+    ///
+    /// Note: When an HTTP error occurs, the error response can be found in the
+    /// `ClientError::Generic`'s `details` field.
+    pub async fn get_url(&self, url: String) -> Result<Vec<u8>, ClientError> {
+        let response = self.inner.http_client().get(url).send().await?;
+        if response.status().is_success() {
+            Ok(response.bytes().await?.into())
+        } else {
+            Err(ClientError::Generic {
+                msg: response.status().to_string(),
+                details: response.text().await.ok(),
+            })
+        }
     }
 
     /// Empty the server version and unstable features cache.