Add support for data: URLs

Fixes #778

src/components/net/data_loader.rs

@@ -0,0 +1,66 @@
+/* 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::{Done, Payload, Metadata, LoadResponse, LoaderTask, start_sending};
+
+use extra::url::Url;
+use extra::base64::FromBase64;
+
+use http::headers::test_utils::from_stream_with_str;
+use http::headers::content_type::MediaType;
+
+pub fn factory() -> LoaderTask {
+    |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(url: Url, start_chan: Chan<LoadResponse>) {
+    assert!("data" == url.scheme);
+
+    let mut metadata = Metadata::default(url.clone());
+
+    // Split out content type and data.
+    let parts: ~[&str] = url.path.splitn_iter(',', 1).to_owned_vec();
+    if parts.len() != 2 {
+        start_sending(start_chan, metadata).send(Done(Err(())));
+        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);
+
+    if is_base64 {
+        match parts[1].from_base64() {
+            Err(*) => {
+                progress_chan.send(Done(Err(())));
+            }
+            Ok(data) => {
+                progress_chan.send(Payload(data));
+                progress_chan.send(Done(Ok(())));
+            }
+        }
+    } else {
+        // FIXME: Since the %-decoded URL is already a str, we can't
+        // handle UTF8-incompatible encodings.
+        progress_chan.send(Payload(parts[1].as_bytes().into_owned()));
+        progress_chan.send(Done(Ok(())));
+    }
+}

src/components/net/net.rc

@@ -26,6 +26,7 @@ pub mod image {
 
 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;

src/components/net/resource_task.rs

@@ -6,6 +6,7 @@
 
 use file_loader;
 use http_loader;
+use data_loader;
 
 use std::cell::Cell;
 use std::comm::{Chan, Port, SharedChan};
@@ -110,6 +111,7 @@ pub fn ResourceTask() -> ResourceTask {
     let loaders = ~[
         (~"file", file_loader::factory),
         (~"http", http_loader::factory),
+        (~"data", data_loader::factory),
     ];
     create_resource_task_with_loaders(loaders)
 }