Implement view-source protocol. Fixes #4181.

This follows the recommendation from issue #4181. A handler for 'view-source' delegates to the HTTP loader. In that loader I check for view-source, adjust the URL to be the URL to be viewed and modify the Content-Type header to be text/plain. This doesn't actually result in the source being viewed as rendering text/plain is not yet implemented.
servo · doublec · Mar 12, 2015 · Mar 13, 2015 · Mar 16, 2015 · 82c52a7a1c2d1fcdad797fc73564d6f624650473
commit 82c52a7a1c2d1fcdad797fc73564d6f624650473
diff --git a/components/net/http_loader.rs b/components/net/http_loader.rs
@@ -14,6 +14,7 @@ use hyper::client::Request;
 use hyper::header::{ContentLength, ContentType, Host, Location};
 use hyper::HttpError;
 use hyper::method::Method;
+use hyper::mime::{Mime, TopLevel, SubLevel};
 use hyper::net::HttpConnector;
 use hyper::status::{StatusCode, StatusClass};
 use std::error::Error;
@@ -54,6 +55,18 @@ fn load(mut load_data: LoadData, start_chan: Sender<TargetedLoadResponse>, cooki
     let mut url = load_data.url.clone();
     let mut redirected_to = HashSet::new();
 
+    // If the URL is a view-source scheme then the scheme data contains the
+    // real URL that should be used for which the source is to be viewed.
+    // Change our existing URL to that and keep note that we are viewing
+    // the source rather than rendering the contents of the URL.
+    let viewing_source = if url.scheme == "view-source" {
+       let inner_url = load_data.url.non_relative_scheme_data().unwrap();
+       url = Url::parse(inner_url).unwrap();
+       true
+    } else {
+      false
+    };
+
     let senders = ResponseSenders {
         immediate_consumer: start_chan,
         eventual_consumer: load_data.consumer
@@ -259,12 +272,16 @@ reason: \"certificate verify failed\" }]";
             }
         }
 
+        let mut adjusted_headers = response.headers.clone();
+        if viewing_source {
+            adjusted_headers.set(ContentType(Mime(TopLevel::Text, SubLevel::Plain, vec![])));
+        }
         let mut metadata = Metadata::default(url);
-        metadata.set_content_type(match response.headers.get() {
+        metadata.set_content_type(match adjusted_headers.get() {
             Some(&ContentType(ref mime)) => Some(mime),
             None => None
         });
-        metadata.headers = Some(response.headers.clone());
+        metadata.headers = Some(adjusted_headers);
         metadata.status = Some(response.status_raw().clone());
 
         let progress_chan = match start_sending_opt(senders, metadata) {

diff --git a/components/net/resource_task.rs b/components/net/resource_task.rs
@@ -333,7 +333,7 @@ impl ResourceManager {
 
         let loader = match load_data.url.scheme.as_slice() {
             "file" => from_factory(file_loader::factory),
-            "http" | "https" => http_loader::factory(self.resource_task.clone()),
+            "http" | "https" | "view-source" => http_loader::factory(self.resource_task.clone()),
             "data" => from_factory(data_loader::factory),
             "about" => from_factory(about_loader::factory),
             _ => {

diff --git a/components/script/parse/html.rs b/components/script/parse/html.rs
@@ -190,6 +190,20 @@ pub fn parse_html(document: JSRef<Document>,
                     let page = format!("<html><body><img src='{}' /></body></html>", url.serialize());
                     parser.parse_chunk(page);
                 },
+                Some((ref t, ref st)) if t.as_slice().eq_ignore_ascii_case("text") &&
+                                         st.as_slice().eq_ignore_ascii_case("plain") => {
+                    // FIXME: When servo/html5ever#109 is fixed remove <plaintext> usage and
+                    // replace with fix from that issue.
+
+                    // text/plain documents require setting the tokenizer into PLAINTEXT mode.
+                    // This is done by using a <plaintext> element as the html5ever tokenizer
+                    // provides no other way to change to that state.
+                    // Spec for text/plain handling is:
+                    // https://html.spec.whatwg.org/multipage/browsers.html#read-text
+                    let page = format!("<pre>\u{000A}<plaintext>");
+                    parser.parse_chunk(page);
+                    parse_progress(&parser, url, &load_response);
+                },
                 _ => {
                     for msg in load_response.progress_port.iter() {
                         match msg {