From cd4f6a94f9275670091326a5aec8a07bce7f8d79 Mon Sep 17 00:00:00 2001
From: Gustavo Noronha Silva <gns@gnome.org>
Date: Mon, 9 Dec 2013 16:20:02 +0100
Subject: sniffing: Bring feed vs HTML up-to-date with the MIMESNIFF spec

* decide on that before doing the image sniffing to match the spec
* use const char* and g_str_has_prefix for comparisons to make it
  more legible
* deal with rdf:RDF tags
---
 libsoup/soup-content-sniffer.c | 117 ++++++++++++++++++++++++++++-------------
 tests/resources/feed.rdf       |  32 +++++++++++
 tests/sniffing-test.c          |  13 +++--
 tests/soup-tests.gresource.xml |   1 +
 4 files changed, 120 insertions(+), 43 deletions(-)
 create mode 100644 tests/resources/feed.rdf

diff --git a/libsoup/soup-content-sniffer.c b/libsoup/soup-content-sniffer.c
index 154df841..5b768bb2 100644
--- a/libsoup/soup-content-sniffer.c
+++ b/libsoup/soup-content-sniffer.c
@@ -491,10 +491,26 @@ sniff_images (SoupContentSniffer *sniffer, SoupBuffer *buffer,
 	return g_strdup (content_type);
 }
 
+static gboolean
+skip_insignificant_space (const char *resource, int *pos, int resource_length)
+{
+	while ((resource[*pos] == '\x09') ||
+	       (resource[*pos] == '\x20') ||
+	       (resource[*pos] == '\x0A') ||
+	       (resource[*pos] == '\x0D')) {
+		*pos = *pos + 1;
+
+		if (*pos > resource_length)
+			return TRUE;
+	}
+
+	return FALSE;
+}
+
 static char*
 sniff_feed_or_html (SoupContentSniffer *sniffer, SoupBuffer *buffer)
 {
-	const guchar *resource = (const guchar *)buffer->data;
+	const char *resource = (const char *)buffer->data;
 	int resource_length = MIN (512, buffer->length);
 	int pos = 0;
 
@@ -509,19 +525,10 @@ sniff_feed_or_html (SoupContentSniffer *sniffer, SoupBuffer *buffer)
 	if (pos > resource_length)
 		goto text_html;
 
-	/* Skip insignificant white space */
-	while ((resource[pos] == '\x09') ||
-	       (resource[pos] == '\x20') ||
-	       (resource[pos] == '\x0A') ||
-	       (resource[pos] == '\x0D')) {
-		pos++;
-
-		if (pos > resource_length)
-			goto text_html;
-	}
+	if (skip_insignificant_space (resource, &pos, resource_length))
+		goto text_html;
 
-	/* != < */
-	if (resource[pos] != '\x3C')
+	if (resource[pos] != '<')
 		return g_strdup ("text/html");
 
 	pos++;
@@ -529,73 +536,106 @@ sniff_feed_or_html (SoupContentSniffer *sniffer, SoupBuffer *buffer)
 	if ((pos + 2) > resource_length)
 		goto text_html;
 
-	/* Skipping comments */
-	if ((resource[pos] == '\x2D') ||
-	    (resource[pos+1] == '\x2D') ||
-	    (resource[pos+2] == '\x3E')) {
+	/* Skip comments. */
+	if (g_str_has_prefix (resource + pos, "!--")) {
 		pos = pos + 3;
 
 		if ((pos + 2) > resource_length)
 			goto text_html;
 
-		while ((resource[pos] != '\x2D') &&
-		       (resource[pos+1] != '\x2D') &&
-		       (resource[pos+2] != '\x3E')) {
+		while (!g_str_has_prefix (resource + pos, "-->")) {
 			pos++;
 
 			if ((pos + 2) > resource_length)
 				goto text_html;
 		}
 
+		pos = pos + 3;
+
 		goto look_for_tag;
 	}
 
 	if (pos > resource_length)
 		goto text_html;
 
-	/* == ! */
-	if (resource[pos] == '\x21') {
+	if (resource[pos] == '!') {
 		do {
 			pos++;
 
 			if (pos > resource_length)
 				goto text_html;
-		} while (resource[pos] != '\x3E');
+		} while (resource[pos] != '>');
 
 		pos++;
 
 		goto look_for_tag;
-	} else if (resource[pos] == '\x3F') { /* ? */
+	} else if (resource[pos] == '?') {
 		do {
 			pos++;
 
 			if ((pos + 1) > resource_length)
 				goto text_html;
-		} while ((resource[pos] != '\x3F') &&
-			 (resource[pos+1] != '\x3E'));
+		} while (!g_str_has_prefix (resource + pos, "?>"));
 
 		pos = pos + 2;
 
 		goto look_for_tag;
 	}
 
-	if ((pos + 2) > resource_length)
+	if ((pos + 3) > resource_length)
 		goto text_html;
 
-	if ((resource[pos] == '\x72') &&
-	    (resource[pos+1] == '\x73') &&
-	    (resource[pos+2] == '\x73'))
+	if (g_str_has_prefix (resource + pos, "rss"))
 		return g_strdup ("application/rss+xml");
 
-	if ((pos + 3) > resource_length)
+	if ((pos + 4) > resource_length)
 		goto text_html;
 
-	if ((resource[pos] == '\x66') &&
-	    (resource[pos+1] == '\x65') &&
-	    (resource[pos+2] == '\x65') &&
-	    (resource[pos+3] == '\x64'))
+	if (g_str_has_prefix (resource + pos, "feed"))
 		return g_strdup ("application/atom+xml");
 
+	if ((pos + 7) > resource_length)
+		goto text_html;
+
+	if (g_str_has_prefix (resource + pos, "rdf:RDF")) {
+		pos = pos + 7;
+
+		if (skip_insignificant_space (resource, &pos, resource_length))
+			goto text_html;
+
+		if ((pos + 32) > resource_length)
+			goto text_html;
+
+		if (g_str_has_prefix (resource + pos, "xmlns=\"http://purl.org/rss/1.0/\"")) {
+			pos = pos + 32;
+
+			if (skip_insignificant_space (resource, &pos, resource_length))
+				goto text_html;
+
+			if ((pos + 55) > resource_length)
+				goto text_html;
+
+			if (g_str_has_prefix (resource + pos, "xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\""))
+				return g_strdup ("application/rss+xml");
+		}
+
+		if ((pos + 55) > resource_length)
+			goto text_html;
+
+		if (g_str_has_prefix (resource + pos, "xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\"")) {
+			pos = pos + 55;
+
+			if (skip_insignificant_space (resource, &pos, resource_length))
+				goto text_html;
+
+			if ((pos + 32) > resource_length)
+				goto text_html;
+
+			if (g_str_has_prefix (resource + pos, "xmlns=\"http://purl.org/rss/1.0/\""))
+				return g_strdup ("application/rss+xml");
+		}
+	}
+
  text_html:
 	return g_strdup ("text/html");
 }
@@ -641,6 +681,10 @@ soup_content_sniffer_real_sniff (SoupContentSniffer *sniffer, SoupMessage *msg,
 	    !g_ascii_strcasecmp (content_type, "application/xml"))
 		return g_strdup (content_type);
 
+	/* 5. Distinguish feed from HTML. */
+	if (!g_ascii_strcasecmp (content_type, "text/html"))
+		return sniff_feed_or_html (sniffer, buffer);
+
 	/* 2.7.5 Content-Type sniffing: image
 	 * The spec says:
 	 *
@@ -659,9 +703,6 @@ soup_content_sniffer_real_sniff (SoupContentSniffer *sniffer, SoupMessage *msg,
 		return sniff_text_or_binary (sniffer, buffer);
 	}
 
-	if (!g_ascii_strcasecmp (content_type, "text/html"))
-		return sniff_feed_or_html (sniffer, buffer);
-
 	return g_strdup (content_type);
 }
 
diff --git a/tests/resources/feed.rdf b/tests/resources/feed.rdf
new file mode 100644
index 00000000..f3d9e276
--- /dev/null
+++ b/tests/resources/feed.rdf
@@ -0,0 +1,32 @@
+<?xml version="1.0"?>
+
+<!-- RDF Site Summary (RSS) 1.0
+     http://groups.yahoo.com/group/rss-dev/files/specification.html
+     Section 5.3
+  -->
+
+<rdf:RDF 
+  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+  xmlns="http://purl.org/rss/1.0/">
+
+  <channel rdf:about="http://www.xml.com/xml/news.rss">
+    <title>XML.com</title>
+    <link>http://xml.com/pub</link>
+    <description>
+    XML.com features a rich mix of information and services 
+      for the XML community.
+    </description>
+
+    <image rdf:resource="http://xml.com/universal/images/xml_tiny.gif" />
+
+    <items>
+      <rdf:Seq>
+        <rdf:li resource="http://xml.com/pub/2000/08/09/xslt/xslt.html" />
+        <rdf:li resource="http://xml.com/pub/2000/08/09/rdfdb/index.html" />
+      </rdf:Seq>
+    </items>
+
+    <textinput rdf:resource="http://search.xml.com" />
+  </channel>
+
+</rdf:RDF>
diff --git a/tests/sniffing-test.c b/tests/sniffing-test.c
index 2dc9fb2c..498df976 100644
--- a/tests/sniffing-test.c
+++ b/tests/sniffing-test.c
@@ -539,11 +539,6 @@ main (int argc, char **argv)
 			      "type/application_xml/home.gif => application/xml",
 			      do_sniffing_test);
 
-	/* Test the image sniffing path */
-	g_test_add_data_func ("/sniffing/type/image",
-			      "type/image_png/home.gif => image/gif",
-			      do_sniffing_test);
-
 	/* Test the feed or html path */
 	g_test_add_data_func ("/sniffing/type/html/html",
 			      "type/text_html/test.html => text/html",
@@ -554,6 +549,14 @@ main (int argc, char **argv)
 	g_test_add_data_func ("/sniffing/type/html/atom",
 			      "type/text_html/atom.xml => application/atom+xml",
 			      do_sniffing_test);
+	g_test_add_data_func ("/sniffing/type/html/rdf",
+			      "type/text_html/feed.rdf => application/rss+xml",
+			      do_sniffing_test);
+
+	/* Test the image sniffing path */
+	g_test_add_data_func ("/sniffing/type/image",
+			      "type/image_png/home.gif => image/gif",
+			      do_sniffing_test);
 
 	/* The spec tells us to only use the last Content-Type header */
 	g_test_add_data_func ("/sniffing/multiple-headers",
diff --git a/tests/soup-tests.gresource.xml b/tests/soup-tests.gresource.xml
index d24a04b0..320cd63d 100644
--- a/tests/soup-tests.gresource.xml
+++ b/tests/soup-tests.gresource.xml
@@ -3,6 +3,7 @@
   <gresource prefix="/org/gnome/libsoup/tests">
     <file>index.txt</file>
     <file>resources/atom.xml</file>
+    <file>resources/feed.rdf</file>
     <file>resources/home.gif</file>
     <file>resources/html_binary.html</file>
     <file>resources/leading_space.html</file>
-- 
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