res_http_media_cache.c: Parse media URLs to find extensions.

Use the URI parsing functions to parse playback URLs in order to find
their file extensions.

For backwards compatibility, we first look at the full URL, then at
any Content-Type header, and finally at just the path portion of the
URL.

ASTERISK-27871 #close

Change-Id: I16d0682f6d794be96539261b3e48f237909139cb

res/res_http_media_cache.c

@@ -35,10 +35,12 @@
 
 #include <curl/curl.h>
 
+#include "asterisk/file.h"
 #include "asterisk/module.h"
 #include "asterisk/bucket.h"
 #include "asterisk/sorcery.h"
 #include "asterisk/threadstorage.h"
+#include "asterisk/uri.h"
 
 #define GLOBAL_USERAGENT "asterisk-libcurl-agent/1.0"
 
@@ -155,6 +157,115 @@ static void bucket_file_set_expiration(struct ast_bucket_file *bucket_file)
 	ast_bucket_file_metadata_set(bucket_file, "__actual_expires", time_buf);
 }
 
+static char *file_extension_from_string(const char *str, char *buffer, size_t capacity)
+{
+	const char *ext;
+
+	ext = strrchr(str, '.');
+	if (ext && ast_get_format_for_file_ext(ext + 1)) {
+		ast_debug(3, "Found extension '%s' at end of string\n", ext);
+		ast_copy_string(buffer, ext, capacity);
+		return buffer;
+	}
+
+	return NULL;
+}
+
+static char *file_extension_from_url(struct ast_bucket_file *bucket_file, char *buffer, size_t capacity)
+{
+	return file_extension_from_string(ast_sorcery_object_get_id(bucket_file), buffer, capacity);
+}
+
+/*!
+ * \internal
+ * \brief Normalize the value of a Content-Type header
+ *
+ * This will trim off any optional parameters after the type/subtype.
+ */
+static void normalize_content_type_header(char *content_type)
+{
+	char *params = strchr(content_type, ';');
+
+	if (params) {
+		*params-- = 0;
+		while (params > content_type && (*params == ' ' || *params == '\t')) {
+			*params-- = 0;
+		}
+	}
+}
+
+static char *file_extension_from_content_type(struct ast_bucket_file *bucket_file, char *buffer, size_t capacity)
+{
+	/* Check for the extension based on the MIME type passed in the Content-Type
+	 * header.
+	 *
+	 * If a match is found then retrieve the extension from the supported list
+	 * corresponding to the mime-type and use that to rename the file */
+
+	struct ast_bucket_metadata *header;
+	char *mime_type;
+
+	header = ast_bucket_file_metadata_get(bucket_file, "content-type");
+	if (!header) {
+		return NULL;
+	}
+
+	mime_type = ast_strdup(header->value);
+	if (mime_type) {
+		normalize_content_type_header(mime_type);
+		if (!ast_strlen_zero(mime_type)) {
+			if (ast_get_extension_for_mime_type(mime_type, buffer, sizeof(buffer))) {
+				ast_debug(3, "Derived extension '%s' from MIME type %s\n",
+					buffer,
+					mime_type);
+				ast_free(mime_type);
+				ao2_ref(header, -1);
+				return buffer;
+			}
+		}
+	}
+	ast_free(mime_type);
+	ao2_ref(header, -1);
+
+	return NULL;
+}
+
+static char *file_extension_from_url_path(struct ast_bucket_file *bucket_file, char *buffer, size_t capacity)
+{
+	struct ast_uri *uri;
+
+	uri = ast_uri_parse(ast_sorcery_object_get_id(bucket_file));
+	if (!uri) {
+		ast_log(LOG_ERROR, "Failed to parse URI: %s\n",
+			ast_sorcery_object_get_id(bucket_file));
+		return NULL;
+	}
+
+	/* Just parse it as a string like before, but without the extra cruft */
+	buffer = file_extension_from_string(ast_uri_path(uri), buffer, capacity);
+	ao2_cleanup(uri);
+	return buffer;
+}
+
+static void bucket_file_set_extension(struct ast_bucket_file *bucket_file)
+{
+	/* We will attempt to determine an extension in the following order for backwards
+	 * compatibility:
+	 *
+	 * 1. Look at tail end of URL for extension
+	 * 2. Use the Content-Type header if present
+	 * 3. Parse the URL (assuming we can) and look at the tail of the path
+	 */
+
+	char buffer[64];
+
+	if (file_extension_from_url(bucket_file, buffer, sizeof(buffer))
+	   || file_extension_from_content_type(bucket_file, buffer, sizeof(buffer))
+	   || file_extension_from_url_path(bucket_file, buffer, sizeof(buffer))) {
+		ast_bucket_file_metadata_set(bucket_file, "ext", buffer);
+	}
+}
+
 /*! \internal
  * \brief Return whether or not we should always revalidate against the server
  */
@@ -278,6 +389,7 @@ static int bucket_file_run_curl(struct ast_bucket_file *bucket_file)
 
 	if (http_code / 100 == 2) {
 		bucket_file_set_expiration(bucket_file);
+		bucket_file_set_extension(bucket_file);
 		return 0;
 	} else {
 		ast_log(LOG_WARNING, "Failed to retrieve URL '%s': server returned %ld\n",