output/httpd/IcyMetaDataServer: pad the string with 15 spaces

Fixes a buffer overflow due to the bad formula rounding the buffer size up. At the same time, remove the "+1" from the meta_length calculation, which takes the padding into account and at the same time implements proper rounding.

output/httpd/IcyMetaDataServer: pad the string with 15 spaces
a73195b7 · Max Kellermann · 1bd00b8a · a73195b7
Commit a73195b7 authored Feb 19, 2017 by Max Kellermann
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Showing with 6 additions and 2 deletions

IcyMetaDataServer.cxx src/output/plugins/httpd/IcyMetaDataServer.cxx +6 -2

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--- a/src/output/plugins/httpd/IcyMetaDataServer.cxx
+++ b/src/output/plugins/httpd/IcyMetaDataServer.cxx
@@ -60,7 +60,11 @@ icy_server_metadata_string(const char *stream_title, const char* stream_url)
 {
 	// The leading n is a placeholder for the length information
 	auto icy_metadata = FormatString("nStreamTitle='%s';"
-					 "StreamUrl='%s';",
+					 "StreamUrl='%s';"
+					 /* pad 15 spaces just in case
+					    the length needs to be
+					    rounded up */
+					 "               ",
 					 stream_title,
 					 stream_url);
@@ -68,7 +72,7 @@ icy_server_metadata_string(const char *stream_title, const char* stream_url)
 	meta_length--; // subtract placeholder
-	meta_length = meta_length / 16 + 1;
+	meta_length = meta_length / 16;
 	icy_metadata[0] = meta_length;