Adds ast_escape_encoded utility to properly handle escaping of quoted field before uri.

This commit backports a feature in trunk affecting initreqprep so that display name won't
be encoded improperly. Also includes unit tests for the ast_escape_quoted function.
This patch gives 1.8 a much improved outlook in countries which don't use standard
ASCII characters.

(closes issue ASTERISK-16949)
Reported by: Örn Arnarson
Review: https://reviewboard.asterisk.org/r/1235/


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@322585 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/utils.h

@@ -273,6 +273,19 @@ char *ast_uri_encode(const char *string, char *outbuf, int buflen, int do_specia
  */
 void ast_uri_decode(char *s);
 
+/*!
+ * \brief Escape characters found in a quoted string.
+ *
+ * \note This function escapes quoted characters based on the 'qdtext' set of
+ * allowed characters from RFC 3261 section 25.1.
+ *
+ * \param string string to be escaped
+ * \param outbuf resulting escaped string
+ * \param buflen size of output buffer
+ * \return a pointer to the escaped string
+ */
+char *ast_escape_quoted(const char *string, char *outbuf, int buflen);
+
 static force_inline void ast_slinear_saturated_add(short *input, short *value)
 {
 	int res;