Ensure user portion of SIP URI matches dialplan when using encoded characters.

This commit takes a simliar approach to 288112 and checks the dialplan to
determine the proper action for an incoming contact header as to whether or not
it should be decoded or not. sip_new was blindly always decoding the extension,
which also caused the outgoing contact header to be incorrect as well as failing
to match the encoded extension in the dialplan.

(closes issue #17892)
Reported by: wdoekes
Patches: 
      bug17892-1.patch uploaded by jpeeler (license 325)
Tested by: wdoekes


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@289699 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -4443,9 +4443,14 @@ static struct ast_channel *sip_new(struct sip_pvt *i, int state, const char *tit
 	 * we should decode the uri before storing it in the channel, but leave it encoded in the sip_pvt
 	 * structure so that there aren't issues when forming URI's
 	 */
+	if (ast_exists_extension(NULL, i->context, i->exten, 1, i->cid_num)) {
+		/* encoded in dialplan, so keep extension encoded */
+		ast_copy_string(tmp->exten, i->exten, sizeof(tmp->exten));
+	} else {
 		decoded_exten = ast_strdupa(i->exten);
 		ast_uri_decode(decoded_exten);
 		ast_copy_string(tmp->exten, decoded_exten, sizeof(tmp->exten));
+	}
 
 	/* Don't use ast_set_callerid() here because it will
 	 * generate an unnecessary NewCallerID event  */