app_callerid: Fix behavior for off-nominal cases.

Properly handle if Caller ID Name and/or Number are empty.
In particular, we need to check if the Caller ID fields are
valid before using them, to avoid copying uninitialized memory.
(Not that it would really make sense to send an empty Caller ID,
hence why this is an off-nominal case.)

Author: InterLinked1

apps/app_callerid.c

@@ -174,6 +174,12 @@ static int cwcid_careful_send(struct ast_channel *chan, unsigned char *buf, int
 	};
 	int amt;
 
+	if (!len) {
+		ast_log(LOG_WARNING, "Send buffer is empty, returning\n");
+		return -1;
+	}
+	ast_debug(2, "Carefully sending %d bytes\n", len);
+
 	if (remain && *remain) {
 		amt = len;
 
@@ -210,7 +216,10 @@ static int cwcid_careful_send(struct ast_channel *chan, unsigned char *buf, int
 
 		/* Drop any frames that are not voice */
 		if (inf->frametype != AST_FRAME_VOICE) {
+			char frametype[32];
+			ast_frame_type2str(inf->frametype, frametype, sizeof(frametype));
 			ast_frfree(inf);
+			ast_debug(1, "Skipping %s\n", frametype);
 			continue;
 		}
 
@@ -237,6 +246,7 @@ static int cwcid_careful_send(struct ast_channel *chan, unsigned char *buf, int
 		buf += amt;
 		len -= amt;
 		ast_frfree(inf);
+		ast_debug(2, "%d bytes remaining\n", len);
 	}
 	return 0;
 }
@@ -288,21 +298,21 @@ static int cwcid_exec(struct ast_channel *chan, const char *data)
 	}
 
 	tz = args.timezone;
-	clidnum = ast_strlen_zero(args.number) ? ast_channel_caller(chan)->id.number.str : args.number;
+	clidnum = !ast_strlen_zero(args.number) ? args.number : ast_channel_caller(chan)->id.number.valid ? ast_channel_caller(chan)->id.number.str : "";
 	if (strlen(clidnum) > 15) {
 		ast_log(LOG_WARNING, "Caller ID number '%s' is greater than 15 characters and will be truncated\n", clidnum);
 	} else if (ast_strlen_zero(clidnum)) {
 		ast_log(LOG_WARNING, "Caller ID number is empty\n");
 	}
-	ast_copy_string(clid, clidnum, 16);
+	ast_copy_string(clid, clidnum, sizeof(clid));
 
-	clidname = ast_strlen_zero(args.name) ? ast_channel_caller(chan)->id.name.str : args.name;
+	clidname = !ast_strlen_zero(args.name) ? args.name : ast_channel_caller(chan)->id.name.valid ? ast_channel_caller(chan)->id.name.str : "";
 	if (strlen(clidname) > 15) {
 		ast_log(LOG_WARNING, "Caller ID name '%s' is greater than 15 characters and will be truncated\n", clidname);
 	} else if (ast_strlen_zero(clidname)) {
 		ast_log(LOG_WARNING, "Caller ID name is empty\n");
 	}
-	ast_copy_string(cnam, clidname, 16);
+	ast_copy_string(cnam, clidname, sizeof(cnam));
 
 	if (!ast_strlen_zero(args.presentation)) {
 		presentation = ast_parse_caller_presentation(args.presentation);