Properly handle '=' while decoding base64 messages and null terminate strings returned from BASE64_DECODE.

(closes issue #15271)
Reported by: chappell
Patches:
      base64_fix.patch uploaded by chappell (license 8)
Tested by: kobaz


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@228378 65c4cc65-6c06-0410-ace0-fbb531ad65f3

funcs/func_base64.c

@@ -53,12 +53,19 @@ static int base64_encode(struct ast_channel *chan, char *cmd, char *data,
 static int base64_decode(struct ast_channel *chan, char *cmd, char *data,
 			 char *buf, size_t len)
 {
+	int decoded_len;
+
 	if (ast_strlen_zero(data)) {
 		ast_log(LOG_WARNING, "Syntax: BASE64_DECODE(<base_64 string>) - missing argument!\n");
 		return -1;
 	}
 
-	ast_base64decode((unsigned char *) buf, data, len);
+	decoded_len = ast_base64decode((unsigned char *) buf, data, len);
+	if (decoded_len <= (len - 1)) {		/* if not truncated, */
+		buf[decoded_len] = '\0';
+	} else {
+		buf[len - 1] = '\0';
+	}
 
 	return 0;
 }

main/utils.c

@@ -269,7 +269,7 @@ int ast_base64decode(unsigned char *dst, const char *src, int max)
 	unsigned int byte = 0;
 	unsigned int bits = 0;
 	int incnt = 0;
-	while(*src && (cnt < max)) {
+	while(*src && *src != '=' && (cnt < max)) {
 		/* Shift in 6 bits of input */
 		byte <<= 6;
 		byte |= (b2a[(int)(*src)]) & 0x3f;