[sr-dev] [kamailio] inline function suip2a() (ip_addr.h) not working for ipv6 (#379)

[topotomaso]

I observed that the inline function suip2a() (ip_addr.h) contains a silly bug and therefor does not work for IPv6 conversions. This silly bug is preventing sip_trace() to work in the onsend_route block for IPv6 sip messages. 
Rem.: The function suip2a() is used only by the siptrace module.

Test background (just for understanding the use case):
- using kamailio 4.1.3 (with an additional patch to let onsend_route be called also for replies taken from kamailio 4.2.x)
- kamailio is used as loadbalancer in stateless mode (using forward() only)
- sip tracing is used by explictly calling sip_trace() in onsend_route, route and onreply routing block to be able to implement an interface specific sip tracing (no SIP transaction based sip tracing is applied by using the siptrace's trace_flag)

The silly bug:

In suip2a() the function ip6tosbuf() is called with an odd buffer length argument of value "sizeof(buf)-4" which is equal to "IP6_MAX_STR_SIZE -1". ip6tosbuf() however needs at least a buffer length of IP6_MAX_STR_SIZE (otherwise it returns immediately without writing anything into the buffer).
So regarding IPv6 adresses the ascii output of suip2a() is alway an empty IPv6 reference ([]).

```
static inline int ip6tosbuf(unsigned char* ip6, char* buff, int len)
{
	int offset;
	register unsigned char a,b,c;
	register unsigned char d;
	register unsigned short hex4;
	int r;
	#define HEXDIG(x) (((x)>=10)?(x)-10+'A':(x)+'0')
	
	
	offset=0;
	if (unlikely(len<IP6_MAX_STR_SIZE))
		return 0;
	...
}

#define SUIP2A_MAX_STR_SIZE  (IP6_MAX_STR_SIZE + 2 /* [] */ + 1 /* \0 */)
/* returns an asciiz string containing the ip
 *  (<ipv4_addr> or [<ipv6_addr>])
 */
static inline char* suip2a(union sockaddr_union* su, int su_len)
{
	static char buf[SUIP2A_MAX_STR_SIZE];
	int offs;

	if (unlikely(su->s.sa_family==AF_INET6)){
		if (unlikely(su_len<sizeof(su->sin6)))
			return "<addr. error>";
		buf[0]='[';
		offs=1+ip6tosbuf((unsigned char*)su->sin6.sin6_addr.s6_addr, &buf[1],
							sizeof(buf)-4);
		buf[offs]=']';
		offs++;
	}else
	if (unlikely(su_len<sizeof(su->sin)))
		return "<addr. error>";
	else
		offs=ip4tosbuf((unsigned char*)&su->sin.sin_addr, buf, sizeof(buf)-2);
	buf[offs]=0;
	return buf;
}
```

A possible verfied patch looks like this (using this patch sip_trace() is working now as expected in this use case).
```
--- ip_addr.h	2014-04-24 12:02:35.000000000 +0200
+++ ip_addr.h	2015-10-22 18:48:40.553177206 +0200
@@ -737,14 +737,14 @@
 			return "<addr. error>";
 		buf[0]='[';
 		offs=1+ip6tosbuf((unsigned char*)su->sin6.sin6_addr.s6_addr, &buf[1],
-							sizeof(buf)-4);
+							IP6_MAX_STR_SIZE);
 		buf[offs]=']';
 		offs++;
 	}else
 	if (unlikely(su_len<sizeof(su->sin)))
 		return "<addr. error>";
 	else
-		offs=ip4tosbuf((unsigned char*)&su->sin.sin_addr, buf, sizeof(buf)-2);
+		offs=ip4tosbuf((unsigned char*)&su->sin.sin_addr, buf, IP4_MAX_STR_SIZE);
 	buf[offs]=0;
 	return buf;
 }

```


---
Reply to this email directly or view it on GitHub:
https://github.com/kamailio/kamailio/issues/379
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