Function set_sl_branch

forward.c:250–329

static inline int set_sl_branch(struct sip_msg* msg)
{
	struct hdr_field *h_via;
	struct via_body  *b_via;
	str *branch;
	int via_parsed;
	char b_md5[MD5_LEN];

	via_parsed = 0;
	branch = 0;

	/* first VIA header must be parsed */
	for( h_via=msg->h_via1 ; h_via ; h_via=h_via->sibling ) {

		b_via = (struct via_body*)h_via->parsed;
		for( ; b_via ; b_via=b_via->next ) {
			/* check if there is any valid branch param */
			if (b_via->branch==0 || b_via->branch->value.s==0
			|| b_via->branch->value.len==0 )
				continue;
			branch = &b_via->branch->value;
			/* check if the branch param has the magic cookie */
			if (branch->len <= (int)MCOOKIE_LEN
			|| memcmp( branch->s, MCOOKIE, MCOOKIE_LEN)!=0 )
				continue;
			/* found a statefull branch -> use it */
			goto found;
		}

		if (!via_parsed) {
			if ( parse_headers(msg,HDR_EOH_F,0)<0 ) {
				LM_ERR("failed to parse all hdrs\n");
				return -1;
			}
			via_parsed = 1;
		}
	}

	/* no statefull branch :(.. -> use the branch from the last via */
found:
	if (branch==NULL) {
		/* no branch found :(.. -> try to use the From TAG param as 
		 * a value to seed the MD5 - the From TAG is per call, so it gives
		 * a bit of uniqueness; if this is empty, as a last resort, use the 
		 * FROM URI (it cannot mis) */
		if ( parse_from_header(msg)!=0 )
		{
			LM_ERR("failed to extract FROM header\n");
			return -1;
		}
		if ( get_from(msg)->tag_value.len )
			branch = &get_from(msg)->tag_value;
		else
			branch = &get_from(msg)->uri;
	}

	/* make an MD5 over the found branch, to ensure a controlable 
	 * length of the resulting branch */