From bfdcef8ef550b74fecc38b1bdb8fcb20ccb279b7 Mon Sep 17 00:00:00 2001
From: Emmanuel Schmidbauer <eschmidbauer@gmail.com>
Date: Fri, 3 Jul 2020 13:33:08 -0400
Subject: [PATCH] core: add function uri_trim_rcv_alias() to trim alias uri
 param from header

---
 src/core/dset.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/core/dset.h |  1 +
 2 files changed, 86 insertions(+)

diff --git a/src/core/dset.c b/src/core/dset.c
index faa61db72b2..db2de4cfc77 100644
--- a/src/core/dset.c
+++ b/src/core/dset.c
@@ -1029,6 +1029,91 @@ int uri_restore_rcv_alias(str *uri, str *nuri, str *suri)
 	return 0;
 }
 
+
+/**
+ * trim alias parameter from uri
+ * - nuri->s must point to a buffer of nuri->len size
+ */
+int uri_trim_rcv_alias(str *uri, str *nuri)
+{
+	char *p;
+	str skip;
+	str ip, port;
+	int proto;
+
+	if(uri == NULL || nuri == NULL) {
+		LM_ERR("invalid parameter value\n");
+		return -1;
+	}
+
+	/* sip:x;alias=1.1.1.1~0~0 */
+	if(uri->len < 23) {
+		/* no alias possible */
+		return 0;
+	}
+	p = uri->s + uri->len - 18;
+	skip.s = 0;
+	while(p > uri->s + 5) {
+		if(strncmp(p, ";alias=", 7) == 0) {
+			skip.s = p;
+			break;
+		}
+		p--;
+	}
+	if(skip.s == 0) {
+		/* alias parameter not found */
+		return 0;
+	}
+	p += 7;
+	ip.s = p;
+	p = (char *)memchr(ip.s, '~', (size_t)(uri->s + uri->len - ip.s));
+	if(p == NULL) {
+		/* proper alias parameter not found */
+		return 0;
+	}
+	ip.len = p - ip.s;
+	p++;
+	if(p >= uri->s + uri->len) {
+		/* proper alias parameter not found */
+		return 0;
+	}
+	port.s = p;
+	p = (char *)memchr(port.s, '~', (size_t)(uri->s + uri->len - port.s));
+	if(p == NULL) {
+		/* proper alias parameter not found */
+		return 0;
+	}
+	port.len = p - port.s;
+	p++;
+	if(p >= uri->s + uri->len) {
+		/* proper alias parameter not found */
+		return 0;
+	}
+	proto = (int)(*p - '0');
+	p++;
+
+	if(p != uri->s + uri->len && *p != ';') {
+		/* proper alias parameter not found */
+		return 0;
+	}
+	skip.len = (int)(p - skip.s);
+	if(nuri->len <= uri->len - skip.len) {
+		LM_ERR("uri buffer too small\n");
+		return -1;
+	}
+
+	p = nuri->s;
+	memcpy(p, uri->s, (size_t)(skip.s - uri->s));
+	p += skip.s - uri->s;
+	memcpy(p, skip.s + skip.len,
+			(size_t)(uri->s + uri->len - skip.s - skip.len));
+	p += uri->s + uri->len - skip.s - skip.len;
+	nuri->len = p - nuri->s;
+
+	LM_DBG("decoded <%.*s> => [%.*s]\n", uri->len, uri->s, nuri->len, nuri->s);
+	return 1;
+}
+
 /* address of record (aor) management */
 
 /* address of record considered case sensitive
diff --git a/src/core/dset.h b/src/core/dset.h
index ccb0f669c95..981f1a5d6a6 100644
--- a/src/core/dset.h
+++ b/src/core/dset.h
@@ -284,6 +284,7 @@ int setbflagsval(unsigned int branch, flag_t val);
 
 int uri_add_rcv_alias(sip_msg_t *msg, str *uri, str *nuri);
 int uri_restore_rcv_alias(str *uri, str *nuri, str *suri);
+int uri_trim_rcv_alias(str *uri, str *nuri);
 
 int init_dst_set(void);