libre SIP/TLS verify

re-sip-tls-verify.patch

diff --git a/include/re_tls.h b/include/re_tls.h
index 319d601c..d4f6d041 100644
--- a/include/re_tls.h
+++ b/include/re_tls.h
@@ -56,6 +56,7 @@ const char *tls_cipher_name(const struct tls_conn *tc);
 int tls_set_ciphers(struct tls *tls, const char *cipherv[], size_t count);
 int tls_set_servername(struct tls_conn *tc, const char *servername);
 int tls_set_verify_server(struct tls_conn *tc, const char *host);
+bool tls_verify_peer_san(const struct tls_conn *tc, const char *host);
 
 
 /* TCP */
diff --git a/src/sip/ctrans.c b/src/sip/ctrans.c
index 0ff32660..c4467b8f 100644
--- a/src/sip/ctrans.c
+++ b/src/sip/ctrans.c
@@ -205,7 +205,7 @@ static void retransmit_handler(void *arg)
 	tmr_start(&ct->tmre, timeout, retransmit_handler, ct);
 
 	err = sip_transp_send(&ct->qent, ct->sip, NULL, ct->tp, &ct->dst,
-			      ct->mb, transport_handler, ct);
+			      ct->mb, transport_handler, ct, NULL);
 	if (err) {
 		terminate(ct, err);
 		mem_deref(ct);
@@ -310,7 +310,7 @@ static bool response_handler(const struct sip_msg *msg, void *arg)
 int sip_ctrans_request(struct sip_ctrans **ctp, struct sip *sip,
 		       enum sip_transp tp, const struct sa *dst, char *met,
 		       char *branch, struct mbuf *mb,
-		       sip_resp_h *resph, void *arg)
+		       sip_resp_h *resph, void *arg, const char *host)
 {
 	struct sip_ctrans *ct;
 	int err;
@@ -336,7 +336,7 @@ int sip_ctrans_request(struct sip_ctrans **ctp, struct sip *sip,
 	ct->arg    = arg;
 
 	err = sip_transp_send(&ct->qent, sip, NULL, tp, dst, mb,
-			      transport_handler, ct);
+			      transport_handler, ct, host);
 	if (err)
 		goto out;
 
@@ -386,7 +386,7 @@ int sip_ctrans_cancel(struct sip_ctrans *ct)
 		goto out;
 
 	err = sip_ctrans_request(NULL, ct->sip, ct->tp, &ct->dst, cancel,
-				 ct->branch, mb, NULL, NULL);
+				 ct->branch, mb, NULL, NULL, NULL);
 	if (err)
 		goto out;
 
diff --git a/src/sip/request.c b/src/sip/request.c
index aca2935e..f60d358e 100644
--- a/src/sip/request.c
+++ b/src/sip/request.c
@@ -194,7 +194,8 @@ static int request(struct sip_request *req, enum sip_transp tp,
 		err = sip_send(req->sip, NULL, tp, dst, mb);
 	else
 		err = sip_ctrans_request(&req->ct, req->sip, tp, dst, req->met,
-					 branch, mb, response_handler, req);
+					 branch, mb, response_handler, req,
+					 req->host);
 	if (err)
 		goto out;
 
diff --git a/src/sip/sip.c b/src/sip/sip.c
index 651628cd..a2617703 100644
--- a/src/sip/sip.c
+++ b/src/sip/sip.c
@@ -173,7 +173,7 @@ void sip_close(struct sip *sip, bool force)
 int sip_send(struct sip *sip, void *sock, enum sip_transp tp,
 	     const struct sa *dst, struct mbuf *mb)
 {
-	return sip_transp_send(NULL, sip, sock, tp, dst, mb, NULL, NULL);
+	return sip_transp_send(NULL, sip, sock, tp, dst, mb, NULL, NULL, NULL);
 }
 
 
diff --git a/src/sip/sip.h b/src/sip/sip.h
index 912c69bb..32ec3f13 100644
--- a/src/sip/sip.h
+++ b/src/sip/sip.h
@@ -50,7 +50,7 @@ struct sip_ctrans;
 int  sip_ctrans_request(struct sip_ctrans **ctp, struct sip *sip,
 			enum sip_transp tp, const struct sa *dst, char *met,
 			char *branch, struct mbuf *mb, sip_resp_h *resph,
-			void *arg);
+			void *arg, const char *host);
 int  sip_ctrans_cancel(struct sip_ctrans *ct);
 int  sip_ctrans_init(struct sip *sip, uint32_t sz);
 int  sip_ctrans_debug(struct re_printf *pf, const struct sip *sip);
@@ -69,7 +69,8 @@ typedef void(sip_transp_h)(int err, void *arg);
 int  sip_transp_init(struct sip *sip, uint32_t sz);
 int  sip_transp_send(struct sip_connqent **qentp, struct sip *sip, void *sock,
 		     enum sip_transp tp, const struct sa *dst, struct mbuf *mb,
-		     sip_transp_h *transph, void *arg);
+		     sip_transp_h *transph, void *arg,
+		     const char *host);
 bool sip_transp_supported(struct sip *sip, enum sip_transp tp, int af);
 const char *sip_transp_srvid(enum sip_transp tp);
 bool sip_transp_reliable(enum sip_transp tp);
diff --git a/src/sip/transp.c b/src/sip/transp.c
index aed33bb0..eb391a7c 100644
--- a/src/sip/transp.c
+++ b/src/sip/transp.c
@@ -57,6 +57,8 @@ struct sip_conn {
 	struct sip *sip;
 	uint32_t ka_interval;
 	bool established;
+	char *host;
+	bool client;
 };
 
 
@@ -104,6 +106,7 @@ static void conn_destructor(void *arg)
 	mem_deref(conn->sc);
 	mem_deref(conn->tc);
 	mem_deref(conn->mb);
+	mem_deref(conn->host);
 }
 
 
@@ -463,6 +466,29 @@ static void tcp_estab_handler(void *arg)
 	tcp_conn_local_get(conn->tc, &conn->laddr);
 #endif
 
+#ifdef USE_TLS
+	if (conn->client && conn->sc) {
+
+		err = tls_peer_verify(conn->sc);
+
+		re_printf(".... tls server cert: (%m)\n", err);
+
+		if (err) {
+			conn_close(conn, err);
+			mem_deref(conn);
+			return;
+		}
+
+		if (!tls_verify_peer_san(conn->sc, conn->host)) {
+			re_printf("sip: could not verify server SAN (%s)\n",
+				  conn->host);
+			conn_close(conn, EAUTH);
+			mem_deref(conn);
+			return;
+		}
+	}
+#endif
+
 	conn->established = true;
 
 	le = list_head(&conn->ql);
@@ -544,7 +570,7 @@ static void tcp_connect_handler(const struct sa *paddr, void *arg)
 
 static int conn_send(struct sip_connqent **qentp, struct sip *sip, bool secure,
 		     const struct sa *dst, struct mbuf *mb,
-		     sip_transp_h *transph, void *arg)
+		     sip_transp_h *transph, void *arg, const char *host)
 {
 	struct sip_conn *conn, *new_conn = NULL;
 	struct sip_connqent *qent;
@@ -565,6 +591,7 @@ static int conn_send(struct sip_connqent **qentp, struct sip *sip, bool secure,
 	hash_append(sip->ht_conn, sa_hash(dst, SA_ALL), &conn->he, conn);
 	conn->paddr = *dst;
 	conn->sip   = sip;
+	conn->client = true;
 
 	err = tcp_connect(&conn->tc, dst, tcp_estab_handler, tcp_recv_handler,
 			  tcp_close_handler, conn);
@@ -588,6 +615,12 @@ static int conn_send(struct sip_connqent **qentp, struct sip *sip, bool secure,
 		err = tls_start_tcp(&conn->sc, transp->tls, conn->tc, 0);
 		if (err)
 			goto out;
+
+		err = str_dup(&conn->host, host);
+		if (err) {
+			re_printf("sip: missing host param for tls\n");
+			goto out;
+		}
 	}
 #endif
 
@@ -716,15 +749,18 @@ void sip_transp_flush(struct sip *sip)
 }
 
 
+/* TODO: find a better way to transfer host from ctrans to transp */
 int sip_transp_send(struct sip_connqent **qentp, struct sip *sip, void *sock,
 		    enum sip_transp tp, const struct sa *dst, struct mbuf *mb,
-		    sip_transp_h *transph, void *arg)
+		    sip_transp_h *transph, void *arg, const char *host)
 {
 	const struct sip_transport *transp;
 	struct sip_conn *conn;
 	bool secure = false;
 	int err;
 
+	re_printf(".... send: host=%s\n", host);
+
 	if (!sip || !dst || !mb)
 		return EINVAL;
 
@@ -753,7 +789,7 @@ int sip_transp_send(struct sip_connqent **qentp, struct sip *sip, void *sock,
 			err = tcp_send(conn->tc, mb);
 		else
 			err = conn_send(qentp, sip, secure, dst, mb,
-					transph, arg);
+					transph, arg, host);
 		break;
 
 	default:
diff --git a/src/tls/openssl/tls.c b/src/tls/openssl/tls.c
index 85e2fd41..79d42127 100644
--- a/src/tls/openssl/tls.c
+++ b/src/tls/openssl/tls.c
@@ -683,11 +683,19 @@ int tls_peer_common_name(const struct tls_conn *tc, char *cn, size_t size)
  */
 int tls_peer_verify(const struct tls_conn *tc)
 {
+	long result;
+
 	if (!tc)
 		return EINVAL;
 
-	if (SSL_get_verify_result(tc->ssl) != X509_V_OK)
+	result = SSL_get_verify_result(tc->ssl);
+	if (result != X509_V_OK) {
+
+		re_printf("tls: verify failed, result = %ld (%s)\n",
+			  result,  X509_verify_cert_error_string(result));
+
 		return EAUTH;
+	}
 
 	return 0;
 }
@@ -937,3 +945,80 @@ struct ssl_ctx_st *tls_openssl_context(const struct tls *tls)
 {
 	return tls ? tls->ctx : NULL;
 }
+
+
+/*
+ * RFC 5922
+ *
+ * Subject Alternative Names (SANs)
+ */
+bool tls_verify_peer_san(const struct tls_conn *tc, const char *host)
+{
+	STACK_OF(GENERAL_NAME) *san_names;
+	X509 *cert;
+	bool match = false;
+	int i;
+	int err;
+
+	re_printf("---- tls: verify SAN: '%s'\n", host);
+
+	if (!tc || !host)
+		return false;
+
+	cert = SSL_get_peer_certificate(tc->ssl);
+	if (!cert)
+		return false;
+
+	san_names = X509_get_ext_d2i(cert, NID_subject_alt_name, NULL, NULL);
+	if (san_names) {
+		for (i=0; i<sk_GENERAL_NAME_num(san_names); i++) {
+
+			const GENERAL_NAME *name;
+			struct pl pl;
+			unsigned char *p = 0;
+			unsigned len;
+			bool lmatch;
+
+			name = sk_GENERAL_NAME_value(san_names, i);
+
+			switch (name->type) {
+
+			case GEN_DNS:
+				len = ASN1_STRING_to_UTF8(&p, name->d.ia5);
+
+				pl.p = (char *)p;
+				pl.l = len;
+
+				lmatch = (0 == pl_strcasecmp(&pl, host));
+				if (lmatch)
+					match = true;
+
+				re_printf("tls: %5s [%u] type DNS: '%r'\n",
+					  lmatch ? "Match" : "", i, &pl);
+				break;
+
+			default:
+				re_printf("cert: unknown type %d\n",
+					  name->type);
+				break;
+			}
+		}
+	}
+	else {
+		char cn[256];
+
+		err = tls_peer_common_name(tc, cn, sizeof(cn));
+		if (err)
+			goto out;
+
+		match = (0==str_casecmp(host, cn));
+	}
+
+ out:
+	if (san_names)
+		sk_GENERAL_NAME_pop_free(san_names, GENERAL_NAME_free);
+	if (cert)
+		X509_free(cert);
+
+	return match;
+}