rtpproxy: fix writev error 22:Invalid argument

 - align code with rtpengine implementation for systems with no IOV_MAX defined

(cherry picked from commit 565e25b)

modules/rtpproxy/rtpproxy.c

@@ -2017,42 +2017,47 @@ rtpp_test(struct rtpp_node *node, int isdisabled, int force)
 
 
 #define RTPPROXY_BUF_SIZE 256
+#define OSIP_IOV_MAX 1024
 
 char *
 send_rtpp_command(struct rtpp_node *node, struct iovec *v, int vcnt)
 {
 	struct sockaddr_un addr;
 	int fd, len, i;
+	int max_vcnt=OSIP_IOV_MAX;
 	char *cp;
 	static char buf[RTPPROXY_BUF_SIZE];
 	struct pollfd fds[1];
 
 
 #ifdef IOV_MAX
-	/* normalize vcntl to IOV_MAX, as on some systems this limit is very low (16 on Solaris) */
-	if (vcnt > IOV_MAX) {
+	if (IOV_MAX < OSIP_IOV_MAX)
+		max_vcnt = IOV_MAX;
+#endif
+
+	/* normalize vcntl to max_vcnt, as on some systems this limit is very low (16 on Solaris) */
+	if (vcnt > max_vcnt) {
 		int i, vec_len = 0;
 		/* use buf if possible :) */
-		for (i = IOV_MAX - 1; i < vcnt; i++)
+		for (i = max_vcnt - 1; i < vcnt; i++)
 			vec_len += v[i].iov_len;
 		/* use buf, error otherwise */
 		if (vec_len > RTPPROXY_BUF_SIZE) {
 			LM_ERR("Command too big %d - max %d\n", vec_len, RTPPROXY_BUF_SIZE);
 			return NULL;
 		}
 		cp = buf;
-		for (i = IOV_MAX - 1; i < vcnt; i++) {
+		for (i = max_vcnt - 1; i < vcnt; i++) {
 			memcpy(cp, v[i].iov_base, v[i].iov_len);
 			cp += v[i].iov_len;
 		}
-		i = IOV_MAX - 1;
+		i = max_vcnt - 1;
 		v[i].iov_len = vec_len;
 		v[i].iov_base = buf;
 		/* finally solve the problem */
-		vcnt = IOV_MAX;
+		vcnt = max_vcnt;
 
 	}
-#endif
 
 	len = 0;
 	cp = buf;