--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rtp-mgr/alloc.c	Sat Mar 11 20:19:14 2023 -0800
@@ -0,0 +1,66 @@
+/*
+ * In this module we implement our RTP port allocation operation.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <syslog.h>
+#include <unistd.h>
+#include "../include/tmgw_const.h"
+#include "struct.h"
+#include "select.h"
+
+get_rtp_port_pair(roe, brc)
+	struct rtp_one_end *roe;
+	struct bind_range_cfg *brc;
+{
+	struct sockaddr_in sin;
+	unsigned tries, rtp_port;
+	int rc;
+
+	sin.sin_family = AF_INET;
+	sin.sin_addr = brc->bind_ip;
+	for (tries = brc->port_tries; tries; tries--) {
+		rtp_port = brc->port_next;
+		brc->port_next += 2;
+		if (brc->port_next >= brc->port_range_end)
+			brc->port_next = brc->port_range_start;
+		sin.sin_port = htons(rtp_port);
+		roe->rtp_fd = socket(AF_INET, SOCK_DGRAM, 0);
+		if (roe->rtp_fd < 0) {
+			syslog(LOG_CRIT, "socket(AF_INET, SOCK_DGRAM, 0): %m");
+			return(-1);
+		}
+		rc = bind(roe->rtp_fd, (struct sockaddr *) &sin, sizeof sin);
+		if (rc < 0) {
+			close(roe->rtp_fd);
+			continue;
+		}
+		bcopy(&sin, &roe->bound_addr, sizeof(struct sockaddr_in));
+		sin.sin_port = htons(rtp_port+1);
+		roe->rtcp_fd = socket(AF_INET, SOCK_DGRAM, 0);
+		if (roe->rtcp_fd < 0) {
+			syslog(LOG_CRIT, "socket(AF_INET, SOCK_DGRAM, 0): %m");
+			close(roe->rtp_fd);
+			return(-1);
+		}
+		rc = bind(roe->rtcp_fd, (struct sockaddr *) &sin, sizeof sin);
+		if (rc < 0) {
+			close(roe->rtp_fd);
+			close(roe->rtcp_fd);
+			continue;
+		}
+		/* all good! */
+		return(0);
+	}
+	/* couldn't find a free port pair */
+	return(-1);
+}