--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sip-in/sip_log.c	Tue Sep 06 20:33:56 2022 -0800
@@ -0,0 +1,68 @@
+/*
+ * In this module we implement debug logging of SIP Rx & Tx messages.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+
+struct timeval cur_event_time;
+
+static FILE *logfile;
+
+open_sip_log_file(filename)
+	char *filename;
+{
+	logfile = fopen(filename, "a");
+	if (!logfile) {
+		perror(filename);
+		return(-1);
+	}
+	return(0);
+}
+
+static void
+log_common(msg, msglen, sin, dir)
+	char *msg, *dir;
+	unsigned msglen;
+	struct sockaddr_in *sin;
+{
+	unsigned sec, ms;
+
+	sec = cur_event_time.tv_sec % 86400;
+	ms = cur_event_time.tv_usec / 1000;
+	fprintf(logfile, "Msg %s %s:%u %u bytes %02u:%02u:%02u.%03u\n", dir,
+		inet_ntoa(sin->sin_addr), ntohs(sin->sin_port), msglen,
+		sec / 3600, (sec / 60) % 60, sec % 60, ms);
+	fwrite(msg, 1, msglen, logfile);
+	putc('\n', logfile);
+	fflush(logfile);
+}
+
+void
+log_sip_msg_rx(msg, msglen, sin)
+	char *msg;
+	unsigned msglen;
+	struct sockaddr_in *sin;
+{
+	if (!logfile)
+		return;
+	log_common(msg, msglen, sin, "from");
+}
+
+void
+log_sip_msg_tx(msg, msglen, sin)
+	char *msg;
+	unsigned msglen;
+	struct sockaddr_in *sin;
+{
+	if (!logfile)
+		return;
+	log_common(msg, msglen, sin, "to");
+}