--- a/sip-in/Makefile	Tue Sep 20 18:58:11 2022 -0800
+++ b/sip-in/Makefile	Tue Sep 20 19:35:34 2022 -0800
@@ -1,7 +1,7 @@
 CC=	gcc
 CFLAGS=	-O2
 PROG=	themwi-sip-in
-OBJS=	call_list.o call_setup.o cancel.o disconnect.o invite.o main.o \
+OBJS=	bye_in.o call_list.o call_setup.o cancel.o disconnect.o invite.o main.o\
 	mgw_ops.o mgw_sock.o mncc_handle.o mncc_sock.o readconf.o retrans.o \
 	sip_ack.o sip_log.o sip_uas.o sip_udp.o
 LIBS=	../libnumdb/libnumdb.a ../libsip/libsip.a ../libutil/libutil.a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sip-in/bye_in.c	Tue Sep 20 19:35:34 2022 -0800
@@ -0,0 +1,94 @@
+/*
+ * Here we implement our handling of incoming SIP BYE requests.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <syslog.h>
+#include "../include/gsm48_const.h"
+#include "../libsip/parse.h"
+#include "../libsip/uas_basic.h"
+#include "../libsip/out_msg.h"
+#include "call.h"
+
+extern struct call *find_call_by_sip_id();
+
+void
+handle_sip_bye(req, ess, sin)
+	struct sip_pkt_rx *req;
+	struct uas_parse_hdrs *ess;
+	struct sockaddr_in *sin;
+{
+	struct call *call;
+	struct sip_msg_out resp;
+	char cseq_str[32];
+	int rc;
+
+	call = find_call_by_sip_id(ess->call_id);
+	if (!call) {
+		start_response_out_msg(&resp, "481 Call-ID not found");
+		rc = add_resp_basic_headers(&resp, ess, req->req_method);
+		if (rc < 0)
+			return;
+		out_msg_finish(&resp);
+		sip_tx_packet(&resp, sin);
+		return;
+	}
+	switch (call->sip_state) {
+	case SIP_STATE_INVITE_PROC:
+	case SIP_STATE_RINGING:
+	case SIP_STATE_RINGING_PRACK:
+		call->overall_state = OVERALL_STATE_TEARDOWN;
+		disconnect_mncc(call, GSM48_CAUSE_LOC_NET_BEYOND,
+				GSM48_CC_CAUSE_NORM_CALL_CLEAR);
+		disconnect_tmgw(call);
+		strcpy(call->invite_fail, "487 Call attempt terminated");
+		signal_invite_error(call);
+		break;
+	case SIP_STATE_INVITE_200:
+	case SIP_STATE_CONNECTED:
+		call->overall_state = OVERALL_STATE_TEARDOWN;
+		disconnect_mncc(call, GSM48_CAUSE_LOC_NET_BEYOND,
+				GSM48_CC_CAUSE_NORM_CALL_CLEAR);
+		disconnect_tmgw(call);
+		call->sip_state = SIP_STATE_ENDED;
+		break;
+	case SIP_STATE_BYE_SENT:
+		call->sip_state = SIP_STATE_ENDED;
+		break;
+	case SIP_STATE_INVITE_ERR:
+	case SIP_STATE_ENDED:
+		break;
+	case SIP_STATE_MSG_SIZE_ERR:
+		return;
+	}
+	/* send 200 response to BYE */
+	start_response_out_msg(&resp, "200 OK");
+	rc = out_msg_add_header(&resp, "From", call->invite_from);
+	if (rc < 0) {
+msg_size_err:	syslog(LOG_ERR, "BYE 200 response length exceeded");
+		call->sip_state = SIP_STATE_MSG_SIZE_ERR;
+		return;
+	}
+	rc = out_msg_add_header(&resp, "To", call->invite_to);
+	if (rc < 0)
+		goto msg_size_err;
+	rc = out_msg_add_header(&resp, "Call-ID", call->sip_call_id);
+	if (rc < 0)
+		goto msg_size_err;
+	sprintf(cseq_str, "%u BYE", ess->cseq_num);
+	rc = out_msg_add_header(&resp, "CSeq", cseq_str);
+	if (rc < 0)
+		goto msg_size_err;
+	rc = out_msg_add_header(&resp, "Via", ess->via);
+	if (rc < 0)
+		goto msg_size_err;
+	out_msg_finish(&resp);
+	sip_tx_packet(&resp, sin);
+}

--- a/sip-in/sip_uas.c	Tue Sep 20 18:58:11 2022 -0800
+++ b/sip-in/sip_uas.c	Tue Sep 20 19:35:34 2022 -0800
@@ -15,16 +15,6 @@
 #include "../libsip/out_msg.h"
 
 static void
-method_tbi(req, ess, sin)
-	struct sip_pkt_rx *req;
-	struct uas_parse_hdrs *ess;
-	struct sockaddr_in *sin;
-{
-	syslog(LOG_ERR, "SIP method %s remains to be implemented",
-		req->req_method);
-}
-
-static void
 unsupported_method(req, ess, sin)
 	struct sip_pkt_rx *req;
 	struct uas_parse_hdrs *ess;
@@ -68,7 +58,7 @@
 	else if (!strcmp(msg->req_method, "CANCEL"))
 		handle_sip_cancel(msg, &ess, sin);
 	else if (!strcmp(msg->req_method, "BYE"))
-		method_tbi(msg, &ess, sin);
+		handle_sip_bye(msg, &ess, sin);
 	else
 		unsupported_method(msg, &ess, sin);
 }