--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sip-manual-out/bye_in.c	Sat Oct 08 23:01:32 2022 -0800
@@ -0,0 +1,68 @@
+/*
+ * Here we handle incoming BYE requests in the UAS role.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include "../libsip/parse.h"
+#include "../libsip/uas_basic.h"
+#include "../libsip/out_msg.h"
+
+extern char call_id[];
+
+static void
+bye_correct_call(req, ess, sin)
+	struct sip_pkt_rx *req;
+	struct uas_parse_hdrs *ess;
+	struct sockaddr_in *sin;
+{
+	struct sip_msg_out resp;
+	int rc;
+
+	printf("Received BYE for our call, responding with 200\n");
+	start_response_out_msg(&resp, "200 OK");
+	rc = add_resp_basic_headers(&resp, ess, req->req_method);
+	if (rc < 0) {
+		fprintf(stderr, "sending 200 response: msg length exceeded\n");
+		return;
+	}
+	out_msg_finish(&resp);
+	sip_tx_packet(&resp, sin);
+}
+
+static void
+bye_unknown_call(req, ess, sin)
+	struct sip_pkt_rx *req;
+	struct uas_parse_hdrs *ess;
+	struct sockaddr_in *sin;
+{
+	struct sip_msg_out resp;
+	int rc;
+
+	printf("Received BYE for unknown call, responding with 481\n");
+	start_response_out_msg(&resp, "481 Call-ID not found");
+	rc = add_resp_basic_headers(&resp, ess, req->req_method);
+	if (rc < 0) {
+		fprintf(stderr, "sending 481 response: msg length exceeded\n");
+		return;
+	}
+	out_msg_finish(&resp);
+	sip_tx_packet(&resp, sin);
+}
+
+void
+handle_bye_req(req, ess, sin)
+	struct sip_pkt_rx *req;
+	struct uas_parse_hdrs *ess;
+	struct sockaddr_in *sin;
+{
+	if (!strcmp(ess->call_id, call_id))
+		bye_correct_call(req, ess, sin);
+	else
+		bye_unknown_call(req, ess, sin);
+}