--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sip-out/uac_out.c	Tue Oct 11 23:04:01 2022 -0800
@@ -0,0 +1,190 @@
+/*
+ * In this module we implement generation of outgoing SIP messages
+ * in the UAC role.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/time.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 "../include/out_routes.h"
+#include "../libsip/out_msg.h"
+#include "../libsip/sdp.h"
+#include "call.h"
+
+extern struct call *find_call_by_sip_id();
+
+extern struct in_addr sip_bind_ip;
+extern unsigned sip_bind_port;
+extern unsigned max_forwards;
+extern struct timeval cur_event_time;
+
+add_req_boilerplate(msg, call, cseq, to_tag)
+	struct sip_msg_out *msg;
+	struct call *call;
+	char *cseq, *to_tag;
+{
+	char strbuf[256];
+	int rc;
+
+	sprintf(strbuf, "SIP/2.0/UDP %s:%u",
+		inet_ntoa(sip_bind_ip), sip_bind_port);
+	rc = out_msg_add_header(msg, "Via", strbuf);
+	if (rc < 0)
+		return rc;
+	rc = out_msg_add_header(msg, "From", call->from_header);
+	if (rc < 0)
+		return rc;
+	if (to_tag && to_tag[0]) {
+		sprintf(strbuf, "<%s>;tag=%s", call->to_uri, to_tag);
+		rc = out_msg_add_header(msg, "To", strbuf);
+	} else
+		rc = out_msg_add_header(msg, "To", call->to_uri);
+	if (rc < 0)
+		return rc;
+	rc = out_msg_add_header(msg, "Call-ID", call->sip_call_id);
+	if (rc < 0)
+		return rc;
+	rc = out_msg_add_header(msg, "CSeq", cseq);
+	if (rc < 0)
+		return rc;
+	sprintf(strbuf, "%u", max_forwards);
+	return out_msg_add_header(msg, "Max-Forwards", strbuf);
+}
+
+add_contact_header(msg)
+	struct sip_msg_out *msg;
+{
+	char strbuf[80];
+
+	sprintf(strbuf, "<sip:%s:%u;transport=udp>",
+		inet_ntoa(sip_bind_ip), sip_bind_port);
+	return out_msg_add_header(msg, "Contact", strbuf);
+}
+
+fill_invite_req_msg(msg, call)
+	struct sip_msg_out *msg;
+	struct call *call;
+{
+	struct sdp_gen sdp;
+	int rc;
+
+	rc = start_request_out_msg(msg, "INVITE", call->to_uri);
+	if (rc < 0)
+		return rc;
+	rc = add_req_boilerplate(msg, call, "1 INVITE", (char *) 0);
+	if (rc < 0)
+		return rc;
+	rc = add_contact_header(msg);
+	if (rc < 0)
+		return rc;
+	rc = out_msg_add_header(msg, "Content-Type", "application/sdp");
+	if (rc < 0)
+		return rc;
+	bzero(&sdp, sizeof sdp);
+	sdp.conn_ip = call->pstn_rtp_local.sin_addr;
+	sdp.conn_port = ntohs(call->pstn_rtp_local.sin_port);
+	sdp.codec_mask = SDP_CODEC_MASK_BOTH;
+	sdp.session_id = sdp.conn_port << 16;
+	sdp.owner_ip = sip_bind_ip;
+	return out_msg_finish_sdp(msg, &sdp);
+}
+
+fill_cancel_req_msg(msg, call)
+	struct sip_msg_out *msg;
+	struct call *call;
+{
+	int rc;
+
+	rc = start_request_out_msg(msg, "CANCEL", call->to_uri);
+	if (rc < 0)
+		return rc;
+	rc = add_req_boilerplate(msg, call, "1 CANCEL", (char *) 0);
+	if (rc < 0)
+		return rc;
+	out_msg_finish(msg);
+	return 0;
+}
+
+fill_bye_req_msg(msg, call)
+	struct sip_msg_out *msg;
+	struct call *call;
+{
+	int rc;
+
+	rc = start_request_out_msg(msg, "BYE", call->to_uri);
+	if (rc < 0)
+		return rc;
+	rc = add_req_boilerplate(msg, call, "2 BYE", call->to_tag);
+	if (rc < 0)
+		return rc;
+	out_msg_finish(msg);
+	return 0;
+}
+
+void
+start_sip_out(call)
+	struct call *call;
+{
+	struct sip_msg_out msg;
+	int rc;
+
+	sprintf(call->sip_call_id, "%08u_%u@%s",
+		(unsigned)(cur_event_time.tv_sec % 100000000),
+		ntohs(call->pstn_rtp_local.sin_port), inet_ntoa(sip_bind_ip));
+	if (find_call_by_sip_id(call->sip_call_id)) {
+		syslog(LOG_ERR, "generated Call-ID collision!");
+		call->overall_state = OVERALL_STATE_TEARDOWN;
+		disconnect_mncc(call, GSM48_CAUSE_LOC_PRN_S_LU,
+				GSM48_CC_CAUSE_SWITCH_CONG);
+		disconnect_tmgw(call);
+		return;
+	}
+	sprintf(call->from_header, "<sip:%s@%s>;tag=out%u", call->from_user,
+		inet_ntoa(sip_bind_ip), ntohs(call->pstn_rtp_local.sin_port));
+	rc = fill_invite_req_msg(&msg, call);
+	if (rc < 0) {
+		syslog(LOG_CRIT, "generated SIP INVITE req exceeds msg size!");
+		call->overall_state = OVERALL_STATE_TEARDOWN;
+		disconnect_mncc(call, GSM48_CAUSE_LOC_PRN_S_LU,
+				GSM48_CC_CAUSE_NETWORK_OOO);
+		disconnect_tmgw(call);
+		return;
+	}
+	sip_tx_packet(&msg, &call->udp_sin);
+	call->overall_state = OVERALL_STATE_SIP_OUT;
+	call->sip_call_exists = 1;
+	call->sip_state = SIP_STATE_INV_SENT;
+	call->sip_tx_count = 1;
+}
+
+void
+initiate_sip_cancel(call)
+	struct call *call;
+{
+	struct sip_msg_out msg;
+
+	fill_cancel_req_msg(&msg, call);
+	sip_tx_packet(&msg, &call->udp_sin);
+	call->sip_state = SIP_STATE_CANCEL_SENT;
+	call->sip_tx_count = 1;
+}
+
+void
+initiate_bye(call)
+	struct call *call;
+{
+	struct sip_msg_out msg;
+
+	fill_bye_req_msg(&msg, call);
+	sip_tx_packet(&msg, &call->udp_sin);
+	call->sip_state = SIP_STATE_BYE_SENT;
+	call->sip_tx_count = 1;
+}