--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libsip/out_msg.c	Tue Sep 06 20:29:44 2022 -0800
@@ -0,0 +1,73 @@
+/*
+ * Functions for constructing outgoing SIP messages.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <strings.h>
+
+#include "out_msg.h"
+
+start_request_out_msg(msg, method, uri)
+	struct sip_msg_out *msg;
+	char *method, *uri;
+{
+	unsigned len;
+
+	len = strlen(method) + strlen(uri) + (2 + 7 + 2);
+	if (len + 2 > MAX_SIP_TX_PACKET)
+		return(-1);
+	sprintf(msg->buf, "%s %s SIP/2.0\r\n", method, uri);
+	msg->msg_len = len;
+	return(0);
+}
+
+start_response_out_msg(msg, status)
+	struct sip_msg_out *msg;
+	char *status;
+{
+	unsigned len;
+
+	len = strlen(status) + (8 + 2);
+	if (len + 2 > MAX_SIP_TX_PACKET)
+		return(-1);
+	sprintf(msg->buf, "SIP/2.0 %s\r\n", status);
+	msg->msg_len = len;
+	return(0);
+}
+
+out_msg_add_header(msg, name, value)
+	struct sip_msg_out *msg;
+	char *name, *value;
+{
+	unsigned len;
+
+	len = strlen(name) + strlen(value) + 4;
+	if (msg->msg_len + len + 2 > MAX_SIP_TX_PACKET)
+		return(-1);
+	sprintf(msg->buf + msg->msg_len, "%s: %s\r\n", name, value);
+	msg->msg_len += len;
+	return(0);
+}
+
+out_msg_finish(msg)
+	struct sip_msg_out *msg;
+{
+	msg->buf[msg->msg_len++] = '\r';
+	msg->buf[msg->msg_len++] = '\n';
+	return(0);
+}
+
+out_msg_finish_body(msg, body, bodylen)
+	struct sip_msg_out *msg;
+	char *body;
+	unsigned bodylen;
+{
+	msg->buf[msg->msg_len++] = '\r';
+	msg->buf[msg->msg_len++] = '\n';
+	if (msg->msg_len + bodylen > MAX_SIP_TX_PACKET)
+		return(-1);
+	bcopy(body, msg->buf + msg->msg_len, bodylen);
+	msg->msg_len += bodylen;
+	return(0);
+}