--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/smsc-sendmt/main.c	Sun Aug 27 16:36:28 2023 -0800
@@ -0,0 +1,87 @@
+/*
+ * This C module is the main for proto-smsc-sendmt, a command line utility
+ * that constructs an MT-forwardSM.req GSUP message and shoots it over to
+ * proto-smsc-daemon for feeding to OsmoHLR.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <ctype.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/socket.h>
+
+#include <osmocom/gsm/gsup.h>
+
+extern void parse_smsc_addr_arg(const char *arg);
+extern void encode_smsc_addr(struct osmo_gsup_message *gmsg);
+extern int grok_imsi_user_arg(const char *arg, char *dest);
+extern void read_pdu_from_stdin(void);
+
+extern uint8_t tpdu_buf[];
+extern unsigned tpdu_len;
+
+static const uint8_t sm_rp_mr = 0xFF;
+
+int main(int argc, char **argv)
+{
+	struct osmo_gsup_message gmsg;
+	struct msgb *msgb;
+	int rc, sock;
+
+	if (argc != 4) {
+		fprintf(stderr, "usage: %s smsc-addr imsi socket-path\n",
+			argv[0]);
+		exit(1);
+	}
+	parse_smsc_addr_arg(argv[1]);
+	memset(&gmsg, 0, sizeof(gmsg));
+	rc = grok_imsi_user_arg(argv[2], gmsg.imsi);
+	if (rc < 0) {
+		fprintf(stderr, "error: invalid IMSI argument\n");
+		exit(1);
+	}
+	read_pdu_from_stdin();
+
+	/* fill out the rest of GSUP msg */
+	gmsg.message_type = OSMO_GSUP_MSGT_MT_FORWARD_SM_REQUEST;
+	gmsg.message_class = OSMO_GSUP_MESSAGE_CLASS_SMS;
+	gmsg.sm_rp_mr = &sm_rp_mr;
+	gmsg.sm_rp_da_type = OSMO_GSUP_SMS_SM_RP_ODA_NULL;
+	gmsg.sm_rp_oa_type = OSMO_GSUP_SMS_SM_RP_ODA_SMSC_ADDR;
+	encode_smsc_addr(&gmsg);
+	gmsg.sm_rp_ui = tpdu_buf;
+	gmsg.sm_rp_ui_len = tpdu_len;
+
+	/* pack it into an msgb */
+	msgb = msgb_alloc_headroom(4000, 64, "sendmt");
+	if (!msgb) {
+		fprintf(stderr, "error: unable to allocate msgb\n");
+		exit(1);
+	}
+	rc = osmo_gsup_encode(msgb, &gmsg);
+	if (rc < 0) {
+		fprintf(stderr, "error: osmo_gsup_encode() failed\n");
+		exit(1);
+	}
+
+	/* send it off via UNIX socket */
+	sock = osmo_sock_unix_init(SOCK_DGRAM, 0, argv[3], OSMO_SOCK_F_CONNECT);
+	if (sock < 0) {
+		fprintf(stderr, "error connecting to %s\n", argv[3]);
+		exit(1);
+	}
+	rc = send(sock, msgb->data, msgb->len, 0);
+	if (rc < 0) {
+		perror("sending dgram on socket");
+		exit(1);
+	}
+	exit(0);
+}