implement simplistic UDP transport for TCAP

Normally, TCAP is not spoken directly on top of UDP, however this
makes it really easy to test...

src/scXp.c

@@ -1,13 +1,17 @@
 /* SCCP / SCTP+SUA interface */
 
 #include <stdio.h>
+#include <unistd.h>
 #include <fcntl.h>
+#include <errno.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-
+#include <sys/socket.h>
+#include <netinet/in.h>
 
 #include <osmocore/logging.h>
 #include <osmocore/msgb.h>
+#include <osmocore/talloc.h>
 
 #include "tcap_user.h"
 #include "tcap.h"
@@ -18,14 +22,103 @@ int tcap_tco_n_unitdata_ind(struct tcap_transport_entity *se, struct msgb *msg);
 /* prototype of what we need to call in case of incoming NOTICE */
 int tcap_tco_n_notice_ind(struct tcap_transport_entity *se);
 
+
+/***********************************************************************/
+/* Simple UDP transport (not according to any kind of official spec) */
+/***********************************************************************/
+
+static int tcap_tp_udp_unitdata_req(struct tcap_transport_entity *se, struct msgb *msg)
+{
+	return write_queue_enqueue(&se->udp.write_queue, msg);
+}
+
+/* called by the write queue / FD magic in case we need to write a message */
+static int udp_write_cb(struct bsc_fd *fd, struct msgb *msg)
+{
+	struct write_queue *wq = container_of(fd, struct write_queue, bfd);
+	struct tcap_transport_entity *tte = container_of(wq, struct tcap_transport_entity, udp.write_queue);
+
+	return sendto(fd->fd, msg->data, msg->len, 0, (struct sockaddr *) &tte->remote_addr, sizeof(tte->remote_addr));
+}
+
+/* called by write queue / FD magic in case the socket has some data */
+static int udp_read_cb(struct bsc_fd *fd)
+{
+	struct write_queue *wq = container_of(fd, struct write_queue, bfd);
+	struct tcap_transport_entity *tte = container_of(wq, struct tcap_transport_entity, udp.write_queue);
+	struct msgb *msg = msgb_alloc_headroom(4096+128, 128, "incoming TCAP/UDP");
+	socklen_t addr_len = sizeof(tte->remote_addr);
+	int rc;
+
+	if (!msg)
+		return -ENOMEM;
+
+	rc = recvfrom(fd->fd, msg->data, msgb_tailroom(msg), 0,
+		      &tte->remote_addr, &addr_len);
+	if (rc < 0)
+		return rc;
+
+	msgb_put(msg, rc);
+
+	return tcap_tco_n_unitdata_ind(tte, msg);
+}
+
+struct tcap_transport_entity *tcap_transp_udp_create(struct sockaddr_storage *local_addr)
+{
+	struct tcap_transport_entity *tte = talloc_zero(NULL, struct tcap_transport_entity);
+	struct write_queue *wq;
+	int rc;
+
+	if (!tte)
+		return NULL;
+
+	memcpy(&tte->local_addr, local_addr, sizeof(tte->local_addr));
+	tte->type = SCXP_T_UDP;
+
+	/* Initialize write queue */
+	wq = &tte->udp.write_queue;
+	write_queue_init(wq, 100);
+	wq->read_cb = udp_read_cb;
+	wq->write_cb = udp_write_cb;
+
+	wq->bfd.fd = socket(tte->local_addr.ss_family, SOCK_DGRAM, IPPROTO_UDP);
+	if (wq->bfd.fd < 0)
+		goto err_free;
+
+	rc = bind(wq->bfd.fd, (struct sockaddr *) &tte->local_addr, sizeof(tte->local_addr));
+	if (rc < 0)
+		goto err_close;
+
+	wq->bfd.when |= BSC_FD_READ;
+	bsc_register_fd(&wq->bfd);
+
+	return tte;
+
+err_close:
+	close(wq->bfd.fd);
+err_free:
+	talloc_free(tte);
+	return NULL;
+}
+
 /* Called by TCAP stack if it wants to request transmission of UNITDATA */
 int tcap_scXp_n_unitdata_req(struct tcap_transport_entity *se, struct msgb *msg)
 {
+	int rc = 0;
+
 	printf("N-UNITDATA.req(%s)\n", hexdump(msg->data, msg->len));
+#if 0
 	int i = open("ber.out", O_CREAT|O_WRONLY|O_TRUNC);
 	write(i, msg->data, msg->len);
 	close(i);
-	tcap_tco_n_unitdata_ind(se, msg);
+#endif
+	switch (se->type) {
+	case SCXP_T_UDP:
+		rc = write_queue_enqueue(&se->udp.write_queue, msg);
+		break;
+	}
+
+	return rc;
 }
 
 

src/tcap_test.c

@@ -3,6 +3,8 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#include <netinet/in.h>
+
 //#include <asn1/OBJECT_IDENTIFIER.h>
 
 #include <osmocore/utils.h>
@@ -10,6 +12,7 @@
 #include "tcap_user.h"
 
 static struct {
+	struct tcap_transport_entity *tte;
 	unsigned int begin_rcvd:1;
 	uint32_t dialg_id;
 } test_state;
@@ -64,6 +67,7 @@ static int send_begin(uint32_t dialg_id, OBJECT_IDENTIFIER_t *app_ctx)
 	memset(&tcdi, 0, sizeof(tcdi));
 	tcdi.dialg_id = dialg_id;
 	tcdi.app_ctx_name = app_ctx;
+	tcdi.transp_ent = test_state.tte;
 
 	return tcap_user_req_dialg(TCAP_PR_TC_BEGIN, &tcdi);
 }
@@ -117,10 +121,30 @@ static int initialize(void)
 
 int main(int argc, char **argv)
 {
+	struct sockaddr_storage ss;
+	struct sockaddr_in *sin = (struct sockaddr_in *)&ss;
+
 	initialize();
 
+	ss.ss_family = AF_INET;
+	sin->sin_addr.s_addr = INADDR_ANY;
+	sin->sin_port = htons(4242);
+
+	test_state.tte = tcap_transp_udp_create(&ss);
+	if (!test_state.tte) {
+		fprintf(stderr, "Cannot create UDP socket\n");
+		exit(1);
+	}
+	/* make sure we sent messages to ourselves */
+	inet_aton("127.0.0.1", &sin->sin_addr);
+	memcpy(&test_state.tte->remote_addr, &ss, sizeof(test_state.tte->remote_addr));
+
 	send_invoke(0x1234, 0, gprs_loc_upd_param, sizeof(gprs_loc_upd_param));
 	send_invoke(0x1234, 1, NULL, 0);
 	send_invoke(0x1234, -1, NULL, 0);
 	send_begin(0x1234, &gprs_loc_upd_ctx_v3_oid);
+
+	while (1) {
+		bsc_select_main(0);
+	}
 }

src/tcap_user.h

@@ -5,6 +5,7 @@
 #include <sys/socket.h>
 
 #include <osmocore/select.h>
+#include <osmocore/write_queue.h>
 
 #include <asn1c/OBJECT_IDENTIFIER.h>
 #include <osmocom/tcap/Parameter.h>
@@ -23,12 +24,12 @@ struct tcap_transport_entity {
 	/* common parts */
 	struct sockaddr_storage local_addr;
 	struct sockaddr_storage remote_addr;
-	struct bsc_fd socket_fd;
 
 	/* type of underlying transport */
 	enum tcap_transport_entity_type type;
 	union {
 		struct {
+			struct write_queue write_queue;
 		} udp;
 		struct {
 		} sccp_ipa;

src/tcu.c

@@ -186,6 +186,8 @@ int tcap_user_req_dialg(enum tcap_primitive prim, struct tcap_dialg_ind *tcdi)
 		switch (prim) {
 		case TCAP_PR_TC_BEGIN:
 			td = tcap_dialg_alloc(tcdi->dialg_id);
+			if (!td)
+				return -EINVAL;
 			break;
 		default:
 			return -EINVAL;
@@ -194,6 +196,7 @@ int tcap_user_req_dialg(enum tcap_primitive prim, struct tcap_dialg_ind *tcdi)
 
 	switch (prim) {
 	case TCAP_PR_TC_BEGIN:
+		td->transp_ent = tcdi->transp_ent;
 		rc = tcap_csl_tc_begin_req(td, tcdi->app_ctx_name, tcdi->user_info);
 		break;
 	case TCAP_PR_TC_CONTINUE:

src/tsl_tco.c

@@ -14,7 +14,7 @@
 uint32_t tid_from_octetstr(struct OCTET_STRING *octstr)
 {
 	if (octstr->size != sizeof(uint32_t))
-		fprintf(stderr, "Transaction ID length != violates spec\n", octstr->size);
+		fprintf(stderr, "Transaction ID length %u != violates spec\n", octstr->size);
 
 	return ntohl(*(uint32_t *)octstr->buf);
 }
@@ -51,6 +51,7 @@ int tcap_tco_n_unitdata_ind(struct tcap_transport_entity *se, struct msgb *msg)
 		tt->tid_local = tcap_trans_id_alloc();
 		/* FIXME: Is TID == no TID ? */
 		/* Send BEGIN.recv to TSM */
+		dialg_by_trans(tt)->transp_ent = se;
 		rc = tcap_tsm_begin_rcvd(tt, tcmsg, msg);
 		break;
 	case TCMessage_PR_continue: