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-rw-r--r--openbsc/src/nat/bsc_mgcp_utils.c473
1 files changed, 473 insertions, 0 deletions
diff --git a/openbsc/src/nat/bsc_mgcp_utils.c b/openbsc/src/nat/bsc_mgcp_utils.c
new file mode 100644
index 000000000..2dbf1fd00
--- /dev/null
+++ b/openbsc/src/nat/bsc_mgcp_utils.c
@@ -0,0 +1,473 @@
+/*
+ * (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010 by On-Waves
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <openbsc/bsc_nat.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/bssap.h>
+#include <openbsc/debug.h>
+#include <openbsc/mgcp.h>
+#include <openbsc/mgcp_internal.h>
+
+#include <osmocore/talloc.h>
+
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <errno.h>
+#include <unistd.h>
+
+int bsc_mgcp_assign(struct sccp_connections *con, struct msgb *msg)
+{
+ struct tlv_parsed tp;
+ u_int16_t cic;
+ u_int8_t timeslot;
+ u_int8_t multiplex;
+
+ if (!msg->l3h) {
+ LOGP(DNAT, LOGL_ERROR, "Assignment message should have l3h pointer.\n");
+ return -1;
+ }
+
+ if (msgb_l3len(msg) < 3) {
+ LOGP(DNAT, LOGL_ERROR, "Assignment message has not enough space for GSM0808.\n");
+ return -1;
+ }
+
+ tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 3, msgb_l3len(msg) - 3, 0, 0);
+ if (!TLVP_PRESENT(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE)) {
+ LOGP(DNAT, LOGL_ERROR, "Circuit identity code not found in assignment message.\n");
+ return -1;
+ }
+
+ cic = ntohs(*(u_int16_t *)TLVP_VAL(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE));
+ timeslot = cic & 0x1f;
+ multiplex = (cic & ~0x1f) >> 5;
+
+ con->msc_timeslot = (32 * multiplex) + timeslot;
+ con->bsc_timeslot = con->msc_timeslot;
+ return 0;
+}
+
+void bsc_mgcp_clear(struct sccp_connections *con)
+{
+ con->msc_timeslot = -1;
+ con->bsc_timeslot = -1;
+}
+
+void bsc_mgcp_free_endpoint(struct bsc_nat *nat, int i)
+{
+ if (nat->bsc_endpoints[i].transaction_id) {
+ talloc_free(nat->bsc_endpoints[i].transaction_id);
+ nat->bsc_endpoints[i].transaction_id = NULL;
+ }
+
+ nat->bsc_endpoints[i].bsc = NULL;
+ mgcp_free_endp(&nat->mgcp_cfg->endpoints[i]);
+}
+
+void bsc_mgcp_free_endpoints(struct bsc_nat *nat)
+{
+ int i;
+
+ for (i = 1; i < nat->mgcp_cfg->number_endpoints; ++i)
+ bsc_mgcp_free_endpoint(nat, i);
+}
+
+struct bsc_connection *bsc_mgcp_find_con(struct bsc_nat *nat, int endpoint)
+{
+ struct sccp_connections *sccp;
+
+ llist_for_each_entry(sccp, &nat->sccp_connections, list_entry) {
+ if (sccp->msc_timeslot == -1)
+ continue;
+ if (mgcp_timeslot_to_endpoint(0, sccp->msc_timeslot) != endpoint)
+ continue;
+
+ return sccp->bsc;
+ }
+
+ LOGP(DMGCP, LOGL_ERROR, "Failed to find the connection.\n");
+ return NULL;
+}
+
+int bsc_mgcp_policy_cb(struct mgcp_config *cfg, int endpoint, int state, const char *transaction_id)
+{
+ struct bsc_nat *nat;
+ struct bsc_endpoint *bsc_endp;
+ struct bsc_connection *bsc_con;
+ struct mgcp_endpoint *mgcp_endp;
+ struct msgb *bsc_msg;
+
+ nat = cfg->data;
+ bsc_endp = &nat->bsc_endpoints[endpoint];
+ mgcp_endp = &nat->mgcp_cfg->endpoints[endpoint];
+
+ bsc_con = bsc_mgcp_find_con(nat, endpoint);
+
+ if (!bsc_con) {
+ LOGP(DMGCP, LOGL_ERROR, "Did not find BSC for a new connection on 0x%x for %d\n", endpoint, state);
+
+ switch (state) {
+ case MGCP_ENDP_CRCX:
+ return MGCP_POLICY_REJECT;
+ break;
+ case MGCP_ENDP_DLCX:
+ return MGCP_POLICY_CONT;
+ break;
+ case MGCP_ENDP_MDCX:
+ return MGCP_POLICY_CONT;
+ break;
+ default:
+ LOGP(DMGCP, LOGL_FATAL, "Unhandled state: %d\n", state);
+ return MGCP_POLICY_CONT;
+ break;
+ }
+ }
+
+ if (bsc_endp->transaction_id) {
+ LOGP(DMGCP, LOGL_ERROR, "One transaction with id '%s' on 0x%x\n",
+ bsc_endp->transaction_id, endpoint);
+ talloc_free(bsc_endp->transaction_id);
+ }
+
+ bsc_endp->transaction_id = talloc_strdup(nat, transaction_id);
+ bsc_endp->bsc = bsc_con;
+ bsc_endp->pending_delete = state == MGCP_ENDP_DLCX;
+
+ /* we need to update some bits */
+ if (state == MGCP_ENDP_CRCX) {
+ struct sockaddr_in sock;
+ socklen_t len = sizeof(sock);
+ if (getpeername(bsc_con->write_queue.bfd.fd, (struct sockaddr *) &sock, &len) != 0) {
+ LOGP(DMGCP, LOGL_ERROR, "Can not get the peername...%d/%s\n",
+ errno, strerror(errno));
+ } else {
+ mgcp_endp->bts = sock.sin_addr;
+ }
+ }
+
+ /* we need to generate a new and patched message */
+ bsc_msg = bsc_mgcp_rewrite((char *) nat->mgcp_msg, nat->mgcp_length,
+ nat->mgcp_cfg->source_addr, mgcp_endp->rtp_port);
+ if (!bsc_msg) {
+ LOGP(DMGCP, LOGL_ERROR, "Failed to patch the msg.\n");
+ return MGCP_POLICY_CONT;
+ }
+
+ bsc_write_mgcp_msg(bsc_con, bsc_msg);
+ return MGCP_POLICY_DEFER;
+}
+
+/*
+ * We have received a msg from the BSC. We will see if we know
+ * this transaction and if it belongs to the BSC. Then we will
+ * need to patch the content to point to the local network and we
+ * need to update the I: that was assigned by the BSS.
+ */
+void bsc_mgcp_forward(struct bsc_connection *bsc, struct msgb *msg)
+{
+ struct msgb *output;
+ struct bsc_endpoint *bsc_endp = NULL;
+ struct mgcp_endpoint *endp = NULL;
+ int i, code;
+ char transaction_id[60];
+
+ /* Some assumption that our buffer is big enough.. and null terminate */
+ if (msgb_l2len(msg) > 2000) {
+ LOGP(DMGCP, LOGL_ERROR, "MGCP message too long.\n");
+ return;
+ }
+
+ msg->l2h[msgb_l2len(msg)] = '\0';
+
+ if (bsc_mgcp_parse_response((const char *) msg->l2h, &code, transaction_id) != 0) {
+ LOGP(DMGCP, LOGL_ERROR, "Failed to parse response code.\n");
+ return;
+ }
+
+ for (i = 1; i < bsc->nat->mgcp_cfg->number_endpoints; ++i) {
+ if (bsc->nat->bsc_endpoints[i].bsc != bsc)
+ continue;
+ /* no one listening? a bug? */
+ if (!bsc->nat->bsc_endpoints[i].transaction_id)
+ continue;
+ if (strcmp(transaction_id, bsc->nat->bsc_endpoints[i].transaction_id) != 0)
+ continue;
+
+ endp = &bsc->nat->mgcp_cfg->endpoints[i];
+ bsc_endp = &bsc->nat->bsc_endpoints[i];
+ break;
+ }
+
+ if (!bsc_endp) {
+ LOGP(DMGCP, LOGL_ERROR, "Could not find active endpoint: %s for msg: '%s'\n",
+ transaction_id, (const char *) msg->l2h);
+ return;
+ }
+
+ /* free some stuff */
+ talloc_free(bsc_endp->transaction_id);
+ bsc_endp->transaction_id = NULL;
+
+ /* make it point to our endpoint */
+ endp->ci = bsc_mgcp_extract_ci((const char *) msg->l2h);
+ output = bsc_mgcp_rewrite((char * ) msg->l2h, msgb_l2len(msg),
+ bsc->nat->mgcp_cfg->source_addr, endp->rtp_port);
+
+ if (bsc_endp->pending_delete) {
+ mgcp_free_endp(endp);
+ bsc_endp->bsc = NULL;
+ bsc_endp->pending_delete = 0;
+ }
+
+ if (!output) {
+ LOGP(DMGCP, LOGL_ERROR, "Failed to rewrite MGCP msg.\n");
+ return;
+ }
+
+ if (write_queue_enqueue(&bsc->nat->mgcp_queue, output) != 0) {
+ LOGP(DMGCP, LOGL_ERROR, "Failed to queue MGCP msg.\n");
+ msgb_free(output);
+ }
+}
+
+int bsc_mgcp_parse_response(const char *str, int *code, char transaction[60])
+{
+ /* we want to parse two strings */
+ return sscanf(str, "%3d %59s\n", code, transaction) != 2;
+}
+
+int bsc_mgcp_extract_ci(const char *str)
+{
+ int ci;
+ char *res = strstr(str, "I: ");
+ if (!res)
+ return CI_UNUSED;
+
+ if (sscanf(res, "I: %d", &ci) != 1)
+ return CI_UNUSED;
+ return ci;
+}
+
+/* we need to replace some strings... */
+struct msgb *bsc_mgcp_rewrite(char *input, int length, const char *ip, int port)
+{
+ static const char *ip_str = "c=IN IP4 ";
+ static const char *aud_str = "m=audio ";
+
+ char buf[128];
+ char *running, *token;
+ struct msgb *output;
+
+ if (length > 4096 - 128) {
+ LOGP(DMGCP, LOGL_ERROR, "Input is too long.\n");
+ return NULL;
+ }
+
+ output = msgb_alloc_headroom(4096, 128, "MGCP rewritten");
+ if (!output) {
+ LOGP(DMGCP, LOGL_ERROR, "Failed to allocate new MGCP msg.\n");
+ return NULL;
+ }
+
+ running = input;
+ output->l2h = output->data;
+ for (token = strsep(&running, "\n"); running; token = strsep(&running, "\n")) {
+ int len = strlen(token);
+ int cr = len > 0 && token[len - 1] == '\r';
+
+ if (strncmp(ip_str, token, (sizeof ip_str) - 1) == 0) {
+ output->l3h = msgb_put(output, strlen(ip_str));
+ memcpy(output->l3h, ip_str, strlen(ip_str));
+ output->l3h = msgb_put(output, strlen(ip));
+ memcpy(output->l3h, ip, strlen(ip));
+
+ if (cr) {
+ output->l3h = msgb_put(output, 2);
+ output->l3h[0] = '\r';
+ output->l3h[1] = '\n';
+ } else {
+ output->l3h = msgb_put(output, 1);
+ output->l3h[0] = '\n';
+ }
+ } else if (strncmp(aud_str, token, (sizeof aud_str) - 1) == 0) {
+ int payload;
+ if (sscanf(token, "m=audio %*d RTP/AVP %d", &payload) != 1) {
+ LOGP(DMGCP, LOGL_ERROR, "Could not parsed audio line.\n");
+ msgb_free(output);
+ return NULL;
+ }
+
+ snprintf(buf, sizeof(buf)-1, "m=audio %d RTP/AVP %d%s",
+ port, payload, cr ? "\r\n" : "\n");
+ buf[sizeof(buf)-1] = '\0';
+
+ output->l3h = msgb_put(output, strlen(buf));
+ memcpy(output->l3h, buf, strlen(buf));
+ } else {
+ output->l3h = msgb_put(output, len + 1);
+ memcpy(output->l3h, token, len);
+ output->l3h[len] = '\n';
+ }
+ }
+
+ return output;
+}
+
+static int mgcp_do_read(struct bsc_fd *fd)
+{
+ struct bsc_nat *nat;
+ struct msgb *msg, *resp;
+ int rc;
+
+ nat = fd->data;
+
+ rc = read(fd->fd, nat->mgcp_msg, sizeof(nat->mgcp_msg) - 1);
+ if (rc <= 0) {
+ LOGP(DMGCP, LOGL_ERROR, "Failed to read errno: %d\n", errno);
+ return -1;
+ }
+
+ nat->mgcp_msg[rc] = '\0';
+ nat->mgcp_length = rc;
+
+ msg = msgb_alloc(sizeof(nat->mgcp_msg), "MGCP GW Read");
+ if (!msg) {
+ LOGP(DMGCP, LOGL_ERROR, "Failed to create buffer.\n");
+ return -1;
+ }
+
+ msg->l2h = msgb_put(msg, rc);
+ memcpy(msg->l2h, nat->mgcp_msg, msgb_l2len(msg));
+ resp = mgcp_handle_message(nat->mgcp_cfg, msg);
+ msgb_free(msg);
+
+ /* we do have a direct answer... e.g. AUEP */
+ if (resp) {
+ if (write_queue_enqueue(&nat->mgcp_queue, resp) != 0) {
+ LOGP(DMGCP, LOGL_ERROR, "Failed to enqueue msg.\n");
+ msgb_free(resp);
+ }
+ }
+
+ return 0;
+}
+
+static int mgcp_do_write(struct bsc_fd *bfd, struct msgb *msg)
+{
+ int rc;
+
+ rc = write(bfd->fd, msg->data, msg->len);
+
+ if (rc != msg->len) {
+ LOGP(DMGCP, LOGL_ERROR, "Failed to write msg to MGCP CallAgent.\n");
+ return -1;
+ }
+
+ return rc;
+}
+
+int bsc_mgcp_init(struct bsc_nat *nat)
+{
+ int on;
+ struct sockaddr_in addr;
+
+ if (!nat->mgcp_cfg->call_agent_addr) {
+ LOGP(DMGCP, LOGL_ERROR, "The BSC nat requires the call agent ip to be set.\n");
+ return -1;
+ }
+
+ if (nat->mgcp_cfg->bts_ip) {
+ LOGP(DMGCP, LOGL_ERROR, "Do not set the BTS ip for the nat.\n");
+ return -1;
+ }
+
+ nat->mgcp_queue.bfd.fd = socket(AF_INET, SOCK_DGRAM, 0);
+ if (nat->mgcp_queue.bfd.fd < 0) {
+ LOGP(DMGCP, LOGL_ERROR, "Failed to create MGCP socket. errno: %d\n", errno);
+ return -1;
+ }
+
+ on = 1;
+ setsockopt(nat->mgcp_queue.bfd.fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
+
+ addr.sin_family = AF_INET;
+ addr.sin_port = htons(nat->mgcp_cfg->source_port);
+ inet_aton(nat->mgcp_cfg->source_addr, &addr.sin_addr);
+
+ if (bind(nat->mgcp_queue.bfd.fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
+ LOGP(DMGCP, LOGL_ERROR, "Failed to bind. errno: %d\n", errno);
+ close(nat->mgcp_queue.bfd.fd);
+ nat->mgcp_queue.bfd.fd = -1;
+ return -1;
+ }
+
+ addr.sin_port = htons(2727);
+ inet_aton(nat->mgcp_cfg->call_agent_addr, &addr.sin_addr);
+ if (connect(nat->mgcp_queue.bfd.fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
+ LOGP(DMGCP, LOGL_ERROR, "Failed to connect to: '%s'. errno: %d\n",
+ nat->mgcp_cfg->call_agent_addr, errno);
+ close(nat->mgcp_queue.bfd.fd);
+ nat->mgcp_queue.bfd.fd = -1;
+ return -1;
+ }
+
+ write_queue_init(&nat->mgcp_queue, 10);
+ nat->mgcp_queue.bfd.when = BSC_FD_READ;
+ nat->mgcp_queue.bfd.data = nat;
+ nat->mgcp_queue.read_cb = mgcp_do_read;
+ nat->mgcp_queue.write_cb = mgcp_do_write;
+
+ if (bsc_register_fd(&nat->mgcp_queue.bfd) != 0) {
+ LOGP(DMGCP, LOGL_ERROR, "Failed to register MGCP fd.\n");
+ close(nat->mgcp_queue.bfd.fd);
+ nat->mgcp_queue.bfd.fd = -1;
+ return -1;
+ }
+
+ /* some more MGCP config handling */
+ nat->mgcp_cfg->audio_payload = -1;
+ nat->mgcp_cfg->data = nat;
+ nat->mgcp_cfg->policy_cb = bsc_mgcp_policy_cb;
+ nat->bsc_endpoints = talloc_zero_array(nat,
+ struct bsc_endpoint,
+ nat->mgcp_cfg->number_endpoints + 1);
+
+ return 0;
+}
+
+void bsc_mgcp_clear_endpoints_for(struct bsc_connection *bsc)
+{
+ int i;
+ for (i = 1; i < bsc->nat->mgcp_cfg->number_endpoints; ++i) {
+ struct bsc_endpoint *bsc_endp = &bsc->nat->bsc_endpoints[i];
+
+ if (bsc_endp->bsc != bsc)
+ continue;
+
+ bsc_endp->bsc = NULL;
+ bsc_endp->pending_delete = 0;
+ if (bsc_endp->transaction_id)
+ talloc_free(bsc_endp->transaction_id);
+ bsc_endp->transaction_id = NULL;
+ mgcp_free_endp(&bsc->nat->mgcp_cfg->endpoints[i]);
+ }
+}
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