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-rw-r--r--src/libtrau/rtp_proxy.c764
1 files changed, 764 insertions, 0 deletions
diff --git a/src/libtrau/rtp_proxy.c b/src/libtrau/rtp_proxy.c
new file mode 100644
index 000000000..6b38ee5fe
--- /dev/null
+++ b/src/libtrau/rtp_proxy.c
@@ -0,0 +1,764 @@
+/* RTP proxy handling for ip.access nanoBTS */
+
+/* (C) 2009-2013 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <errno.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <sys/time.h> /* gettimeofday() */
+#include <unistd.h> /* get..() */
+#include <time.h> /* clock() */
+#include <sys/utsname.h> /* uname() */
+
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/utils.h>
+#include <openbsc/gsm_data.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/select.h>
+#include <openbsc/debug.h>
+#include <openbsc/rtp_proxy.h>
+#include <openbsc/mncc.h>
+#include <openbsc/trau_upqueue.h>
+
+#include <osmocom/netif/rtp.h>
+
+/* attempt to determine byte order */
+#include <sys/param.h>
+#include <limits.h>
+
+static LLIST_HEAD(rtp_sockets);
+
+/* should we mangle the CNAME inside SDES of RTCP packets? We disable
+ * this by default, as it seems to be not needed */
+static int mangle_rtcp_cname = 0;
+
+enum rtp_bfd_priv {
+ RTP_PRIV_NONE,
+ RTP_PRIV_RTP,
+ RTP_PRIV_RTCP
+};
+
+#define RTP_ALLOC_SIZE 1500
+
+#define RTCP_TYPE_SDES 202
+
+#define RTCP_IE_CNAME 1
+
+
+#define RTP_VERSION 2
+
+/* 33 for FR, all other codecs have smaller size */
+#define MAX_RTP_PAYLOAD_LEN 33
+
+/* decode an rtp frame and create a new buffer with payload */
+static int rtp_decode(struct msgb *msg, uint32_t callref, struct msgb **data)
+{
+ struct msgb *new_msg;
+ struct gsm_data_frame *frame;
+ struct rtp_hdr *rtph = (struct rtp_hdr *)msg->data;
+ struct rtp_x_hdr *rtpxh;
+ uint8_t *payload, *payload_out;
+ int payload_len;
+ int msg_type;
+ int x_len;
+
+ if (msg->len < 12) {
+ DEBUGPC(DLMUX, "received RTP frame too short (len = %d)\n",
+ msg->len);
+ return -EINVAL;
+ }
+ if (rtph->version != RTP_VERSION) {
+ DEBUGPC(DLMUX, "received RTP version %d not supported.\n",
+ rtph->version);
+ return -EINVAL;
+ }
+ payload = msg->data + sizeof(struct rtp_hdr) + (rtph->csrc_count << 2);
+ payload_len = msg->len - sizeof(struct rtp_hdr) - (rtph->csrc_count << 2);
+ if (payload_len < 0) {
+ DEBUGPC(DLMUX, "received RTP frame too short (len = %d, "
+ "csrc count = %d)\n", msg->len, rtph->csrc_count);
+ return -EINVAL;
+ }
+ if (rtph->extension) {
+ if (payload_len < sizeof(struct rtp_x_hdr)) {
+ DEBUGPC(DLMUX, "received RTP frame too short for "
+ "extension header\n");
+ return -EINVAL;
+ }
+ rtpxh = (struct rtp_x_hdr *)payload;
+ x_len = ntohs(rtpxh->length) * 4 + sizeof(struct rtp_x_hdr);
+ payload += x_len;
+ payload_len -= x_len;
+ if (payload_len < 0) {
+ DEBUGPC(DLMUX, "received RTP frame too short, "
+ "extension header exceeds frame length\n");
+ return -EINVAL;
+ }
+ }
+ if (rtph->padding) {
+ if (payload_len < 1) {
+ DEBUGPC(DLMUX, "received RTP frame too short for "
+ "padding length\n");
+ return -EINVAL;
+ }
+ payload_len -= payload[payload_len - 1];
+ if (payload_len < 0) {
+ DEBUGPC(DLMUX, "received RTP frame with padding "
+ "greater than payload\n");
+ return -EINVAL;
+ }
+ }
+
+ switch (rtph->payload_type) {
+ case RTP_PT_GSM_FULL:
+ msg_type = GSM_TCHF_FRAME;
+ if (payload_len != RTP_LEN_GSM_FULL) {
+ DEBUGPC(DLMUX, "received RTP full rate frame with "
+ "payload length != %d (len = %d)\n",
+ RTP_LEN_GSM_FULL, payload_len);
+ return -EINVAL;
+ }
+ break;
+ case RTP_PT_GSM_EFR:
+ msg_type = GSM_TCHF_FRAME_EFR;
+ if (payload_len != RTP_LEN_GSM_EFR) {
+ DEBUGPC(DLMUX, "received RTP extended full rate frame "
+ "with payload length != %d (len = %d)\n",
+ RTP_LEN_GSM_EFR, payload_len);
+ return -EINVAL;
+ }
+ break;
+ case RTP_PT_GSM_HALF:
+ msg_type = GSM_TCHH_FRAME;
+ if (payload_len != RTP_LEN_GSM_HALF) {
+ DEBUGPC(DLMUX, "received RTP half rate frame with "
+ "payload length != %d (len = %d)\n",
+ RTP_LEN_GSM_HALF, payload_len);
+ return -EINVAL;
+ }
+ break;
+ case RTP_PT_AMR:
+ msg_type = GSM_TCH_FRAME_AMR;
+ break;
+ default:
+ DEBUGPC(DLMUX, "received RTP frame with unknown payload "
+ "type %d\n", rtph->payload_type);
+ return -EINVAL;
+ }
+
+ if (payload_len > MAX_RTP_PAYLOAD_LEN ||
+ (rtph->payload_type == RTP_PT_AMR &&
+ payload_len > MAX_RTP_PAYLOAD_LEN - 1)) {
+ DEBUGPC(DLMUX, "RTP payload too large (%d octets)\n",
+ payload_len);
+ return -EINVAL;
+ }
+
+ /* always allocate for the maximum possible size to avoid
+ * fragmentation */
+ new_msg = msgb_alloc(sizeof(struct gsm_data_frame) +
+ MAX_RTP_PAYLOAD_LEN+1, "GSM-DATA (TCH)");
+
+ if (!new_msg)
+ return -ENOMEM;
+ frame = (struct gsm_data_frame *) msgb_put(new_msg, sizeof(struct gsm_data_frame));
+ frame->msg_type = msg_type;
+ frame->callref = callref;
+ if (rtph->payload_type == RTP_PT_AMR) {
+ /* for FR/HR/EFR the length is implicit. In AMR, we
+ * need to make it explicit by using the first byte of
+ * the data[] buffer as length byte */
+ uint8_t *data0 = msgb_put(new_msg, 1);
+ *data0 = payload_len;
+ }
+ payload_out = msgb_put(new_msg, payload_len);
+ memcpy(payload_out, payload, payload_len);
+
+ *data = new_msg;
+ return 0;
+}
+
+/*! \brief encode and send a rtp frame
+ * \param[in] rs RTP socket through which we shall send
+ * \param[in] frame GSM RTP frame to be sent
+ */
+int rtp_send_frame(struct rtp_socket *rs, struct gsm_data_frame *frame)
+{
+ struct rtp_sub_socket *rss = &rs->rtp;
+ struct msgb *msg;
+ struct rtp_hdr *rtph;
+ uint8_t *payload;
+ int payload_type;
+ int payload_len;
+ int duration; /* in samples */
+ int is_bfi = 0;
+
+ if (rs->tx_action != RTP_SEND_DOWNSTREAM) {
+ /* initialize sequences */
+ rs->tx_action = RTP_SEND_DOWNSTREAM;
+ rs->transmit.ssrc = rand();
+ rs->transmit.sequence = random();
+ rs->transmit.timestamp = random();
+ }
+
+ switch (frame->msg_type) {
+ case GSM_TCHF_FRAME:
+ payload_type = RTP_PT_GSM_FULL;
+ payload_len = RTP_LEN_GSM_FULL;
+ duration = RTP_GSM_DURATION;
+ break;
+ case GSM_TCHF_FRAME_EFR:
+ payload_type = RTP_PT_GSM_EFR;
+ payload_len = RTP_LEN_GSM_EFR;
+ duration = RTP_GSM_DURATION;
+ break;
+ case GSM_TCHH_FRAME:
+ payload_type = RTP_PT_GSM_HALF;
+ payload_len = RTP_LEN_GSM_HALF;
+ duration = RTP_GSM_DURATION;
+ break;
+ case GSM_TCH_FRAME_AMR:
+ payload_type = RTP_PT_AMR;
+ payload_len = frame->data[0];
+ duration = RTP_GSM_DURATION;
+ break;
+ case GSM_BAD_FRAME:
+ payload_type = 0;
+ payload_len = 0;
+ duration = RTP_GSM_DURATION;
+ is_bfi = 1;
+ break;
+ default:
+ DEBUGPC(DLMUX, "unsupported message type %d\n",
+ frame->msg_type);
+ return -EINVAL;
+ }
+
+ if (payload_len > MAX_RTP_PAYLOAD_LEN) {
+ DEBUGPC(DLMUX, "RTP payload too large (%d octets)\n",
+ payload_len);
+ return -EINVAL;
+ }
+
+ if (is_bfi) {
+ /* In case of a bad frame, just count and drop packet. */
+ rs->transmit.timestamp += duration;
+ rs->transmit.sequence++;
+ return 0;
+ }
+
+ msg = msgb_alloc(sizeof(struct rtp_hdr) + payload_len, "RTP-GSM");
+ if (!msg)
+ return -ENOMEM;
+ rtph = (struct rtp_hdr *) msgb_put(msg, sizeof(struct rtp_hdr));
+ rtph->version = RTP_VERSION;
+ rtph->padding = 0;
+ rtph->extension = 0;
+ rtph->csrc_count = 0;
+ rtph->marker = 0;
+ rtph->payload_type = payload_type;
+ rtph->sequence = htons(rs->transmit.sequence++);
+ rtph->timestamp = htonl(rs->transmit.timestamp);
+ rs->transmit.timestamp += duration;
+ rtph->ssrc = htonl(rs->transmit.ssrc);
+
+ payload = msgb_put(msg, payload_len);
+ if (frame->msg_type == GSM_TCH_FRAME_AMR)
+ memcpy(payload, frame->data + 1, payload_len);
+ else
+ memcpy(payload, frame->data, payload_len);
+ msgb_enqueue(&rss->tx_queue, msg);
+ rss->bfd.when |= BSC_FD_WRITE;
+
+ return 0;
+}
+
+/* iterate over all chunks in one RTCP message, look for CNAME IEs and
+ * replace all of those with 'new_cname' */
+static int rtcp_sdes_cname_mangle(struct msgb *msg, struct rtcp_hdr *rh,
+ uint16_t *rtcp_len, const char *new_cname)
+{
+ uint8_t *rtcp_end;
+ uint8_t *cur = (uint8_t *) rh;
+ uint8_t tag, len = 0;
+
+ rtcp_end = cur + *rtcp_len;
+ /* move cur to end of RTP header */
+ cur += sizeof(*rh);
+
+ /* iterate over Chunks */
+ while (cur+4 < rtcp_end) {
+ /* skip four bytes SSRC/CSRC */
+ cur += 4;
+
+ /* iterate over IE's inside the chunk */
+ while (cur+1 < rtcp_end) {
+ tag = *cur++;
+ if (tag == 0) {
+ /* end of chunk, skip additional zero */
+ while ((*cur++ == 0) && (cur < rtcp_end)) { }
+ break;
+ }
+ len = *cur++;
+
+ if (tag == RTCP_IE_CNAME) {
+ /* we've found the CNAME, lets mangle it */
+ if (len < strlen(new_cname)) {
+ /* we need to make more space */
+ int increase = strlen(new_cname) - len;
+
+ msgb_push(msg, increase);
+ memmove(cur+len+increase, cur+len,
+ rtcp_end - (cur+len));
+ /* FIXME: we have to respect RTCP
+ * padding/alignment rules! */
+ len += increase;
+ *(cur-1) += increase;
+ rtcp_end += increase;
+ *rtcp_len += increase;
+ }
+ /* copy new CNAME into message */
+ memcpy(cur, new_cname, strlen(new_cname));
+ /* FIXME: zero the padding in case new CNAME
+ * is smaller than old one !!! */
+ }
+ cur += len;
+ }
+ }
+
+ return 0;
+}
+
+static int rtcp_mangle(struct msgb *msg, struct rtp_socket *rs)
+{
+ struct rtp_sub_socket *rss = &rs->rtcp;
+ struct rtcp_hdr *rtph;
+ uint16_t old_len;
+ int rc;
+
+ if (!mangle_rtcp_cname)
+ return 0;
+
+ printf("RTCP\n");
+ /* iterate over list of RTCP messages */
+ rtph = (struct rtcp_hdr *)msg->data;
+ while ((void *)rtph + sizeof(*rtph) <= (void *)msg->data + msg->len) {
+ old_len = (ntohs(rtph->length) + 1) * 4;
+ if ((void *)rtph + old_len > (void *)msg->data + msg->len) {
+ DEBUGPC(DLMUX, "received RTCP packet too short for "
+ "length element\n");
+ return -EINVAL;
+ }
+ if (rtph->type == RTCP_TYPE_SDES) {
+ char new_cname[255];
+ osmo_strlcpy(new_cname,
+ inet_ntoa(rss->sin_local.sin_addr),
+ sizeof(new_cname));
+ rc = rtcp_sdes_cname_mangle(msg, rtph, &old_len,
+ new_cname);
+ if (rc < 0)
+ return rc;
+ }
+ rtph = (void *)rtph + old_len;
+ }
+
+ return 0;
+}
+
+/* read from incoming RTP/RTCP socket */
+static int rtp_socket_read(struct rtp_socket *rs, struct rtp_sub_socket *rss)
+{
+ int rc;
+ struct msgb *msg = msgb_alloc(RTP_ALLOC_SIZE, "RTP/RTCP");
+ struct msgb *new_msg;
+ struct rtp_sub_socket *other_rss;
+
+ if (!msg)
+ return -ENOMEM;
+
+ rc = read(rss->bfd.fd, msg->data, RTP_ALLOC_SIZE);
+ if (rc == 0) {
+ rss->bfd.when &= ~BSC_FD_READ;
+ goto out_free;
+ } else if (rc < 0) {
+ /* Ignore "connection refused". this happens, If we open the
+ * socket faster than the remote side. */
+ if (errno == ECONNREFUSED)
+ goto out_free;
+ DEBUGPC(DLMUX, "Read of RTP socket (%p) failed (errno %d, "
+ "%s)\n", rs, errno, strerror(errno));
+ rss->bfd.when &= ~BSC_FD_READ;
+ goto out_free;
+ }
+
+ msgb_put(msg, rc);
+
+ switch (rs->rx_action) {
+ case RTP_PROXY:
+ if (!rs->proxy.other_sock) {
+ rc = -EIO;
+ goto out_free;
+ }
+ if (rss->bfd.priv_nr == RTP_PRIV_RTP)
+ other_rss = &rs->proxy.other_sock->rtp;
+ else if (rss->bfd.priv_nr == RTP_PRIV_RTCP) {
+ other_rss = &rs->proxy.other_sock->rtcp;
+ /* modify RTCP SDES CNAME */
+ rc = rtcp_mangle(msg, rs);
+ if (rc < 0)
+ goto out_free;
+ } else {
+ rc = -EINVAL;
+ goto out_free;
+ }
+ msgb_enqueue(&other_rss->tx_queue, msg);
+ other_rss->bfd.when |= BSC_FD_WRITE;
+ break;
+
+ case RTP_RECV_UPSTREAM:
+ if (!rs->receive.callref || !rs->receive.net) {
+ rc = -EIO;
+ goto out_free;
+ }
+ if (rss->bfd.priv_nr == RTP_PRIV_RTCP) {
+ if (!mangle_rtcp_cname) {
+ msgb_free(msg);
+ break;
+ }
+ /* modify RTCP SDES CNAME */
+ rc = rtcp_mangle(msg, rs);
+ if (rc < 0)
+ goto out_free;
+ msgb_enqueue(&rss->tx_queue, msg);
+ rss->bfd.when |= BSC_FD_WRITE;
+ break;
+ }
+ if (rss->bfd.priv_nr != RTP_PRIV_RTP) {
+ rc = -EINVAL;
+ goto out_free;
+ }
+ rc = rtp_decode(msg, rs->receive.callref, &new_msg);
+ if (rc < 0)
+ goto out_free;
+ msgb_free(msg);
+ trau_tx_to_mncc(rs->receive.net, new_msg);
+ break;
+
+ case RTP_NONE: /* if socket exists, but disabled by app */
+ msgb_free(msg);
+ break;
+ }
+
+ return 0;
+
+out_free:
+ msgb_free(msg);
+ return rc;
+}
+
+/* \brief write from tx_queue to RTP/RTCP socket */
+static int rtp_socket_write(struct rtp_socket *rs, struct rtp_sub_socket *rss)
+{
+ struct msgb *msg;
+ int written;
+
+ msg = msgb_dequeue(&rss->tx_queue);
+ if (!msg) {
+ rss->bfd.when &= ~BSC_FD_WRITE;
+ return 0;
+ }
+
+ written = write(rss->bfd.fd, msg->data, msg->len);
+ if (written < msg->len) {
+ LOGP(DLMIB, LOGL_ERROR, "short write");
+ msgb_free(msg);
+ return -EIO;
+ }
+
+ msgb_free(msg);
+
+ return 0;
+}
+
+
+/*! \brief callback for the select.c:bfd_* layer */
+static int rtp_bfd_cb(struct osmo_fd *bfd, unsigned int flags)
+{
+ struct rtp_socket *rs = bfd->data;
+ struct rtp_sub_socket *rss;
+
+ switch (bfd->priv_nr) {
+ case RTP_PRIV_RTP:
+ rss = &rs->rtp;
+ break;
+ case RTP_PRIV_RTCP:
+ rss = &rs->rtcp;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (flags & BSC_FD_READ)
+ rtp_socket_read(rs, rss);
+
+ if (flags & BSC_FD_WRITE)
+ rtp_socket_write(rs, rss);
+
+ return 0;
+}
+
+/*! \brief initialize one rtp sub-socket */
+static void init_rss(struct rtp_sub_socket *rss,
+ struct rtp_socket *rs, int fd, int priv_nr)
+{
+ /* initialize bfd */
+ rss->bfd.fd = fd;
+ rss->bfd.data = rs;
+ rss->bfd.priv_nr = priv_nr;
+ rss->bfd.cb = rtp_bfd_cb;
+}
+
+/*! \brief create a new RTP/RTCP socket and bind it */
+struct rtp_socket *rtp_socket_create(void)
+{
+ int rc;
+ struct rtp_socket *rs;
+
+ DEBUGP(DLMUX, "rtp_socket_create(): ");
+
+ rs = talloc_zero(tall_bsc_ctx, struct rtp_socket);
+ if (!rs)
+ return NULL;
+
+ INIT_LLIST_HEAD(&rs->rtp.tx_queue);
+ INIT_LLIST_HEAD(&rs->rtcp.tx_queue);
+
+ rc = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+ if (rc < 0)
+ goto out_free;
+
+ init_rss(&rs->rtp, rs, rc, RTP_PRIV_RTP);
+ rc = osmo_fd_register(&rs->rtp.bfd);
+ if (rc < 0)
+ goto out_rtp_socket;
+
+ rc = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+ if (rc < 0)
+ goto out_rtp_bfd;
+
+ init_rss(&rs->rtcp, rs, rc, RTP_PRIV_RTCP);
+ rc = osmo_fd_register(&rs->rtcp.bfd);
+ if (rc < 0)
+ goto out_rtcp_socket;
+
+ DEBUGPC(DLMUX, "success\n");
+
+ rc = rtp_socket_bind(rs, INADDR_ANY);
+ if (rc < 0)
+ goto out_rtcp_bfd;
+
+ return rs;
+
+out_rtcp_bfd:
+ osmo_fd_unregister(&rs->rtcp.bfd);
+out_rtcp_socket:
+ close(rs->rtcp.bfd.fd);
+out_rtp_bfd:
+ osmo_fd_unregister(&rs->rtp.bfd);
+out_rtp_socket:
+ close(rs->rtp.bfd.fd);
+out_free:
+ talloc_free(rs);
+ DEBUGPC(DLMUX, "failed\n");
+ return NULL;
+}
+
+static int rtp_sub_socket_bind(struct rtp_sub_socket *rss, uint32_t ip,
+ uint16_t port)
+{
+ int rc;
+ socklen_t alen = sizeof(rss->sin_local);
+
+ rss->sin_local.sin_family = AF_INET;
+ rss->sin_local.sin_addr.s_addr = htonl(ip);
+ rss->sin_local.sin_port = htons(port);
+ rss->bfd.when |= BSC_FD_READ;
+
+ rc = bind(rss->bfd.fd, (struct sockaddr *)&rss->sin_local,
+ sizeof(rss->sin_local));
+ if (rc < 0)
+ return rc;
+
+ /* retrieve the address we actually bound to, in case we
+ * passed INADDR_ANY as IP address */
+ return getsockname(rss->bfd.fd, (struct sockaddr *)&rss->sin_local,
+ &alen);
+}
+
+#define RTP_PORT_BASE 30000
+static unsigned int next_udp_port = RTP_PORT_BASE;
+
+/*! \brief bind a RTP socket to a specific local address
+ * \param[in] rs RTP socket to be bound
+ * \param[in] ip local IP address to which socket is to be bound
+ */
+int rtp_socket_bind(struct rtp_socket *rs, uint32_t ip)
+{
+ int rc = -EIO;
+ struct in_addr ia;
+
+ ia.s_addr = htonl(ip);
+ DEBUGP(DLMUX, "rtp_socket_bind(rs=%p, IP=%s): ", rs,
+ inet_ntoa(ia));
+
+ /* try to bind to a consecutive pair of ports */
+ for (next_udp_port = next_udp_port % 0xffff;
+ next_udp_port < 0xffff; next_udp_port += 2) {
+ rc = rtp_sub_socket_bind(&rs->rtp, ip, next_udp_port);
+ if (rc != 0)
+ continue;
+
+ rc = rtp_sub_socket_bind(&rs->rtcp, ip, next_udp_port+1);
+ if (rc == 0)
+ break;
+ }
+ if (rc < 0) {
+ DEBUGPC(DLMUX, "failed\n");
+ return rc;
+ }
+
+ ia.s_addr = rs->rtp.sin_local.sin_addr.s_addr;
+ DEBUGPC(DLMUX, "BOUND_IP=%s, BOUND_PORT=%u\n",
+ inet_ntoa(ia), ntohs(rs->rtp.sin_local.sin_port));
+ return ntohs(rs->rtp.sin_local.sin_port);
+}
+
+static int rtp_sub_socket_connect(struct rtp_sub_socket *rss,
+ uint32_t ip, uint16_t port)
+{
+ int rc;
+ socklen_t alen = sizeof(rss->sin_local);
+
+ rss->sin_remote.sin_family = AF_INET;
+ rss->sin_remote.sin_addr.s_addr = htonl(ip);
+ rss->sin_remote.sin_port = htons(port);
+
+ rc = connect(rss->bfd.fd, (struct sockaddr *) &rss->sin_remote,
+ sizeof(rss->sin_remote));
+ if (rc < 0)
+ return rc;
+
+ return getsockname(rss->bfd.fd, (struct sockaddr *)&rss->sin_local,
+ &alen);
+}
+
+/*! \brief 'connect' a RTP socket to a remote peer
+ * \param[in] rs RTP socket to be connected
+ * \param[in] ip remote IP address to which to connect
+ * \param[in] port remote UDP port number to which to connect
+ */
+int rtp_socket_connect(struct rtp_socket *rs, uint32_t ip, uint16_t port)
+{
+ int rc;
+ struct in_addr ia;
+
+ ia.s_addr = htonl(ip);
+ DEBUGP(DLMUX, "rtp_socket_connect(rs=%p, ip=%s, port=%u)\n",
+ rs, inet_ntoa(ia), port);
+
+ rc = rtp_sub_socket_connect(&rs->rtp, ip, port);
+ if (rc < 0)
+ return rc;
+
+ return rtp_sub_socket_connect(&rs->rtcp, ip, port+1);
+}
+
+/*! \brief bind two RTP/RTCP sockets together in the proxy
+ * \param[in] this First RTP socket
+ * \param[in] other Second RTP socket
+ */
+int rtp_socket_proxy(struct rtp_socket *this, struct rtp_socket *other)
+{
+ DEBUGP(DLMUX, "rtp_socket_proxy(this=%p, other=%p)\n",
+ this, other);
+
+ this->rx_action = RTP_PROXY;
+ this->proxy.other_sock = other;
+
+ other->rx_action = RTP_PROXY;
+ other->proxy.other_sock = this;
+
+ return 0;
+}
+
+/*! \brief bind RTP/RTCP socket to application, disabling proxy
+ * \param[in] this RTP socket
+ * \param[in] net gsm_network argument to trau_tx_to_mncc()
+ * \param[in] callref callref argument to trau_tx_to_mncc()
+ */
+int rtp_socket_upstream(struct rtp_socket *this, struct gsm_network *net,
+ uint32_t callref)
+{
+ DEBUGP(DLMUX, "rtp_socket_proxy(this=%p, callref=%u)\n",
+ this, callref);
+
+ if (callref) {
+ this->rx_action = RTP_RECV_UPSTREAM;
+ this->receive.net = net;
+ this->receive.callref = callref;
+ } else
+ this->rx_action = RTP_NONE;
+
+ return 0;
+}
+
+static void free_tx_queue(struct rtp_sub_socket *rss)
+{
+ struct msgb *msg;
+
+ while ((msg = msgb_dequeue(&rss->tx_queue)))
+ msgb_free(msg);
+}
+
+/*! \brief Free/release a previously allocated RTP socket
+ * \param[in[] rs RTP/RTCP socket to be released
+ */
+int rtp_socket_free(struct rtp_socket *rs)
+{
+ DEBUGP(DLMUX, "rtp_socket_free(rs=%p)\n", rs);
+
+ /* make sure we don't leave references dangling to us */
+ if (rs->rx_action == RTP_PROXY &&
+ rs->proxy.other_sock)
+ rs->proxy.other_sock->proxy.other_sock = NULL;
+
+ osmo_fd_unregister(&rs->rtp.bfd);
+ close(rs->rtp.bfd.fd);
+ free_tx_queue(&rs->rtp);
+
+ osmo_fd_unregister(&rs->rtcp.bfd);
+ close(rs->rtcp.bfd.fd);
+ free_tx_queue(&rs->rtcp);
+
+ talloc_free(rs);
+
+ return 0;
+}