diff options
Diffstat (limited to 'openbsc/src/rtp_proxy.c')
-rw-r--r-- | openbsc/src/rtp_proxy.c | 274 |
1 files changed, 268 insertions, 6 deletions
diff --git a/openbsc/src/rtp_proxy.c b/openbsc/src/rtp_proxy.c index 59c0735a5..0f4e32799 100644 --- a/openbsc/src/rtp_proxy.c +++ b/openbsc/src/rtp_proxy.c @@ -24,6 +24,10 @@ #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 <openbsc/talloc.h> #include <openbsc/gsm_data.h> @@ -57,6 +61,213 @@ struct rtcp_hdr { #define RTCP_IE_CNAME 1 +/* according to RFC 3550 */ +struct rtp_hdr { + u_int8_t csrc_count:4, + extension:1, + padding:1, + version:2; + u_int8_t payload_type:7, + marker:1; + u_int16_t sequence; + u_int32_t timestamp; + u_int32_t ssrc; +} __attribute__((packed)); + +struct rtp_x_hdr { + u_int16_t by_profile; + u_int16_t length; +} __attribute__((packed)); + +#define RTP_VERSION 2 + +#define RTP_PT_GSM_FULL 3 +#define RTP_PT_GSM_EFR 97 + +/* decode an rtp frame and create a new buffer with payload */ +static int rtp_decode(struct msgb *msg, u_int32_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; + u_int8_t *payload; + int payload_len; + int msg_type; + int x_len; + + if (msg->len < 12) { + DEBUGPC(DMUX, "received RTP frame too short (len = %d)\n", + msg->len); + return -EINVAL; + } + if (rtph->version != RTP_VERSION) { + DEBUGPC(DMUX, "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(DMUX, "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(DMUX, "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(DMUX, "received RTP frame too short, " + "extension header exceeds frame length\n"); + return -EINVAL; + } + } + if (rtph->padding) { + if (payload_len < 0) { + DEBUGPC(DMUX, "received RTP frame too short for " + "padding length\n"); + return -EINVAL; + } + payload_len -= payload[payload_len - 1]; + if (payload_len < 0) { + DEBUGPC(DMUX, "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 != 33) { + DEBUGPC(DMUX, "received RTP full rate frame with " + "payload length != 32 (len = %d)\n", + payload_len); + return -EINVAL; + } + break; + case RTP_PT_GSM_EFR: + msg_type = GSM_TCHF_FRAME_EFR; + break; + default: + DEBUGPC(DMUX, "received RTP frame with unknown payload " + "type %d\n", rtph->payload_type); + return -EINVAL; + } + + new_msg = msgb_alloc(sizeof(struct gsm_data_frame) + payload_len, + "GSM-DATA"); + if (!new_msg) + return -ENOMEM; + frame = (struct gsm_data_frame *)(new_msg->data); + frame->msg_type = msg_type; + frame->callref = callref; + memcpy(frame->data, payload, payload_len); + msgb_put(new_msg, sizeof(struct gsm_data_frame) + payload_len); + + *data = new_msg; + return 0; +} + +/* "to - from" */ +static void tv_difference(struct timeval *diff, const struct timeval *from, + const struct timeval *__to) +{ + struct timeval _to = *__to, *to = &_to; + + if (to->tv_usec < from->tv_usec) { + to->tv_sec -= 1; + to->tv_usec += 1000000; + } + + diff->tv_usec = to->tv_usec - from->tv_usec; + diff->tv_sec = to->tv_sec - from->tv_sec; +} + +/* encode and send a rtp frame */ +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; + int payload_type; + int payload_len; + int duration; /* in samples */ + + 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 = 33; + duration = 160; + break; + case GSM_TCHF_FRAME_EFR: + payload_type = RTP_PT_GSM_EFR; + payload_len = 31; + duration = 160; + break; + default: + DEBUGPC(DMUX, "unsupported message type %d\n", + frame->msg_type); + return -EINVAL; + } + + { + struct timeval tv, tv_diff; + long int usec_diff, frame_diff; + + gettimeofday(&tv, NULL); + tv_difference(&tv_diff, &rs->transmit.last_tv, &tv); + rs->transmit.last_tv = tv; + + usec_diff = tv_diff.tv_sec * 1000000 + tv_diff.tv_usec; + frame_diff = (usec_diff / 20000); + + if (abs(frame_diff) > 1) { + long int frame_diff_excess = frame_diff - 1; + + DEBUGP(DMUX, "Correcting frame difference of %ld frames\n", frame_diff_excess); + rs->transmit.sequence += frame_diff_excess; + rs->transmit.timestamp += frame_diff_excess * duration; + } + } + + msg = msgb_alloc(sizeof(struct rtp_hdr) + payload_len, "RTP-GSM-FULL"); + if (!msg) + return -ENOMEM; + rtph = (struct rtp_hdr *)msg->data; + 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); + memcpy(msg->data + sizeof(struct rtp_hdr), frame->data, payload_len); + msgb_put(msg, sizeof(struct rtp_hdr) + 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, @@ -123,10 +334,16 @@ static int rtcp_mangle(struct msgb *msg, struct rtp_socket *rs) 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) { + 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(DMUX, "received RTCP packet too short for " + "length element\n"); + return -EINVAL; + } if (rtph->type == RTCP_TYPE_SDES) { char new_cname[255]; strncpy(new_cname, inet_ntoa(rss->sin_local.sin_addr), @@ -148,6 +365,7 @@ 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) @@ -184,13 +402,40 @@ static int rtp_socket_read(struct rtp_socket *rs, struct rtp_sub_socket *rss) break; case RTP_RECV_UPSTREAM: - case RTP_NONE: - /* FIXME: other cases */ - DEBUGP(DMUX, "unhandled action: %d\n", rs->rx_action); + 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); + msgb_enqueue(&rs->receive.net->upqueue, new_msg); + break; + + case RTP_NONE: /* if socket exists, but disabled by app */ + msgb_free(msg); break; } - return rc; + return 0; out_free: msgb_free(msg); @@ -211,7 +456,7 @@ static int rtp_socket_write(struct rtp_socket *rs, struct rtp_sub_socket *rss) written = write(rss->bfd.fd, msg->data, msg->len); if (written < msg->len) { - perror("short write"); + LOGP(DMIB, LOGL_ERROR, "short write"); msgb_free(msg); return -EIO; } @@ -420,6 +665,23 @@ int rtp_socket_proxy(struct rtp_socket *this, struct rtp_socket *other) return 0; } +/* bind RTP/RTCP socket to application */ +int rtp_socket_upstream(struct rtp_socket *this, struct gsm_network *net, + u_int32_t callref) +{ + DEBUGP(DMUX, "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; |