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Diffstat (limited to 'src/osmux_output.c')
| -rw-r--r-- | src/osmux_output.c | 396 |
1 files changed, 396 insertions, 0 deletions
diff --git a/src/osmux_output.c b/src/osmux_output.c new file mode 100644 index 0000000..664ed60 --- /dev/null +++ b/src/osmux_output.c @@ -0,0 +1,396 @@ +/* + * (C) 2012-2017 by Pablo Neira Ayuso <pablo@gnumonks.org> + * (C) 2012 by On Waves ehf <http://www.on-waves.com> + * (C) 2015-2022 by sysmocom - s.f.m.c. GmbH + * + * SPDX-License-Identifier: GPL-2.0+ + * + * 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. + */ + +#include <stdio.h> +#include <string.h> + +#include <osmocom/core/msgb.h> +#include <osmocom/core/timer.h> +#include <osmocom/core/timer_compat.h> +#include <osmocom/core/select.h> +#include <osmocom/core/talloc.h> +#include <osmocom/core/logging.h> + +#include <osmocom/netif/amr.h> +#include <osmocom/netif/rtp.h> +#include <osmocom/netif/osmux.h> + +#include <arpa/inet.h> + +/* delta time between two RTP messages (in microseconds) */ +#define DELTA_RTP_MSG 20000 +/* delta time between two RTP messages (in samples, 8kHz) */ +#define DELTA_RTP_TIMESTAMP 160 + + +/*! \addtogroup osmux Osmocom Multiplex Protocol + * @{ + * + * This code implements a variety of utility functions related to the + * OSMUX user-plane multiplexing protocol, an efficient alternative to + * plain UDP/RTP streams for voice transport in back-haul of cellular + * networks. + * + * For information about the OSMUX protocol design, please see the + * OSMUX reference manual at + * http://ftp.osmocom.org/docs/latest/osmux-reference.pdf + */ + +/*! \file osmux_output.c + * \brief Osmocom multiplex protocol helpers (output) + */ +static uint32_t osmux_ft_dummy_size(uint8_t amr_ft, uint8_t batch_factor) +{ + return sizeof(struct osmux_hdr) + (osmo_amr_bytes(amr_ft) * batch_factor); +} + +struct osmux_hdr *osmux_xfrm_output_pull(struct msgb *msg) +{ + struct osmux_hdr *osmuxh; + size_t len; + +next: + if (msgb_length(msg) == 0) + return NULL; /* base case, we drained the msg successfully, tell user it is done. */ + + if (msgb_length(msg) < sizeof(struct osmux_hdr)) { + LOGP(DLMUX, LOGL_ERROR, "remaining %d bytes, broken osmuxhdr?\n", msgb_length(msg)); + return NULL; + } + + osmuxh = (struct osmux_hdr *)msgb_data(msg); + switch (osmuxh->ft) { + case OSMUX_FT_VOICE_AMR: + if (!osmo_amr_ft_valid(osmuxh->amr_ft)) { + LOGP(DLMUX, LOGL_ERROR, "Discarding bad AMR FT %d\n", osmuxh->amr_ft); + return NULL; + } + len = osmo_amr_bytes(osmuxh->amr_ft) * (osmuxh->ctr + 1) + sizeof(struct osmux_hdr); + if (msgb_length(msg) < len) { + LOGP(DLMUX, LOGL_ERROR, + "Discarding malformed OSMUX message: %s\n", + osmo_hexdump(msgb_data(msg), msgb_length(msg))); + return NULL; + } + msgb_pull(msg, len); + return osmuxh; + + case OSMUX_FT_DUMMY: + if (!osmo_amr_ft_valid(osmuxh->amr_ft)) { + LOGP(DLMUX, LOGL_ERROR, "Discarding bad Dummy FT: amr_ft=%u\n", osmuxh->amr_ft); + return NULL; + } + len = osmux_ft_dummy_size(osmuxh->amr_ft, osmuxh->ctr + 1); + if (msgb_length(msg) < len) { + LOGP(DLMUX, LOGL_ERROR, "Discarding bad Dummy FT: %s\n", + osmo_hexdump(msgb_data(msg), msgb_length(msg))); + return NULL; + } + msgb_pull(msg, len); + goto next; + + default: + LOGP(DLMUX, LOGL_ERROR, "Discarding unsupported Osmux FT %d\n", + osmuxh->ft); + return NULL; + } +} + +static struct msgb * +osmux_rebuild_rtp(struct osmux_out_handle *h, struct osmux_hdr *osmuxh, + void *payload, int payload_len, bool first_pkt) +{ + struct msgb *prev_msg, *out_msg; + struct timespec *prev_ts, *out_ts; + struct rtp_hdr *rtph; + struct amr_hdr *amrh; + struct timespec delta = { .tv_sec = 0, .tv_nsec = DELTA_RTP_MSG*1000 }; + unsigned int msg_len = sizeof(struct rtp_hdr) + + sizeof(struct amr_hdr) + + payload_len; + + if (h->rtp_msgb_alloc_cb) { + out_msg = h->rtp_msgb_alloc_cb(h->rtp_msgb_alloc_cb_data, msg_len); + } else { + out_msg = msgb_alloc(msg_len, "osmux-rtp"); + } + if (out_msg == NULL) + return NULL; + + /* Reconstruct RTP header */ + rtph = (struct rtp_hdr *)out_msg->data; + rtph->csrc_count = 0; + rtph->extension = 0; + rtph->version = RTP_VERSION; + rtph->payload_type = h->rtp_payload_type; + /* ... emulate timestamp and ssrc */ + rtph->timestamp = htonl(h->rtp_timestamp); + rtph->sequence = htons(h->rtp_seq); + rtph->ssrc = htonl(h->rtp_ssrc); + /* rtp packet with the marker bit is always guaranteed to be the first + * one. We want to notify with marker in 2 scenarios: + * 1- Sender told us through osmux frame rtp_m. + * 2- Intermediate osmux frame lost (seq gap), otherwise rtp receiver only sees + * steady increase of delay + */ + rtph->marker = first_pkt && + (osmuxh->rtp_m || (osmuxh->seq != ((h->osmux_seq_ack + 1) & 0xff))); + + msgb_put(out_msg, sizeof(struct rtp_hdr)); + + /* Reconstruct AMR header */ + amrh = (struct amr_hdr *)out_msg->tail; + amrh->cmr = osmuxh->amr_cmr; + amrh->f = osmuxh->amr_f; + amrh->ft = osmuxh->amr_ft; + amrh->q = osmuxh->amr_q; + + msgb_put(out_msg, sizeof(struct amr_hdr)); + + /* add AMR speech data */ + if (payload_len > 0) { + memcpy(out_msg->tail, payload, payload_len); + msgb_put(out_msg, payload_len); + } + + /* bump last RTP sequence number and timestamp that has been used */ + h->rtp_seq++; + h->rtp_timestamp += DELTA_RTP_TIMESTAMP; + + out_ts = ((struct timespec *)&((out_msg)->cb[0])); + if (first_pkt || llist_empty(&h->list)) { + osmo_clock_gettime(CLOCK_MONOTONIC, out_ts); + } else { + prev_msg = llist_last_entry(&h->list, struct msgb, list); + prev_ts = ((struct timespec *)&((prev_msg)->cb[0])); + timespecadd(prev_ts, &delta, out_ts); + } + + return out_msg; +} + +static void osmux_xfrm_output_trigger(void *data) +{ + struct osmux_out_handle *h = data; + struct timespec delay_ts, now; + struct msgb *msg, *next; + + llist_for_each_entry_safe(msg, next, &h->list, list) { + osmo_clock_gettime(CLOCK_MONOTONIC, &now); + struct timespec *msg_ts = ((struct timespec *)&((msg)->cb[0])); + if (timespeccmp(msg_ts, &now, >)) { + timespecsub(msg_ts, &now, &delay_ts); + osmo_timer_schedule(&h->timer, + delay_ts.tv_sec, delay_ts.tv_nsec / 1000); + return; + } + + /* Transmit the rtp packet */ + llist_del(&msg->list); + if (h->tx_cb) + h->tx_cb(msg, h->data); + else + msgb_free(msg); + } +} + +/*! \brief Generate RTP packets from osmux frame AMR payload set and schedule + * them for transmission at appropriate time. + * \param[in] h the osmux out handle handling a specific CID + * \param[in] osmuxh Buffer pointing to osmux frame header structure and AMR payload + * \return Number of generated RTP packets + * + * The osmux frame passed to this function must be of the type OSMUX_FT_VOICE_AMR. + * The generated RTP packets are kept into h's internal list and sent to the + * callback configured through osmux_xfrm_output_set_tx_cb when are ready to be + * transmitted according to schedule. + */ +int osmux_xfrm_output_sched(struct osmux_out_handle *h, struct osmux_hdr *osmuxh) +{ + struct timespec now, *msg_ts; + struct msgb *msg; + int i; + bool was_empty = llist_empty(&h->list); + + if (!was_empty) { + /* If we received new data it means we are behind schedule and + * we should flush all previous quickly */ + osmo_clock_gettime(CLOCK_MONOTONIC, &now); + llist_for_each_entry(msg, &h->list, list) { + msg_ts = ((struct timespec *)&((msg)->cb[0])); + *msg_ts = now; + } + osmo_timer_schedule(&h->timer, 0, 0); + } + + for (i = 0; i < osmuxh->ctr + 1; i++) { + struct rtp_hdr *rtph; + + msg = osmux_rebuild_rtp(h, osmuxh, + osmux_get_payload(osmuxh) + + i * osmo_amr_bytes(osmuxh->amr_ft), + osmo_amr_bytes(osmuxh->amr_ft), !i); + if (msg == NULL) + continue; + + rtph = osmo_rtp_get_hdr(msg); + if (rtph == NULL) + continue; + + llist_add_tail(&msg->list, &h->list); + } + + /* Update last seen seq number: */ + h->osmux_seq_ack = osmuxh->seq; + + /* In case list is still empty after parsing messages, no need to rearm */ + if (was_empty && !llist_empty(&h->list)) + osmux_xfrm_output_trigger(h); + return i; +} + +/*! \brief Flush all scheduled RTP packets still pending to be transmitted + * \param[in] h the osmux out handle to flush + * + * This function will immediately call the transmit callback for all queued RTP + * packets, making sure the list ends up empty. It will also stop all internal + * timers to make sure the osmux_out_handle can be dropped or re-used by calling + * osmux_xfrm_output on it. + */ +void osmux_xfrm_output_flush(struct osmux_out_handle *h) +{ + struct msgb *msg, *next; + + if (osmo_timer_pending(&h->timer)) + osmo_timer_del(&h->timer); + + llist_for_each_entry_safe(msg, next, &h->list, list) { + llist_del(&msg->list); + if (h->tx_cb) + h->tx_cb(msg, h->data); + else + msgb_free(msg); + } +} + +struct osmux_tx_handle { + struct osmo_timer_list timer; + struct msgb *msg; + void (*tx_cb)(struct msgb *msg, void *data); + void *data; +}; + +static int osmux_xfrm_output_talloc_destructor(struct osmux_out_handle *h) +{ + osmux_xfrm_output_flush(h); + return 0; +} + +/* Placeholder to avoid init code duplication while keeping backward + * compatilbility with deprecated osmux_xfrm_output_init{2}() APIs. */ +static void _osmux_xfrm_output_init(struct osmux_out_handle *h, uint32_t rtp_ssrc, uint8_t rtp_payload_type) +{ + h->rtp_seq = (uint16_t)random(); + h->rtp_timestamp = (uint32_t)random(); + h->rtp_ssrc = rtp_ssrc; + h->rtp_payload_type = rtp_payload_type; + INIT_LLIST_HEAD(&h->list); + osmo_timer_setup(&h->timer, osmux_xfrm_output_trigger, h); +} + +/*! \brief Allocate a new osmux out handle + * \param[in] ctx talloc context to use when allocating the returned struct + * \return Allocated osmux out handle + * + * This object contains configuration and state to handle a specific CID in + * incoming network Osmux messages, repackaging the frames for that CID as RTP + * packets and pushing them up the protocol stack. + * Returned pointer can be freed with regular talloc_free, queue will be flushed + * and all internal data will be freed. */ +struct osmux_out_handle *osmux_xfrm_output_alloc(void *ctx) +{ + struct osmux_out_handle *h; + + h = talloc_zero(ctx, struct osmux_out_handle); + OSMO_ASSERT(h); + + _osmux_xfrm_output_init(h, (uint32_t)random(), 98); + + talloc_set_destructor(h, osmux_xfrm_output_talloc_destructor); + return h; +} + +/*! \deprecated: Use osmux_xfrm_output_alloc() and osmux_xfrm_output_set_rtp_*() instead */ +void osmux_xfrm_output_init2(struct osmux_out_handle *h, uint32_t rtp_ssrc, uint8_t rtp_payload_type) +{ + memset(h, 0, sizeof(*h)); + _osmux_xfrm_output_init(h, rtp_ssrc, rtp_payload_type); +} + +/*! \deprecated: Use osmux_xfrm_output_alloc() and osmux_xfrm_output_set_rtp_*() instead */ +void osmux_xfrm_output_init(struct osmux_out_handle *h, uint32_t rtp_ssrc) +{ + /* backward compatibility with old users, where 98 was harcoded in osmux_rebuild_rtp() */ + memset(h, 0, sizeof(*h)); + _osmux_xfrm_output_init(h, rtp_ssrc, 98); +} + +/*! \brief Set transmission callback to call when a generated RTP packet is to be transmitted + * \param[in] h the osmux out handle handling a specific CID + * \param[in] osmuxh Buffer pointing to osmux frame header structure and AMR payload + * \return Number of generated RTP packets + * + * This Function sets the callback called by the interal timer set by + * osmux_xfrm_out_sched function. + */ +void osmux_xfrm_output_set_tx_cb(struct osmux_out_handle *h, + void (*tx_cb)(struct msgb *msg, void *data), + void *data) +{ + h->tx_cb = tx_cb; + h->data = data; +} + +/*! \brief Set callback to call when an RTP packet to be generated is to be allocated + * \param[in] h the osmux out handle handling a specific CID + * \param[in] cb User defined msgb alloc function for generated RTP pkts + * \param[in] cb_data Opaque data pointer set by user and passed in \ref cb + * \return msgb structure to be used to fill in generated RTP pkt content + */ +void osmux_xfrm_output_set_rtp_msgb_alloc_cb(struct osmux_out_handle *h, + rtp_msgb_alloc_cb_t cb, + void *cb_data) +{ + h->rtp_msgb_alloc_cb = cb; + h->rtp_msgb_alloc_cb_data = cb_data; +} + +/*! \brief Set SSRC of generated RTP packets from Osmux frames + * \param[in] h the osmux out handle handling a specific CID + * \param[in] rtp_ssrc the RTP SSRC to set + */ +void osmux_xfrm_output_set_rtp_ssrc(struct osmux_out_handle *h, uint32_t rtp_ssrc) +{ + h->rtp_ssrc = rtp_ssrc; +} + +/*! \brief Set Payload Type of generated RTP packets from Osmux frames + * \param[in] h the osmux out handle handling a specific CID + * \param[in] rtp_payload_type the RTP Payload Type to set + */ +void osmux_xfrm_output_set_rtp_pl_type(struct osmux_out_handle *h, uint32_t rtp_payload_type) +{ + h->rtp_payload_type = rtp_payload_type; +} + +/*! @} */ |