libsrt.c

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/*
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
 
/**
 * @file
 * Haivision Open SRT (Secure Reliable Transport) protocol
 */
 
#include <srt/srt.h>
 
#include "libavutil/mem.h"
#include "libavutil/opt.h"
#include "libavutil/parseutils.h"
#include "libavutil/time.h"
 
#include "avformat.h"
#include "internal.h"
#include "network.h"
#include "os_support.h"
#include "url.h"
#include "urldecode.h"
 
/* This is for MPEG-TS and it's a default SRTO_PAYLOADSIZE for SRTT_LIVE (8 TS packets) */
#ifndef SRT_LIVE_DEFAULT_PAYLOAD_SIZE
#define SRT_LIVE_DEFAULT_PAYLOAD_SIZE 1316
#endif
 
/* This is the maximum payload size for Live mode, should you have a different payload type than MPEG-TS */
#ifndef SRT_LIVE_MAX_PAYLOAD_SIZE
#define SRT_LIVE_MAX_PAYLOAD_SIZE 1456
#endif
 
enum SRTMode {
    SRT_MODE_CALLER = 0,
    SRT_MODE_LISTENER = 1,
    SRT_MODE_RENDEZVOUS = 2
};
 
typedef struct SRTContext {
    const AVClass *class;
    int fd;
    int eid;
    int64_t rw_timeout;
    int64_t listen_timeout;
    int recv_buffer_size;
    int send_buffer_size;
 
    int64_t maxbw;
    int pbkeylen;
    char *passphrase;
#if SRT_VERSION_VALUE >= 0x010302
    int enforced_encryption;
    int kmrefreshrate;
    int kmpreannounce;
    int64_t snddropdelay;
#endif
    int mss;
    int ffs;
    int ipttl;
    int iptos;
    int64_t inputbw;
    int oheadbw;
    int64_t latency;
    int tlpktdrop;
    int nakreport;
    int64_t connect_timeout;
    int payload_size;
    int64_t rcvlatency;
    int64_t peerlatency;
    /* enum SRTMode, use int for AVOption */
    int mode;
    int sndbuf;
    int rcvbuf;
    int lossmaxttl;
    int minversion;
    char *streamid;
    char *smoother;
    int messageapi;
    SRT_TRANSTYPE transtype;
    int linger;
    int tsbpd;
#if SRT_VERSION_VALUE >= 0x010400
    int ipv6only;
#endif
} SRTContext;
 
#define D AV_OPT_FLAG_DECODING_PARAM
#define E AV_OPT_FLAG_ENCODING_PARAM
#define OFFSET(x) offsetof(SRTContext, x)
static const AVOption libsrt_options[] = {
    { "timeout",        "Timeout of socket I/O operations (in microseconds)",                   OFFSET(rw_timeout),       AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
    { "listen_timeout", "Connection awaiting timeout (in microseconds)" ,                       OFFSET(listen_timeout),   AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
    { "send_buffer_size", "Socket send buffer size (in bytes)",                                 OFFSET(send_buffer_size), AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, INT_MAX,   .flags = D|E },
    { "recv_buffer_size", "Socket receive buffer size (in bytes)",                              OFFSET(recv_buffer_size), AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, INT_MAX,   .flags = D|E },
    { "pkt_size",       "Maximum SRT packet size",                                              OFFSET(payload_size),     AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, SRT_LIVE_MAX_PAYLOAD_SIZE, .flags = D|E, .unit = "payload_size" },
    { "payload_size",   "Maximum SRT packet size",                                              OFFSET(payload_size),     AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, SRT_LIVE_MAX_PAYLOAD_SIZE, .flags = D|E, .unit = "payload_size" },
    { "ts_size",        NULL, 0, AV_OPT_TYPE_CONST,  { .i64 = SRT_LIVE_DEFAULT_PAYLOAD_SIZE }, INT_MIN, INT_MAX, .flags = D|E, .unit = "payload_size" },
    { "max_size",       NULL, 0, AV_OPT_TYPE_CONST,  { .i64 = SRT_LIVE_MAX_PAYLOAD_SIZE },     INT_MIN, INT_MAX, .flags = D|E, .unit = "payload_size" },
    { "maxbw",          "Maximum bandwidth (bytes per second) that the connection can use",     OFFSET(maxbw),            AV_OPT_TYPE_INT64,    { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
    { "pbkeylen",       "Crypto key len in bytes {16,24,32} Default: 16 (128-bit)",             OFFSET(pbkeylen),         AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, 32,        .flags = D|E },
    { "passphrase",     "Crypto PBKDF2 Passphrase size[0,10..64] 0:disable crypto",             OFFSET(passphrase),       AV_OPT_TYPE_STRING,   { .str = NULL },              .flags = D|E },
#if SRT_VERSION_VALUE >= 0x010302
    { "enforced_encryption", "Enforces that both connection parties have the same passphrase set",                              OFFSET(enforced_encryption), AV_OPT_TYPE_BOOL,  { .i64 = -1 }, -1, 1,         .flags = D|E },
    { "kmrefreshrate",       "The number of packets to be transmitted after which the encryption key is switched to a new key", OFFSET(kmrefreshrate),       AV_OPT_TYPE_INT,   { .i64 = -1 }, -1, INT_MAX,   .flags = D|E },
    { "kmpreannounce",       "The interval between when a new encryption key is sent and when switchover occurs",               OFFSET(kmpreannounce),       AV_OPT_TYPE_INT,   { .i64 = -1 }, -1, INT_MAX,   .flags = D|E },
    { "snddropdelay",        "The sender's extra delay(in microseconds) before dropping packets",                                     OFFSET(snddropdelay),        AV_OPT_TYPE_INT64,   { .i64 = -2 }, -2, INT64_MAX,   .flags = D|E },
#endif
    { "mss",            "The Maximum Segment Size",                                             OFFSET(mss),              AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, 1500,      .flags = D|E },
    { "ffs",            "Flight flag size (window size) (in bytes)",                            OFFSET(ffs),              AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, INT_MAX,   .flags = D|E },
    { "ipttl",          "IP Time To Live",                                                      OFFSET(ipttl),            AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, 255,       .flags = D|E },
    { "iptos",          "IP Type of Service",                                                   OFFSET(iptos),            AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, 255,       .flags = D|E },
    { "inputbw",        "Estimated input stream rate",                                          OFFSET(inputbw),          AV_OPT_TYPE_INT64,    { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
    { "oheadbw",        "MaxBW ceiling based on % over input stream rate",                      OFFSET(oheadbw),          AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, 100,       .flags = D|E },
    { "latency",        "receiver delay (in microseconds) to absorb bursts of missed packet retransmissions",                     OFFSET(latency),          AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
    { "tsbpddelay",     "deprecated, same effect as latency option",                            OFFSET(latency),          AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
    { "rcvlatency",     "receive latency (in microseconds)",                                    OFFSET(rcvlatency),       AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
    { "peerlatency",    "peer latency (in microseconds)",                                       OFFSET(peerlatency),      AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
    { "tlpktdrop",      "Enable too-late pkt drop",                                             OFFSET(tlpktdrop),        AV_OPT_TYPE_BOOL,     { .i64 = -1 }, -1, 1,         .flags = D|E },
    { "nakreport",      "Enable receiver to send periodic NAK reports",                         OFFSET(nakreport),        AV_OPT_TYPE_BOOL,     { .i64 = -1 }, -1, 1,         .flags = D|E },
    { "connect_timeout", "Connect timeout(in milliseconds). Caller default: 3000, rendezvous (x 10)",                            OFFSET(connect_timeout),  AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
    { "mode",           "Connection mode (caller, listener, rendezvous)",                       OFFSET(mode),             AV_OPT_TYPE_INT,      { .i64 = SRT_MODE_CALLER }, SRT_MODE_CALLER, SRT_MODE_RENDEZVOUS, .flags = D|E, .unit = "mode" },
    { "caller",         NULL, 0, AV_OPT_TYPE_CONST,  { .i64 = SRT_MODE_CALLER },     INT_MIN, INT_MAX, .flags = D|E, .unit = "mode" },
    { "listener",       NULL, 0, AV_OPT_TYPE_CONST,  { .i64 = SRT_MODE_LISTENER },   INT_MIN, INT_MAX, .flags = D|E, .unit = "mode" },
    { "rendezvous",     NULL, 0, AV_OPT_TYPE_CONST,  { .i64 = SRT_MODE_RENDEZVOUS }, INT_MIN, INT_MAX, .flags = D|E, .unit = "mode" },
    { "sndbuf",         "Send buffer size (in bytes)",                                          OFFSET(sndbuf),           AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, INT_MAX,   .flags = D|E },
    { "rcvbuf",         "Receive buffer size (in bytes)",                                       OFFSET(rcvbuf),           AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, INT_MAX,   .flags = D|E },
    { "lossmaxttl",     "Maximum possible packet reorder tolerance",                            OFFSET(lossmaxttl),       AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, INT_MAX,   .flags = D|E },
    { "minversion",     "The minimum SRT version that is required from the peer",               OFFSET(minversion),       AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, INT_MAX,   .flags = D|E },
    { "streamid",       "A string of up to 512 characters that an Initiator can pass to a Responder",  OFFSET(streamid),  AV_OPT_TYPE_STRING,   { .str = NULL },              .flags = D|E },
    { "srt_streamid",   "A string of up to 512 characters that an Initiator can pass to a Responder",  OFFSET(streamid),  AV_OPT_TYPE_STRING,   { .str = NULL },              .flags = D|E },
    { "smoother",       "The type of Smoother used for the transmission for that socket",       OFFSET(smoother),         AV_OPT_TYPE_STRING,   { .str = NULL },              .flags = D|E },
    { "messageapi",     "Enable message API",                                                   OFFSET(messageapi),       AV_OPT_TYPE_BOOL,     { .i64 = -1 }, -1, 1,         .flags = D|E },
    { "transtype",      "The transmission type for the socket",                                 OFFSET(transtype),        AV_OPT_TYPE_INT,      { .i64 = SRTT_INVALID }, SRTT_LIVE, SRTT_INVALID, .flags = D|E, .unit = "transtype" },
    { "live",           NULL, 0, AV_OPT_TYPE_CONST,  { .i64 = SRTT_LIVE }, INT_MIN, INT_MAX, .flags = D|E, .unit = "transtype" },
    { "file",           NULL, 0, AV_OPT_TYPE_CONST,  { .i64 = SRTT_FILE }, INT_MIN, INT_MAX, .flags = D|E, .unit = "transtype" },
    { "linger",         "Number of seconds that the socket waits for unsent data when closing", OFFSET(linger),           AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, INT_MAX,   .flags = D|E },
    { "tsbpd",          "Timestamp-based packet delivery",                                      OFFSET(tsbpd),            AV_OPT_TYPE_BOOL,     { .i64 = -1 }, -1, 1,         .flags = D|E },
#if SRT_VERSION_VALUE >= 0x010400
    { "ipv6only",       "Accept IPv4 or not while using the IPv6 wildcard address",             OFFSET(ipv6only),         AV_OPT_TYPE_BOOL,     { .i64 = -1 }, -1, 1,         .flags = D|E },
#endif
    { NULL }
};
 
static int libsrt_neterrno(URLContext *h)
{
    int os_errno;
    int err = srt_getlasterror(&os_errno);
    if (err == SRT_EASYNCRCV || err == SRT_EASYNCSND)
        return AVERROR(EAGAIN);
    av_log(h, AV_LOG_ERROR, "%s\n", srt_getlasterror_str());
    return os_errno ? AVERROR(os_errno) : AVERROR_UNKNOWN;
}
 
static int libsrt_getsockopt(URLContext *h, int fd, SRT_SOCKOPT optname, const char * optnamestr, void * optval, int * optlen)
{
    if (srt_getsockopt(fd, 0, optname, optval, optlen) < 0) {
        av_log(h, AV_LOG_ERROR, "failed to get option %s on socket: %s\n", optnamestr, srt_getlasterror_str());
        return AVERROR(EIO);
    }
    return 0;
}
 
static int libsrt_socket_nonblock(int socket, int enable)
{
    int ret, blocking = enable ? 0 : 1;
    /* Setting SRTO_{SND,RCV}SYN options to 1 enable blocking mode, setting them to 0 enable non-blocking mode. */
    ret = srt_setsockopt(socket, 0, SRTO_SNDSYN, &blocking, sizeof(blocking));
    if (ret < 0)
        return ret;
    return srt_setsockopt(socket, 0, SRTO_RCVSYN, &blocking, sizeof(blocking));
}
 
static int libsrt_epoll_create(URLContext *h, int fd, int write)
{
    int modes = SRT_EPOLL_ERR | (write ? SRT_EPOLL_OUT : SRT_EPOLL_IN);
    int eid = srt_epoll_create();
    if (eid < 0)
        return libsrt_neterrno(h);
    if (srt_epoll_add_usock(eid, fd, &modes) < 0) {
        srt_epoll_release(eid);
        return libsrt_neterrno(h);
    }
    return eid;
}
 
static int libsrt_network_wait_fd(URLContext *h, int eid, int write)
{
    int ret, len = 1, errlen = 1;
    SRTSOCKET ready[1];
    SRTSOCKET error[1];
 
    if (write) {
        ret = srt_epoll_wait(eid, error, &errlen, ready, &len, POLLING_TIME, 0, 0, 0, 0);
    } else {
        ret = srt_epoll_wait(eid, ready, &len, error, &errlen, POLLING_TIME, 0, 0, 0, 0);
    }
    if (ret < 0) {
        if (srt_getlasterror(NULL) == SRT_ETIMEOUT)
            ret = AVERROR(EAGAIN);
        else
            ret = libsrt_neterrno(h);
    } else {
        ret = errlen ? AVERROR(EIO) : 0;
    }
    return ret;
}
 
/* TODO de-duplicate code from ff_network_wait_fd_timeout() */
 
static int libsrt_network_wait_fd_timeout(URLContext *h, int eid, int write, int64_t timeout, AVIOInterruptCB *int_cb)
{
    int ret;
    int64_t wait_start = 0;
 
    while (1) {
        if (ff_check_interrupt(int_cb))
            return AVERROR_EXIT;
        ret = libsrt_network_wait_fd(h, eid, write);
        if (ret != AVERROR(EAGAIN))
            return ret;
        if (timeout > 0) {
            if (!wait_start)
                wait_start = av_gettime_relative();
            else if (av_gettime_relative() - wait_start > timeout)
                return AVERROR(ETIMEDOUT);
        }
    }
}
 
static int libsrt_listen(int eid, int fd, const struct sockaddr *addr, socklen_t addrlen, URLContext *h, int64_t timeout)
{
    int ret;
    int reuse = 1;
    /* Max streamid length plus an extra space for the terminating null character */
    char streamid[513];
    int streamid_len = sizeof(streamid);
    if (srt_setsockopt(fd, SOL_SOCKET, SRTO_REUSEADDR, &reuse, sizeof(reuse))) {
        av_log(h, AV_LOG_WARNING, "setsockopt(SRTO_REUSEADDR) failed\n");
    }
    if (srt_bind(fd, addr, addrlen))
        return libsrt_neterrno(h);
 
    if (srt_listen(fd, 1))
        return libsrt_neterrno(h);
 
    ret = libsrt_network_wait_fd_timeout(h, eid, 0, timeout, &h->interrupt_callback);
    if (ret < 0)
        return ret;
 
    ret = srt_accept(fd, NULL, NULL);
    if (ret < 0)
        return libsrt_neterrno(h);
    if (libsrt_socket_nonblock(ret, 1) < 0)
        av_log(h, AV_LOG_DEBUG, "libsrt_socket_nonblock failed\n");
    if (!libsrt_getsockopt(h, ret, SRTO_STREAMID, "SRTO_STREAMID", streamid, &streamid_len))
        /* Note: returned streamid_len doesn't count the terminating null character */
        av_log(h, AV_LOG_VERBOSE, "accept streamid [%s], length %d\n", streamid, streamid_len);
 
    return ret;
}
 
static int libsrt_listen_connect(int eid, int fd, const struct sockaddr *addr, socklen_t addrlen, int64_t timeout, URLContext *h, int will_try_next)
{
    int ret;
 
    if (srt_connect(fd, addr, addrlen) < 0)
        return libsrt_neterrno(h);
 
    ret = libsrt_network_wait_fd_timeout(h, eid, 1, timeout, &h->interrupt_callback);
    if (ret < 0) {
        if (will_try_next) {
            av_log(h, AV_LOG_WARNING,
                   "Connection to %s failed (%s), trying next address\n",
                   h->filename, av_err2str(ret));
        } else {
            av_log(h, AV_LOG_ERROR, "Connection to %s failed: %s\n",
                   h->filename, av_err2str(ret));
        }
    }
    return ret;
}
 
static int libsrt_setsockopt(URLContext *h, int fd, SRT_SOCKOPT optname, const char * optnamestr, const void * optval, int optlen)
{
    if (srt_setsockopt(fd, 0, optname, optval, optlen) < 0) {
        av_log(h, AV_LOG_ERROR, "failed to set option %s on socket: %s\n", optnamestr, srt_getlasterror_str());
        return AVERROR(EIO);
    }
    return 0;
}
 
/* - The "POST" options can be altered any time on a connected socket.
     They MAY have also some meaning when set prior to connecting; such
     option is SRTO_RCVSYN, which makes connect/accept call asynchronous.
     Because of that this option is treated special way in this app. */
static int libsrt_set_options_post(URLContext *h, int fd)
{
    SRTContext *s = h->priv_data;
 
    if ((s->inputbw >= 0 && libsrt_setsockopt(h, fd, SRTO_INPUTBW, "SRTO_INPUTBW", &s->inputbw, sizeof(s->inputbw)) < 0) ||
        (s->oheadbw >= 0 && libsrt_setsockopt(h, fd, SRTO_OHEADBW, "SRTO_OHEADBW", &s->oheadbw, sizeof(s->oheadbw)) < 0)) {
        return AVERROR(EIO);
    }
    return 0;
}
 
/* - The "PRE" options must be set prior to connecting and can't be altered
     on a connected socket, however if set on a listening socket, they are
     derived by accept-ed socket. */
static int libsrt_set_options_pre(URLContext *h, int fd)
{
    SRTContext *s = h->priv_data;
    int yes = 1;
    int latency = s->latency / 1000;
    int rcvlatency = s->rcvlatency / 1000;
    int peerlatency = s->peerlatency / 1000;
#if SRT_VERSION_VALUE >= 0x010302
    int snddropdelay = s->snddropdelay > 0 ? s->snddropdelay / 1000 : s->snddropdelay;
#endif
    int connect_timeout = s->connect_timeout;
 
    if ((s->mode == SRT_MODE_RENDEZVOUS && libsrt_setsockopt(h, fd, SRTO_RENDEZVOUS, "SRTO_RENDEZVOUS", &yes, sizeof(yes)) < 0) ||
        (s->transtype != SRTT_INVALID && libsrt_setsockopt(h, fd, SRTO_TRANSTYPE, "SRTO_TRANSTYPE", &s->transtype, sizeof(s->transtype)) < 0) ||
        (s->maxbw >= 0 && libsrt_setsockopt(h, fd, SRTO_MAXBW, "SRTO_MAXBW", &s->maxbw, sizeof(s->maxbw)) < 0) ||
        (s->pbkeylen >= 0 && libsrt_setsockopt(h, fd, SRTO_PBKEYLEN, "SRTO_PBKEYLEN", &s->pbkeylen, sizeof(s->pbkeylen)) < 0) ||
        (s->passphrase && libsrt_setsockopt(h, fd, SRTO_PASSPHRASE, "SRTO_PASSPHRASE", s->passphrase, strlen(s->passphrase)) < 0) ||
#if SRT_VERSION_VALUE >= 0x010302
#if SRT_VERSION_VALUE >= 0x010401
        (s->enforced_encryption >= 0 && libsrt_setsockopt(h, fd, SRTO_ENFORCEDENCRYPTION, "SRTO_ENFORCEDENCRYPTION", &s->enforced_encryption, sizeof(s->enforced_encryption)) < 0) ||
#else
        /* SRTO_STRICTENC == SRTO_ENFORCEDENCRYPTION (53), but for compatibility, we used SRTO_STRICTENC */
        (s->enforced_encryption >= 0 && libsrt_setsockopt(h, fd, SRTO_STRICTENC, "SRTO_STRICTENC", &s->enforced_encryption, sizeof(s->enforced_encryption)) < 0) ||
#endif
        (s->kmrefreshrate >= 0 && libsrt_setsockopt(h, fd, SRTO_KMREFRESHRATE, "SRTO_KMREFRESHRATE", &s->kmrefreshrate, sizeof(s->kmrefreshrate)) < 0) ||
        (s->kmpreannounce >= 0 && libsrt_setsockopt(h, fd, SRTO_KMPREANNOUNCE, "SRTO_KMPREANNOUNCE", &s->kmpreannounce, sizeof(s->kmpreannounce)) < 0) ||
        (s->snddropdelay  >=-1 && libsrt_setsockopt(h, fd, SRTO_SNDDROPDELAY,  "SRTO_SNDDROPDELAY",  &snddropdelay, sizeof(snddropdelay)) < 0) ||
#endif
        (s->mss >= 0 && libsrt_setsockopt(h, fd, SRTO_MSS, "SRTO_MSS", &s->mss, sizeof(s->mss)) < 0) ||
        (s->ffs >= 0 && libsrt_setsockopt(h, fd, SRTO_FC, "SRTO_FC", &s->ffs, sizeof(s->ffs)) < 0) ||
        (s->ipttl >= 0 && libsrt_setsockopt(h, fd, SRTO_IPTTL, "SRTO_IPTTL", &s->ipttl, sizeof(s->ipttl)) < 0) ||
        (s->iptos >= 0 && libsrt_setsockopt(h, fd, SRTO_IPTOS, "SRTO_IPTOS", &s->iptos, sizeof(s->iptos)) < 0) ||
        (s->latency >= 0 && libsrt_setsockopt(h, fd, SRTO_LATENCY, "SRTO_LATENCY", &latency, sizeof(latency)) < 0) ||
        (s->rcvlatency >= 0 && libsrt_setsockopt(h, fd, SRTO_RCVLATENCY, "SRTO_RCVLATENCY", &rcvlatency, sizeof(rcvlatency)) < 0) ||
        (s->peerlatency >= 0 && libsrt_setsockopt(h, fd, SRTO_PEERLATENCY, "SRTO_PEERLATENCY", &peerlatency, sizeof(peerlatency)) < 0) ||
        (s->tlpktdrop >= 0 && libsrt_setsockopt(h, fd, SRTO_TLPKTDROP, "SRTO_TLPKTDROP", &s->tlpktdrop, sizeof(s->tlpktdrop)) < 0) ||
        (s->nakreport >= 0 && libsrt_setsockopt(h, fd, SRTO_NAKREPORT, "SRTO_NAKREPORT", &s->nakreport, sizeof(s->nakreport)) < 0) ||
        (connect_timeout >= 0 && libsrt_setsockopt(h, fd, SRTO_CONNTIMEO, "SRTO_CONNTIMEO", &connect_timeout, sizeof(connect_timeout)) <0 ) ||
        (s->sndbuf >= 0 && libsrt_setsockopt(h, fd, SRTO_SNDBUF, "SRTO_SNDBUF", &s->sndbuf, sizeof(s->sndbuf)) < 0) ||
        (s->rcvbuf >= 0 && libsrt_setsockopt(h, fd, SRTO_RCVBUF, "SRTO_RCVBUF", &s->rcvbuf, sizeof(s->rcvbuf)) < 0) ||
        (s->lossmaxttl >= 0 && libsrt_setsockopt(h, fd, SRTO_LOSSMAXTTL, "SRTO_LOSSMAXTTL", &s->lossmaxttl, sizeof(s->lossmaxttl)) < 0) ||
        (s->minversion >= 0 && libsrt_setsockopt(h, fd, SRTO_MINVERSION, "SRTO_MINVERSION", &s->minversion, sizeof(s->minversion)) < 0) ||
        (s->streamid && libsrt_setsockopt(h, fd, SRTO_STREAMID, "SRTO_STREAMID", s->streamid, strlen(s->streamid)) < 0) ||
#if SRT_VERSION_VALUE >= 0x010401
        (s->smoother && libsrt_setsockopt(h, fd, SRTO_CONGESTION, "SRTO_CONGESTION", s->smoother, strlen(s->smoother)) < 0) ||
#else
        (s->smoother && libsrt_setsockopt(h, fd, SRTO_SMOOTHER, "SRTO_SMOOTHER", s->smoother, strlen(s->smoother)) < 0) ||
#endif
        (s->messageapi >= 0 && libsrt_setsockopt(h, fd, SRTO_MESSAGEAPI, "SRTO_MESSAGEAPI", &s->messageapi, sizeof(s->messageapi)) < 0) ||
        (s->payload_size >= 0 && libsrt_setsockopt(h, fd, SRTO_PAYLOADSIZE, "SRTO_PAYLOADSIZE", &s->payload_size, sizeof(s->payload_size)) < 0) ||
        ((h->flags & AVIO_FLAG_WRITE) && libsrt_setsockopt(h, fd, SRTO_SENDER, "SRTO_SENDER", &yes, sizeof(yes)) < 0) ||
        (s->tsbpd >= 0 && libsrt_setsockopt(h, fd, SRTO_TSBPDMODE, "SRTO_TSBPDMODE", &s->tsbpd, sizeof(s->tsbpd)) < 0)) {
        return AVERROR(EIO);
    }
 
    if (s->linger >= 0) {
        struct linger lin;
        lin.l_linger = s->linger;
        lin.l_onoff  = lin.l_linger > 0 ? 1 : 0;
        if (libsrt_setsockopt(h, fd, SRTO_LINGER, "SRTO_LINGER", &lin, sizeof(lin)) < 0)
            return AVERROR(EIO);
    }
    return 0;
}
 
 
static int libsrt_setup(URLContext *h, const char *uri, int flags)
{
    struct addrinfo hints = { 0 }, *ai, *cur_ai;
    int port, fd;
    SRTContext *s = h->priv_data;
    int ret;
    char hostname[1024],proto[1024],path[1024];
    char portstr[10];
    int64_t open_timeout = 0;
    int eid;
 
    av_url_split(proto, sizeof(proto), NULL, 0, hostname, sizeof(hostname),
        &port, path, sizeof(path), uri);
    if (strcmp(proto, "srt"))
        return AVERROR(EINVAL);
    if (port <= 0 || port >= 65536) {
        av_log(h, AV_LOG_ERROR, "Port missing in uri\n");
        return AVERROR(EINVAL);
    }
    if (s->rw_timeout >= 0) {
        open_timeout = h->rw_timeout = s->rw_timeout;
    }
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_DGRAM;
    snprintf(portstr, sizeof(portstr), "%d", port);
    if (s->mode == SRT_MODE_LISTENER)
        hints.ai_flags |= AI_PASSIVE;
    ret = getaddrinfo(hostname[0] ? hostname : NULL, portstr, &hints, &ai);
    if (ret) {
        av_log(h, AV_LOG_ERROR,
               "Failed to resolve hostname %s: %s\n",
               hostname, gai_strerror(ret));
        return AVERROR(EIO);
    }
 
    cur_ai = ai;
 
 restart:
 
#if SRT_VERSION_VALUE >= 0x010401
    fd = srt_create_socket();
#else
    fd = srt_socket(cur_ai->ai_family, cur_ai->ai_socktype, 0);
#endif
    if (fd < 0) {
        ret = libsrt_neterrno(h);
        goto fail;
    }
 
    if ((ret = libsrt_set_options_pre(h, fd)) < 0) {
        goto fail;
    }
 
    /* Set the socket's send or receive buffer sizes, if specified.
       If unspecified or setting fails, system default is used. */
    if (s->recv_buffer_size > 0) {
        srt_setsockopt(fd, SOL_SOCKET, SRTO_UDP_RCVBUF, &s->recv_buffer_size, sizeof (s->recv_buffer_size));
    }
    if (s->send_buffer_size > 0) {
        srt_setsockopt(fd, SOL_SOCKET, SRTO_UDP_SNDBUF, &s->send_buffer_size, sizeof (s->send_buffer_size));
    }
    if (libsrt_socket_nonblock(fd, 1) < 0)
        av_log(h, AV_LOG_DEBUG, "libsrt_socket_nonblock failed\n");
 
    if (s->mode == SRT_MODE_LISTENER) {
#if SRT_VERSION_VALUE >= 0x010400
        if (s->ipv6only != -1) {
            if (srt_setsockopt(fd, SOL_SOCKET, SRTO_IPV6ONLY, &s->ipv6only, sizeof(s->ipv6only))) {
                av_log(h, AV_LOG_WARNING, "setsockopt(SRTO_IPV6ONLY) failed\n");
            }
        }
#if SRT_VERSION_VALUE >= 0x010502
        else if (cur_ai->ai_family == AF_INET6) {
            struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)cur_ai->ai_addr;
            if (IN6_IS_ADDR_UNSPECIFIED(&(ipv6->sin6_addr))) {
                av_log(h, AV_LOG_ERROR, "You must specify \"ipv6only\" option if you use a IPv6 wildcard address\n");
                ret = AVERROR(EINVAL);
                goto fail1;
            }
        }
#endif
#endif
        int read_eid = ret = libsrt_epoll_create(h, fd, 0);
        if (ret < 0)
            goto fail1;
        // multi-client
        ret = libsrt_listen(read_eid, fd, cur_ai->ai_addr, cur_ai->ai_addrlen, h, s->listen_timeout);
        srt_epoll_release(read_eid);
        if (ret < 0)
            goto fail1;
        srt_close(fd);
        fd = ret;
    } else {
        int write_eid = ret = libsrt_epoll_create(h, fd, 1);
        if (ret < 0)
            goto fail1;
        if (s->mode == SRT_MODE_RENDEZVOUS) {
            if (srt_bind(fd, cur_ai->ai_addr, cur_ai->ai_addrlen)) {
                ret = libsrt_neterrno(h);
                srt_epoll_release(write_eid);
                goto fail1;
            }
        }
 
        ret = libsrt_listen_connect(write_eid, fd, cur_ai->ai_addr, cur_ai->ai_addrlen,
                                    open_timeout, h, !!cur_ai->ai_next);
        srt_epoll_release(write_eid);
        if (ret < 0) {
            if (ret == AVERROR_EXIT)
                goto fail1;
            else
                goto fail;
        }
    }
    if ((ret = libsrt_set_options_post(h, fd)) < 0) {
        goto fail;
    }
 
    if (flags & AVIO_FLAG_WRITE) {
        int packet_size = 0;
        int optlen = sizeof(packet_size);
        ret = libsrt_getsockopt(h, fd, SRTO_PAYLOADSIZE, "SRTO_PAYLOADSIZE", &packet_size, &optlen);
        if (ret < 0)
            goto fail1;
        if (packet_size > 0)
            h->max_packet_size = packet_size;
    }
 
    ret = eid = libsrt_epoll_create(h, fd, flags & AVIO_FLAG_WRITE);
    if (eid < 0)
        goto fail1;
 
    h->is_streamed = 1;
    s->fd = fd;
    s->eid = eid;
 
    freeaddrinfo(ai);
    return 0;
 
 fail:
    if (cur_ai->ai_next) {
        /* Retry with the next sockaddr */
        cur_ai = cur_ai->ai_next;
        if (fd >= 0)
            srt_close(fd);
        ret = 0;
        goto restart;
    }
 fail1:
    if (fd >= 0)
        srt_close(fd);
    freeaddrinfo(ai);
    return ret;
}
 
static int libsrt_open(URLContext *h, const char *uri, int flags)
{
    SRTContext *s = h->priv_data;
    const char * p;
    int ret = 0;
 
    if (srt_startup() < 0) {
        return AVERROR_UNKNOWN;
    }
 
    /* SRT options (srt/srt.h) */
    p = strchr(uri, '?');
    if (p) {
        ret = ff_parse_opts_from_query_string(s, p, 0);
        if (ret < 0)
            goto err;
    }
    ret = libsrt_setup(h, uri, flags);
    if (ret < 0)
        goto err;
    return 0;
 
err:
    srt_cleanup();
    return ret;
}
 
static int libsrt_read(URLContext *h, uint8_t *buf, int size)
{
    SRTContext *s = h->priv_data;
    int ret;
 
    if (!(h->flags & AVIO_FLAG_NONBLOCK)) {
        ret = libsrt_network_wait_fd_timeout(h, s->eid, 0, h->rw_timeout, &h->interrupt_callback);
        if (ret)
            return ret;
    }
 
    ret = srt_recvmsg(s->fd, buf, size);
    if (ret < 0) {
        ret = libsrt_neterrno(h);
    }
 
    return ret;
}
 
static int libsrt_write(URLContext *h, const uint8_t *buf, int size)
{
    SRTContext *s = h->priv_data;
    int ret;
 
    if (!(h->flags & AVIO_FLAG_NONBLOCK)) {
        ret = libsrt_network_wait_fd_timeout(h, s->eid, 1, h->rw_timeout, &h->interrupt_callback);
        if (ret)
            return ret;
    }
 
    ret = srt_sendmsg(s->fd, buf, size, -1, 1);
    if (ret < 0) {
        ret = libsrt_neterrno(h);
    }
 
    return ret;
}
 
static int libsrt_close(URLContext *h)
{
    SRTContext *s = h->priv_data;
 
    srt_epoll_release(s->eid);
    srt_close(s->fd);
 
    srt_cleanup();
 
    return 0;
}
 
static const AVClass libsrt_class = {
    .class_name = "libsrt",
    .item_name  = av_default_item_name,
    .option     = libsrt_options,
    .version    = LIBAVUTIL_VERSION_INT,
};
 
const URLProtocol ff_libsrt_protocol = {
    .name                = "srt",
    .url_open            = libsrt_open,
    .url_read            = libsrt_read,
    .url_write           = libsrt_write,
    .url_close           = libsrt_close,
    .priv_data_size      = sizeof(SRTContext),
    .flags               = URL_PROTOCOL_FLAG_NETWORK,
    .priv_data_class     = &libsrt_class,
};