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Implement ICE lite support #43

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Implement ICE lite support #43

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28 changes: 28 additions & 0 deletions libavformat/whip.c
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Original file line number Diff line number Diff line change
Expand Up @@ -156,9 +156,11 @@
/* STUN Attribute, comprehension-required range (0x0000-0x7FFF) */
enum STUNAttr {
STUN_ATTR_USERNAME = 0x0006, /// shared secret response/bind request
STUN_ATTR_PRIORITY = 0x0024, /// ICE controlling/controlled
STUN_ATTR_USE_CANDIDATE = 0x0025, /// bind request
STUN_ATTR_MESSAGE_INTEGRITY = 0x0008, /// bind request/response
STUN_ATTR_FINGERPRINT = 0x8028, /// rfc5389
STUN_ATTR_ICE_CONTROLLING = 0x802A, /// full agent talking to ice-lite
};

enum WHIPState {
Expand Down Expand Up @@ -303,6 +305,11 @@ typedef struct WHIPContext {
/* The certificate and private key used for DTLS handshake. */
char* cert_file;
char* key_file;


/* ICE-lite support */
int ice_lite_remote;
uint64_t ice_tie_breaker; /* random 64-bit, for ICE-CONTROLLING */
} WHIPContext;

/**
Expand Down Expand Up @@ -412,6 +419,9 @@ static av_cold int initialize(AVFormatContext *s)
seed = av_get_random_seed();
av_lfg_init(&whip->rnd, seed);

/* 64-bit tie-breaker for ICE-CONTROLLING (RFC 8445 6.1.1) */
whip->ice_tie_breaker = ((uint64_t)av_lfg_get(&whip->rnd) << 32) | (uint64_t)av_lfg_get(&whip->rnd);

if (whip->pkt_size < ideal_pkt_size)
av_log(whip, AV_LOG_WARNING, "WHIP: pkt_size=%d(<%d) is too small, may cause packet loss\n",
whip->pkt_size, ideal_pkt_size);
Expand Down Expand Up @@ -894,6 +904,8 @@ static int parse_answer(AVFormatContext *s)
goto end;
}
}
} else if (av_strstart(line, "a=ice-lite", NULL)) {
whip->ice_lite_remote = 1;
}
}

Expand Down Expand Up @@ -985,6 +997,22 @@ static int ice_create_request(AVFormatContext *s, uint8_t *buf, int buf_size, in
avio_wb16(pb, STUN_ATTR_USE_CANDIDATE); /* attribute type use-candidate */
avio_wb16(pb, 0); /* size of use-candidate */

/**
* For ICE-lite peers we are *always* the controlling agent (RFC 8445 6.1.3.1).
* Add PRIORITY + ICE-CONTROLLING attributes.
*/
if (whip->ice_lite_remote) {
/* we are controlling, use host-candidate priority 126 << 24 | 65535 << 8 | 255 = 2130706431 */
avio_wb16(pb, STUN_ATTR_PRIORITY);
avio_wb16(pb, 4);
avio_wb32(pb, 2130706431);

avio_wb16(pb, STUN_ATTR_ICE_CONTROLLING);
avio_wb16(pb, 8);
avio_wb32(pb, (uint32_t)(whip->ice_tie_breaker >> 32));
avio_wb32(pb, (uint32_t)(whip->ice_tie_breaker & 0xffffffff));
}

/* Build and update message integrity */
avio_wb16(pb, STUN_ATTR_MESSAGE_INTEGRITY); /* attribute type message integrity */
avio_wb16(pb, 20); /* size of message integrity */
Expand Down