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feat: initial receive
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@Neko-Life
Neko-Life committed Sep 21, 2024
1 parent b002e89 commit d742b71
Showing 1 changed file with 123 additions and 124 deletions.
247 changes: 123 additions & 124 deletions src/dpp/discordvoiceclient.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -716,145 +716,144 @@ void discord_voice_client::read_ready()
uint8_t buffer[65535];
int packet_size = this->udp_recv((char*)buffer, sizeof(buffer));

if (packet_size > 0 && (!creator->on_voice_receive.empty() || !creator->on_voice_receive_combined.empty())) {
constexpr size_t header_size = 12;
if (static_cast<size_t>(packet_size) < header_size) {
/* Invalid RTP payload */
return;
}
bool receive_handler_is_empty = creator->on_voice_receive.empty() && creator->on_voice_receive_combined.empty();
if (packet_size <= 0 || receive_handler_is_empty) {
/* Nothing to do */
return;
}

/* It's a "silence packet" - throw it away. */
if (packet_size < 44) {
return;
}
constexpr size_t header_size = 12;
if (static_cast<size_t>(packet_size) < header_size) {
/* Invalid RTP payload */
return;
}

if (uint8_t payload_type = buffer[1] & 0b0111'1111;
72 <= payload_type && payload_type <= 76) {
/*
* This is an RTCP payload. Discord is known to send
* RTCP Receiver Reports.
*
* See https://datatracker.ietf.org/doc/html/rfc3551#section-6
*/
return;
}
/* It's a "silence packet" - throw it away. */
if (packet_size < 44) {
return;
}

voice_payload vp{0, // seq, populate later
0, // timestamp, populate later
std::make_unique<voice_receive_t>(nullptr, std::string((char*)buffer, packet_size))};
if (uint8_t payload_type = buffer[1] & 0b0111'1111;
72 <= payload_type && payload_type <= 76) {
/*
* This is an RTCP payload. Discord is known to send
* RTCP Receiver Reports.
*
* See https://datatracker.ietf.org/doc/html/rfc3551#section-6
*/
return;
}

vp.vr->voice_client = this;
voice_payload vp{0, // seq, populate later
0, // timestamp, populate later
std::make_unique<voice_receive_t>(nullptr, std::string((char*)buffer, packet_size))};

{ /* Get the User ID of the speaker */
uint32_t speaker_ssrc;
std::memcpy(&speaker_ssrc, &buffer[8], sizeof(uint32_t));
speaker_ssrc = ntohl(speaker_ssrc);
vp.vr->user_id = ssrc_map[speaker_ssrc];
}
vp.vr->voice_client = this;

/* Get the sequence number of the voice UDP packet */
std::memcpy(&vp.seq, &buffer[2], sizeof(rtp_seq_t));
vp.seq = ntohs(vp.seq);
/* Get the timestamp of the voice UDP packet */
std::memcpy(&vp.timestamp, &buffer[4], sizeof(rtp_timestamp_t));
vp.timestamp = ntohl(vp.timestamp);

// nonce is 4 byte at the end of payload now
// change accordingly
// /* Nonce is the RTP Header with zero padding */
// uint8_t nonce[24] = { 0 };
// std::memcpy(nonce, buffer, header_size);

// /* Get the number of CSRC in header */
// const size_t csrc_count = buffer[0] & 0b0000'1111;
// /* Skip to the encrypted voice data */
// const ptrdiff_t offset_to_data = header_size + sizeof(uint32_t) * csrc_count;
// uint8_t* ciphertext = buffer + offset_to_data;
// const size_t ciphertext_len = packet_size - offset_to_data;

unsigned long long decrypted_len = 0;

// if (crypto_aead_xchacha20poly1305_ietf_decrypt(buffer, &decrypted_len,
// NULL,
// ciphertext, ciphertext_len,
// NULL,
// NULL,
// nonce, secret_key) != 0) {
// /* Invalid Discord RTP payload. */
// return;
// }

// if(crypto_aead_xchacha20poly1305_ietf_decrypt() != 0)

// if (crypto_secretbox_open_easy(encrypted_data, encrypted_data,
// encrypted_data_len, nonce, secret_key)) {
// /* Invalid Discord RTP payload. */
// return;
// }

// const uint8_t* decrypted_data = encrypted_data;
// size_t decrypted_data_len = encrypted_data_len - crypto_box_MACBYTES;
// if ([[maybe_unused]] const bool uses_extension = (buffer[0] >> 4) & 0b0001) {
// /* Skip the RTP Extensions */
// size_t ext_len = 0;
// {
// uint16_t ext_len_in_words;
// memcpy(&ext_len_in_words, &decrypted_data[2], sizeof(uint16_t));
// ext_len_in_words = ntohs(ext_len_in_words);
// ext_len = sizeof(uint32_t) * ext_len_in_words;
// }
// constexpr size_t ext_header_len = sizeof(uint16_t) * 2;
// decrypted_data += ext_header_len + ext_len;
// decrypted_data_len -= ext_header_len + ext_len;
// }
{ /* Get the User ID of the speaker */
uint32_t speaker_ssrc;
std::memcpy(&speaker_ssrc, &buffer[8], sizeof(uint32_t));
speaker_ssrc = ntohl(speaker_ssrc);
vp.vr->user_id = ssrc_map[speaker_ssrc];
}

/*
* We're left with the decrypted, opus-encoded data.
* Park the payload and decode on the voice courier thread.
*/
vp.vr->audio_data.assign(buffer, buffer + decrypted_len);
/* Get the sequence number of the voice UDP packet */
std::memcpy(&vp.seq, &buffer[2], sizeof(rtp_seq_t));
vp.seq = ntohs(vp.seq);
/* Get the timestamp of the voice UDP packet */
std::memcpy(&vp.timestamp, &buffer[4], sizeof(rtp_timestamp_t));
vp.timestamp = ntohl(vp.timestamp);

constexpr size_t nonce_size = sizeof(uint32_t);
/* Nonce is 4 byte at the end of payload with zero padding */
uint8_t nonce[24] = { 0 };
std::memcpy(nonce, buffer + packet_size - nonce_size, nonce_size);

/* Get the number of CSRC in header */
const size_t csrc_count = buffer[0] & 0b0000'1111;
/* Skip to the encrypted voice data */
const ptrdiff_t offset_to_data = header_size + sizeof(uint32_t) * csrc_count;
uint8_t* ciphertext = buffer + offset_to_data;
const size_t ciphertext_len = packet_size - offset_to_data - nonce_size;

uint8_t header[header_size] = { 0 };
memcpy(header, buffer, header_size);

unsigned long long decrypted_len = 0;
if (crypto_aead_xchacha20poly1305_ietf_decrypt(
buffer, &decrypted_len,
NULL,
ciphertext, ciphertext_len,
header,
header_size,
nonce, secret_key) != 0) {
/* Invalid Discord RTP payload. */
std::cout << "INVALID PACKET\n";
return;
}

{
std::lock_guard lk(voice_courier_shared_state.mtx);
auto& [range, payload_queue, pending_decoder_ctls, decoder] = voice_courier_shared_state.parked_voice_payloads[vp.vr->user_id];
// const uint8_t* decrypted_data = buffer;
// size_t decrypted_data_len = encrypted_data_len - crypto_box_MACBYTES;
// if ([[maybe_unused]] const bool uses_extension = (buffer[0] >> 4) & 0b0001) {
// /* Skip the RTP Extensions */
// size_t ext_len = 0;
// {
// uint16_t ext_len_in_words;
// memcpy(&ext_len_in_words, &decrypted_data[2], sizeof(uint16_t));
// ext_len_in_words = ntohs(ext_len_in_words);
// ext_len = sizeof(uint32_t) * ext_len_in_words;
// }
// constexpr size_t ext_header_len = sizeof(uint16_t) * 2;
// decrypted_data += ext_header_len + ext_len;
// decrypted_data_len -= ext_header_len + ext_len;
// }

/*
* We're left with the decrypted, opus-encoded data.
* Park the payload and decode on the voice courier thread.
*/
vp.vr->audio_data.assign(buffer, buffer + decrypted_len);

if (!decoder) {
/*
* Most likely this is the first time we encounter this speaker.
* Do some initialization for not only the decoder but also the range.
{
std::lock_guard lk(voice_courier_shared_state.mtx);
auto& [range, payload_queue, pending_decoder_ctls, decoder] = voice_courier_shared_state.parked_voice_payloads[vp.vr->user_id];

if (!decoder) {
/*
* Most likely this is the first time we encounter this speaker.
* Do some initialization for not only the decoder but also the range.
*/
range.min_seq = vp.seq;
range.min_timestamp = vp.timestamp;

int opus_error = 0;
decoder.reset(opus_decoder_create(opus_sample_rate_hz, opus_channel_count, &opus_error),
&opus_decoder_destroy);
if (opus_error) {
/**
* NOTE: The -10 here makes the opus_error match up with values of exception_error_code,
* which would otherwise conflict as every C library loves to use values from -1 downwards.
*/
range.min_seq = vp.seq;
range.min_timestamp = vp.timestamp;

int opus_error = 0;
decoder.reset(opus_decoder_create(opus_sample_rate_hz, opus_channel_count, &opus_error),
&opus_decoder_destroy);
if (opus_error) {
/**
* NOTE: The -10 here makes the opus_error match up with values of exception_error_code,
* which would otherwise conflict as every C library loves to use values from -1 downwards.
*/
throw dpp::voice_exception((exception_error_code)(opus_error - 10), "discord_voice_client::discord_voice_client; opus_decoder_create() failed");
}
throw dpp::voice_exception((exception_error_code)(opus_error - 10), "discord_voice_client::discord_voice_client; opus_decoder_create() failed");
}
}

if (vp.seq < range.min_seq && vp.timestamp < range.min_timestamp) {
/* This packet arrived too late. We can only discard it. */
return;
}
range.max_seq = vp.seq;
range.max_timestamp = vp.timestamp;
payload_queue.push(std::move(vp));
if (vp.seq < range.min_seq && vp.timestamp < range.min_timestamp) {
/* This packet arrived too late. We can only discard it. */
return;
}
range.max_seq = vp.seq;
range.max_timestamp = vp.timestamp;
payload_queue.push(std::move(vp));
}

voice_courier_shared_state.signal_iteration.notify_one();
voice_courier_shared_state.signal_iteration.notify_one();

if (!voice_courier.joinable()) {
/* Courier thread is not running, start it */
voice_courier = std::thread(&voice_courier_loop,
std::ref(*this),
std::ref(voice_courier_shared_state));
}
if (!voice_courier.joinable()) {
/* Courier thread is not running, start it */
voice_courier = std::thread(&voice_courier_loop,
std::ref(*this),
std::ref(voice_courier_shared_state));
}
#else
throw dpp::voice_exception(err_no_voice_support, "Voice support not enabled in this build of D++");
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