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sip.cpp
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// (C) 2020-2023 by folkert van heusden <[email protected]>, CC0 license
#include <cstring>
#include <math.h>
#include <optional>
#include <poll.h>
#include <samplerate.h>
#include <stdint.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include "md5.h"
#include "net.h"
#include "sip.h"
#include "utils.h"
static void resample(SRC_STATE *const state, const short *const in, const int in_rate, const int n_samples, short **const out, const int out_rate, int *const out_n_samples)
{
float *in_float = new float[n_samples]();
src_short_to_float_array(in, in_float, n_samples);
double ratio = out_rate / double(in_rate);
size_t n_out_allocated = ceil(n_samples * ratio);
float *out_float = new float[n_out_allocated]();
SRC_DATA sd { 0 };
sd.data_in = in_float;
sd.data_out = out_float;
sd.input_frames = n_samples;
sd.output_frames = n_out_allocated;
sd.input_frames_used = 0;
sd.output_frames_gen = 0;
sd.end_of_input = 0;
sd.src_ratio = ratio;
int rc = -1;
if ((rc = src_process(state, &sd)) != 0)
DOLOG(warning, "SIP: resample failed: %s", src_strerror(rc));
*out_n_samples = sd.output_frames_gen;
*out = new short[*out_n_samples]();
src_float_to_short_array(out_float, *out, *out_n_samples);
delete [] out_float;
delete [] in_float;
}
// from
// http://dystopiancode.blogspot.com/2012/02/pcm-law-and-u-law-companding-algorithms.html
static int8_t encode_alaw(int16_t number)
{
uint16_t mask = 0x800;
uint8_t sign = 0;
uint8_t position = 11;
uint8_t lsb = 0;
if (number < 0) {
number = -number;
sign = 0x80;
}
number >>= 4; // 16 -> 12
for(; ((number & mask) != mask && position >= 5); mask >>= 1, position--) {
}
lsb = (number >> ((position == 4) ? (1) : (position - 4))) & 0x0f;
return (sign | ((position - 4) << 4) | lsb) ^ 0x55;
}
static int8_t encode_mulaw(int16_t number)
{
const uint16_t MULAW_MAX = 0x1FFF;
const uint16_t MULAW_BIAS = 33;
uint16_t mask = 0x1000;
uint8_t sign = 0;
uint8_t position = 12;
uint8_t lsb = 0;
if (number < 0) {
number = -number;
sign = 0x80;
}
number += MULAW_BIAS;
if (number > MULAW_MAX)
number = MULAW_MAX;
for (; ((number & mask) != mask && position >= 5); mask >>= 1, position--) {
}
lsb = (number >> (position - 4)) & 0x0f;
return ~(sign | ((position - 5) << 4) | lsb);
}
sip::sip(const std::string & upstream_sip_server, const std::string & upstream_sip_user, const std::string & upstream_sip_password,
const std::optional<std::string> & myip, const int myport,
const int sip_register_interval, const int samplerate,
std::function<bool(sip_session_t *const session, const std::string & from)> new_session_callback,
std::function<bool(const short *const samples, const size_t n_samples, sip_session_t *const session)> recv_callback,
std::function<bool(short **const samples, size_t *const n_samples, sip_session_t *const session)> send_callback,
std::function<void(sip_session_t *const session)> end_session_callback,
std::function<bool(const uint8_t dtmf_code, const bool is_end, const uint8_t volume, sip_session_t *const session)> dtmf_callback,
void *const global_private_data) :
upstream_server(upstream_sip_server), username(upstream_sip_user), password(upstream_sip_password),
interval(sip_register_interval),
samplerate(samplerate),
new_session_callback(new_session_callback), recv_callback(recv_callback), send_callback(send_callback), end_session_callback(end_session_callback), dtmf_callback(dtmf_callback),
global_private_data(global_private_data)
{
if (myip.has_value())
this->myip = myip.value();
else {
auto interface = find_interface_for(upstream_sip_server);
if (!interface.has_value())
error_exit(false, "Cannot find local IP address to reach \"%s\"", upstream_sip_server.c_str());
this->myip = sockaddr_to_str(interface.value());
DOLOG(debug, "Local IP address: %s\n", this->myip.c_str());
}
sip_fd = create_datagram_socket(myport);
if (myport == 0) {
if (sip_fd == -1)
error_exit(true, "Cannot auto allocate UDP port (for SIP)");
this->myport = get_local_addr(sip_fd).second;
DOLOG(debug, "Local port number: %d\n", this->myport);
}
else if (sip_fd == -1) {
error_exit(true, "Selected port for SIP (UDP %d) is not available", myport);
}
myaddr = this->myip + myformat(":%d", this->myport);
tag = random_hex(16);
th1 = new std::thread(&sip::session_cleaner, this); // session cleaner
th2 = new std::thread(&sip::register_thread, this); // keep-alive to upstream SIP
th3 = new std::thread(&sip::sip_listener, this); // listens for SIP packets
}
sip::~sip()
{
stop_flag = true;
close(sip_fd);
th3->join();
delete th3;
th2->join();
delete th2;
th1->join();
delete th1;
}
void sip::sip_listener()
{
struct pollfd fds[] { { sip_fd, POLLIN, 0 } };
for(;!stop_flag;) {
int rc = poll(fds, 1, 500);
if (rc == -1)
break;
if (rc == 1) {
uint8_t buffer[65536] { 0 };
sockaddr_in addr { 0 };
socklen_t addr_len { sizeof addr };
ssize_t recv_rc = recvfrom(sip_fd, buffer, sizeof buffer - 1, 0, reinterpret_cast<struct sockaddr *>(&addr), &addr_len);
if (recv_rc > 0) {
std::optional<std::string> source_addr = get_host_as_text(reinterpret_cast<struct sockaddr *>(&addr));
if (source_addr.has_value())
DOLOG(debug, "[FROM %s] %s", source_addr.value().c_str(), buffer);
else
DOLOG(debug, "[FROM ?] %s", buffer);
sip_input(&addr, sip_fd, buffer, recv_rc);
}
}
}
}
void sip::sip_input(const sockaddr_in *const a, const int fd, uint8_t *const payload, const size_t payload_size)
{
if (payload_size == 0)
return;
std::string pl_str = std::string((const char *)payload, payload_size);
std::vector<std::string> pl_parts = split(pl_str, "\r\n\r\n");
std::vector<std::string> header_lines = split(pl_parts.at(0), "\r\n");
std::vector<std::string> parts = split(header_lines.at(0), " ");
uint64_t now = get_us();
if (parts.size() == 3 && parts.at(0) == "OPTIONS" && parts.at(2) == "SIP/2.0") {
reply_to_OPTIONS(a, fd, &header_lines);
}
else if (parts.size() == 3 && parts.at(0) == "INVITE" && parts.at(2) == "SIP/2.0" && pl_parts.size() == 2) {
std::vector<std::string> body_lines = split(pl_parts.at(1), "\r\n");
reply_to_INVITE(a, fd, &header_lines, &body_lines);
}
else if (parts.size() == 3 && parts.at(0) == "BYE" && parts.at(2) == "SIP/2.0") {
DOLOG(debug, "Received BYE\n");
reply_to_BYE(a, fd, &header_lines);
}
else if (parts.size() >= 2 && parts.at(0) == "SIP/2.0") {
auto str_call_id = find_header(&header_lines, "Call-ID");
if (str_call_id.has_value() == false) {
DOLOG(info, "Call-ID missing in headers\n");
return;
}
if (str_call_id.value() == register_cid) {
std::unique_lock<std::mutex> lck(registered_lock);
if (parts.at(1) == "401") {
if (now - ddos_protection > 1000000) {
lck.unlock();
reply_to_UNAUTHORIZED(&header_lines);
ddos_protection = now;
}
else {
DOLOG(info, "SIP: drop 401 packet\n");
}
}
else if (parts.at(1) == "200") {
is_registered = true;
registered_cv.notify_all();
}
}
else {
if (parts.at(1) == "401")
DOLOG(debug, "Unauthorized header received, regenerate auth-header for %s\n", str_call_id.value().c_str());
std::unique_lock<std::mutex> lck(sessions_lock);
for(auto & entry : sessions_pending) {
if (entry.first == str_call_id.value()) {
entry.second.first = atoi(parts.at(1).c_str());
entry.second.second = pl_parts;
sessions_cv.notify_all();
break;
}
}
}
}
else {
DOLOG(info, "SIP: request \"%s\" not understood\n", header_lines.at(0).c_str());
}
}
static void create_response_headers(const std::string & request, std::vector<std::string> *const target, const bool upd_cseq, const std::vector<std::string> *const source, const size_t c_size, const sockaddr_in & a, const std::string & myaddr)
{
target->push_back(request);
auto str_via = find_header(source, "Via");
auto str_from = find_header(source, "From");
auto str_to = find_header(source, "To");
auto str_call_id = find_header(source, "Call-ID");
auto str_cseq = find_header(source, "CSeq");
if (str_via.has_value())
target->push_back("Via: " + str_via.value());
if (str_from.has_value())
target->push_back("From: " + str_from.value());
if (str_to.has_value())
target->push_back("To: " + str_to.value());
if (str_call_id.has_value())
target->push_back("Call-ID: " + str_call_id.value());
if (str_cseq.has_value()) {
if (upd_cseq) {
std::string request_method = request.substr(0, request.find(' '));
int cseq = str_cseq.has_value() ? atoi(str_cseq.value().c_str()) : 0;
target->push_back(myformat("CSeq: %u %s", cseq + 1, request_method.c_str()));
}
else {
target->push_back("CSeq: " + str_cseq.value());
}
}
target->push_back(myformat("Server: %s", myaddr.c_str()));
//target->push_back("Allow: INVITE, ASK, CANCEL, OPTIONS, BYE");
target->push_back("Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH, MESSAGE");
if (str_to.has_value()) {
std::string::size_type lt = str_to.value().rfind('<');
std::string::size_type gt = str_to.value().rfind('>');
if (lt != std::string::npos && gt != std::string::npos) {
std::string contact = str_to.value().substr(lt, gt - lt + 1);
target->push_back(myformat("Contact: %s", contact.c_str()));
}
}
target->push_back("User-Agent: libHappy");
if (c_size > 0)
target->push_back("Content-Type: application/sdp");
target->push_back(myformat("Content-Length: %zu", c_size));
}
bool sip::transmit_packet(const sockaddr_in *const a, const int fd, const uint8_t *const data, const size_t data_size, const bool log)
{
if (log) {
std::optional<std::string> dest_addr = get_host_as_text(const_cast<struct sockaddr *>(reinterpret_cast<const struct sockaddr *>(a)));
if (dest_addr.has_value())
DOLOG(debug, "[TO %s] %s", dest_addr.value().c_str(), reinterpret_cast<const char *>(data));
else
DOLOG(debug, "[TO ?] %s", reinterpret_cast<const char *>(data));
}
return sendto(fd, data, data_size, 0, reinterpret_cast<const struct sockaddr *>(a), sizeof *a) == ssize_t(data_size);
}
std::vector<std::string> sip::generate_sdp_payload(const std::string & ip, const std::string & proto, const int rtp_port)
{
std::vector<std::string> payload;
payload.push_back("v=0");
payload.push_back("o=jdoe 0 0 IN " + proto + " " + ip);
payload.push_back("c=IN " + proto + " " + ip);
payload.push_back("s=libHappy");
payload.push_back("t=0 0");
payload.push_back(myformat("m=audio %u RTP/AVP 0 8 9 11", rtp_port));
payload.push_back("a=sendrecv");
// payload.push_back(myformat("a=rtpmap:0 PCMU/%u", samplerate));
payload.push_back(myformat("a=rtpmap:8 PCMA/%u", samplerate));
payload.push_back(myformat("a=rtpmap:9 G722/8000"));
payload.push_back(myformat("a=rtpmap:11 L16/%u", samplerate));
payload.push_back(myformat("a=rtpmap:101 telephone-event/%u", samplerate));
return payload;
}
void sip::reply_to_OPTIONS(const sockaddr_in *const a, const int fd, const std::vector<std::string> *const headers)
{
std::string proto = a->sin_family == AF_INET ? "IP4" : "IP6";
std::vector<std::string> content = generate_sdp_payload(sockaddr_to_str(*a), proto, 0); // port is not allocated yet
std::string content_out = merge(content, "\r\n");
std::vector<std::string> hout;
create_response_headers("SIP/2.0 200 OK", &hout, false, headers, content_out.size(), *a, myaddr);
std::string headers_out = merge(hout, "\r\n");
std::string out = headers_out + "\r\n" + content_out;
if (transmit_packet(a, fd, reinterpret_cast<const uint8_t *>(out.c_str()), out.size(), true) == false)
DOLOG(info, "sip::reply_to_OPTIONS: transmit failed");
}
// sockaddr_in points to the RTP target
std::optional<std::pair<codec_t, struct sockaddr_in> > dissect_sdp(const std::vector<std::string> *const body, const int max_rate)
{
codec_t best { 255, "", "", -1, -1 };
int rtp_target_port { -1 };
std::string rtp_target_host;
int frame_duration = 20;
std::vector<std::string> order;
// id, (org-)name, rate
std::map<int, std::pair<std::string, int> > options;
for(auto & line : *body) {
DOLOG(debug, "SPD: %s\n", line.c_str());
if (line.substr(0, 11) == "a=maxptime:") {
frame_duration = std::min(40, atoi(line.substr(11).c_str()));
DOLOG(debug, "dissect_sdp: frame duration set to %dms\n", frame_duration);
continue;
}
if (line.substr(0, 2) == "o=") {
auto parts = split(line, " ");
rtp_target_host = parts[5];
continue;
}
if (line.substr(0, 7) == "m=audio") {
order = split(line, " ");
rtp_target_port = atoi(order.at(1).c_str());
// "m=audio 19206 RTP/AVP" are not of interest
order.erase(order.begin(), order.begin() + 3);
continue;
}
if (line.substr(0, 9) != "a=rtpmap:")
continue;
std::string pars = line.substr(9);
std::size_t lspace = pars.find(' ');
if (lspace == std::string::npos)
continue;
std::string type_rate = pars.substr(lspace + 1);
std::size_t slash = type_rate.find('/');
if (slash == std::string::npos)
continue;
uint8_t id = atoi(pars.substr(0, lspace).c_str());
std::string name = type_rate.substr(0, slash);
int rate = atoi(type_rate.substr(slash + 1).c_str());
options.insert({ id, { name, rate } });
}
for(auto & order_element : order) {
int order_id = atoi(order_element.c_str());
auto it = options.find(order_id);
// might be missing due to bugs in the other end
if (it == options.end())
continue;
std::string name = str_tolower(it->second.first);
if (name == "pcma" || name == "alaw" ||
name == "l16" ||
name == "g722") {
best.id = order_id;
best.name = name;
best.org_name = it->second.first;
best.rate = it->second.second;
break;
}
}
if (best.id == 255) {
DOLOG(info, "SIP: no suitable codec found\n");
return { };
}
// usually 20ms
best.frame_size = best.rate * frame_duration / 1000;
best.frame_duration = frame_duration;
DOLOG(info, "SIP: CODEC chosen: %s/%d (id: %u), frame size: %d\n", best.name.c_str(), best.rate, best.id, best.frame_size);
if (rtp_target_port == -1 || rtp_target_host.empty()) {
DOLOG(info, "SIP: RTP target not found in SDP payload\n");
return { };
}
auto resolved_addr = resolve_name(rtp_target_host, rtp_target_port);
if (resolved_addr.has_value() == false) {
DOLOG(info, "SIP: cannot resolve RTP target\n");
return { };
}
struct sockaddr_in rtp_target = *reinterpret_cast<struct sockaddr_in *>(&resolved_addr.value());
return { { best, rtp_target } };
}
sip_session_t * sip::allocate_sip_session()
{
sip_session_t *ss = new sip_session_t();
ss->th = nullptr;
ss->start_ts = get_us();
ss->samplerate = samplerate;
ss->g722_encoder = g722_encoder_new(64000, G722_SAMPLE_RATE_8000);
ss->g722_decoder = g722_decoder_new(64000, G722_SAMPLE_RATE_8000);
ss->global_private_data = global_private_data;
// init audio resampler
int dummy = 0;
ss->audio_in_resample = src_new(SRC_SINC_BEST_QUALITY, 1, &dummy);
ss->audio_out_resample = src_new(SRC_SINC_BEST_QUALITY, 1, &dummy);
if (!ss->audio_in_resample || !ss->audio_out_resample || !ss->g722_encoder || !ss->g722_decoder) {
delete ss;
return nullptr;
}
return ss;
}
void sip::reply_to_INVITE(const sockaddr_in *const a, const int fd, const std::vector<std::string> *const headers, const std::vector<std::string> *const body)
{
std::string proto = a->sin_family == AF_INET ? "IP4" : "IP6";
std::vector<std::string> content;
content.push_back("v=0");
content.push_back("o=jdoe 0 0 IN " + proto + " " + myip.c_str());
content.push_back("c=IN " + proto + " " + myip.c_str());
content.push_back("s=Happy");
content.push_back("t=0 0");
auto m = find_header(body, "m", "=");
if (m.has_value()) {
auto schema_addr = dissect_sdp(body, samplerate);
if (schema_addr.has_value() == false)
return;
codec_t & schema = schema_addr.value().first;
if (schema.id != 255) {
auto call_id = find_header(headers, "Call-ID");
if (call_id.has_value() == false) {
DOLOG(info, "Call-ID header missing\n");
return;
}
auto from = find_header(headers, "From");
if (from.has_value() == false) {
DOLOG(info, "From header missing\n");
return;
}
int rtp_fd = create_datagram_socket(0);
if (rtp_fd == -1) {
DOLOG(info, "Cannot allocate RTP (UDP) port\n");
return;
}
std::string from_value = from.value();
std::size_t semi_colon = from_value.find(';');
if (semi_colon != std::string::npos)
from_value = from_value.substr(0, semi_colon);
sip_session_t *ss = allocate_sip_session();
ss->headers = *headers;
memcpy(&ss->sip_addr_peer, a, sizeof ss->sip_addr_peer);
ss->schema = schema;
ss->fd = rtp_fd;
ss->audio_port = get_local_addr(ss->fd).second;
ss->call_id = call_id.value();
ss->peer = from_value;
src_set_ratio(ss->audio_in_resample, double(samplerate) / schema.rate); // TODO error checking, fail and send CANCEL
src_set_ratio(ss->audio_out_resample, schema.rate / double(samplerate)); // TODO error checking
content.push_back("a=sendrecv");
content.push_back(myformat("a=rtpmap:%u %s/%u", schema.id, schema.org_name.c_str(), schema.rate));
content.push_back(myformat("m=audio %d RTP/AVP %u", ss->audio_port, schema.id));
std::string content_out = merge(content, "\r\n");
if (new_session_callback(ss, from_value)) {
// merge headers
std::vector<std::string> hout;
create_response_headers("SIP/2.0 200 OK", &hout, false, headers, content_out.size(), ss->sip_addr_peer, myaddr);
std::string headers_out = merge(hout, "\r\n");
std::string out = headers_out + "\r\n" + content_out;
// send INVITE reply
if (transmit_packet(a, fd, reinterpret_cast<const uint8_t *>(out.c_str()), out.size(), true) == false) {
DOLOG(info, "sip::reply_to_INVITE: ok transmit failed");
end_session_callback(ss); // cannot transmit, session ended
delete ss;
}
else {
ss->th = new std::thread(&sip::session, this, schema_addr.value().second, ss);
std::unique_lock<std::mutex> lck(sessions_lock);
sessions.insert({ call_id.value(), ss });
sessions_cv.notify_all();
}
}
else {
// merge headers
std::vector<std::string> hout;
create_response_headers("SIP/2.0 608 Rejected", &hout, false, headers, content_out.size(), ss->sip_addr_peer, myaddr);
std::string headers_out = merge(hout, "\r\n");
std::string out = headers_out + "\r\n" + content_out;
// send rejection reply
if (transmit_packet(a, fd, reinterpret_cast<const uint8_t *>(out.c_str()), out.size(), true) == false)
DOLOG(info, "sip::reply_to_INVITE: rejection transmit failed");
delete ss;
}
}
}
}
void sip::send_ACK(const sockaddr_in *const a, const int fd, const std::vector<std::string> *const headers)
{
std::vector<std::string> hout;
create_response_headers("SIP/2.0 200 OK", &hout, false, headers, 0, *a, myaddr);
std::string out = merge(hout, "\r\n");
if (transmit_packet(a, fd, reinterpret_cast<const uint8_t *>(out.c_str()), out.size(), true) == false)
DOLOG(info, "sip::send_ACK: transmit failed");
}
void sip::reply_to_BYE(const sockaddr_in *const a, const int fd, const std::vector<std::string> *const headers)
{
auto call_id = find_header(headers, "Call-ID");
if (call_id.has_value() == false) {
DOLOG(warning, "sip::reply_to_BYE: \"Call-ID\" not found in headers\n");
return;
}
{
std::unique_lock<std::mutex> lck(sessions_lock);
auto it = sessions.find(call_id.value());
if (it != sessions.end()) {
DOLOG(info, "sip::reply_to_BYE: asking thread for session \"%s\" to terminate\n", call_id.value().c_str());
it->second->stop_flag = true;
}
else {
DOLOG(warning, "sip::reply_to_BYE: session \"%s\" not found\n", call_id.value().c_str());
}
}
send_ACK(a, fd, headers);
}
static std::string calculate_digest(const std::string & username, const std::string & realm, const std::string & secret, const std::string & method, const std::string & uri, const std::string & nonce)
{
std::string a1 = md5(username + ":" + realm + ":" + secret);
std::string a2 = md5(method + ":" + uri);
std::string digest = md5(a1 + ":" + nonce + ":" + a2);
return digest;
}
std::string sip::generate_authorize_header(const std::vector<std::string> *const headers, const std::string & uri, const std::string & method)
{
auto str_wa = find_header(headers, "WWW-Authenticate");
if (!str_wa.has_value()) {
DOLOG(info, "SIP: \"WWW-Authenticate\" missing");
return "";
}
auto call_id = find_header(headers, "Call-ID");
std::string work = replace(str_wa.value(), ",", " ");
std::vector<std::string> parameters = split(work, " ");
std::string digest_alg = "MD5";
auto str_da = find_header(¶meters, "algorithm", "=");
if (str_da.has_value())
digest_alg = str_da.value();
std::string realm;
auto str_realm = find_header(¶meters, "realm", "=");
if (str_realm.has_value())
realm = replace(str_realm.value(), "\"", "");
std::string opaque;
auto str_opaque = find_header(¶meters, "opaque", "=");
if (str_opaque.has_value())
opaque = replace(str_opaque.value(), "\"", "");
std::string nonce;
auto str_nonce = find_header(¶meters, "nonce", "=");
if (str_nonce.has_value())
nonce = replace(str_nonce.value(), "\"", "");
std::string digest = calculate_digest(username, realm, password, method, uri, nonce);
std::string authorize = "Authorization: Digest username=\"" + username + "\",realm=\"" + realm + "\",nonce=\"" + nonce + "\",uri=\"" + uri + "\",algorithm=MD5,response=\"" + digest + "\"";
if (opaque.empty() == false)
authorize += ",opaque=\"" + opaque + "\"";
std::string call_id_str = call_id.has_value() ? call_id.value() : "";
{
std::unique_lock<std::mutex> lck(registered_lock);
register_authline = authorize;
}
return authorize;
}
void sip::reply_to_UNAUTHORIZED(const std::vector<std::string> *const headers)
{
std::string auth_header = generate_authorize_header(headers, "sip:" + myaddr, "REGISTER");
auto call_id = find_header(headers, "Call-ID");
std::string call_id_str = call_id.has_value() ? call_id.value() : "";
send_REGISTER(call_id_str, auth_header);
}
static std::pair<uint8_t *, int> create_rtp_packet(const uint32_t ssrc, const uint16_t seq_nr, const uint32_t t, const codec_t & schema, const short *const samples, const int n_samples, G722_ENC_CTX *const g722_enc)
{
int sample_size = 0;
if (schema.name == "alaw" || schema.name == "pcma") // a-law and mu-law
sample_size = sizeof(uint8_t);
else if (schema.name == "g722") // G722
sample_size = sizeof(uint8_t);
else if (schema.name == "l16") // l16 mono
sample_size = sizeof(uint16_t);
else {
DOLOG(ll_error, "SIP: Invalid rtp payload schema %s/%d\n", schema.name.c_str(), schema.rate);
return { nullptr, 0 };
}
size_t size = 3 * 4 + n_samples * sample_size;
uint8_t *rtp_packet = new uint8_t[size]();
rtp_packet[0] |= 128; // v2
rtp_packet[1] = schema.id;
rtp_packet[2] = seq_nr >> 8;
rtp_packet[3] = seq_nr;
rtp_packet[4] = t >> 24;
rtp_packet[5] = t >> 16;
rtp_packet[6] = t >> 8;
rtp_packet[7] = t;
rtp_packet[8] = ssrc >> 24;
rtp_packet[9] = ssrc >> 16;
rtp_packet[10] = ssrc >> 8;
rtp_packet[11] = ssrc;
if (schema.name == "alaw" || schema.name == "pcma") { // a-law
for(int i=0; i<n_samples; i++)
rtp_packet[12 + i] = encode_alaw(samples[i]);
}
else if (schema.name == "g722") { // g.722
g722_encode(g722_enc, samples, n_samples, &rtp_packet[12]);
}
else if (schema.name == "l16") { // l16 mono
for(int i=0; i<n_samples; i++) {
rtp_packet[12 + i * 2 + 0] = samples[i] >> 8;
rtp_packet[12 + i * 2 + 1] = samples[i];
}
}
return { rtp_packet, size };
}
void sip::send_BYE_or_CANCEL(const sockaddr_in *const a, const std::vector<std::string> & headers, const bool is_bye)
{
std::string extension = "0";
auto str_to = find_header(&headers, "To");
if (str_to.has_value()) {
std::string::size_type lt = str_to.value().rfind('<');
std::string::size_type gt = str_to.value().rfind('>');
if (lt != std::string::npos && gt != std::string::npos)
extension = str_to.value().substr(lt + 1, gt - lt - 1);
}
std::vector<std::string> hout;
create_response_headers(myformat("%s %s SIP/2.0", is_bye ? "BYE " : "CANCEL", extension.c_str()), &hout, true, &headers, 0, *a, myaddr);
std::string out = merge(hout, "\r\n") + "\r\n";
if (transmit_packet(a, sip_fd, reinterpret_cast<const uint8_t *>(out.c_str()), out.size(), true) == false)
DOLOG(info, "sip::send_BYE: transmit failed");
}
bool sip::transmit_audio(const sockaddr_in tgt_addr, sip_session_t *const ss, const short *const audio_in, const int n_audio_in, uint16_t *const seq_nr, uint32_t *const t, const uint32_t ssrc)
{
int offset = 0;
int n_audio = 0;
short *audio = nullptr;
bool resampled = false;
if (samplerate == ss->schema.rate)
n_audio = n_audio_in;
else {
resample(ss->audio_out_resample, audio_in, samplerate, n_audio_in, &audio, ss->schema.rate, &n_audio);
resampled = true;
}
while(n_audio > 0 && !stop_flag && !ss->stop_flag) {
int cur_n = std::min(n_audio, ss->schema.frame_size);
auto rtpp = create_rtp_packet(ssrc, *seq_nr, *t, ss->schema, &(resampled ? audio : audio_in)[offset], cur_n, ss->g722_encoder);
offset += cur_n;
n_audio -= cur_n;
(*t) += cur_n;
(*seq_nr)++;
if (rtpp.second) {
if (transmit_packet(&tgt_addr, ss->fd, rtpp.first, rtpp.second, false) == false) {
DOLOG(info, "transmit_audio: transmit failed");
return false;
}
delete [] rtpp.first;
}
double sleep = 1000000.0 / (ss->schema.rate / double(cur_n / 8.0));
myusleep(sleep);
}
if (resampled)
delete [] audio;
return true;
}
void sip::wait_for_audio(sip_session_t *const ss)
{
DOLOG(info, "sip::wait_for_audio: audio receive handler thread started\n");
// TODO: check if source address is expected
// wait for packets on ss->fd
// send them to audio_input()
struct pollfd fds[] { { ss->fd, POLLIN, 0 } };
for(;!stop_flag && !ss->stop_flag;) {
int rc = poll(fds, 1, 500);
if (rc == -1)
break;
if (rc == 1) {
uint8_t buffer[1600] { 0 };
sockaddr_in addr { 0 };
socklen_t addr_len { sizeof addr };
ssize_t recv_rc = recvfrom(ss->fd, buffer, sizeof buffer, 0, reinterpret_cast<struct sockaddr *>(&addr), &addr_len);
if (recv_rc > 0) {
if ((buffer[1] & 127) == 101) {
// 101 is statically assigned (in this library) to "telephone-event" rtp-type
dolog(debug, "TELEPHONE EVENT %d, %02x\n", buffer[12], buffer[13]);
if (!dtmf_callback(buffer[12], !!(buffer[13] & 128), buffer[13] & 63, ss)) {
ss->stop_flag = true;
break;
}
}
else {
if (!audio_input(buffer, recv_rc, ss)) {
ss->stop_flag = true;
break;
}
}
}
}
}
}
void generate_beep(const double f, const double duration, const int samplerate, short **const beep, size_t *const beep_n)
{
*beep_n = samplerate * duration;
*beep = new short[*beep_n]();
double mul = 2.0 * M_PI * f;
for(size_t i=0; i<*beep_n; i++)
(*beep)[i] = 32767 * sin(mul * (i + i / double(samplerate)));
}
void sip::session(const struct sockaddr_in tgt_addr, sip_session_t *const ss)
{
set_thread_name("SIP-RTP");
struct sockaddr_in work_addr = tgt_addr;
DOLOG(info, "sip::session: session handler thread started. transmit to %s:%d at rate %d\n", sockaddr_to_str(work_addr).c_str(), ntohs(work_addr.sin_port), ss->schema.rate);
std::thread audio_recv_thread([this, ss]() { wait_for_audio(ss); });
uint16_t seq_nr = 0;
uint32_t t = 0;
uint32_t ssrc = 0;
get_random(reinterpret_cast<uint8_t *>(&ssrc), sizeof ssrc);
for(;!stop_flag && !ss->stop_flag;) {
short *samples = nullptr;
size_t n_samples = 0;
if (send_callback(&samples, &n_samples, ss) == false) {
DOLOG(debug, "sip::session: callback indicated end\n");
break;
}
if (transmit_audio(work_addr, ss, samples, n_samples, &seq_nr, &t, ssrc) == false) {
DOLOG(debug, "sip::session: transmit audio failed\n");
break;
}
delete [] samples;
}
ss->stop_flag = true;
send_BYE_or_CANCEL(&tgt_addr, ss->headers, true);
send_REGISTER("", ""); // required?
audio_recv_thread.join();
end_session_callback(ss);