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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2023
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include "td/net/Socks5.h"
#include "td/utils/common.h"
#include "td/utils/logging.h"
#include "td/utils/misc.h"
#include "td/utils/Slice.h"
#include "td/utils/SliceBuilder.h"
namespace td {
void Socks5::send_greeting() {
VLOG(proxy) << "Send greeting to proxy";
CHECK(state_ == State::SendGreeting);
state_ = State::WaitGreetingResponse;
string greeting;
greeting += '\x05';
bool use_username = !username_.empty();
char authentication_count = use_username ? '\x02' : '\x01';
greeting += authentication_count;
greeting += '\0';
if (use_username) {
greeting += '\x02';
}
fd_.output_buffer().append(greeting);
}
Status Socks5::wait_greeting_response() {
auto &buf = fd_.input_buffer();
VLOG(proxy) << "Receive greeting response of size " << buf.size();
if (buf.size() < 2) {
return Status::OK();
}
auto buffer_slice = buf.read_as_buffer_slice(2);
auto slice = buffer_slice.as_slice();
if (slice[0] != '\x05') {
return Status::Error(PSLICE() << "Unsupported socks protocol version " << static_cast<int>(slice[0]));
}
auto authentication_method = slice[1];
if (authentication_method == '\0') {
send_ip_address();
return Status::OK();
}
if (authentication_method == '\x02') {
return send_username_password();
}
return Status::Error("Unsupported authentication mode");
}
Status Socks5::send_username_password() {
VLOG(proxy) << "Send username and password";
if (username_.size() >= 128) {
return Status::Error("Username is too long");
}
if (password_.size() >= 128) {
return Status::Error("Password is too long");
}
string request;
request += '\x01';
request += narrow_cast<char>(username_.size());
request += username_;
request += narrow_cast<char>(password_.size());
request += password_;
fd_.output_buffer().append(request);
state_ = State::WaitPasswordResponse;
return Status::OK();
}
Status Socks5::wait_password_response() {
auto &buf = fd_.input_buffer();
VLOG(proxy) << "Receive password response of size " << buf.size();
if (buf.size() < 2) {
return Status::OK();
}
auto buffer_slice = buf.read_as_buffer_slice(2);
auto slice = buffer_slice.as_slice();
if (slice[0] != '\x01') {
return Status::Error(PSLICE() << "Unsupported socks subnegotiation protocol version "
<< static_cast<int>(slice[0]));
}
if (slice[1] != '\x00') {
return Status::Error("Wrong username or password");
}
send_ip_address();
return Status::OK();
}
void Socks5::send_ip_address() {
VLOG(proxy) << "Send IP address";
callback_->on_connected();
string request;
request += '\x05';
request += '\x01';
request += '\x00';
if (ip_address_.is_ipv4()) {
request += '\x01';
auto ipv4 = ntohl(ip_address_.get_ipv4());
request += static_cast<char>(ipv4 & 255);
request += static_cast<char>((ipv4 >> 8) & 255);
request += static_cast<char>((ipv4 >> 16) & 255);
request += static_cast<char>((ipv4 >> 24) & 255);
} else {
request += '\x04';
request += ip_address_.get_ipv6();
}
auto port = ip_address_.get_port();
request += static_cast<char>((port >> 8) & 255);
request += static_cast<char>(port & 255);
fd_.output_buffer().append(request);
state_ = State::WaitIpAddressResponse;
}
Status Socks5::wait_ip_address_response() {
CHECK(state_ == State::WaitIpAddressResponse);
auto it = fd_.input_buffer().clone();
VLOG(proxy) << "Receive IP address response of size " << it.size();
if (it.size() < 4) {
return Status::OK();
}
char c;
MutableSlice c_slice(&c, 1);
it.advance(1, c_slice);
if (c != '\x05') {
return Status::Error("Invalid response");
}
it.advance(1, c_slice);
if (c != '\0') {
return Status::Error(PSLICE() << "Receive error code " << static_cast<int32>(c) << " from server");
}
it.advance(1, c_slice);
if (c != '\0') {
return Status::Error("Byte must be zero");
}
it.advance(1, c_slice);
size_t total_size = 6;
if (c == '\x01') {
if (it.size() < 4) {
return Status::OK();
}
it.advance(4);
total_size += 4;
} else if (c == '\x04') {
if (it.size() < 16) {
return Status::OK();
}
it.advance(16);
total_size += 16;
} else {
return Status::Error("Invalid response");
}
if (it.size() < 2) {
return Status::OK();
}
it.advance(2);
fd_.input_buffer().advance(total_size);
stop();
return Status::OK();
}
Status Socks5::loop_impl() {
switch (state_) {
case State::SendGreeting:
send_greeting();
break;
case State::WaitGreetingResponse:
TRY_STATUS(wait_greeting_response());
break;
case State::WaitPasswordResponse:
TRY_STATUS(wait_password_response());
break;
case State::WaitIpAddressResponse:
TRY_STATUS(wait_ip_address_response());
break;
default:
UNREACHABLE();
}
return Status::OK();
}
} // namespace td
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