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Merge bitcoin/bitcoin#28649: Do the SOCKS5 handshake reliably

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af0fca530e4d8311bcb24a14c416e5ad7c30ff78 netbase: use reliable send() during SOCKS5 handshake (Vasil Dimov)
1b19d1117ca5373a15313227b547ef4392022dbd sock: change Sock::SendComplete() to take Span (Vasil Dimov)

Pull request description:

  The `Socks5()` function which does the SOCKS5 handshake with the SOCKS5 proxy sends bytes to the socket without retrying partial writes.

  `send(2)` may write only part of the provided data and return. In this case the caller is responsible for retrying the operation with the remaining data. Change `Socks5()` to do that. There is already a method `Sock::SendComplete()` which does exactly that, so use it in `Socks5()`.

  A minor complication for this PR is that `Sock::SendComplete()` takes `std::string` argument whereas `Socks5()` has `std::vector<uint8_t>`. Thus the necessity for the first commit. It is possible to do also in other ways - convert the data in `Socks5()` to `std::string` or have just one `Sock::SendComplete()` that takes `void*` and change the callers to pass `str.data(), str.size()` or `vec.data(), vec.size()`.

  This came up while testing https://github.com/bitcoin/bitcoin/pull/27375.

ACKs for top commit:
  achow101:
    ACK af0fca530e4d8311bcb24a14c416e5ad7c30ff78
  jonatack:
    ACK af0fca530e4d8311bcb24a14c416e5ad7c30ff78
  pinheadmz:
    ACK af0fca530e4d8311bcb24a14c416e5ad7c30ff78

Tree-SHA512: 1d4a53d0628f7607378038ac56dc3b8624ce9322b034c9547a0c3ce052eafb4b18213f258aa3b57bcb4d990a5e0548a37ec70af2bd55f6e8e6399936f1ce047a
This commit is contained in:
Andrew Chow 2023-11-07 14:11:46 -05:00
commit 0528cfd307
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GPG Key ID: 17565732E08E5E41
6 changed files with 122 additions and 114 deletions
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3
src/net.cpp
View File

@ -3219,7 +3219,6 @@ bool CConnman::Start(CScheduler& scheduler, const Options& connOptions)
// Start threads
//
assert(m_msgproc);
InterruptSocks5(false);
interruptNet.reset();
flagInterruptMsgProc = false;
@ -3291,7 +3290,7 @@ void CConnman::Interrupt()
condMsgProc.notify_all();
interruptNet();
InterruptSocks5(true);
g_socks5_interrupt();
if (semOutbound) {
for (int i=0; i<m_max_outbound; i++) {

205
src/netbase.cpp
View File

@ -30,7 +30,7 @@ bool fNameLookup = DEFAULT_NAME_LOOKUP;
// Need ample time for negotiation for very slow proxies such as Tor
std::chrono::milliseconds g_socks5_recv_timeout = 20s;
static std::atomic<bool> interruptSocks5Recv(false);
CThreadInterrupt g_socks5_interrupt;
ReachableNets g_reachable_nets;
@ -271,7 +271,7 @@ enum class IntrRecvError {
* IntrRecvError::OK only if all of the specified number of bytes were
* read.
*
* @see This function can be interrupted by calling InterruptSocks5(bool).
* @see This function can be interrupted by calling g_socks5_interrupt().
* Sockets can be made non-blocking with Sock::SetNonBlocking().
*/
static IntrRecvError InterruptibleRecv(uint8_t* data, size_t len, std::chrono::milliseconds timeout, const Sock& sock)
@ -299,8 +299,9 @@ static IntrRecvError InterruptibleRecv(uint8_t* data, size_t len, std::chrono::m
return IntrRecvError::NetworkError;
}
}
if (interruptSocks5Recv)
if (g_socks5_interrupt) {
return IntrRecvError::Interrupted;
}
curTime = Now<SteadyMilliseconds>();
}
return len == 0 ? IntrRecvError::OK : IntrRecvError::Timeout;
@ -333,103 +334,93 @@ static std::string Socks5ErrorString(uint8_t err)
bool Socks5(const std::string& strDest, uint16_t port, const ProxyCredentials* auth, const Sock& sock)
{
IntrRecvError recvr;
LogPrint(BCLog::NET, "SOCKS5 connecting %s\n", strDest);
if (strDest.size() > 255) {
return error("Hostname too long");
}
// Construct the version identifier/method selection message
std::vector<uint8_t> vSocks5Init;
vSocks5Init.push_back(SOCKSVersion::SOCKS5); // We want the SOCK5 protocol
if (auth) {
vSocks5Init.push_back(0x02); // 2 method identifiers follow...
vSocks5Init.push_back(SOCKS5Method::NOAUTH);
vSocks5Init.push_back(SOCKS5Method::USER_PASS);
} else {
vSocks5Init.push_back(0x01); // 1 method identifier follows...
vSocks5Init.push_back(SOCKS5Method::NOAUTH);
}
ssize_t ret = sock.Send(vSocks5Init.data(), vSocks5Init.size(), MSG_NOSIGNAL);
if (ret != (ssize_t)vSocks5Init.size()) {
return error("Error sending to proxy");
}
uint8_t pchRet1[2];
if (InterruptibleRecv(pchRet1, 2, g_socks5_recv_timeout, sock) != IntrRecvError::OK) {
LogPrintf("Socks5() connect to %s:%d failed: InterruptibleRecv() timeout or other failure\n", strDest, port);
return false;
}
if (pchRet1[0] != SOCKSVersion::SOCKS5) {
return error("Proxy failed to initialize");
}
if (pchRet1[1] == SOCKS5Method::USER_PASS && auth) {
// Perform username/password authentication (as described in RFC1929)
std::vector<uint8_t> vAuth;
vAuth.push_back(0x01); // Current (and only) version of user/pass subnegotiation
if (auth->username.size() > 255 || auth->password.size() > 255)
return error("Proxy username or password too long");
vAuth.push_back(auth->username.size());
vAuth.insert(vAuth.end(), auth->username.begin(), auth->username.end());
vAuth.push_back(auth->password.size());
vAuth.insert(vAuth.end(), auth->password.begin(), auth->password.end());
ret = sock.Send(vAuth.data(), vAuth.size(), MSG_NOSIGNAL);
if (ret != (ssize_t)vAuth.size()) {
return error("Error sending authentication to proxy");
try {
IntrRecvError recvr;
LogPrint(BCLog::NET, "SOCKS5 connecting %s\n", strDest);
if (strDest.size() > 255) {
return error("Hostname too long");
}
LogPrint(BCLog::PROXY, "SOCKS5 sending proxy authentication %s:%s\n", auth->username, auth->password);
uint8_t pchRetA[2];
if (InterruptibleRecv(pchRetA, 2, g_socks5_recv_timeout, sock) != IntrRecvError::OK) {
return error("Error reading proxy authentication response");
}
if (pchRetA[0] != 0x01 || pchRetA[1] != 0x00) {
return error("Proxy authentication unsuccessful");
}
} else if (pchRet1[1] == SOCKS5Method::NOAUTH) {
// Perform no authentication
} else {
return error("Proxy requested wrong authentication method %02x", pchRet1[1]);
}
std::vector<uint8_t> vSocks5;
vSocks5.push_back(SOCKSVersion::SOCKS5); // VER protocol version
vSocks5.push_back(SOCKS5Command::CONNECT); // CMD CONNECT
vSocks5.push_back(0x00); // RSV Reserved must be 0
vSocks5.push_back(SOCKS5Atyp::DOMAINNAME); // ATYP DOMAINNAME
vSocks5.push_back(strDest.size()); // Length<=255 is checked at beginning of function
vSocks5.insert(vSocks5.end(), strDest.begin(), strDest.end());
vSocks5.push_back((port >> 8) & 0xFF);
vSocks5.push_back((port >> 0) & 0xFF);
ret = sock.Send(vSocks5.data(), vSocks5.size(), MSG_NOSIGNAL);
if (ret != (ssize_t)vSocks5.size()) {
return error("Error sending to proxy");
}
uint8_t pchRet2[4];
if ((recvr = InterruptibleRecv(pchRet2, 4, g_socks5_recv_timeout, sock)) != IntrRecvError::OK) {
if (recvr == IntrRecvError::Timeout) {
/* If a timeout happens here, this effectively means we timed out while connecting
* to the remote node. This is very common for Tor, so do not print an
* error message. */
return false;
// Construct the version identifier/method selection message
std::vector<uint8_t> vSocks5Init;
vSocks5Init.push_back(SOCKSVersion::SOCKS5); // We want the SOCK5 protocol
if (auth) {
vSocks5Init.push_back(0x02); // 2 method identifiers follow...
vSocks5Init.push_back(SOCKS5Method::NOAUTH);
vSocks5Init.push_back(SOCKS5Method::USER_PASS);
} else {
return error("Error while reading proxy response");
vSocks5Init.push_back(0x01); // 1 method identifier follows...
vSocks5Init.push_back(SOCKS5Method::NOAUTH);
}
}
if (pchRet2[0] != SOCKSVersion::SOCKS5) {
return error("Proxy failed to accept request");
}
if (pchRet2[1] != SOCKS5Reply::SUCCEEDED) {
// Failures to connect to a peer that are not proxy errors
LogPrintf("Socks5() connect to %s:%d failed: %s\n", strDest, port, Socks5ErrorString(pchRet2[1]));
return false;
}
if (pchRet2[2] != 0x00) { // Reserved field must be 0
return error("Error: malformed proxy response");
}
uint8_t pchRet3[256];
switch (pchRet2[3])
{
sock.SendComplete(vSocks5Init, g_socks5_recv_timeout, g_socks5_interrupt);
uint8_t pchRet1[2];
if (InterruptibleRecv(pchRet1, 2, g_socks5_recv_timeout, sock) != IntrRecvError::OK) {
LogPrintf("Socks5() connect to %s:%d failed: InterruptibleRecv() timeout or other failure\n", strDest, port);
return false;
}
if (pchRet1[0] != SOCKSVersion::SOCKS5) {
return error("Proxy failed to initialize");
}
if (pchRet1[1] == SOCKS5Method::USER_PASS && auth) {
// Perform username/password authentication (as described in RFC1929)
std::vector<uint8_t> vAuth;
vAuth.push_back(0x01); // Current (and only) version of user/pass subnegotiation
if (auth->username.size() > 255 || auth->password.size() > 255)
return error("Proxy username or password too long");
vAuth.push_back(auth->username.size());
vAuth.insert(vAuth.end(), auth->username.begin(), auth->username.end());
vAuth.push_back(auth->password.size());
vAuth.insert(vAuth.end(), auth->password.begin(), auth->password.end());
sock.SendComplete(vAuth, g_socks5_recv_timeout, g_socks5_interrupt);
LogPrint(BCLog::PROXY, "SOCKS5 sending proxy authentication %s:%s\n", auth->username, auth->password);
uint8_t pchRetA[2];
if (InterruptibleRecv(pchRetA, 2, g_socks5_recv_timeout, sock) != IntrRecvError::OK) {
return error("Error reading proxy authentication response");
}
if (pchRetA[0] != 0x01 || pchRetA[1] != 0x00) {
return error("Proxy authentication unsuccessful");
}
} else if (pchRet1[1] == SOCKS5Method::NOAUTH) {
// Perform no authentication
} else {
return error("Proxy requested wrong authentication method %02x", pchRet1[1]);
}
std::vector<uint8_t> vSocks5;
vSocks5.push_back(SOCKSVersion::SOCKS5); // VER protocol version
vSocks5.push_back(SOCKS5Command::CONNECT); // CMD CONNECT
vSocks5.push_back(0x00); // RSV Reserved must be 0
vSocks5.push_back(SOCKS5Atyp::DOMAINNAME); // ATYP DOMAINNAME
vSocks5.push_back(strDest.size()); // Length<=255 is checked at beginning of function
vSocks5.insert(vSocks5.end(), strDest.begin(), strDest.end());
vSocks5.push_back((port >> 8) & 0xFF);
vSocks5.push_back((port >> 0) & 0xFF);
sock.SendComplete(vSocks5, g_socks5_recv_timeout, g_socks5_interrupt);
uint8_t pchRet2[4];
if ((recvr = InterruptibleRecv(pchRet2, 4, g_socks5_recv_timeout, sock)) != IntrRecvError::OK) {
if (recvr == IntrRecvError::Timeout) {
/* If a timeout happens here, this effectively means we timed out while connecting
* to the remote node. This is very common for Tor, so do not print an
* error message. */
return false;
} else {
return error("Error while reading proxy response");
}
}
if (pchRet2[0] != SOCKSVersion::SOCKS5) {
return error("Proxy failed to accept request");
}
if (pchRet2[1] != SOCKS5Reply::SUCCEEDED) {
// Failures to connect to a peer that are not proxy errors
LogPrintf("Socks5() connect to %s:%d failed: %s\n", strDest, port, Socks5ErrorString(pchRet2[1]));
return false;
}
if (pchRet2[2] != 0x00) { // Reserved field must be 0
return error("Error: malformed proxy response");
}
uint8_t pchRet3[256];
switch (pchRet2[3]) {
case SOCKS5Atyp::IPV4: recvr = InterruptibleRecv(pchRet3, 4, g_socks5_recv_timeout, sock); break;
case SOCKS5Atyp::IPV6: recvr = InterruptibleRecv(pchRet3, 16, g_socks5_recv_timeout, sock); break;
case SOCKS5Atyp::DOMAINNAME:
{
case SOCKS5Atyp::DOMAINNAME: {
recvr = InterruptibleRecv(pchRet3, 1, g_socks5_recv_timeout, sock);
if (recvr != IntrRecvError::OK) {
return error("Error reading from proxy");
@ -439,15 +430,18 @@ bool Socks5(const std::string& strDest, uint16_t port, const ProxyCredentials* a
break;
}
default: return error("Error: malformed proxy response");
}
if (recvr != IntrRecvError::OK) {
return error("Error reading from proxy");
}
if (InterruptibleRecv(pchRet3, 2, g_socks5_recv_timeout, sock) != IntrRecvError::OK) {
return error("Error reading from proxy");
}
LogPrint(BCLog::NET, "SOCKS5 connected %s\n", strDest);
return true;
} catch (const std::runtime_error& e) {
return error("Error during SOCKS5 proxy handshake: %s", e.what());
}
if (recvr != IntrRecvError::OK) {
return error("Error reading from proxy");
}
if (InterruptibleRecv(pchRet3, 2, g_socks5_recv_timeout, sock) != IntrRecvError::OK) {
return error("Error reading from proxy");
}
LogPrint(BCLog::NET, "SOCKS5 connected %s\n", strDest);
return true;
}
std::unique_ptr<Sock> CreateSockTCP(const CService& address_family)
@ -681,11 +675,6 @@ CSubNet LookupSubNet(const std::string& subnet_str)
return subnet;
}
void InterruptSocks5(bool interrupt)
{
interruptSocks5Recv = interrupt;
}
bool IsBadPort(uint16_t port)
{
/* Don't forget to update doc/p2p-bad-ports.md if you change this list. */

6
src/netbase.h
View File

@ -13,6 +13,7 @@
#include <netaddress.h>
#include <serialize.h>
#include <util/sock.h>
#include <util/threadinterrupt.h>
#include <functional>
#include <memory>
@ -274,7 +275,10 @@ bool ConnectSocketDirectly(const CService &addrConnect, const Sock& sock, int nT
*/
bool ConnectThroughProxy(const Proxy& proxy, const std::string& strDest, uint16_t port, const Sock& sock, int nTimeout, bool& outProxyConnectionFailed);
void InterruptSocks5(bool interrupt);
/**
* Interrupt SOCKS5 reads or writes.
*/
extern CThreadInterrupt g_socks5_interrupt;
/**
* Connect to a specified destination service through an already connected

4
src/test/fuzz/socks5.cpp
View File

@ -32,7 +32,9 @@ FUZZ_TARGET(socks5, .init = initialize_socks5)
ProxyCredentials proxy_credentials;
proxy_credentials.username = fuzzed_data_provider.ConsumeRandomLengthString(512);
proxy_credentials.password = fuzzed_data_provider.ConsumeRandomLengthString(512);
InterruptSocks5(fuzzed_data_provider.ConsumeBool());
if (fuzzed_data_provider.ConsumeBool()) {
g_socks5_interrupt();
}
// Set FUZZED_SOCKET_FAKE_LATENCY=1 to exercise recv timeout code paths. This
// will slow down fuzzing.
g_socks5_recv_timeout = (fuzzed_data_provider.ConsumeBool() && std::getenv("FUZZED_SOCKET_FAKE_LATENCY") != nullptr) ? 1ms : default_socks5_recv_timeout;

9
src/util/sock.cpp
View File

@ -242,7 +242,7 @@ bool Sock::WaitMany(std::chrono::milliseconds timeout, EventsPerSock& events_per
#endif /* USE_POLL */
}
void Sock::SendComplete(const std::string& data,
void Sock::SendComplete(Span<const unsigned char> data,
std::chrono::milliseconds timeout,
CThreadInterrupt& interrupt) const
{
@ -283,6 +283,13 @@ void Sock::SendComplete(const std::string& data,
}
}
void Sock::SendComplete(Span<const char> data,
std::chrono::milliseconds timeout,
CThreadInterrupt& interrupt) const
{
SendComplete(MakeUCharSpan(data), timeout, interrupt);
}
std::string Sock::RecvUntilTerminator(uint8_t terminator,
std::chrono::milliseconds timeout,
CThreadInterrupt& interrupt,

9
src/util/sock.h
View File

@ -228,7 +228,14 @@ public:
* @throws std::runtime_error if the operation cannot be completed. In this case only some of
* the data will be written to the socket.
*/
virtual void SendComplete(const std::string& data,
virtual void SendComplete(Span<const unsigned char> data,
std::chrono::milliseconds timeout,
CThreadInterrupt& interrupt) const;
/**
* Convenience method, equivalent to `SendComplete(MakeUCharSpan(data), timeout, interrupt)`.
*/
virtual void SendComplete(Span<const char> data,
std::chrono::milliseconds timeout,
CThreadInterrupt& interrupt) const;