Merge pull request 'net: add optional SOCKS5 outbound proxy' (#27) from socks5-proxy into main

1 files changed, 329 insertions, 0 deletions

diff --git a/src/proxy.cpp b/src/proxy.cpp
new file mode 100644
index 0000000..d7dc324
--- /dev/null
+++ b/src/proxy.cpp
@@ -0,0 +1,329 @@
+// Copyright (c) 2026 Bitflash developers
+// Distributed under the MIT/X11 software license.
+
+#include "headers_core.h"
+#include "proxy.h"
+#include "sockcount.h"
+
+#include <errno.h>
+
+static CCriticalSection cs_socks5;
+static bool g_fSocks5Proxy = false;
+static std::string g_socks5Host;
+static unsigned short g_socks5Port = 0;
+
+static void SetSocketTimeout(SOCKET s, int nTimeoutSecs)
+{
+    if (nTimeoutSecs <= 0)
+        return;
+#ifdef _WIN32
+    DWORD tv = (DWORD)nTimeoutSecs * 1000;
+    setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, (const char*)&tv, sizeof(tv));
+    setsockopt(s, SOL_SOCKET, SO_SNDTIMEO, (const char*)&tv, sizeof(tv));
+#else
+    struct timeval tv;
+    tv.tv_sec = nTimeoutSecs;
+    tv.tv_usec = 0;
+    setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
+    setsockopt(s, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
+#endif
+}
+
+static bool ReadN(SOCKET s, void* buf, int n)
+{
+    char* p = (char*)buf;
+    int off = 0;
+    while (off < n)
+    {
+        int r = recv(s, p + off, n - off, 0);
+        if (r <= 0)
+            return false;
+        off += r;
+    }
+    return true;
+}
+
+static bool WriteN(SOCKET s, const void* buf, int n)
+{
+    const char* p = (const char*)buf;
+    int off = 0;
+    while (off < n)
+    {
+        int r = send(s, p + off, n - off, 0);
+        if (r <= 0)
+            return false;
+        off += r;
+    }
+    return true;
+}
+
+static bool ValidProxyHostChar(char c)
+{
+    return isalnum((unsigned char)c) || c == '.' || c == '-' || c == '_';
+}
+
+static bool ValidProxyIpv6HostChar(char c)
+{
+    return isxdigit((unsigned char)c) || c == ':' || c == '.';
+}
+
+static bool ParsePort(const std::string& port, unsigned short& portOut,
+                      std::string& errOut)
+{
+    if (port.empty())
+    {
+        errOut = "port is empty";
+        return false;
+    }
+    for (size_t i = 0; i < port.size(); i++)
+    {
+        if (!isdigit((unsigned char)port[i]))
+        {
+            errOut = "port is not numeric";
+            return false;
+        }
+    }
+
+    errno = 0;
+    char* end = NULL;
+    long nPort = strtol(port.c_str(), &end, 10);
+    if (errno == ERANGE || end == NULL || *end != '\0' || nPort <= 0 || nPort > 65535)
+    {
+        errOut = "port is out of range";
+        return false;
+    }
+    portOut = (unsigned short)nPort;
+    return true;
+}
+
+bool BtfParseSocks5Proxy(const std::string& spec, std::string& hostOut,
+                         unsigned short& portOut, std::string& errOut)
+{
+    hostOut.clear();
+    portOut = 0;
+    errOut.clear();
+
+    std::string host;
+    std::string port;
+    bool fBracketedIpv6 = false;
+    if (!spec.empty() && spec[0] == '[')
+    {
+        size_t close = spec.find(']');
+        if (close == std::string::npos || close == 1 || close + 1 >= spec.size() || spec[close + 1] != ':')
+        {
+            errOut = "expected [IPv6]:PORT";
+            return false;
+        }
+        host = spec.substr(1, close - 1);
+        port = spec.substr(close + 2);
+        fBracketedIpv6 = true;
+    }
+    else
+    {
+        size_t colon = spec.rfind(':');
+        if (colon == std::string::npos || colon == 0 || colon + 1 >= spec.size())
+        {
+            errOut = "expected HOST:PORT";
+            return false;
+        }
+        host = spec.substr(0, colon);
+        port = spec.substr(colon + 1);
+        if (host.find(':') != std::string::npos)
+        {
+            errOut = "IPv6 proxy hosts must use [ADDR]:PORT";
+            return false;
+        }
+    }
+
+    if (host.size() > 255)
+    {
+        errOut = "host is too long";
+        return false;
+    }
+    if (fBracketedIpv6)
+    {
+        bool fHasColon = false;
+        for (size_t i = 0; i < host.size(); i++)
+        {
+            fHasColon = fHasColon || host[i] == ':';
+            if (!ValidProxyIpv6HostChar(host[i]))
+            {
+                errOut = "IPv6 proxy host contains unsupported characters";
+                return false;
+            }
+        }
+        if (!fHasColon)
+        {
+            errOut = "bracketed proxy host is not IPv6";
+            return false;
+        }
+    }
+    else
+    {
+        for (size_t i = 0; i < host.size(); i++)
+        {
+            if (!ValidProxyHostChar(host[i]))
+            {
+                errOut = "host contains unsupported characters";
+                return false;
+            }
+        }
+    }
+    if (!ParsePort(port, portOut, errOut))
+        return false;
+
+    hostOut = host;
+    return true;
+}
+
+bool BtfSetSocks5Proxy(const std::string& spec, std::string& errOut)
+{
+    std::string host;
+    unsigned short port = 0;
+    if (!BtfParseSocks5Proxy(spec, host, port, errOut))
+        return false;
+    CRITICAL_BLOCK(cs_socks5)
+    {
+        g_socks5Host = host;
+        g_socks5Port = port;
+        g_fSocks5Proxy = true;
+    }
+    return true;
+}
+
+void BtfClearSocks5Proxy()
+{
+    CRITICAL_BLOCK(cs_socks5)
+    {
+        g_fSocks5Proxy = false;
+        g_socks5Host.clear();
+        g_socks5Port = 0;
+    }
+}
+
+bool BtfSocks5ProxyEnabled()
+{
+    CRITICAL_BLOCK(cs_socks5)
+        return g_fSocks5Proxy;
+    return false;
+}
+
+std::string BtfSocks5ProxyName()
+{
+    CRITICAL_BLOCK(cs_socks5)
+    {
+        if (!g_fSocks5Proxy)
+            return "";
+        if (g_socks5Host.find(':') != std::string::npos)
+            return strprintf("[%s]:%u", g_socks5Host.c_str(), (unsigned)g_socks5Port);
+        return strprintf("%s:%u", g_socks5Host.c_str(), (unsigned)g_socks5Port);
+    }
+    return "";
+}
+
+static SOCKET ConnectDirect(const std::string& host, unsigned short port,
+                            int nSockSite, int nTimeoutSecs)
+{
+    struct addrinfo hints, *res = NULL, *rp = NULL;
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_family = AF_UNSPEC;
+    hints.ai_socktype = SOCK_STREAM;
+    char portstr[16];
+    sprintf(portstr, "%u", (unsigned)port);
+    if (getaddrinfo(host.c_str(), portstr, &hints, &res) != 0 || !res)
+        return INVALID_SOCKET;
+
+    SOCKET s = INVALID_SOCKET;
+    for (rp = res; rp != NULL; rp = rp->ai_next)
+    {
+        s = BtfSocketTag(socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol), nSockSite);
+        if (s == INVALID_SOCKET)
+            continue;
+        SetSocketTimeout(s, nTimeoutSecs);
+        if (connect(s, rp->ai_addr, (int)rp->ai_addrlen) == 0)
+            break;
+        BtfCloseSocket(s);
+        s = INVALID_SOCKET;
+    }
+    freeaddrinfo(res);
+    return s;
+}
+
+static bool Socks5Connect(SOCKET s, const std::string& destHost,
+                          unsigned short destPort)
+{
+    if (destHost.empty() || destHost.size() > 255)
+        return false;
+
+    unsigned char hello[3] = { 0x05, 0x01, 0x00 }; // SOCKS5, one method, no auth
+    if (!WriteN(s, hello, sizeof(hello)))
+        return false;
+    unsigned char choice[2] = { 0, 0 };
+    if (!ReadN(s, choice, sizeof(choice)) || choice[0] != 0x05 || choice[1] != 0x00)
+        return false;
+
+    std::vector<unsigned char> req;
+    req.reserve(7 + destHost.size());
+    req.push_back(0x05); // version
+    req.push_back(0x01); // CONNECT
+    req.push_back(0x00); // reserved
+    req.push_back(0x03); // domain name; proxy resolves, avoiding local DNS leak
+    req.push_back((unsigned char)destHost.size());
+    req.insert(req.end(), destHost.begin(), destHost.end());
+    req.push_back((unsigned char)(destPort >> 8));
+    req.push_back((unsigned char)(destPort & 0xff));
+    if (!WriteN(s, &req[0], (int)req.size()))
+        return false;
+
+    unsigned char rep[4] = {0,0,0,0};
+    if (!ReadN(s, rep, sizeof(rep)) || rep[0] != 0x05)
+        return false;
+    if (rep[1] != 0x00)
+    {
+        error("SOCKS5 CONNECT to %s:%u failed with reply 0x%02x\n",
+              destHost.c_str(), (unsigned)destPort, (unsigned)rep[1]);
+        return false;
+    }
+    int nAddr = 0;
+    if (rep[3] == 0x01) nAddr = 4;
+    else if (rep[3] == 0x04) nAddr = 16;
+    else if (rep[3] == 0x03)
+    {
+        unsigned char len = 0;
+        if (!ReadN(s, &len, 1))
+            return false;
+        nAddr = len;
+    }
+    else
+        return false;
+
+    std::vector<unsigned char> discard(nAddr + 2);
+    return ReadN(s, &discard[0], (int)discard.size());
+}
+
+SOCKET BtfConnectSocket(const std::string& destHost, unsigned short destPort,
+                        int nSockSite, int nTimeoutSecs)
+{
+    std::string proxyHost;
+    unsigned short proxyPort = 0;
+    bool fProxy = false;
+    CRITICAL_BLOCK(cs_socks5)
+    {
+        fProxy = g_fSocks5Proxy;
+        proxyHost = g_socks5Host;
+        proxyPort = g_socks5Port;
+    }
+
+    if (!fProxy)
+        return ConnectDirect(destHost, destPort, nSockSite, nTimeoutSecs);
+
+    SOCKET s = ConnectDirect(proxyHost, proxyPort, nSockSite, nTimeoutSecs);
+    if (s == INVALID_SOCKET)
+        return INVALID_SOCKET;
+    if (!Socks5Connect(s, destHost, destPort))
+    {
+        BtfCloseSocket(s);
+        return INVALID_SOCKET;
+    }
+    return s;
+}