netbase.cpp

// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2012 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or https://opensource.org/licenses/mit-license.php.

#include "netbase.h"
#include "util.h"
#include "sync.h"

#if !defined(HAVE_MSG_NOSIGNAL)
#define MSG_NOSIGNAL 0
#endif

#ifndef WIN32
#include <fcntl.h>
#endif

#include <boost/algorithm/string/predicate.hpp> // for startswith() and endswith()

using namespace std;

// Settings
static proxyType proxyInfo[NET_MAX];
static CService nameProxy;
static CCriticalSection cs_proxyInfos;
int nConnectTimeout = 5000;
bool fNameLookup = false;

enum Network ParseNetwork(std::string net) {
    net = ToLower(net);
    if (net == "ipv4") return NET_IPV4;
    if (net == "ipv6") return NET_IPV6;
    if (net == "tor")  return NET_TOR;
    return NET_UNROUTABLE;
}

bool static LookupIntern(const char *pszName, std::vector<CNetAddr>& vIP, unsigned int nMaxSolutions, bool fAllowLookup)
{
    vIP.clear();

    {
        CNetAddr addr;
        if (addr.SetSpecial(std::string(pszName))) {
            vIP.push_back(addr);
            return true;
        }
    }

    struct addrinfo aiHint;
    memset(&aiHint, 0, sizeof(struct addrinfo));

    aiHint.ai_socktype = SOCK_STREAM;
    aiHint.ai_protocol = IPPROTO_TCP;
    aiHint.ai_family = AF_UNSPEC;
#ifdef WIN32
    aiHint.ai_flags = fAllowLookup ? 0 : AI_NUMERICHOST;
#else
    aiHint.ai_flags = fAllowLookup ? AI_ADDRCONFIG : AI_NUMERICHOST;
#endif
    struct addrinfo *aiRes = nullptr;
    int nErr = getaddrinfo(pszName, nullptr, &aiHint, &aiRes);
    if (nErr)
        return false;

    struct addrinfo *aiTrav = aiRes;
    while (aiTrav != nullptr && (nMaxSolutions == 0 || vIP.size() < nMaxSolutions))
    {
        CNetAddr resolved;
        if (aiTrav->ai_family == AF_INET)
        {
            assert(aiTrav->ai_addrlen >= sizeof(sockaddr_in));
            resolved = CNetAddr(((struct sockaddr_in*)(aiTrav->ai_addr))->sin_addr);
        }

        if (aiTrav->ai_family == AF_INET6)
        {
            assert(aiTrav->ai_addrlen >= sizeof(sockaddr_in6));
            struct sockaddr_in6* s6 = (struct sockaddr_in6*) aiTrav->ai_addr;
            resolved = CNetAddr(s6->sin6_addr, s6->sin6_scope_id);
        }
        /* Never allow resolving to an internal address. Consider any such result invalid */
        if (!resolved.IsInternal()) {
            vIP.push_back(resolved);
        }

        aiTrav = aiTrav->ai_next;
    }

    freeaddrinfo(aiRes);

    return (vIP.size() > 0);
}

bool LookupHost(const char *pszName, std::vector<CNetAddr>& vIP, unsigned int nMaxSolutions, bool fAllowLookup)
{
    std::string strHost(pszName);
    if (strHost.empty())
        return false;
    if (boost::algorithm::starts_with(strHost, "[") && boost::algorithm::ends_with(strHost, "]"))
    {
        strHost = strHost.substr(1, strHost.size() - 2);
    }

    return LookupIntern(strHost.c_str(), vIP, nMaxSolutions, fAllowLookup);
}

bool LookupHost(const char *pszName, CNetAddr& addr, bool fAllowLookup)
{
    std::vector<CNetAddr> vIP;
    LookupHost(pszName, vIP, 1, fAllowLookup);
    if(vIP.empty())
        return false;
    addr = vIP.front();
    return true;
}

bool Lookup(const char *pszName, std::vector<CService>& vAddr, int portDefault, bool fAllowLookup, unsigned int nMaxSolutions)
{
    if (pszName[0] == 0)
        return false;
    int port = portDefault;
    std::string hostname = "";
    SplitHostPort(std::string(pszName), port, hostname);

    std::vector<CNetAddr> vIP;
    bool fRet = LookupIntern(hostname.c_str(), vIP, nMaxSolutions, fAllowLookup);
    if (!fRet)
        return false;
    vAddr.resize(vIP.size());
    for (unsigned int i = 0; i < vIP.size(); i++)
        vAddr[i] = CService(vIP[i], port);
    return true;
}

bool Lookup(const char *pszName, CService& addr, int portDefault, bool fAllowLookup)
{
    std::vector<CService> vService;
    bool fRet = Lookup(pszName, vService, portDefault, fAllowLookup, 1);
    if (!fRet)
        return false;
    addr = vService[0];
    return true;
}

CService LookupNumeric(const char *pszName, int portDefault)
{
    CService addr;
    // "1.2:345" will fail to resolve the ip, but will still set the port.
    // If the ip fails to resolve, re-init the result.
    if(!Lookup(pszName, addr, portDefault, false))
        addr = CService();
    return addr;
}

bool LookupSubNet(const char* pszName, CSubNet& ret)
{
    std::string strSubnet(pszName);
    size_t slash = strSubnet.find_last_of('/');
    std::vector<CNetAddr> vIP;

    std::string strAddress = strSubnet.substr(0, slash);
    if (LookupHost(strAddress.c_str(), vIP, 1, false))
    {
        CNetAddr network = vIP[0];
        if (slash != strSubnet.npos)
        {
            std::string strNetmask = strSubnet.substr(slash + 1);
            int32_t n;
            // IPv4 addresses start at offset 12, and first 12 bytes must match, so just offset n
            if (ParseInt32(strNetmask, &n)) { // If valid number, assume /24 syntax
                ret = CSubNet(network, n);
                return ret.IsValid();
            }
            else // If not a valid number, try full netmask syntax
            {
                // Never allow lookup for netmask
                if (LookupHost(strNetmask.c_str(), vIP, 1, false)) {
                    ret = CSubNet(network, vIP[0]);
                    return ret.IsValid();
                }
            }
        }
        else
        {
            ret = CSubNet(network);
            return ret.IsValid();
        }
    }
    return false;
}

bool static Socks5(string strDest, int port, SOCKET& hSocket)
{
    LogPrintf("SOCKS5 connecting %s", strDest);
    if (strDest.size() > 255)
    {
        closesocket(hSocket);
        return error("Hostname too long");
    }
    char pszSocks5Init[] = "\5\1\0";
    char *pszSocks5 = pszSocks5Init;
    ssize_t nSize = sizeof(pszSocks5Init) - 1;

    ssize_t ret = send(hSocket, pszSocks5, nSize, MSG_NOSIGNAL);
    if (ret != nSize)
    {
        closesocket(hSocket);
        return error("Error sending to proxy");
    }
    char pchRet1[2];
    if (recv(hSocket, pchRet1, 2, 0) != 2)
    {
        closesocket(hSocket);
        return error("Error reading proxy response");
    }
    if (pchRet1[0] != 0x05 || pchRet1[1] != 0x00)
    {
        closesocket(hSocket);
        return error("Proxy failed to initialize");
    }
    string strSocks5("\5\1");
    strSocks5 += '\000'; strSocks5 += '\003';
    strSocks5 += static_cast<char>(std::min((int)strDest.size(), 255));
    strSocks5 += strDest;
    strSocks5 += static_cast<char>((port >> 8) & 0xFF);
    strSocks5 += static_cast<char>((port >> 0) & 0xFF);
    ret = send(hSocket, strSocks5.c_str(), strSocks5.size(), MSG_NOSIGNAL);
    if (ret != (ssize_t)strSocks5.size())
    {
        closesocket(hSocket);
        return error("Error sending to proxy");
    }
    char pchRet2[4];
    if (recv(hSocket, pchRet2, 4, 0) != 4)
    {
        closesocket(hSocket);
        return error("Error reading proxy response");
    }
    if (pchRet2[0] != 0x05)
    {
        closesocket(hSocket);
        return error("Proxy failed to accept request");
    }
    if (pchRet2[1] != 0x00)
    {
        closesocket(hSocket);
        switch (pchRet2[1])
        {
            case 0x01: return error("Proxy error: general failure");
            case 0x02: return error("Proxy error: connection not allowed");
            case 0x03: return error("Proxy error: network unreachable");
            case 0x04: return error("Proxy error: host unreachable");
            case 0x05: return error("Proxy error: connection refused");
            case 0x06: return error("Proxy error: TTL expired");
            case 0x07: return error("Proxy error: protocol error");
            case 0x08: return error("Proxy error: address type not supported");
            default:   return error("Proxy error: unknown");
        }
    }
    if (pchRet2[2] != 0x00)
    {
        closesocket(hSocket);
        return error("Error: malformed proxy response");
    }
    char pchRet3[256];
    switch (pchRet2[3])
    {
        case 0x01: ret = recv(hSocket, pchRet3, 4, 0) != 4; break;
        case 0x04: ret = recv(hSocket, pchRet3, 16, 0) != 16; break;
        case 0x03:
        {
            ret = recv(hSocket, pchRet3, 1, 0) != 1;
            if (ret) {
                closesocket(hSocket);
                return error("Error reading from proxy");
            }
            int nRecv = pchRet3[0];
            ret = recv(hSocket, pchRet3, nRecv, 0) != nRecv;
            break;
        }
        default: closesocket(hSocket); return error("Error: malformed proxy response");
    }
    if (ret)
    {
        closesocket(hSocket);
        return error("Error reading from proxy");
    }
    if (recv(hSocket, pchRet3, 2, 0) != 2)
    {
        closesocket(hSocket);
        return error("Error reading from proxy");
    }
    LogPrintf("SOCKS5 connected %s", strDest);
    return true;
}

bool static ConnectSocketDirectly(const CService &addrConnect, SOCKET& hSocketRet, int nTimeout)
{
    hSocketRet = INVALID_SOCKET;

    struct sockaddr_storage sockaddr;
    socklen_t len = sizeof(sockaddr);
    if (!addrConnect.GetSockAddr((struct sockaddr*)&sockaddr, &len)) {
        LogPrintf("Cannot connect to %s: unsupported network", addrConnect.ToString());
        return false;
    }

    SOCKET hSocket = socket(((struct sockaddr*)&sockaddr)->sa_family, SOCK_STREAM, IPPROTO_TCP);
    if (hSocket == INVALID_SOCKET)
        return false;
#ifdef SO_NOSIGPIPE
    int set = 1;
    setsockopt(hSocket, SOL_SOCKET, SO_NOSIGPIPE, (void*)&set, sizeof(int));
#endif

#ifdef WIN32
    u_long fNonblock = 1;
    if (ioctlsocket(hSocket, FIONBIO, &fNonblock) == SOCKET_ERROR)
#else
    int fFlags = fcntl(hSocket, F_GETFL, 0);
    if (fcntl(hSocket, F_SETFL, fFlags | O_NONBLOCK) == -1)
#endif
    {
        closesocket(hSocket);
        return false;
    }

    if (connect(hSocket, (struct sockaddr*)&sockaddr, len) == SOCKET_ERROR)
    {
        int nErr = WSAGetLastError();
        // WSAEINVAL is here because some legacy version of winsock uses it
        if (nErr == WSAEINPROGRESS || nErr == WSAEWOULDBLOCK || nErr == WSAEINVAL)
        {
            struct timeval timeout;
            timeout.tv_sec  = nTimeout / 1000;
            timeout.tv_usec = (nTimeout % 1000) * 1000;

            fd_set fdset;
            FD_ZERO(&fdset);
            FD_SET(hSocket, &fdset);
            int nRet = select(hSocket + 1, nullptr, &fdset, nullptr, &timeout);
            if (nRet == 0)
            {
                closesocket(hSocket);
                return false;
            }
            if (nRet == SOCKET_ERROR)
            {
                LogPrintf("select() for connection failed: %i",WSAGetLastError());
                closesocket(hSocket);
                return false;
            }
            socklen_t nRetSize = sizeof(nRet);
#ifdef WIN32
            if (getsockopt(hSocket, SOL_SOCKET, SO_ERROR, (char*)(&nRet), &nRetSize) == SOCKET_ERROR)
#else
            if (getsockopt(hSocket, SOL_SOCKET, SO_ERROR, &nRet, &nRetSize) == SOCKET_ERROR)
#endif
            {
                LogPrintf("getsockopt() for connection failed: %i",WSAGetLastError());
                closesocket(hSocket);
                return false;
            }
            if (nRet != 0)
            {
                LogPrint(BCLog::LogFlags::NOISY, "socket connect() failed after select(): %s, Destination Addr %s ",
                         strerror(nRet), addrConnect.ToString());

                closesocket(hSocket);
                return false;
            }
        }
#ifdef WIN32
        else if (WSAGetLastError() != WSAEISCONN)
#else
        else
#endif
        {
            LogPrintf("connect() failed: %i",WSAGetLastError());
            closesocket(hSocket);
            return false;
        }
    }

    // this isn't even strictly necessary
    // CNode::ConnectNode immediately turns the socket back to non-blocking
    // but we'll turn it back to blocking just in case
#ifdef WIN32
    fNonblock = 0;
    if (ioctlsocket(hSocket, FIONBIO, &fNonblock) == SOCKET_ERROR)
#else
    fFlags = fcntl(hSocket, F_GETFL, 0);
    if (fcntl(hSocket, F_SETFL, fFlags & !O_NONBLOCK) == SOCKET_ERROR)
#endif
    {
        closesocket(hSocket);
        return false;
    }

    hSocketRet = hSocket;
    return true;
}

bool SetProxy(enum Network net, const CService &addrProxy) {
    assert(net >= 0 && net < NET_MAX);
    if (!addrProxy.IsValid())
        return false;
    LOCK(cs_proxyInfos);
    proxyInfo[net] = addrProxy;
    return true;
}

bool GetProxy(enum Network net, proxyType &proxyInfoOut) {
    assert(net >= 0 && net < NET_MAX);
    LOCK(cs_proxyInfos);
    if (!proxyInfo[net].IsValid())
        return false;
    proxyInfoOut = proxyInfo[net];
    return true;
}

bool SetNameProxy(const CService &addrProxy) {
    if (!addrProxy.IsValid())
        return false;
    LOCK(cs_proxyInfos);
    nameProxy = addrProxy;
    return true;
}

bool GetNameProxy(CService &nameProxyOut) {
    LOCK(cs_proxyInfos);
    if(!nameProxy.IsValid())
        return false;
    nameProxyOut = nameProxy;
    return true;
}

bool HaveNameProxy() {
    LOCK(cs_proxyInfos);
    return nameProxy.IsValid();
}

bool IsProxy(const CNetAddr &addr) {
    LOCK(cs_proxyInfos);
    for (int i = 0; i < NET_MAX; i++) {
        if (addr == (CNetAddr)proxyInfo[i])
            return true;
    }
    return false;
}

bool ConnectSocket(const CService &addrDest, SOCKET& hSocketRet, int nTimeout)
{
    proxyType proxy;

    // no proxy needed (none set for target network)
    if (!GetProxy(addrDest.GetNetwork(), proxy))
        return ConnectSocketDirectly(addrDest, hSocketRet, nTimeout);

    SOCKET hSocket = INVALID_SOCKET;

    // first connect to proxy server
    if (!ConnectSocketDirectly(proxy, hSocket, nTimeout))
        return false;

    // do socks negotiation
    if (!Socks5(addrDest.ToStringIP(), addrDest.GetPort(), hSocket))
        return false;

    hSocketRet = hSocket;
    return true;
}

bool ConnectSocketByName(CService &addr, SOCKET& hSocketRet, const char *pszDest, int portDefault, int nTimeout)
{
    string strDest;
    int port = portDefault;
    SplitHostPort(string(pszDest), port, strDest);

    SOCKET hSocket = INVALID_SOCKET;

    CService nameProxy;
    GetNameProxy(nameProxy);

    CService addrResolved;
    if (Lookup(strDest.c_str(), addrResolved, port, fNameLookup && !HaveNameProxy())) {
        if (addrResolved.IsValid()) {
            addr = addrResolved;
            return ConnectSocket(addr, hSocketRet, nTimeout);
        }
    }
    addr = CService();

    if (!HaveNameProxy())
        return false;
    // first connect to name proxy server
    if (!ConnectSocketDirectly(nameProxy, hSocket, nTimeout))
        return false;
    // do socks negotiation
    if (!Socks5(strDest, (unsigned short)port, hSocket))
        return false;

    hSocketRet = hSocket;
    return true;
}