dash/net.cpp

// Copyright (c) 2009 Satoshi Nakamoto
// Distributed under the MIT/X11 software license, see the accompanying
// file license.txt or http://www.opensource.org/licenses/mit-license.php.

#include "headers.h"
#include <winsock2.h>

void ThreadMessageHandler2(void* parg);
void ThreadSocketHandler2(void* parg);
void ThreadOpenConnections2(void* parg);






//
// Global state variables
//
bool fClient = false;
uint64 nLocalServices = (fClient ? 0 : NODE_NETWORK);
CAddress addrLocalHost(0, DEFAULT_PORT, nLocalServices);
CNode nodeLocalHost(INVALID_SOCKET, CAddress("127.0.0.1", nLocalServices));
CNode* pnodeLocalHost = &nodeLocalHost;
bool fShutdown = false;
array<int, 10> vnThreadsRunning;

vector<CNode*> vNodes;
CCriticalSection cs_vNodes;
map<vector<unsigned char>, CAddress> mapAddresses;
CCriticalSection cs_mapAddresses;
map<CInv, CDataStream> mapRelay;
deque<pair<int64, CInv> > vRelayExpiration;
CCriticalSection cs_mapRelay;
map<CInv, int64> mapAlreadyAskedFor;



CAddress addrProxy;

bool ConnectSocket(const CAddress& addrConnect, SOCKET& hSocketRet)
{
    hSocketRet = INVALID_SOCKET;

    SOCKET hSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (hSocket == INVALID_SOCKET)
        return false;

    bool fRoutable = !(addrConnect.GetByte(3) == 10 || (addrConnect.GetByte(3) == 192 && addrConnect.GetByte(2) == 168));
    bool fProxy = (addrProxy.ip && fRoutable);
    struct sockaddr_in sockaddr = (fProxy ? addrProxy.GetSockAddr() : addrConnect.GetSockAddr());

    if (connect(hSocket, (struct sockaddr*)&sockaddr, sizeof(sockaddr)) == SOCKET_ERROR)
    {
        closesocket(hSocket);
        return false;
    }

    if (fProxy)
    {
        printf("Proxy connecting %s\n", addrConnect.ToStringLog().c_str());
        char pszSocks4IP[] = "\4\1\0\0\0\0\0\0user";
        memcpy(pszSocks4IP + 2, &addrConnect.port, 2);
        memcpy(pszSocks4IP + 4, &addrConnect.ip, 4);
        char* pszSocks4 = pszSocks4IP;
        int nSize = sizeof(pszSocks4IP);

        int ret = send(hSocket, pszSocks4, nSize, 0);
        if (ret != nSize)
        {
            closesocket(hSocket);
            return error("Error sending to proxy\n");
        }
        char pchRet[8];
        if (recv(hSocket, pchRet, 8, 0) != 8)
        {
            closesocket(hSocket);
            return error("Error reading proxy response\n");
        }
        if (pchRet[1] != 0x5a)
        {
            closesocket(hSocket);
            return error("Proxy returned error %d\n", pchRet[1]);
        }
        printf("Proxy connection established %s\n", addrConnect.ToStringLog().c_str());
    }

    hSocketRet = hSocket;
    return true;
}



bool GetMyExternalIP2(const CAddress& addrConnect, const char* pszGet, const char* pszKeyword, unsigned int& ipRet)
{
    SOCKET hSocket;
    if (!ConnectSocket(addrConnect, hSocket))
        return error("GetMyExternalIP() : connection to %s failed\n", addrConnect.ToString().c_str());

    send(hSocket, pszGet, strlen(pszGet), 0);

    string strLine;
    while (RecvLine(hSocket, strLine))
    {
        if (strLine.empty())
        {
            loop
            {
                if (!RecvLine(hSocket, strLine))
                {
                    closesocket(hSocket);
                    return false;
                }
                if (strLine.find(pszKeyword) != -1)
                {
                    strLine = strLine.substr(strLine.find(pszKeyword) + strlen(pszKeyword));
                    break;
                }
            }
            closesocket(hSocket);
            if (strLine.find("<"))
                strLine = strLine.substr(0, strLine.find("<"));
            strLine = strLine.substr(strspn(strLine.c_str(), " \t\n\r"));
            strLine = wxString(strLine).Trim();
            CAddress addr(strLine.c_str());
            printf("GetMyExternalIP() received [%s] %s\n", strLine.c_str(), addr.ToString().c_str());
            if (addr.ip == 0 || !addr.IsRoutable())
                return false;
            ipRet = addr.ip;
            return true;
        }
    }
    closesocket(hSocket);
    return error("GetMyExternalIP() : connection closed\n");
}


bool GetMyExternalIP(unsigned int& ipRet)
{
    CAddress addrConnect;
    char* pszGet;
    char* pszKeyword;

    for (int nLookup = 0; nLookup <= 1; nLookup++)
    for (int nHost = 1; nHost <= 2; nHost++)
    {
        if (nHost == 1)
        {
            addrConnect = CAddress("70.86.96.218:80"); // www.ipaddressworld.com

            if (nLookup == 1)
            {
                struct hostent* phostent = gethostbyname("www.ipaddressworld.com");
                if (phostent && phostent->h_addr_list && phostent->h_addr_list[0])
                    addrConnect = CAddress(*(u_long*)phostent->h_addr_list[0], htons(80));
            }

            pszGet = "GET /ip.php HTTP/1.1\r\n"
                     "Host: www.ipaddressworld.com\r\n"
                     "User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)\r\n"
                     "Connection: close\r\n"
                     "\r\n";

            pszKeyword = "IP:";
        }
        else if (nHost == 2)
        {
            addrConnect = CAddress("208.78.68.70:80"); // checkip.dyndns.org

            if (nLookup == 1)
            {
                struct hostent* phostent = gethostbyname("checkip.dyndns.org");
                if (phostent && phostent->h_addr_list && phostent->h_addr_list[0])
                    addrConnect = CAddress(*(u_long*)phostent->h_addr_list[0], htons(80));
            }

            pszGet = "GET / HTTP/1.1\r\n"
                     "Host: checkip.dyndns.org\r\n"
                     "User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)\r\n"
                     "Connection: close\r\n"
                     "\r\n";

            pszKeyword = "Address:";
        }

        if (GetMyExternalIP2(addrConnect, pszGet, pszKeyword, ipRet))
            return true;
    }

    return false;
}





bool AddAddress(CAddrDB& addrdb, const CAddress& addr)
{
    if (!addr.IsRoutable())
        return false;
    if (addr.ip == addrLocalHost.ip)
        return false;
    CRITICAL_BLOCK(cs_mapAddresses)
    {
        map<vector<unsigned char>, CAddress>::iterator it = mapAddresses.find(addr.GetKey());
        if (it == mapAddresses.end())
        {
            // New address
            mapAddresses.insert(make_pair(addr.GetKey(), addr));
            addrdb.WriteAddress(addr);
            return true;
        }
        else
        {
            CAddress& addrFound = (*it).second;
            if ((addrFound.nServices | addr.nServices) != addrFound.nServices)
            {
                // Services have been added
                addrFound.nServices |= addr.nServices;
                addrdb.WriteAddress(addrFound);
                return true;
            }
            else if (addrFound.nTime < GetAdjustedTime() - 24 * 60 * 60)
            {
                // Periodically update most recently seen time
                addrFound.nTime = GetAdjustedTime();
                addrdb.WriteAddress(addrFound);
                return false;
            }
        }
    }
    return false;
}





void AbandonRequests(void (*fn)(void*, CDataStream&), void* param1)
{
    // If the dialog might get closed before the reply comes back,
    // call this in the destructor so it doesn't get called after it's deleted.
    CRITICAL_BLOCK(cs_vNodes)
    {
        foreach(CNode* pnode, vNodes)
        {
            CRITICAL_BLOCK(pnode->cs_mapRequests)
            {
                for (map<uint256, CRequestTracker>::iterator mi = pnode->mapRequests.begin(); mi != pnode->mapRequests.end();)
                {
                    CRequestTracker& tracker = (*mi).second;
                    if (tracker.fn == fn && tracker.param1 == param1)
                        pnode->mapRequests.erase(mi++);
                    else
                        mi++;
                }
            }
        }
    }
}







//
// Subscription methods for the broadcast and subscription system.
// Channel numbers are message numbers, i.e. MSG_TABLE and MSG_PRODUCT.
//
// The subscription system uses a meet-in-the-middle strategy.
// With 100,000 nodes, if senders broadcast to 1000 random nodes and receivers
// subscribe to 1000 random nodes, 99.995% (1 - 0.99^1000) of messages will get through.
//

bool AnySubscribed(unsigned int nChannel)
{
    if (pnodeLocalHost->IsSubscribed(nChannel))
        return true;
    CRITICAL_BLOCK(cs_vNodes)
        foreach(CNode* pnode, vNodes)
            if (pnode->IsSubscribed(nChannel))
                return true;
    return false;
}

bool CNode::IsSubscribed(unsigned int nChannel)
{
    if (nChannel >= vfSubscribe.size())
        return false;
    return vfSubscribe[nChannel];
}

void CNode::Subscribe(unsigned int nChannel, unsigned int nHops)
{
    if (nChannel >= vfSubscribe.size())
        return;

    if (!AnySubscribed(nChannel))
    {
        // Relay subscribe
        CRITICAL_BLOCK(cs_vNodes)
            foreach(CNode* pnode, vNodes)
                if (pnode != this)
                    pnode->PushMessage("subscribe", nChannel, nHops);
    }

    vfSubscribe[nChannel] = true;
}

void CNode::CancelSubscribe(unsigned int nChannel)
{
    if (nChannel >= vfSubscribe.size())
        return;

    // Prevent from relaying cancel if wasn't subscribed
    if (!vfSubscribe[nChannel])
        return;
    vfSubscribe[nChannel] = false;

    if (!AnySubscribed(nChannel))
    {
        // Relay subscription cancel
        CRITICAL_BLOCK(cs_vNodes)
            foreach(CNode* pnode, vNodes)
                if (pnode != this)
                    pnode->PushMessage("sub-cancel", nChannel);

        // Clear memory, no longer subscribed
        if (nChannel == MSG_PRODUCT)
            CRITICAL_BLOCK(cs_mapProducts)
                mapProducts.clear();
    }
}









CNode* FindNode(unsigned int ip)
{
    CRITICAL_BLOCK(cs_vNodes)
    {
        foreach(CNode* pnode, vNodes)
            if (pnode->addr.ip == ip)
                return (pnode);
    }
    return NULL;
}

CNode* FindNode(CAddress addr)
{
    CRITICAL_BLOCK(cs_vNodes)
    {
        foreach(CNode* pnode, vNodes)
            if (pnode->addr == addr)
                return (pnode);
    }
    return NULL;
}

CNode* ConnectNode(CAddress addrConnect, int64 nTimeout)
{
    if (addrConnect.ip == addrLocalHost.ip)
        return NULL;

    // Look for an existing connection
    CNode* pnode = FindNode(addrConnect.ip);
    if (pnode)
    {
        if (nTimeout != 0)
            pnode->AddRef(nTimeout);
        else
            pnode->AddRef();
        return pnode;
    }

    /// debug print
    printf("trying connection %s\n", addrConnect.ToStringLog().c_str());

    // Connect
    SOCKET hSocket;
    if (ConnectSocket(addrConnect, hSocket))
    {
        /// debug print
        printf("connected %s\n", addrConnect.ToStringLog().c_str());

        // Set to nonblocking
        u_long nOne = 1;
        if (ioctlsocket(hSocket, FIONBIO, &nOne) == SOCKET_ERROR)
            printf("ConnectSocket() : ioctlsocket nonblocking setting failed, error %d\n", WSAGetLastError());

        // Add node
        CNode* pnode = new CNode(hSocket, addrConnect, false);
        if (nTimeout != 0)
            pnode->AddRef(nTimeout);
        else
            pnode->AddRef();
        CRITICAL_BLOCK(cs_vNodes)
            vNodes.push_back(pnode);

        CRITICAL_BLOCK(cs_mapAddresses)
            mapAddresses[addrConnect.GetKey()].nLastFailed = 0;
        return pnode;
    }
    else
    {
        CRITICAL_BLOCK(cs_mapAddresses)
            mapAddresses[addrConnect.GetKey()].nLastFailed = GetTime();
        return NULL;
    }
}

void CNode::Disconnect()
{
    printf("disconnecting node %s\n", addr.ToStringLog().c_str());

    closesocket(hSocket);

    // If outbound and never got version message, mark address as failed
    if (!fInbound && nVersion == 0)
        CRITICAL_BLOCK(cs_mapAddresses)
            mapAddresses[addr.GetKey()].nLastFailed = GetTime();

    // All of a nodes broadcasts and subscriptions are automatically torn down
    // when it goes down, so a node has to stay up to keep its broadcast going.

    CRITICAL_BLOCK(cs_mapProducts)
        for (map<uint256, CProduct>::iterator mi = mapProducts.begin(); mi != mapProducts.end();)
            AdvertRemoveSource(this, MSG_PRODUCT, 0, (*(mi++)).second);

    // Cancel subscriptions
    for (unsigned int nChannel = 0; nChannel < vfSubscribe.size(); nChannel++)
        if (vfSubscribe[nChannel])
            CancelSubscribe(nChannel);
}













void ThreadSocketHandler(void* parg)
{
    IMPLEMENT_RANDOMIZE_STACK(ThreadSocketHandler(parg));

    loop
    {
        vnThreadsRunning[0] = true;
        CheckForShutdown(0);
        try
        {
            ThreadSocketHandler2(parg);
            vnThreadsRunning[0] = false;
        }
        catch (std::exception& e) {
            vnThreadsRunning[0] = false;
            PrintException(&e, "ThreadSocketHandler()");
        } catch (...) {
            vnThreadsRunning[0] = false;
            PrintException(NULL, "ThreadSocketHandler()");
        }
        Sleep(5000);
    }
}

void ThreadSocketHandler2(void* parg)
{
    printf("ThreadSocketHandler started\n");
    SOCKET hListenSocket = *(SOCKET*)parg;
    list<CNode*> vNodesDisconnected;
    int nPrevNodeCount = 0;

    loop
    {
        //
        // Disconnect nodes
        //
        CRITICAL_BLOCK(cs_vNodes)
        {
            // Disconnect unused nodes
            vector<CNode*> vNodesCopy = vNodes;
            foreach(CNode* pnode, vNodesCopy)
            {
                if (pnode->ReadyToDisconnect() && pnode->vRecv.empty() && pnode->vSend.empty())
                {
                    // remove from vNodes
                    vNodes.erase(remove(vNodes.begin(), vNodes.end(), pnode), vNodes.end());
                    pnode->Disconnect();

                    // hold in disconnected pool until all refs are released
                    pnode->nReleaseTime = max(pnode->nReleaseTime, GetTime() + 5 * 60);
                    if (pnode->fNetworkNode)
                        pnode->Release();
                    vNodesDisconnected.push_back(pnode);
                }
            }

            // Delete disconnected nodes
            list<CNode*> vNodesDisconnectedCopy = vNodesDisconnected;
            foreach(CNode* pnode, vNodesDisconnectedCopy)
            {
                // wait until threads are done using it
                if (pnode->GetRefCount() <= 0)
                {
                    bool fDelete = false;
                    TRY_CRITICAL_BLOCK(pnode->cs_vSend)
                     TRY_CRITICAL_BLOCK(pnode->cs_vRecv)
                      TRY_CRITICAL_BLOCK(pnode->cs_mapRequests)
                       TRY_CRITICAL_BLOCK(pnode->cs_inventory)
                        fDelete = true;
                    if (fDelete)
                    {
                        vNodesDisconnected.remove(pnode);
                        delete pnode;
                    }
                }
            }
        }
        if (vNodes.size() != nPrevNodeCount)
        {
            nPrevNodeCount = vNodes.size();
            MainFrameRepaint();
        }


        //
        // Find which sockets have data to receive
        //
        struct timeval timeout;
        timeout.tv_sec  = 0;
        timeout.tv_usec = 50000; // frequency to poll pnode->vSend

        struct fd_set fdsetRecv;
        struct fd_set fdsetSend;
        FD_ZERO(&fdsetRecv);
        FD_ZERO(&fdsetSend);
        SOCKET hSocketMax = 0;
        FD_SET(hListenSocket, &fdsetRecv);
        hSocketMax = max(hSocketMax, hListenSocket);
        CRITICAL_BLOCK(cs_vNodes)
        {
            foreach(CNode* pnode, vNodes)
            {
                FD_SET(pnode->hSocket, &fdsetRecv);
                hSocketMax = max(hSocketMax, pnode->hSocket);
                TRY_CRITICAL_BLOCK(pnode->cs_vSend)
                    if (!pnode->vSend.empty())
                        FD_SET(pnode->hSocket, &fdsetSend);
            }
        }

        vnThreadsRunning[0] = false;
        int nSelect = select(hSocketMax + 1, &fdsetRecv, &fdsetSend, NULL, &timeout);
        vnThreadsRunning[0] = true;
        CheckForShutdown(0);
        if (nSelect == SOCKET_ERROR)
        {
            int nErr = WSAGetLastError();
            printf("select failed: %d\n", nErr);
            for (int i = 0; i <= hSocketMax; i++)
            {
                FD_SET(i, &fdsetRecv);
                FD_SET(i, &fdsetSend);
            }
            Sleep(timeout.tv_usec/1000);
        }
        RandAddSeed();

        //// debug print
        //foreach(CNode* pnode, vNodes)
        //{
        //    printf("vRecv = %-5d ", pnode->vRecv.size());
        //    printf("vSend = %-5d    ", pnode->vSend.size());
        //}
        //printf("\n");


        //
        // Accept new connections
        //
        if (FD_ISSET(hListenSocket, &fdsetRecv))
        {
            struct sockaddr_in sockaddr;
            int len = sizeof(sockaddr);
            SOCKET hSocket = accept(hListenSocket, (struct sockaddr*)&sockaddr, &len);
            CAddress addr(sockaddr);
            if (hSocket == INVALID_SOCKET)
            {
                if (WSAGetLastError() != WSAEWOULDBLOCK)
                    printf("ERROR ThreadSocketHandler accept failed: %d\n", WSAGetLastError());
            }
            else
            {
                printf("accepted connection %s\n", addr.ToStringLog().c_str());
                CNode* pnode = new CNode(hSocket, addr, true);
                pnode->AddRef();
                CRITICAL_BLOCK(cs_vNodes)
                    vNodes.push_back(pnode);
            }
        }


        //
        // Service each socket
        //
        vector<CNode*> vNodesCopy;
        CRITICAL_BLOCK(cs_vNodes)
            vNodesCopy = vNodes;
        foreach(CNode* pnode, vNodesCopy)
        {
            CheckForShutdown(0);
            SOCKET hSocket = pnode->hSocket;

            //
            // Receive
            //
            if (FD_ISSET(hSocket, &fdsetRecv))
            {
                TRY_CRITICAL_BLOCK(pnode->cs_vRecv)
                {
                    CDataStream& vRecv = pnode->vRecv;
                    unsigned int nPos = vRecv.size();

                    // typical socket buffer is 8K-64K
                    const unsigned int nBufSize = 0x10000;
                    vRecv.resize(nPos + nBufSize);
                    int nBytes = recv(hSocket, &vRecv[nPos], nBufSize, 0);
                    vRecv.resize(nPos + max(nBytes, 0));
                    if (nBytes == 0)
                    {
                        // socket closed gracefully
                        if (!pnode->fDisconnect)
                            printf("recv: socket closed\n");
                        pnode->fDisconnect = true;
                    }
                    else if (nBytes < 0)
                    {
                        // socket error
                        int nErr = WSAGetLastError();
                        if (nErr != WSAEWOULDBLOCK && nErr != WSAEMSGSIZE && nErr != WSAEINTR && nErr != WSAEINPROGRESS)
                        {
                            if (!pnode->fDisconnect)
                                printf("recv failed: %d\n", nErr);
                            pnode->fDisconnect = true;
                        }
                    }
                }
            }

            //
            // Send
            //
            if (FD_ISSET(hSocket, &fdsetSend))
            {
                TRY_CRITICAL_BLOCK(pnode->cs_vSend)
                {
                    CDataStream& vSend = pnode->vSend;
                    if (!vSend.empty())
                    {
                        int nBytes = send(hSocket, &vSend[0], vSend.size(), 0);
                        if (nBytes > 0)
                        {
                            vSend.erase(vSend.begin(), vSend.begin() + nBytes);
                        }
                        else if (nBytes == 0)
                        {
                            if (pnode->ReadyToDisconnect())
                                pnode->vSend.clear();
                        }
                        else
                        {
                            printf("send error %d\n", nBytes);
                            if (pnode->ReadyToDisconnect())
                                pnode->vSend.clear();
                        }
                    }
                }
            }
        }


        Sleep(10);
    }
}










void ThreadOpenConnections(void* parg)
{
    IMPLEMENT_RANDOMIZE_STACK(ThreadOpenConnections(parg));

    loop
    {
        vnThreadsRunning[1] = true;
        CheckForShutdown(1);
        try
        {
            ThreadOpenConnections2(parg);
            vnThreadsRunning[1] = false;
        }
        catch (std::exception& e) {
            vnThreadsRunning[1] = false;
            PrintException(&e, "ThreadOpenConnections()");
        } catch (...) {
            vnThreadsRunning[1] = false;
            PrintException(NULL, "ThreadOpenConnections()");
        }
        Sleep(5000);
    }
}

void ThreadOpenConnections2(void* parg)
{
    printf("ThreadOpenConnections started\n");

    // Initiate network connections
    int nTry = 0;
    bool fIRCOnly = false;
    const int nMaxConnections = 15;
    loop
    {
        // Wait
        vnThreadsRunning[1] = false;
        Sleep(500);
        while (vNodes.size() >= nMaxConnections || vNodes.size() >= mapAddresses.size())
        {
            CheckForShutdown(1);
            Sleep(2000);
        }
        vnThreadsRunning[1] = true;
        CheckForShutdown(1);


        //
        // The IP selection process is designed to limit vulnerability to address flooding.
        // Any class C (a.b.c.?) has an equal chance of being chosen, then an IP is
        // chosen within the class C.  An attacker may be able to allocate many IPs, but
        // they would normally be concentrated in blocks of class C's.  They can hog the
        // attention within their class C, but not the whole IP address space overall.
        // A lone node in a class C will get as much attention as someone holding all 255
        // IPs in another class C.
        //

        // Every other try is with IRC addresses only
        fIRCOnly = !fIRCOnly;
        if (mapIRCAddresses.empty())
            fIRCOnly = false;
        else if (nTry++ < 30 && vNodes.size() < nMaxConnections/2)
            fIRCOnly = true;

        // Make a list of unique class C's
        unsigned char pchIPCMask[4] = { 0xff, 0xff, 0xff, 0x00 };
        unsigned int nIPCMask = *(unsigned int*)pchIPCMask;
        vector<unsigned int> vIPC;
        CRITICAL_BLOCK(cs_mapIRCAddresses)
        CRITICAL_BLOCK(cs_mapAddresses)
        {
            vIPC.reserve(mapAddresses.size());
            unsigned int nPrev = 0;
            foreach(const PAIRTYPE(vector<unsigned char>, CAddress)& item, mapAddresses)
            {
                const CAddress& addr = item.second;
                if (!addr.IsIPv4())
                    continue;
                if (fIRCOnly && !mapIRCAddresses.count(item.first))
                    continue;

                // Taking advantage of mapAddresses being in sorted order,
                // with IPs of the same class C grouped together.
                unsigned int ipC = addr.ip & nIPCMask;
                if (ipC != nPrev)
                    vIPC.push_back(nPrev = ipC);
            }
        }
        if (vIPC.empty())
            continue;

        // Choose a random class C
        unsigned int ipC = vIPC[GetRand(vIPC.size())];

        // Organize all addresses in the class C by IP
        map<unsigned int, vector<CAddress> > mapIP;
        CRITICAL_BLOCK(cs_mapIRCAddresses)
        CRITICAL_BLOCK(cs_mapAddresses)
        {
            int64 nDelay = ((30 * 60) << vNodes.size());
            if (!fIRCOnly)
            {
                nDelay *= 2;
                if (vNodes.size() >= 3)
                    nDelay *= 4;
                if (!mapIRCAddresses.empty())
                    nDelay *= 100;
            }

            for (map<vector<unsigned char>, CAddress>::iterator mi = mapAddresses.lower_bound(CAddress(ipC, 0).GetKey());
                 mi != mapAddresses.upper_bound(CAddress(ipC | ~nIPCMask, 0xffff).GetKey());
                 ++mi)
            {
                const CAddress& addr = (*mi).second;
                if (fIRCOnly && !mapIRCAddresses.count((*mi).first))
                    continue;

                int64 nRandomizer = (addr.nLastFailed * addr.ip * 7777U) % 20000;
                if (GetTime() - addr.nLastFailed > nDelay * nRandomizer / 10000)
                    mapIP[addr.ip].push_back(addr);
            }
        }
        if (mapIP.empty())
            continue;

        // Choose a random IP in the class C
        map<unsigned int, vector<CAddress> >::iterator mi = mapIP.begin();
        advance(mi, GetRand(mapIP.size()));

        // Once we've chosen an IP, we'll try every given port before moving on
        foreach(const CAddress& addrConnect, (*mi).second)
        {
            //
            // Initiate outbound network connection
            //
            CheckForShutdown(1);
            if (addrConnect.ip == addrLocalHost.ip || !addrConnect.IsIPv4() || FindNode(addrConnect.ip))
                continue;

            vnThreadsRunning[1] = false;
            CNode* pnode = ConnectNode(addrConnect);
            vnThreadsRunning[1] = true;
            CheckForShutdown(1);
            if (!pnode)
                continue;
            pnode->fNetworkNode = true;

            if (addrLocalHost.IsRoutable())
            {
                // Advertise our address
                vector<CAddress> vAddrToSend;
                vAddrToSend.push_back(addrLocalHost);
                pnode->PushMessage("addr", vAddrToSend);
            }

            // Get as many addresses as we can
            pnode->PushMessage("getaddr");

            ////// should the one on the receiving end do this too?
            // Subscribe our local subscription list
            const unsigned int nHops = 0;
            for (unsigned int nChannel = 0; nChannel < pnodeLocalHost->vfSubscribe.size(); nChannel++)
                if (pnodeLocalHost->vfSubscribe[nChannel])
                    pnode->PushMessage("subscribe", nChannel, nHops);

            break;
        }
    }
}








void ThreadMessageHandler(void* parg)
{
    IMPLEMENT_RANDOMIZE_STACK(ThreadMessageHandler(parg));

    loop
    {
        vnThreadsRunning[2] = true;
        CheckForShutdown(2);
        try
        {
            ThreadMessageHandler2(parg);
            vnThreadsRunning[2] = false;
        }
        catch (std::exception& e) {
            vnThreadsRunning[2] = false;
            PrintException(&e, "ThreadMessageHandler()");
        } catch (...) {
            vnThreadsRunning[2] = false;
            PrintException(NULL, "ThreadMessageHandler()");
        }
        Sleep(5000);
    }
}

void ThreadMessageHandler2(void* parg)
{
    printf("ThreadMessageHandler started\n");
    SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_BELOW_NORMAL);
    loop
    {
        // Poll the connected nodes for messages
        vector<CNode*> vNodesCopy;
        CRITICAL_BLOCK(cs_vNodes)
            vNodesCopy = vNodes;
        foreach(CNode* pnode, vNodesCopy)
        {
            pnode->AddRef();

            // Receive messages
            TRY_CRITICAL_BLOCK(pnode->cs_vRecv)
                ProcessMessages(pnode);

            // Send messages
            TRY_CRITICAL_BLOCK(pnode->cs_vSend)
                SendMessages(pnode);

            pnode->Release();
        }

        // Wait and allow messages to bunch up
        vnThreadsRunning[2] = false;
        Sleep(100);
        vnThreadsRunning[2] = true;
        CheckForShutdown(2);
    }
}










bool StartNode(string& strError)
{
    strError = "";

    // Sockets startup
    WSADATA wsadata;
    int ret = WSAStartup(MAKEWORD(2,2), &wsadata);
    if (ret != NO_ERROR)
    {
        strError = strprintf("Error: TCP/IP socket library failed to start (WSAStartup returned error %d)", ret);
        printf("%s\n", strError.c_str());
        return false;
    }

    // Get local host ip
    char pszHostName[255];
    if (gethostname(pszHostName, 255) == SOCKET_ERROR)
    {
        strError = strprintf("Error: Unable to get IP address of this computer (gethostname returned error %d)", WSAGetLastError());
        printf("%s\n", strError.c_str());
        return false;
    }
    struct hostent* phostent = gethostbyname(pszHostName);
    if (!phostent)
    {
        strError = strprintf("Error: Unable to get IP address of this computer (gethostbyname returned error %d)", WSAGetLastError());
        printf("%s\n", strError.c_str());
        return false;
    }
    addrLocalHost = CAddress(*(long*)(phostent->h_addr_list[0]),
                             DEFAULT_PORT,
                             nLocalServices);
    printf("addrLocalHost = %s\n", addrLocalHost.ToString().c_str());

    // Create socket for listening for incoming connections
    SOCKET hListenSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (hListenSocket == INVALID_SOCKET)
    {
        strError = strprintf("Error: Couldn't open socket for incoming connections (socket returned error %d)", WSAGetLastError());
        printf("%s\n", strError.c_str());
        return false;
    }

    // Set to nonblocking, incoming connections will also inherit this
    u_long nOne = 1;
    if (ioctlsocket(hListenSocket, FIONBIO, &nOne) == SOCKET_ERROR)
    {
        strError = strprintf("Error: Couldn't set properties on socket for incoming connections (ioctlsocket returned error %d)", WSAGetLastError());
        printf("%s\n", strError.c_str());
        return false;
    }

    // The sockaddr_in structure specifies the address family,
    // IP address, and port for the socket that is being bound
    int nRetryLimit = 15;
    struct sockaddr_in sockaddr = addrLocalHost.GetSockAddr();
    if (bind(hListenSocket, (struct sockaddr*)&sockaddr, sizeof(sockaddr)) == SOCKET_ERROR)
    {
        int nErr = WSAGetLastError();
        if (nErr == WSAEADDRINUSE)
            strError = strprintf("Error: Unable to bind to port %s on this computer. The program is probably already running.", addrLocalHost.ToString().c_str());
        else
            strError = strprintf("Error: Unable to bind to port %s on this computer (bind returned error %d)", addrLocalHost.ToString().c_str(), nErr);
        printf("%s\n", strError.c_str());
        return false;
    }
    printf("bound to addrLocalHost = %s\n\n", addrLocalHost.ToString().c_str());

    // Listen for incoming connections
    if (listen(hListenSocket, SOMAXCONN) == SOCKET_ERROR)
    {
        strError = strprintf("Error: Listening for incoming connections failed (listen returned error %d)", WSAGetLastError());
        printf("%s\n", strError.c_str());
        return false;
    }

    // Get our external IP address for incoming connections
    if (addrIncoming.ip)
        addrLocalHost.ip = addrIncoming.ip;

    if (GetMyExternalIP(addrLocalHost.ip))
    {
        addrIncoming = addrLocalHost;
        CWalletDB().WriteSetting("addrIncoming", addrIncoming);
    }

    // Get addresses from IRC and advertise ours
    if (_beginthread(ThreadIRCSeed, 0, NULL) == -1)
        printf("Error: _beginthread(ThreadIRCSeed) failed\n");

    //
    // Start threads
    //
    if (_beginthread(ThreadSocketHandler, 0, new SOCKET(hListenSocket)) == -1)
    {
        strError = "Error: _beginthread(ThreadSocketHandler) failed";
        printf("%s\n", strError.c_str());
        return false;
    }

    if (_beginthread(ThreadOpenConnections, 0, NULL) == -1)
    {
        strError = "Error: _beginthread(ThreadOpenConnections) failed";
        printf("%s\n", strError.c_str());
        return false;
    }

    if (_beginthread(ThreadMessageHandler, 0, NULL) == -1)
    {
        strError = "Error: _beginthread(ThreadMessageHandler) failed";
        printf("%s\n", strError.c_str());
        return false;
    }

    return true;
}

bool StopNode()
{
    printf("StopNode()\n");
    fShutdown = true;
    nTransactionsUpdated++;
    int64 nStart = GetTime();
    while (vnThreadsRunning[0] || vnThreadsRunning[2] || vnThreadsRunning[3])
    {
        if (GetTime() - nStart > 15)
            break;
        Sleep(20);
    }
    if (vnThreadsRunning[0]) printf("ThreadSocketHandler still running\n");
    if (vnThreadsRunning[1]) printf("ThreadOpenConnections still running\n");
    if (vnThreadsRunning[2]) printf("ThreadMessageHandler still running\n");
    if (vnThreadsRunning[3]) printf("ThreadBitcoinMiner still running\n");
    while (vnThreadsRunning[2])
        Sleep(20);
    Sleep(50);

    // Sockets shutdown
    WSACleanup();
    return true;
}

void CheckForShutdown(int n)
{
    if (fShutdown)
    {
        if (n != -1)
            vnThreadsRunning[n] = false;
        if (n == 0)
            foreach(CNode* pnode, vNodes)
                closesocket(pnode->hSocket);
        _endthread();
    }
}