path: root/src/net.cpp

// Copyright (c) 2009-2010 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 "irc.h"
#include "db.h"
#include "net.h"
#include "init.h"
#include "strlcpy.h"

#ifdef USE_UPNP
#include <miniupnpc/miniwget.h>
#include <miniupnpc/miniupnpc.h>
#include <miniupnpc/upnpcommands.h>
#include <miniupnpc/upnperrors.h>
#endif

using namespace std;
using namespace boost;

static const int MAX_OUTBOUND_CONNECTIONS = 8;

void ThreadMessageHandler2(void* parg);
void ThreadSocketHandler2(void* parg);
void ThreadOpenConnections2(void* parg);
#ifdef USE_UPNP
void ThreadMapPort2(void* parg);
#endif
bool OpenNetworkConnection(const CAddress& addrConnect);





//
// Global state variables
//
bool fClient = false;
bool fAllowDNS = false;
uint64 nLocalServices = (fClient ? 0 : NODE_NETWORK);
CAddress addrLocalHost("0.0.0.0", 0, false, nLocalServices);
CNode* pnodeLocalHost = NULL;
uint64 nLocalHostNonce = 0;
array<int, 10> vnThreadsRunning;
SOCKET hListenSocket = INVALID_SOCKET;

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;

// Settings
int fUseProxy = false;
int nConnectTimeout = 5000;
CAddress addrProxy("127.0.0.1",9050);




unsigned short GetListenPort()
{
    return (unsigned short)(GetArg("-port", GetDefaultPort()));
}

void CNode::PushGetBlocks(CBlockIndex* pindexBegin, uint256 hashEnd)
{
    // Filter out duplicate requests
    if (pindexBegin == pindexLastGetBlocksBegin && hashEnd == hashLastGetBlocksEnd)
        return;
    pindexLastGetBlocksBegin = pindexBegin;
    hashLastGetBlocksEnd = hashEnd;

    PushMessage("getblocks", CBlockLocator(pindexBegin), hashEnd);
}





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

    SOCKET hSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (hSocket == INVALID_SOCKET)
        return false;
#ifdef BSD
    int set = 1;
    setsockopt(hSocket, SOL_SOCKET, SO_NOSIGPIPE, (void*)&set, sizeof(int));
#endif

    bool fProxy = (fUseProxy && addrConnect.IsRoutable());
    struct sockaddr_in sockaddr = (fProxy ? addrProxy.GetSockAddr() : addrConnect.GetSockAddr());

#ifdef __WXMSW__
    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, sizeof(sockaddr)) == SOCKET_ERROR)
    {
        // WSAEINVAL is here because some legacy version of winsock uses it
        if (WSAGetLastError() == WSAEINPROGRESS || WSAGetLastError() == WSAEWOULDBLOCK || WSAGetLastError() == 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, NULL, &fdset, NULL, &timeout);
            if (nRet == 0)
            {
                printf("connection timeout\n");
                closesocket(hSocket);
                return false;
            }
            if (nRet == SOCKET_ERROR)
            {
                printf("select() for connection failed: %i\n",WSAGetLastError());
                closesocket(hSocket);
                return false;
            }
            socklen_t nRetSize = sizeof(nRet);
#ifdef __WXMSW__
            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
            {
                printf("getsockopt() for connection failed: %i\n",WSAGetLastError());
                closesocket(hSocket);
                return false;
            }
            if (nRet != 0)
            {
                printf("connect() failed after select(): %i\n",nRet);
                closesocket(hSocket);
                return false;
            }
        }
#ifdef __WXMSW__
        else if (WSAGetLastError() != WSAEISCONN)
#else
        else
#endif
        {
            printf("connect() failed: %i\n",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 __WXMSW__
    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;
    }

    if (fProxy)
    {
        printf("proxy connecting %s\n", addrConnect.ToString().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, MSG_NOSIGNAL);
        if (ret != nSize)
        {
            closesocket(hSocket);
            return error("Error sending to proxy");
        }
        char pchRet[8];
        if (recv(hSocket, pchRet, 8, 0) != 8)
        {
            closesocket(hSocket);
            return error("Error reading proxy response");
        }
        if (pchRet[1] != 0x5a)
        {
            closesocket(hSocket);
            if (pchRet[1] != 0x5b)
                printf("ERROR: Proxy returned error %d\n", pchRet[1]);
            return false;
        }
        printf("proxy connected %s\n", addrConnect.ToString().c_str());
    }

    hSocketRet = hSocket;
    return true;
}

// portDefault is in host order
bool Lookup(const char *pszName, vector<CAddress>& vaddr, int nServices, int nMaxSolutions, bool fAllowLookup, int portDefault, bool fAllowPort)
{
    vaddr.clear();
    if (pszName[0] == 0)
        return false;
    int port = portDefault;
    char psz[256];
    char *pszHost = psz;
    strlcpy(psz, pszName, sizeof(psz));
    if (fAllowPort)
    {
        char* pszColon = strrchr(psz+1,':');
        char *pszPortEnd = NULL;
        int portParsed = pszColon ? strtoul(pszColon+1, &pszPortEnd, 10) : 0;
        if (pszColon && pszPortEnd && pszPortEnd[0] == 0)
        {
            if (psz[0] == '[' && pszColon[-1] == ']')
            {
                // Future: enable IPv6 colon-notation inside []
                pszHost = psz+1;
                pszColon[-1] = 0;
            }
            else
                pszColon[0] = 0;
            port = portParsed;
            if (port < 0 || port > USHRT_MAX)
                port = USHRT_MAX;
        }
    }

    unsigned int addrIP = inet_addr(pszHost);
    if (addrIP != INADDR_NONE)
    {
        // valid IP address passed
        vaddr.push_back(CAddress(addrIP, port, nServices));
        return true;
    }

    if (!fAllowLookup)
        return false;

    struct hostent* phostent = gethostbyname(pszHost);
    if (!phostent)
        return false;

    if (phostent->h_addrtype != AF_INET)
        return false;

    char** ppAddr = phostent->h_addr_list;
    while (*ppAddr != NULL && vaddr.size() != nMaxSolutions)
    {
        CAddress addr(((struct in_addr*)ppAddr[0])->s_addr, port, nServices);
        if (addr.IsValid())
            vaddr.push_back(addr);
        ppAddr++;
    }

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

// portDefault is in host order
bool Lookup(const char *pszName, CAddress& addr, int nServices, bool fAllowLookup, int portDefault, bool fAllowPort)
{
    vector<CAddress> vaddr;
    bool fRet = Lookup(pszName, vaddr, nServices, 1, fAllowLookup, portDefault, fAllowPort);
    if (fRet)
        addr = vaddr[0];
    return fRet;
}

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", addrConnect.ToString().c_str());

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

    string strLine;
    while (RecvLine(hSocket, strLine))
    {
        if (strLine.empty()) // HTTP response is separated from headers by blank line
        {
            loop
            {
                if (!RecvLine(hSocket, strLine))
                {
                    closesocket(hSocket);
                    return false;
                }
                if (pszKeyword == NULL)
                    break;
                if (strLine.find(pszKeyword) != -1)
                {
                    strLine = strLine.substr(strLine.find(pszKeyword) + strlen(pszKeyword));
                    break;
                }
            }
            closesocket(hSocket);
            if (strLine.find("<") != -1)
                strLine = strLine.substr(0, strLine.find("<"));
            strLine = strLine.substr(strspn(strLine.c_str(), " \t\n\r"));
            while (strLine.size() > 0 && isspace(strLine[strLine.size()-1]))
                strLine.resize(strLine.size()-1);
            CAddress addr(strLine,0,true);
            printf("GetMyExternalIP() received [%s] %s\n", strLine.c_str(), addr.ToString().c_str());
            if (addr.ip == 0 || addr.ip == INADDR_NONE || !addr.IsRoutable())
                return false;
            ipRet = addr.ip;
            return true;
        }
    }
    closesocket(hSocket);
    return error("GetMyExternalIP() : connection closed");
}

// We now get our external IP from the IRC server first and only use this as a backup
bool GetMyExternalIP(unsigned int& ipRet)
{
    CAddress addrConnect;
    const char* pszGet;
    const char* pszKeyword;

    if (fUseProxy)
        return false;

    for (int nLookup = 0; nLookup <= 1; nLookup++)
    for (int nHost = 1; nHost <= 2; nHost++)
    {
        // We should be phasing out our use of sites like these.  If we need
        // replacements, we should ask for volunteers to put this simple
        // php file on their webserver that prints the client IP:
        //  <?php echo $_SERVER["REMOTE_ADDR"]; ?>
        if (nHost == 1)
        {
            addrConnect = CAddress("91.198.22.70",80); // checkip.dyndns.org

            if (nLookup == 1)
            {
                CAddress addrIP("checkip.dyndns.org", 80, true);
                if (addrIP.IsValid())
                    addrConnect = addrIP;
            }

            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:";
        }
        else if (nHost == 2)
        {
            addrConnect = CAddress("74.208.43.192", 80); // www.showmyip.com

            if (nLookup == 1)
            {
                CAddress addrIP("www.showmyip.com", 80, true);
                if (addrIP.IsValid())
                    addrConnect = addrIP;
            }

            pszGet = "GET /simple/ HTTP/1.1\r\n"
                     "Host: www.showmyip.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 = NULL; // Returns just IP address
        }

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

    return false;
}

void ThreadGetMyExternalIP(void* parg)
{
    // Wait for IRC to get it first
    if (!GetBoolArg("-noirc"))
    {
        for (int i = 0; i < 2 * 60; i++)
        {
            Sleep(1000);
            if (fGotExternalIP || fShutdown)
                return;
        }
    }

    // Fallback in case IRC fails to get it
    if (GetMyExternalIP(addrLocalHost.ip))
    {
        printf("GetMyExternalIP() returned %s\n", addrLocalHost.ToStringIP().c_str());
        if (addrLocalHost.IsRoutable())
        {
            // If we already connected to a few before we had our IP, go back and addr them.
            // setAddrKnown automatically filters any duplicate sends.
            CAddress addr(addrLocalHost);
            addr.nTime = GetAdjustedTime();
            CRITICAL_BLOCK(cs_vNodes)
                BOOST_FOREACH(CNode* pnode, vNodes)
                    pnode->PushAddress(addr);
        }
    }
}





bool AddAddress(CAddress addr, int64 nTimePenalty)
{
    if (!addr.IsRoutable())
        return false;
    if (addr.ip == addrLocalHost.ip)
        return false;
    addr.nTime = max((int64)0, (int64)addr.nTime - nTimePenalty);
    CRITICAL_BLOCK(cs_mapAddresses)
    {
        map<vector<unsigned char>, CAddress>::iterator it = mapAddresses.find(addr.GetKey());
        if (it == mapAddresses.end())
        {
            // New address
            printf("AddAddress(%s)\n", addr.ToString().c_str());
            mapAddresses.insert(make_pair(addr.GetKey(), addr));
            CAddrDB().WriteAddress(addr);
            return true;
        }
        else
        {
            bool fUpdated = false;
            CAddress& addrFound = (*it).second;
            if ((addrFound.nServices | addr.nServices) != addrFound.nServices)
            {
                // Services have been added
                addrFound.nServices |= addr.nServices;
                fUpdated = true;
            }
            bool fCurrentlyOnline = (GetAdjustedTime() - addr.nTime < 24 * 60 * 60);
            int64 nUpdateInterval = (fCurrentlyOnline ? 60 * 60 : 24 * 60 * 60);
            if (addrFound.nTime < addr.nTime - nUpdateInterval)
            {
                // Periodically update most recently seen time
                addrFound.nTime = addr.nTime;
                fUpdated = true;
            }
            if (fUpdated)
                CAddrDB().WriteAddress(addrFound);
        }
    }
    return false;
}

void AddressCurrentlyConnected(const CAddress& addr)
{
    CRITICAL_BLOCK(cs_mapAddresses)
    {
        // Only if it's been published already
        map<vector<unsigned char>, CAddress>::iterator it = mapAddresses.find(addr.GetKey());
        if (it != mapAddresses.end())
        {
            CAddress& addrFound = (*it).second;
            int64 nUpdateInterval = 20 * 60;
            if (addrFound.nTime < GetAdjustedTime() - nUpdateInterval)
            {
                // Periodically update most recently seen time
                addrFound.nTime = GetAdjustedTime();
                CAddrDB addrdb;
                addrdb.WriteAddress(addrFound);
            }
        }
    }
}





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)
    {
        BOOST_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)
        BOOST_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)
            BOOST_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)
            BOOST_FOREACH(CNode* pnode, vNodes)
                if (pnode != this)
                    pnode->PushMessage("sub-cancel", nChannel);
    }
}









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

CNode* FindNode(CAddress addr)
{
    CRITICAL_BLOCK(cs_vNodes)
    {
        BOOST_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 lastseen=%.1fhrs lasttry=%.1fhrs\n",
        addrConnect.ToString().c_str(),
        (double)(addrConnect.nTime - GetAdjustedTime())/3600.0,
        (double)(addrConnect.nLastTry - GetAdjustedTime())/3600.0);

    CRITICAL_BLOCK(cs_mapAddresses)
        mapAddresses[addrConnect.GetKey()].nLastTry = GetAdjustedTime();

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

        // Set to nonblocking
#ifdef __WXMSW__
        u_long nOne = 1;
        if (ioctlsocket(hSocket, FIONBIO, &nOne) == SOCKET_ERROR)
            printf("ConnectSocket() : ioctlsocket nonblocking setting failed, error %d\n", WSAGetLastError());
#else
        if (fcntl(hSocket, F_SETFL, O_NONBLOCK) == SOCKET_ERROR)
            printf("ConnectSocket() : fcntl nonblocking setting failed, error %d\n", errno);
#endif

        // 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);

        pnode->nTimeConnected = GetTime();
        return pnode;
    }
    else
    {
        return NULL;
    }
}

void CNode::CloseSocketDisconnect()
{
    fDisconnect = true;
    if (hSocket != INVALID_SOCKET)
    {
        if (fDebug)
            printf("%s ", DateTimeStrFormat("%x %H:%M:%S", GetTime()).c_str());
        printf("disconnecting node %s\n", addr.ToString().c_str());
        closesocket(hSocket);
        hSocket = INVALID_SOCKET;
    }
}

void CNode::Cleanup()
{
    // 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.

    // 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));
    try
    {
        vnThreadsRunning[0]++;
        ThreadSocketHandler2(parg);
        vnThreadsRunning[0]--;
    }
    catch (std::exception& e) {
        vnThreadsRunning[0]--;
        PrintException(&e, "ThreadSocketHandler()");
    } catch (...) {
        vnThreadsRunning[0]--;
        throw; // support pthread_cancel()
    }
    printf("ThreadSocketHandler exiting\n");
}

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

    loop
    {
        //
        // Disconnect nodes
        //
        CRITICAL_BLOCK(cs_vNodes)
        {
            // Disconnect unused nodes
            vector<CNode*> vNodesCopy = vNodes;
            BOOST_FOREACH(CNode* pnode, vNodesCopy)
            {
                if (pnode->fDisconnect ||
                    (pnode->GetRefCount() <= 0 && pnode->vRecv.empty() && pnode->vSend.empty()))
                {
                    // remove from vNodes
                    vNodes.erase(remove(vNodes.begin(), vNodes.end(), pnode), vNodes.end());

                    // close socket and cleanup
                    pnode->CloseSocketDisconnect();
                    pnode->Cleanup();

                    // hold in disconnected pool until all refs are released
                    pnode->nReleaseTime = max(pnode->nReleaseTime, GetTime() + 15 * 60);
                    if (pnode->fNetworkNode || pnode->fInbound)
                        pnode->Release();
                    vNodesDisconnected.push_back(pnode);
                }
            }

            // Delete disconnected nodes
            list<CNode*> vNodesDisconnectedCopy = vNodesDisconnected;
            BOOST_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

        fd_set fdsetRecv;
        fd_set fdsetSend;
        fd_set fdsetError;
        FD_ZERO(&fdsetRecv);
        FD_ZERO(&fdsetSend);
        FD_ZERO(&fdsetError);
        SOCKET hSocketMax = 0;

        if(hListenSocket != INVALID_SOCKET)
            FD_SET(hListenSocket, &fdsetRecv);
        hSocketMax = max(hSocketMax, hListenSocket);
        CRITICAL_BLOCK(cs_vNodes)
        {
            BOOST_FOREACH(CNode* pnode, vNodes)
            {
                if (pnode->hSocket == INVALID_SOCKET || pnode->hSocket < 0)
                    continue;
                FD_SET(pnode->hSocket, &fdsetRecv);
                FD_SET(pnode->hSocket, &fdsetError);
                hSocketMax = max(hSocketMax, pnode->hSocket);
                TRY_CRITICAL_BLOCK(pnode->cs_vSend)
                    if (!pnode->vSend.empty())
                        FD_SET(pnode->hSocket, &fdsetSend);
            }
        }

        vnThreadsRunning[0]--;
        int nSelect = select(hSocketMax + 1, &fdsetRecv, &fdsetSend, &fdsetError, &timeout);
        vnThreadsRunning[0]++;
        if (fShutdown)
            return;
        if (nSelect == SOCKET_ERROR)
        {
            int nErr = WSAGetLastError();
            if (hSocketMax > -1)
            {
                printf("socket select error %d\n", nErr);
                for (int i = 0; i <= hSocketMax; i++)
                    FD_SET(i, &fdsetRecv);
            }
            FD_ZERO(&fdsetSend);
            FD_ZERO(&fdsetError);
            Sleep(timeout.tv_usec/1000);
        }


        //
        // Accept new connections
        //
        if (hListenSocket != INVALID_SOCKET && FD_ISSET(hListenSocket, &fdsetRecv))
        {
            struct sockaddr_in sockaddr;
            socklen_t len = sizeof(sockaddr);
            SOCKET hSocket = accept(hListenSocket, (struct sockaddr*)&sockaddr, &len);
            CAddress addr(sockaddr);
            int nInbound = 0;

            CRITICAL_BLOCK(cs_vNodes)
                BOOST_FOREACH(CNode* pnode, vNodes)
                if (pnode->fInbound)
                    nInbound++;
            if (hSocket == INVALID_SOCKET)
            {
                if (WSAGetLastError() != WSAEWOULDBLOCK)
                    printf("socket error accept failed: %d\n", WSAGetLastError());
            }
            else if (nInbound >= GetArg("-maxconnections", 125) - MAX_OUTBOUND_CONNECTIONS)
            {
                closesocket(hSocket);
            }
            else
            {
                printf("accepted connection %s\n", addr.ToString().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;
            BOOST_FOREACH(CNode* pnode, vNodesCopy)
                pnode->AddRef();
        }
        BOOST_FOREACH(CNode* pnode, vNodesCopy)
        {
            if (fShutdown)
                return;

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

                    if (nPos > ReceiveBufferSize()) {
                        if (!pnode->fDisconnect)
                            printf("socket recv flood control disconnect (%d bytes)\n", vRecv.size());
                        pnode->CloseSocketDisconnect();
                    }
                    else {
                        // typical socket buffer is 8K-64K
                        char pchBuf[0x10000];
                        int nBytes = recv(pnode->hSocket, pchBuf, sizeof(pchBuf), MSG_DONTWAIT);
                        if (nBytes > 0)
                        {
                            vRecv.resize(nPos + nBytes);
                            memcpy(&vRecv[nPos], pchBuf, nBytes);
                            pnode->nLastRecv = GetTime();
                        }
                        else if (nBytes == 0)
                        {
                            // socket closed gracefully
                            if (!pnode->fDisconnect)
                                printf("socket closed\n");
                            pnode->CloseSocketDisconnect();
                        }
                        else if (nBytes < 0)
                        {
                            // error
                            int nErr = WSAGetLastError();
                            if (nErr != WSAEWOULDBLOCK && nErr != WSAEMSGSIZE && nErr != WSAEINTR && nErr != WSAEINPROGRESS)
                            {
                                if (!pnode->fDisconnect)
                                    printf("socket recv error %d\n", nErr);
                                pnode->CloseSocketDisconnect();
                            }
                        }
                    }
                }
            }

            //
            // Send
            //
            if (pnode->hSocket == INVALID_SOCKET)
                continue;
            if (FD_ISSET(pnode->hSocket, &fdsetSend))
            {
                TRY_CRITICAL_BLOCK(pnode->cs_vSend)
                {
                    CDataStream& vSend = pnode->vSend;
                    if (!vSend.empty())
                    {
                        int nBytes = send(pnode->hSocket, &vSend[0], vSend.size(), MSG_NOSIGNAL | MSG_DONTWAIT);
                        if (nBytes > 0)
                        {
                            vSend.erase(vSend.begin(), vSend.begin() + nBytes);
                            pnode->nLastSend = GetTime();
                        }
                        else if (nBytes < 0)
                        {
                            // error
                            int nErr = WSAGetLastError();
                            if (nErr != WSAEWOULDBLOCK && nErr != WSAEMSGSIZE && nErr != WSAEINTR && nErr != WSAEINPROGRESS)
                            {
                                printf("socket send error %d\n", nErr);
                                pnode->CloseSocketDisconnect();
                            }
                        }
                        if (vSend.size() > SendBufferSize()) {
                            if (!pnode->fDisconnect)
                                printf("socket send flood control disconnect (%d bytes)\n", vSend.size());
                            pnode->CloseSocketDisconnect();
                        }
                    }
                }
            }

            //
            // Inactivity checking
            //
            if (pnode->vSend.empty())
                pnode->nLastSendEmpty = GetTime();
            if (GetTime() - pnode->nTimeConnected > 60)
            {
                if (pnode->nLastRecv == 0 || pnode->nLastSend == 0)
                {
                    printf("socket no message in first 60 seconds, %d %d\n", pnode->nLastRecv != 0, pnode->nLastSend != 0);
                    pnode->fDisconnect = true;
                }
                else if (GetTime() - pnode->nLastSend > 90*60 && GetTime() - pnode->nLastSendEmpty > 90*60)
                {
                    printf("socket not sending\n");
                    pnode->fDisconnect = true;
                }
                else if (GetTime() - pnode->nLastRecv > 90*60)
                {
                    printf("socket inactivity timeout\n");
                    pnode->fDisconnect = true;
                }
            }
        }
        CRITICAL_BLOCK(cs_vNodes)
        {
            BOOST_FOREACH(CNode* pnode, vNodesCopy)
                pnode->Release();
        }

        Sleep(10);
    }
}









#ifdef USE_UPNP
void ThreadMapPort(void* parg)
{
    IMPLEMENT_RANDOMIZE_STACK(ThreadMapPort(parg));
    try
    {
        vnThreadsRunning[5]++;
        ThreadMapPort2(parg);
        vnThreadsRunning[5]--;
    }
    catch (std::exception& e) {
        vnThreadsRunning[5]--;
        PrintException(&e, "ThreadMapPort()");
    } catch (...) {
        vnThreadsRunning[5]--;
        PrintException(NULL, "ThreadMapPort()");
    }
    printf("ThreadMapPort exiting\n");
}

void ThreadMapPort2(void* parg)
{
    printf("ThreadMapPort started\n");

    char port[6];
    sprintf(port, "%d", GetListenPort());

    const char * rootdescurl = 0;
    const char * multicastif = 0;
    const char * minissdpdpath = 0;
    struct UPNPDev * devlist = 0;
    char lanaddr[64];

    devlist = upnpDiscover(2000, multicastif, minissdpdpath, 0);

    struct UPNPUrls urls;
    struct IGDdatas data;
    int r;

    r = UPNP_GetValidIGD(devlist, &urls, &data, lanaddr, sizeof(lanaddr));
    if (r == 1)
    {
        char intClient[16];
        char intPort[6];

#ifndef __WXMSW__
        r = UPNP_AddPortMapping(urls.controlURL, data.first.servicetype,
	                        port, port, lanaddr, 0, "TCP", 0);
#else
        r = UPNP_AddPortMapping(urls.controlURL, data.first.servicetype,
	                        port, port, lanaddr, 0, "TCP", 0, "0");
#endif
        if(r!=UPNPCOMMAND_SUCCESS)
            printf("AddPortMapping(%s, %s, %s) failed with code %d (%s)\n",
                port, port, lanaddr, r, strupnperror(r));
        else
            printf("UPnP Port Mapping successful.\n");
        loop {
            if (fShutdown || !fUseUPnP)
            {
                r = UPNP_DeletePortMapping(urls.controlURL, data.first.servicetype, port, "TCP", 0);
                printf("UPNP_DeletePortMapping() returned : %d\n", r);
                freeUPNPDevlist(devlist); devlist = 0;
                FreeUPNPUrls(&urls);
                return;
            }
            Sleep(2000);
        }
    } else {
        printf("No valid UPnP IGDs found\n");
        freeUPNPDevlist(devlist); devlist = 0;
        if (r != 0)
            FreeUPNPUrls(&urls);
        loop {
            if (fShutdown || !fUseUPnP)
                return;
            Sleep(2000);
        }
    }
}

void MapPort(bool fMapPort)
{
    if (fUseUPnP != fMapPort)
    {
        fUseUPnP = fMapPort;
        WriteSetting("fUseUPnP", fUseUPnP);
    }
    if (fUseUPnP && vnThreadsRunning[5] < 1)
    {
        if (!CreateThread(ThreadMapPort, NULL))
            printf("Error: ThreadMapPort(ThreadMapPort) failed\n");
    }
}
#endif










static const char *strDNSSeed[] = {
    "bitseed.xf2.org",
    "bitseed.bitcoin.org.uk",
    "dnsseed.bluematt.me",
};

void DNSAddressSeed()
{
    int found = 0;

    if (!fTestNet)
    {
        printf("Loading addresses from DNS seeds (could take a while)\n");

        for (int seed_idx = 0; seed_idx < ARRAYLEN(strDNSSeed); seed_idx++) {
            vector<CAddress> vaddr;
            if (Lookup(strDNSSeed[seed_idx], vaddr, NODE_NETWORK, -1, true))
            {
                BOOST_FOREACH (CAddress& addr, vaddr)
                {
                    if (addr.GetByte(3) != 127)
                    {
                        addr.nTime = 0;
                        AddAddress(addr);
                        found++;
                    }
                }
            }
        }
    }

    printf("%d addresses found from DNS seeds\n", found);
}



unsigned int pnSeed[] =
{
    0x1ddb1032, 0x6242ce40, 0x52d6a445, 0x2dd7a445, 0x8a53cd47, 0x73263750, 0xda23c257, 0xecd4ed57,
    0x0a40ec59, 0x75dce160, 0x7df76791, 0x89370bad, 0xa4f214ad, 0x767700ae, 0x638b0418, 0x868a1018,
    0xcd9f332e, 0x0129653e, 0xcc92dc3e, 0x96671640, 0x56487e40, 0x5b66f440, 0xb1d01f41, 0xf1dc6041,
    0xc1d12b42, 0x86ba1243, 0x6be4df43, 0x6d4cef43, 0xd18e0644, 0x1ab0b344, 0x6584a345, 0xe7c1a445,
    0x58cea445, 0xc5daa445, 0x21dda445, 0x3d3b5346, 0x13e55347, 0x1080d24a, 0x8e611e4b, 0x81518e4b,
    0x6c839e4b, 0xe2ad0a4c, 0xfbbc0a4c, 0x7f5b6e4c, 0x7244224e, 0x1300554e, 0x20690652, 0x5a48b652,
    0x75c5c752, 0x4335cc54, 0x340fd154, 0x87c07455, 0x087b2b56, 0x8a133a57, 0xac23c257, 0x70374959,
    0xfb63d45b, 0xb9a1685c, 0x180d765c, 0x674f645d, 0x04d3495e, 0x1de44b5e, 0x4ee8a362, 0x0ded1b63,
    0xc1b04b6d, 0x8d921581, 0x97b7ea82, 0x1cf83a8e, 0x91490bad, 0x09dc75ae, 0x9a6d79ae, 0xa26d79ae,
    0x0fd08fae, 0x0f3e3fb2, 0x4f944fb2, 0xcca448b8, 0x3ecd6ab8, 0xa9d5a5bc, 0x8d0119c1, 0x045997d5,
    0xca019dd9, 0x0d526c4d, 0xabf1ba44, 0x66b1ab55, 0x1165f462, 0x3ed7cbad, 0xa38fae6e, 0x3bd2cbad,
    0xd36f0547, 0x20df7840, 0x7a337742, 0x549f8e4b, 0x9062365c, 0xd399f562, 0x2b5274a1, 0x8edfa153,
    0x3bffb347, 0x7074bf58, 0xb74fcbad, 0x5b5a795b, 0x02fa29ce, 0x5a6738d4, 0xe8a1d23e, 0xef98c445,
    0x4b0f494c, 0xa2bc1e56, 0x7694ad63, 0xa4a800c3, 0x05fda6cd, 0x9f22175e, 0x364a795b, 0x536285d5,
    0xac44c9d4, 0x0b06254d, 0x150c2fd4, 0x32a50dcc, 0xfd79ce48, 0xf15cfa53, 0x66c01e60, 0x6bc26661,
    0xc03b47ae, 0x4dda1b81, 0x3285a4c1, 0x883ca96d, 0x35d60a4c, 0xdae09744, 0x2e314d61, 0x84e247cf,
    0x6c814552, 0x3a1cc658, 0x98d8f382, 0xe584cb5b, 0x15e86057, 0x7b01504e, 0xd852dd48, 0x56382f56,
    0x0a5df454, 0xa0d18d18, 0x2e89b148, 0xa79c114c, 0xcbdcd054, 0x5523bc43, 0xa9832640, 0x8a066144,
    0x3894c3bc, 0xab76bf58, 0x6a018ac1, 0xfebf4f43, 0x2f26c658, 0x31102f4e, 0x85e929d5, 0x2a1c175e,
    0xfc6c2cd1, 0x27b04b6d, 0xdf024650, 0x161748b8, 0x28be6580, 0x57be6580, 0x1cee677a, 0xaa6bb742,
    0x9a53964b, 0x0a5a2d4d, 0x2434c658, 0x9a494f57, 0x1ebb0e48, 0xf610b85d, 0x077ecf44, 0x085128bc,
    0x5ba17a18, 0x27ca1b42, 0xf8a00b56, 0xfcd4c257, 0xcf2fc15e, 0xd897e052, 0x4cada04f, 0x2f35f6d5,
    0x382ce8c9, 0xe523984b, 0x3f946846, 0x60c8be43, 0x41da6257, 0xde0be142, 0xae8a544b, 0xeff0c254,
    0x1e0f795b, 0xaeb28890, 0xca16acd9, 0x1e47ddd8, 0x8c8c4829, 0xd27dc747, 0xd53b1663, 0x4096b163,
    0x9c8dd958, 0xcb12f860, 0x9e79305c, 0x40c1a445, 0x4a90c2bc, 0x2c3a464d, 0x2727f23c, 0x30b04b6d,
    0x59024cb8, 0xa091e6ad, 0x31b04b6d, 0xc29d46a6, 0x63934fb2, 0xd9224dbe, 0x9f5910d8, 0x7f530a6b,
    0x752e9c95, 0x65453548, 0xa484be46, 0xce5a1b59, 0x710e0718, 0x46a13d18, 0xdaaf5318, 0xc4a8ff53,
    0x87abaa52, 0xb764cf51, 0xb2025d4a, 0x6d351e41, 0xc035c33e, 0xa432c162, 0x61ef34ae, 0xd16fddbc,
    0x0870e8c1, 0x3070e8c1, 0x9c71e8c1, 0xa4992363, 0x85a1f663, 0x4184e559, 0x18d96ed8, 0x17b8dbd5,
    0x60e7cd18, 0xe5ee104c, 0xab17ac62, 0x1e786e1b, 0x5d23b762, 0xf2388fae, 0x88270360, 0x9e5b3d80,
    0x7da518b2, 0xb5613b45, 0x1ad41f3e, 0xd550854a, 0x8617e9a9, 0x925b229c, 0xf2e92542, 0x47af0544,
    0x73b5a843, 0xb9b7a0ad, 0x03a748d0, 0x0a6ff862, 0x6694df62, 0x3bfac948, 0x8e098f4f, 0x746916c3,
    0x02f38e4f, 0x40bb1243, 0x6a54d162, 0x6008414b, 0xa513794c, 0x514aa343, 0x63781747, 0xdbb6795b,
    0xed065058, 0x42d24b46, 0x1518794c, 0x9b271681, 0x73e4ffad, 0x0654784f, 0x438dc945, 0x641846a6,
    0x2d1b0944, 0x94b59148, 0x8d369558, 0xa5a97662, 0x8b705b42, 0xce9204ae, 0x8d584450, 0x2df61555,
    0xeebff943, 0x2e75fb4d, 0x3ef8fc57, 0x9921135e, 0x8e31042e, 0xb5afad43, 0x89ecedd1, 0x9cfcc047,
    0x8fcd0f4c, 0xbe49f5ad, 0x146a8d45, 0x98669ab8, 0x98d9175e, 0xd1a8e46d, 0x839a3ab8, 0x40a0016c,
    0x6d27c257, 0x977fffad, 0x7baa5d5d, 0x1213be43, 0xb167e5a9, 0x640fe8ca, 0xbc9ea655, 0x0f820a4c,
    0x0f097059, 0x69ac957c, 0x366d8453, 0xb1ba2844, 0x8857f081, 0x70b5be63, 0xc545454b, 0xaf36ded1,
    0xb5a4b052, 0x21f062d1, 0x72ab89b2, 0x74a45318, 0x8312e6bc, 0xb916965f, 0x8aa7c858, 0xfe7effad,
};



void ThreadOpenConnections(void* parg)
{
    IMPLEMENT_RANDOMIZE_STACK(ThreadOpenConnections(parg));
    try
    {
        vnThreadsRunning[1]++;
        ThreadOpenConnections2(parg);
        vnThreadsRunning[1]--;
    }
    catch (std::exception& e) {
        vnThreadsRunning[1]--;
        PrintException(&e, "ThreadOpenConnections()");
    } catch (...) {
        vnThreadsRunning[1]--;
        PrintException(NULL, "ThreadOpenConnections()");
    }
    printf("ThreadOpenConnections exiting\n");
}

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

    // Connect to specific addresses
    if (mapArgs.count("-connect"))
    {
        for (int64 nLoop = 0;; nLoop++)
        {
            BOOST_FOREACH(string strAddr, mapMultiArgs["-connect"])
            {
                CAddress addr(strAddr, fAllowDNS);
                if (addr.IsValid())
                    OpenNetworkConnection(addr);
                for (int i = 0; i < 10 && i < nLoop; i++)
                {
                    Sleep(500);
                    if (fShutdown)
                        return;
                }
            }
        }
    }

    // Connect to manually added nodes first
    if (mapArgs.count("-addnode"))
    {
        BOOST_FOREACH(string strAddr, mapMultiArgs["-addnode"])
        {
            CAddress addr(strAddr, fAllowDNS);
            if (addr.IsValid())
            {
                OpenNetworkConnection(addr);
                Sleep(500);
                if (fShutdown)
                    return;
            }
        }
    }

    // Initiate network connections
    int64 nStart = GetTime();
    loop
    {
        // Limit outbound connections
        vnThreadsRunning[1]--;
        Sleep(500);
        loop
        {
            int nOutbound = 0;
            CRITICAL_BLOCK(cs_vNodes)
                BOOST_FOREACH(CNode* pnode, vNodes)
                    if (!pnode->fInbound)
                        nOutbound++;
            int nMaxOutboundConnections = MAX_OUTBOUND_CONNECTIONS;
            nMaxOutboundConnections = min(nMaxOutboundConnections, (int)GetArg("-maxconnections", 125));
            if (nOutbound < nMaxOutboundConnections)
                break;
            Sleep(2000);
            if (fShutdown)
                return;
        }
        vnThreadsRunning[1]++;
        if (fShutdown)
            return;

        CRITICAL_BLOCK(cs_mapAddresses)
        {
            // Add seed nodes if IRC isn't working
            static bool fSeedUsed;
            bool fTOR = (fUseProxy && addrProxy.port == htons(9050));
            if (mapAddresses.empty() && (GetTime() - nStart > 60 || fTOR) && !fTestNet)
            {
                for (int i = 0; i < ARRAYLEN(pnSeed); i++)
                {
                    // It'll only connect to one or two seed nodes because once it connects,
                    // it'll get a pile of addresses with newer timestamps.
                    CAddress addr;
                    addr.ip = pnSeed[i];
                    addr.nTime = 0;
                    AddAddress(addr);
                }
                fSeedUsed = true;
            }

            if (fSeedUsed && mapAddresses.size() > ARRAYLEN(pnSeed) + 100)
            {
                // Disconnect seed nodes
                set<unsigned int> setSeed(pnSeed, pnSeed + ARRAYLEN(pnSeed));
                static int64 nSeedDisconnected;
                if (nSeedDisconnected == 0)
                {
                    nSeedDisconnected = GetTime();
                    CRITICAL_BLOCK(cs_vNodes)
                        BOOST_FOREACH(CNode* pnode, vNodes)
                            if (setSeed.count(pnode->addr.ip))
                                pnode->fDisconnect = true;
                }

                // Keep setting timestamps to 0 so they won't reconnect
                if (GetTime() - nSeedDisconnected < 60 * 60)
                {
                    BOOST_FOREACH(PAIRTYPE(const vector<unsigned char>, CAddress)& item, mapAddresses)
                    {
                        if (setSeed.count(item.second.ip) && item.second.nTime != 0)
                        {
                            item.second.nTime = 0;
                            CAddrDB().WriteAddress(item.second);
                        }
                    }
                }
            }
        }


        //
        // Choose an address to connect to based on most recently seen
        //
        CAddress addrConnect;
        int64 nBest = INT64_MIN;

        // Only connect to one address per a.b.?.? range.
        // Do this here so we don't have to critsect vNodes inside mapAddresses critsect.
        set<unsigned int> setConnected;
        CRITICAL_BLOCK(cs_vNodes)
            BOOST_FOREACH(CNode* pnode, vNodes)
                setConnected.insert(pnode->addr.ip & 0x0000ffff);

        CRITICAL_BLOCK(cs_mapAddresses)
        {
            BOOST_FOREACH(const PAIRTYPE(vector<unsigned char>, CAddress)& item, mapAddresses)
            {
                const CAddress& addr = item.second;
                if (!addr.IsIPv4() || !addr.IsValid() || setConnected.count(addr.ip & 0x0000ffff))
                    continue;
                int64 nSinceLastSeen = GetAdjustedTime() - addr.nTime;
                int64 nSinceLastTry = GetAdjustedTime() - addr.nLastTry;

                // Randomize the order in a deterministic way, putting the standard port first
                int64 nRandomizer = (uint64)(nStart * 4951 + addr.nLastTry * 9567851 + addr.ip * 7789) % (2 * 60 * 60);
                if (addr.port != htons(GetDefaultPort()))
                    nRandomizer += 2 * 60 * 60;

                // Last seen  Base retry frequency
                //   <1 hour   10 min
                //    1 hour    1 hour
                //    4 hours   2 hours
                //   24 hours   5 hours
                //   48 hours   7 hours
                //    7 days   13 hours
                //   30 days   27 hours
                //   90 days   46 hours
                //  365 days   93 hours
                int64 nDelay = (int64)(3600.0 * sqrt(fabs((double)nSinceLastSeen) / 3600.0) + nRandomizer);

                // Fast reconnect for one hour after last seen
                if (nSinceLastSeen < 60 * 60)
                    nDelay = 10 * 60;

                // Limit retry frequency
                if (nSinceLastTry < nDelay)
                    continue;

                // If we have IRC, we'll be notified when they first come online,
                // and again every 24 hours by the refresh broadcast.
                if (nGotIRCAddresses > 0 && vNodes.size() >= 2 && nSinceLastSeen > 24 * 60 * 60)
                    continue;

                // Only try the old stuff if we don't have enough connections
                if (vNodes.size() >= 8 && nSinceLastSeen > 24 * 60 * 60)
                    continue;

                // If multiple addresses are ready, prioritize by time since
                // last seen and time since last tried.
                int64 nScore = min(nSinceLastTry, (int64)24 * 60 * 60) - nSinceLastSeen - nRandomizer;
                if (nScore > nBest)
                {
                    nBest = nScore;
                    addrConnect = addr;
                }
            }
        }

        if (addrConnect.IsValid())
            OpenNetworkConnection(addrConnect);
    }
}

bool OpenNetworkConnection(const CAddress& addrConnect)
{
    //
    // Initiate outbound network connection
    //
    if (fShutdown)
        return false;
    if (addrConnect.ip == addrLocalHost.ip || !addrConnect.IsIPv4() || FindNode(addrConnect.ip))
        return false;

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

    return true;
}








void ThreadMessageHandler(void* parg)
{
    IMPLEMENT_RANDOMIZE_STACK(ThreadMessageHandler(parg));
    try
    {
        vnThreadsRunning[2]++;
        ThreadMessageHandler2(parg);
        vnThreadsRunning[2]--;
    }
    catch (std::exception& e) {
        vnThreadsRunning[2]--;
        PrintException(&e, "ThreadMessageHandler()");
    } catch (...) {
        vnThreadsRunning[2]--;
        PrintException(NULL, "ThreadMessageHandler()");
    }
    printf("ThreadMessageHandler exiting\n");
}

void ThreadMessageHandler2(void* parg)
{
    printf("ThreadMessageHandler started\n");
    SetThreadPriority(THREAD_PRIORITY_BELOW_NORMAL);
    while (!fShutdown)
    {
        vector<CNode*> vNodesCopy;
        CRITICAL_BLOCK(cs_vNodes)
        {
            vNodesCopy = vNodes;
            BOOST_FOREACH(CNode* pnode, vNodesCopy)
                pnode->AddRef();
        }

        // Poll the connected nodes for messages
        CNode* pnodeTrickle = NULL;
        if (!vNodesCopy.empty())
            pnodeTrickle = vNodesCopy[GetRand(vNodesCopy.size())];
        BOOST_FOREACH(CNode* pnode, vNodesCopy)
        {
            // Receive messages
            TRY_CRITICAL_BLOCK(pnode->cs_vRecv)
                ProcessMessages(pnode);
            if (fShutdown)
                return;

            // Send messages
            TRY_CRITICAL_BLOCK(pnode->cs_vSend)
                SendMessages(pnode, pnode == pnodeTrickle);
            if (fShutdown)
                return;
        }

        CRITICAL_BLOCK(cs_vNodes)
        {
            BOOST_FOREACH(CNode* pnode, vNodesCopy)
                pnode->Release();
        }

        // Wait and allow messages to bunch up.
        // Reduce vnThreadsRunning so StopNode has permission to exit while
        // we're sleeping, but we must always check fShutdown after doing this.
        vnThreadsRunning[2]--;
        Sleep(100);
        if (fRequestShutdown)
            Shutdown(NULL);
        vnThreadsRunning[2]++;
        if (fShutdown)
            return;
    }
}






bool BindListenPort(string& strError)
{
    strError = "";
    int nOne = 1;
    addrLocalHost.port = htons(GetListenPort());

#ifdef __WXMSW__
    // Initialize Windows Sockets
    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;
    }
#endif

    // Create socket for listening for incoming connections
    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;
    }

#ifdef BSD
    // Different way of disabling SIGPIPE on BSD
    setsockopt(hListenSocket, SOL_SOCKET, SO_NOSIGPIPE, (void*)&nOne, sizeof(int));
#endif

#ifndef __WXMSW__
    // Allow binding if the port is still in TIME_WAIT state after
    // the program was closed and restarted.  Not an issue on windows.
    setsockopt(hListenSocket, SOL_SOCKET, SO_REUSEADDR, (void*)&nOne, sizeof(int));
#endif

#ifdef __WXMSW__
    // Set to nonblocking, incoming connections will also inherit this
    if (ioctlsocket(hListenSocket, FIONBIO, (u_long*)&nOne) == SOCKET_ERROR)
#else
    if (fcntl(hListenSocket, F_SETFL, O_NONBLOCK) == SOCKET_ERROR)
#endif
    {
        strError = strprintf("Error: Couldn't set properties on socket for incoming connections (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
    struct sockaddr_in sockaddr;
    memset(&sockaddr, 0, sizeof(sockaddr));
    sockaddr.sin_family = AF_INET;
    sockaddr.sin_addr.s_addr = INADDR_ANY; // bind to all IPs on this computer
    sockaddr.sin_port = htons(GetListenPort());
    if (::bind(hListenSocket, (struct sockaddr*)&sockaddr, sizeof(sockaddr)) == SOCKET_ERROR)
    {
        int nErr = WSAGetLastError();
        if (nErr == WSAEADDRINUSE)
            strError = strprintf(_("Unable to bind to port %d on this computer.  Bitcoin is probably already running."), ntohs(sockaddr.sin_port));
        else
            strError = strprintf("Error: Unable to bind to port %d on this computer (bind returned error %d)", ntohs(sockaddr.sin_port), nErr);
        printf("%s\n", strError.c_str());
        return false;
    }
    printf("Bound to port %d\n", ntohs(sockaddr.sin_port));

    // 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;
    }

    return true;
}

void StartNode(void* parg)
{
    if (pnodeLocalHost == NULL)
        pnodeLocalHost = new CNode(INVALID_SOCKET, CAddress("127.0.0.1", 0, false, nLocalServices));

#ifdef __WXMSW__
    // Get local host ip
    char pszHostName[1000] = "";
    if (gethostname(pszHostName, sizeof(pszHostName)) != SOCKET_ERROR)
    {
        vector<CAddress> vaddr;
        if (Lookup(pszHostName, vaddr, nLocalServices, -1, true))
            BOOST_FOREACH (const CAddress &addr, vaddr)
                if (addr.GetByte(3) != 127)
                {
                    addrLocalHost = addr;
                    break;
                }
    }
#else
    // Get local host ip
    struct ifaddrs* myaddrs;
    if (getifaddrs(&myaddrs) == 0)
    {
        for (struct ifaddrs* ifa = myaddrs; ifa != NULL; ifa = ifa->ifa_next)
        {
            if (ifa->ifa_addr == NULL) continue;
            if ((ifa->ifa_flags & IFF_UP) == 0) continue;
            if (strcmp(ifa->ifa_name, "lo") == 0) continue;
            if (strcmp(ifa->ifa_name, "lo0") == 0) continue;
            char pszIP[100];
            if (ifa->ifa_addr->sa_family == AF_INET)
            {
                struct sockaddr_in* s4 = (struct sockaddr_in*)(ifa->ifa_addr);
                if (inet_ntop(ifa->ifa_addr->sa_family, (void*)&(s4->sin_addr), pszIP, sizeof(pszIP)) != NULL)
                    printf("ipv4 %s: %s\n", ifa->ifa_name, pszIP);

                // Take the first IP that isn't loopback 127.x.x.x
                CAddress addr(*(unsigned int*)&s4->sin_addr, GetListenPort(), nLocalServices);
                if (addr.IsValid() && addr.GetByte(3) != 127)
                {
                    addrLocalHost = addr;
                    break;
                }
            }
            else if (ifa->ifa_addr->sa_family == AF_INET6)
            {
                struct sockaddr_in6* s6 = (struct sockaddr_in6*)(ifa->ifa_addr);
                if (inet_ntop(ifa->ifa_addr->sa_family, (void*)&(s6->sin6_addr), pszIP, sizeof(pszIP)) != NULL)
                    printf("ipv6 %s: %s\n", ifa->ifa_name, pszIP);
            }
        }
        freeifaddrs(myaddrs);
    }
#endif
    printf("addrLocalHost = %s\n", addrLocalHost.ToString().c_str());

    if (fUseProxy || mapArgs.count("-connect") || fNoListen)
    {
        // Proxies can't take incoming connections
        addrLocalHost.ip = CAddress("0.0.0.0").ip;
        printf("addrLocalHost = %s\n", addrLocalHost.ToString().c_str());
    }
    else
    {
        CreateThread(ThreadGetMyExternalIP, NULL);
    }

    //
    // Start threads
    //

    // Map ports with UPnP
    if (fHaveUPnP)
        MapPort(fUseUPnP);

    // Get addresses from IRC and advertise ours
    if (!CreateThread(ThreadIRCSeed, NULL))
        printf("Error: CreateThread(ThreadIRCSeed) failed\n");

    // Send and receive from sockets, accept connections
    pthread_t hThreadSocketHandler = CreateThread(ThreadSocketHandler, NULL, true);

    // Initiate outbound connections
    if (!CreateThread(ThreadOpenConnections, NULL))
        printf("Error: CreateThread(ThreadOpenConnections) failed\n");

    // Process messages
    if (!CreateThread(ThreadMessageHandler, NULL))
        printf("Error: CreateThread(ThreadMessageHandler) failed\n");

    // Generate coins in the background
    GenerateBitcoins(fGenerateBitcoins, pwalletMain);
}

bool StopNode()
{
    printf("StopNode()\n");
    fShutdown = true;
    nTransactionsUpdated++;
    int64 nStart = GetTime();
    while (vnThreadsRunning[0] > 0 || vnThreadsRunning[2] > 0 || vnThreadsRunning[3] > 0 || vnThreadsRunning[4] > 0
#ifdef USE_UPNP
        || vnThreadsRunning[5] > 0
#endif
    )
    {
        if (GetTime() - nStart > 20)
            break;
        Sleep(20);
    }
    if (vnThreadsRunning[0] > 0) printf("ThreadSocketHandler still running\n");
    if (vnThreadsRunning[1] > 0) printf("ThreadOpenConnections still running\n");
    if (vnThreadsRunning[2] > 0) printf("ThreadMessageHandler still running\n");
    if (vnThreadsRunning[3] > 0) printf("ThreadBitcoinMiner still running\n");
    if (vnThreadsRunning[4] > 0) printf("ThreadRPCServer still running\n");
    if (fHaveUPnP && vnThreadsRunning[5] > 0) printf("ThreadMapPort still running\n");
    while (vnThreadsRunning[2] > 0 || vnThreadsRunning[4] > 0)
        Sleep(20);
    Sleep(50);

    return true;
}

class CNetCleanup
{
public:
    CNetCleanup()
    {
    }
    ~CNetCleanup()
    {
        // Close sockets
        BOOST_FOREACH(CNode* pnode, vNodes)
            if (pnode->hSocket != INVALID_SOCKET)
                closesocket(pnode->hSocket);
        if (hListenSocket != INVALID_SOCKET)
            if (closesocket(hListenSocket) == SOCKET_ERROR)
                printf("closesocket(hListenSocket) failed with error %d\n", WSAGetLastError());

#ifdef __WXMSW__
        // Shutdown Windows Sockets
        WSACleanup();
#endif
    }
}
instance_of_cnetcleanup;