dhtproxy: tunnel DHT traffic into TCP connections

Makefile.am

@@ -156,6 +156,7 @@ BITCOIN_TWISTER_SOURCES = \
     src/leveldb.cpp \
     src/txdb.cpp \
     src/chainparams.cpp \
+    src/dhtproxy.cpp \
     src/twister.cpp \
     src/twister_rss.cpp \
     src/twister_utils.cpp \

src/dhtproxy.cpp

@@ -0,0 +1,330 @@
+// Copyright (c) 2014 Miguel Freitas
+// tunnel DHT requests into tcp connection
+// see: https://groups.google.com/forum/#!topic/twister-dev/uKjFGSw24yA
+
+#include <boost/assign/list_of.hpp> // for 'map_list_of()'
+#include <boost/assign.hpp>
+#include <boost/foreach.hpp>
+#include <algorithm>    // std::random_shuffle
+
+#include "dhtproxy.h"
+
+#include "libtorrent/alert_manager.hpp"
+#include "libtorrent/alert_types.hpp"
+#include "libtorrent/peer_id.hpp"
+#include "libtorrent/bencode.hpp"
+
+#include "main.h"
+#include "uint256.h"
+#include "script.h"
+#include "init.h"
+#include "twister.h"
+#include "twister_utils.h"
+
+//#define dbgprintf OutputDebugStringF
+#define dbgprintf(...) // no debug printf
+
+using namespace libtorrent;
+
+namespace DhtProxy
+{
+    bool fEnabled = true;
+    CCriticalSection cs_dhtProxy;
+    map<sha1_hash, std::list<alert_manager*> > m_dhtgetMap;
+    map<sha1_hash, std::list<CService> > m_dhtgetPeersReq;
+
+    class PeerBanStats {
+      public:
+        PeerBanStats() : active(0), count(0), limit(time_now()) {}
+        int active;
+        int count;
+        ptime limit;
+    };
+    map<CService, PeerBanStats> m_peerBanStats;
+    size_t numProxiesToUse = 4;
+    
+    void dhtgetMapAdd(sha1_hash &ih, alert_manager *am)
+    {
+        LOCK(cs_dhtProxy);
+        m_dhtgetMap[ih].push_back(am);
+    }
+    
+    void dhtgetMapRemove(sha1_hash &ih, alert_manager *am)
+    {
+        LOCK(cs_dhtProxy);
+        std::map<sha1_hash, std::list<alert_manager*> >::iterator mi = m_dhtgetMap.find(ih);
+        if( mi != m_dhtgetMap.end() ) {
+            std::list<alert_manager *> &amList = (*mi).second;
+            amList.remove(am);
+            if( !amList.size() ) {
+                m_dhtgetMap.erase(ih);
+            }
+        }
+    }
+    
+    void dhtgetMapPost(sha1_hash &ih, const alert &a)
+    {
+        LOCK(cs_dhtProxy);
+        std::map<sha1_hash, std::list<alert_manager*> >::iterator mi = m_dhtgetMap.find(ih);
+        if( mi != m_dhtgetMap.end() ) {
+            std::list<alert_manager *> &amList = (*mi).second;
+            BOOST_FOREACH(alert_manager *am, amList) {
+                am->post_alert(a);
+            }
+        }
+    }
+    
+    vector<CNode*> getRandomDhtProxies()
+    {
+        // (cs_vNodes) lock must be held!
+        vector<CNode*> vNodesProxy;
+        BOOST_FOREACH(CNode* pnode, vNodes) {
+            if (pnode->nVersion >= DHT_PROXY_VERSION && !pnode->fNoDhtProxy) {
+                vNodesProxy.push_back(pnode);
+            }
+        }
+        std::random_shuffle(vNodesProxy.begin(),vNodesProxy.end());
+        if(vNodesProxy.size() > numProxiesToUse) {
+            vNodesProxy.resize(numProxiesToUse);
+        }
+        
+        return vNodesProxy;
+    }
+
+    vector<CNode*> dhtgetStartRequest(std::string const &username, std::string const &resource, bool multi)
+    {
+        CDHTGetRequest req;
+        req.vchUsername = std::vector<char>(username.begin(), username.end());
+        req.vchResource = std::vector<char>(resource.begin(), resource.end());
+        req.resTypeMulti = multi;
+        req.stopReq = false;
+    
+        LOCK(cs_vNodes);
+        vector<CNode*> vNodesReq = getRandomDhtProxies();
+        BOOST_FOREACH(CNode* pnode, vNodesReq) {
+            dbgprintf("DhtProxy::dhtgetStartRequest: pushMessage to %s\n", pnode->addr.ToString().c_str());
+            pnode->PushMessage("dhtgetreq", req);
+            pnode->AddRef();
+        }
+        if( !vNodesReq.size() ) {
+            dbgprintf("DhtProxy::dhtgetStartRequest: sorry, no dht proxy found.\n");
+            
+            // fake no data to wakeup listener
+            dht_reply_data_done_alert dd("","",false,false,false);
+            sha1_hash ih = dhtTargetHash(username, resource, multi ? "m" : "s");
+            dhtgetMapPost(ih, dd);
+        }
+        return vNodesReq;
+    }
+
+    void dhtgetStopRequest(vector<CNode*> vNodesReq, std::string const &username, std::string const &resource, bool multi)
+    {   
+        CDHTGetRequest req;
+        req.vchUsername = std::vector<char>(username.begin(), username.end());
+        req.vchResource = std::vector<char>(resource.begin(), resource.end());
+        req.resTypeMulti = multi;
+        req.stopReq = true;
+        
+        BOOST_FOREACH(CNode* pnode, vNodesReq) {
+            dbgprintf("DhtProxy::dhtgetStopRequest: pushMessage to %s\n", pnode->addr.ToString().c_str());
+            pnode->PushMessage("dhtgetreq", req);
+            pnode->Release();
+        }
+    }
+    
+    void dhtgetPeerReqAdd(sha1_hash &ih, const CNode *pnode)
+    {
+        LOCK(cs_dhtProxy);
+        m_dhtgetPeersReq[ih].push_back(pnode->addr);
+        m_peerBanStats[pnode->addr].active++;
+    }
+    
+    void dhtgetPeerReqRemove(sha1_hash &ih, const CNode *pnode)
+    {
+        LOCK(cs_dhtProxy);
+        std::map<sha1_hash, std::list<CService> >::iterator mi = m_dhtgetPeersReq.find(ih);
+        if( mi != m_dhtgetPeersReq.end() ) {
+            std::list<CService> &addrList = (*mi).second;
+            addrList.remove(pnode->addr);
+            if( !addrList.size() ) {
+                m_dhtgetPeersReq.erase(ih);
+            }
+            m_peerBanStats[pnode->addr].active--;
+        }
+    }
+    
+    void dhtgetPeerReqReply(sha1_hash &ih, const alert *a)
+    {
+        CDHTGetReply reply;
+        reply.vchTargetHash = std::vector<char>(ih.begin(), ih.end());
+        dht_reply_data_alert const* rd = alert_cast<dht_reply_data_alert>(a);
+        if (rd) {
+            bencode(std::back_inserter(reply.vchBencodedData), rd->m_lst);
+        }
+    
+        LOCK(cs_dhtProxy);
+        std::map<sha1_hash, std::list<CService> >::iterator mi = m_dhtgetPeersReq.find(ih);
+        if( mi != m_dhtgetPeersReq.end() ) {
+            std::list<CService> &addrList = (*mi).second;
+            BOOST_FOREACH(CService &addr, addrList) {
+                LOCK(cs_vNodes);
+                BOOST_FOREACH(CNode* pnode, vNodes) {
+                    if ((CService)pnode->addr == addr) {
+                        dbgprintf("DhtProxy::dhtgetPeerReqReply: pushMessage to %s\n", pnode->addr.ToString().c_str());
+                        pnode->PushMessage("dhtgetreply", reply);
+                    }
+                }
+            }
+        }
+    }
+    
+    bool checkForAbuse(CNode* pfrom)
+    {
+        LOCK(cs_dhtProxy);
+
+        // logic inspired/copied from dht_tracker.cpp:incoming_packet
+        ptime now = time_now();
+        PeerBanStats *match = &m_peerBanStats[pfrom->addr];
+        match->count++;
+        if( match->count >= 500 ) {
+            if (now < match->limit) {
+                if( match->count == 500 ) {
+                    dbgprintf("DhtProxy::checkForAbuse: %s misbehaving, too much requests.\n", 
+                               pfrom->addr.ToString().c_str());
+                }
+                match->limit = now + minutes(5);
+                return true;
+            }
+            match->count = 0;
+            match->limit = now + seconds(5);
+        }
+        if( match->active > 10 ) {
+            dbgprintf("DhtProxy::checkForAbuse: %s misbehaving, max active requests reached.\n", 
+                       pfrom->addr.ToString().c_str());
+            return true;
+        }
+        return false;
+    }
+
+    bool dhtgetRequestReceived(const CDHTGetRequest& req, CNode* pfrom)
+    {
+        if( fEnabled ) {
+            // we are using proxy ourselves, we can't be proxy to anyone else
+            pfrom->PushMessage("nodhtproxy");
+            return true;
+        } else if( !req.stopReq && checkForAbuse(pfrom) ) {
+            return false;
+        } else {
+            std::string username(req.vchUsername.data(), req.vchUsername.size());
+            std::string resource(req.vchResource.data(), req.vchResource.size());
+            bool           multi(req.resTypeMulti);
+            
+            dbgprintf("DhtProxy::dhtgetRequestReceived: (%s,%s,%d,stop=%d) from %s\n", 
+                      username.c_str(), resource.c_str(), multi, req.stopReq,
+                      pfrom->addr.ToString().c_str());
+            
+            sha1_hash ih = dhtTargetHash(username, resource, multi ? "m" : "s");
+            if( !req.stopReq ) {
+                dhtgetPeerReqAdd(ih, pfrom);
+                dhtGetData(username, resource, multi);
+            } else {
+                dhtgetPeerReqRemove(ih, pfrom);
+            }
+            return true;
+        }
+    }
+    
+    bool dhtgetReplyReceived(const CDHTGetReply& reply, CNode* pfrom)
+    {
+        std::string strTargetHash(reply.vchTargetHash.data(), reply.vchTargetHash.size());
+        sha1_hash ih(strTargetHash);
+        
+        if( !reply.vchBencodedData.size() ) {
+            dbgprintf("DhtProxy::dhtgetReplyReceived: empty data from %s\n", 
+                      pfrom->addr.ToString().c_str());
+                  
+            // No reply - these fields are not used, we just want cast in twister.cpp:dhtget to fail
+            dht_reply_data_done_alert dd("","",false,false,false);
+            dhtgetMapPost(ih, dd);
+        } else {
+            lazy_entry v;
+            int pos;
+            libtorrent::error_code ec;
+            if (lazy_bdecode(reply.vchBencodedData.data(), reply.vchBencodedData.data() + 
+                             reply.vchBencodedData.size(), v, ec, &pos) == 0 && v.type() == lazy_entry::list_t ) {
+                entry lst;
+                lst = v;
+                dbgprintf("DhtProxy::dhtgetReplyReceived: %zd entries from %s\n", 
+                           lst.list().size(), pfrom->addr.ToString().c_str());
+                dht_reply_data_alert rd(lst.list());
+                dhtgetMapPost(ih, rd);
+            } else {
+                dbgprintf("DhtProxy::dhtgetReplyReceived: parsing error (data from %s)\n", 
+                           pfrom->addr.ToString().c_str());
+                return false;
+            }
+        }
+        return true;
+    }
+
+
+    void dhtputRequest(std::string const &username, std::string const &resource, bool multi,
+                       std::string const &str_p, std::string const &sig_p, std::string const &sig_user)
+    {
+        CDHTPutRequest req;
+        req.vchUsername = std::vector<char>(username.begin(), username.end());
+        req.vchResource = std::vector<char>(resource.begin(), resource.end());
+        req.resTypeMulti = multi;
+        req.vchStr_p    = std::vector<char>(str_p.begin(), str_p.end());
+        req.vchSig_p    = std::vector<char>(sig_p.begin(), sig_p.end());
+        req.vchSig_user = std::vector<char>(sig_user.begin(), sig_user.end());
+    
+        LOCK(cs_vNodes);
+        vector<CNode*> vNodesReq = getRandomDhtProxies();
+        BOOST_FOREACH(CNode* pnode, vNodesReq) {
+            dbgprintf("DhtProxy::dhtputRequest: pushMessage to %s\n", pnode->addr.ToString().c_str());
+            pnode->PushMessage("dhtputreq", req);
+        }
+        if( !vNodesReq.size() ) {
+            dbgprintf("DhtProxy::dhtputRequest: sorry, no dht proxy found.\n");
+        }
+    }
+
+    bool dhtputRequestReceived(const CDHTPutRequest& req, CNode* pfrom)
+    {
+        if( fEnabled ) {
+            // we are using proxy ourselves, we can't be proxy to anyone else
+            pfrom->PushMessage("nodhtproxy");
+            return true;
+        } else if( checkForAbuse(pfrom) ) {
+            return false;
+        } else {
+            std::string username(req.vchUsername.data(), req.vchUsername.size());
+            std::string resource(req.vchResource.data(), req.vchResource.size());
+            bool           multi(req.resTypeMulti);
+            
+            dbgprintf("DhtProxy::dhtputRequestReceived: (%s,%s,%d) from %s\n", 
+                      username.c_str(), resource.c_str(), multi,
+                      pfrom->addr.ToString().c_str());
+
+            lazy_entry v;
+            int pos;
+            libtorrent::error_code ec;
+            if (lazy_bdecode(req.vchStr_p.data(), req.vchStr_p.data() + 
+                             req.vchStr_p.size(), v, ec, &pos) == 0 ) {
+                entry p;
+                p = v;
+                std::string sig_p(req.vchSig_p.data(), req.vchSig_p.size());
+                std::string sig_user(req.vchSig_user.data(), req.vchSig_user.size());
+
+                dhtPutDataSigned(username,resource,multi,p,sig_p,sig_user, false);
+            } else {
+                dbgprintf("DhtProxy::dhtputRequestReceived: parsing error (data from %s)\n", 
+                           pfrom->addr.ToString().c_str());
+                return false;
+            }
+            return true;
+        }
+    }
+
+}

src/dhtproxy.h

@@ -0,0 +1,195 @@
+// Copyright (c) 2014 Miguel Freitas
+
+#ifndef DHTPROXY_H
+#define DHTPROXY_H
+
+#include "serialize.h"
+#include "net.h"
+#include "uint256.h"
+
+#include <vector>
+
+// just a small set of declarations to avoid main.c depending on libtorrent headers
+namespace libtorrent {
+    class alert_manager;
+    class big_number;
+    typedef big_number sha1_hash;
+    class alert;
+}
+
+class CDHTTarget;
+class CDHTGetRequest;
+class CDHTGetReply;
+class CDHTPutRequest;
+
+/** 
+ *   DHTGet Sequence:
+ *
+ *            Client                       Server
+ * 1)      dhtgetMapAdd
+ * 2)      dhtgetStartRequest
+ *                  => CDHTGetRequest =>
+ * 3)                                      dhtgetRequestReceived(stopReq=False)
+ * 4)                                      (dhtgetPeerReqAdd)
+ * 5)                                      (ses->dht_getData)
+ * 6.1)                                    dhtgetPeerReqReply (from ThreadSessionAlerts)
+ * 6.2)               <= CDHTGetReply <=
+ * 6.3)    dhtgetReplyReceived
+ * 6.4)    (dhtgetMapPost)
+ * [ ..item 6 repeats... ]
+ * 7)     dhtgetMapRemove
+ * 8)     dhtgetStopRequest
+ *                 => CDHTGetRequest =>
+ * 9)                                     dhtgetRequestReceived(stopReq=True)
+ * 10)                                     (dhtgetPeerReqRemove)
+ *
+ **
+ *   DHTPut Sequence:
+ *
+ *            Client                       Server
+ * 1)      dhtputRequest
+ *                  => CDHTPutRequest =>
+ * 2)                                      dhtputRequestReceived
+ * 3)                                      (ses->dht_putDataSigned)
+ */
+namespace DhtProxy
+{
+    extern bool fEnabled;
+
+    // Register a listener for dhtget requests (client side)
+    void dhtgetMapAdd(libtorrent::sha1_hash &ih, libtorrent::alert_manager *am);
+    
+    // Unregister the dhtget listener (client side)
+    void dhtgetMapRemove(libtorrent::sha1_hash &ih, libtorrent::alert_manager *am);
+
+    // Request a dhtget. Returns the list of node the request was sent to. (client side)
+    vector<CNode*> dhtgetStartRequest(std::string const &username, std::string const &resource, bool multi);
+    
+    // Stop a dhtget request to the nodes listed. (client side)
+    void dhtgetStopRequest(vector<CNode*> vNodesReq, std::string const &username, std::string const &resource, bool multi);
+
+    // Handle a dhtget request received from TCP. send request to UDP. (server side)
+    // return true if accepted.
+    bool dhtgetRequestReceived(const CDHTGetRequest& req, CNode* pfrom);
+    
+    // Handle a dhtget reply received from UDP, send it to the peers that made the request. (server side)
+    void dhtgetPeerReqReply(libtorrent::sha1_hash &ih, const libtorrent::alert *a);
+
+    // Handle a dhtget reply received from TCP. Will call dhtgetMapPost as needed. (client side)
+    // return true if accepted.
+    bool dhtgetReplyReceived(const CDHTGetReply& reply, CNode* pfrom);
+    
+    // Request a dhtput.
+    void dhtputRequest(std::string const &username, std::string const &resource, bool multi,
+                       std::string const &str_p, std::string const &sig_p, std::string const &sig_user);
+
+    // Handle a dhtput request received from TCP. send request to UDP. (server side)
+    // return true if accepted.
+    bool dhtputRequestReceived(const CDHTPutRequest& req, CNode* pfrom);
+}
+
+class CDHTTarget
+{
+public:
+    std::vector<char> vchUsername;
+    std::vector<char> vchResource;
+    bool resTypeMulti;
+
+    CDHTTarget()
+    {
+        SetNull();
+    }
+
+    IMPLEMENT_SERIALIZE
+    (
+        READWRITE(vchUsername);
+        READWRITE(vchResource);
+        READWRITE(resTypeMulti);
+    )
+
+    void SetNull()
+    {
+        vchUsername.clear();
+        vchResource.clear();
+        resTypeMulti = false;
+    }
+};
+
+class CDHTGetRequest : public CDHTTarget
+{
+public:
+    bool stopReq;
+
+    CDHTGetRequest() : CDHTTarget()
+    {
+        SetNull();
+    }
+
+    IMPLEMENT_SERIALIZE
+    (
+        CDHTTarget* pthis = (CDHTTarget*)(this);
+        READWRITE(*pthis);
+        READWRITE(stopReq);
+    )
+
+    void SetNull()
+    {
+        stopReq = false;
+    }
+};
+
+class CDHTGetReply
+{
+public:
+    std::vector<char> vchTargetHash;
+    std::vector<char> vchBencodedData;
+
+    CDHTGetReply()
+    {
+        SetNull();
+    }
+
+    IMPLEMENT_SERIALIZE
+    (
+        READWRITE(vchTargetHash);
+        READWRITE(vchBencodedData);
+    )
+
+    void SetNull()
+    {
+        vchTargetHash.clear();
+        vchBencodedData.clear();
+    }
+};
+
+class CDHTPutRequest : public CDHTTarget
+{
+public:
+    std::vector<char> vchStr_p;
+    std::vector<char> vchSig_p;
+    std::vector<char> vchSig_user;
+
+    CDHTPutRequest() : CDHTTarget()
+    {
+        SetNull();
+    }
+
+    IMPLEMENT_SERIALIZE
+    (
+        CDHTTarget* pthis = (CDHTTarget*)(this);
+        READWRITE(*pthis);
+        READWRITE(vchStr_p);
+        READWRITE(vchSig_p);
+        READWRITE(vchSig_user);
+    )
+
+    void SetNull()
+    {
+        vchStr_p.clear();
+        vchSig_p.clear();
+        vchSig_user.clear();
+    }
+};
+
+
+#endif

src/init.cpp

@@ -431,7 +431,11 @@ bool AppInit2(boost::thread_group& threadGroup)
         // to protect privacy, do not listen by default if a proxy server is specified
         SoftSetBoolArg("-listen", false);
     }
-
+    
+    if (mapArgs.count("-proxy") || mapArgs.count("-tor")) {
+        SoftSetBoolArg("-dhtproxy", true);
+    }
+    
     if (!GetBoolArg("-listen", true)) {
         // do not map ports or try to retrieve public IP when not listening (pointless)
         SoftSetBoolArg("-upnp", false);

src/main.cpp

@@ -13,6 +13,7 @@
 #include "ui_interface.h"
 #include "checkqueue.h"
 #include "chainparams.h"
+#include "dhtproxy.h"
 
 #include "twister.h"
 #include "utf8core.h"
@@ -3185,6 +3186,46 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         pfrom->fRelayTxes = true;
     }
 
+    else if (strCommand == "dhtgetreq")
+    {
+        CDHTGetRequest req;
+        vRecv >> req;
+
+        if( DhtProxy::dhtgetRequestReceived(req, pfrom) ) {
+            // ok
+        } else {
+            pfrom->Misbehaving(20);
+        }
+    }
+
+    else if (strCommand == "dhtputreq")
+    {
+        CDHTPutRequest req;
+        vRecv >> req;
+
+        if( DhtProxy::dhtputRequestReceived(req, pfrom) ) {
+            // ok
+        } else {
+            pfrom->Misbehaving(20);
+        }
+    }
+
+    else if (strCommand == "dhtgetreply")
+    {
+        CDHTGetReply reply;
+        vRecv >> reply;
+
+        if( DhtProxy::dhtgetReplyReceived(reply, pfrom) ) {
+            // ok
+        } else {
+            pfrom->Misbehaving(20);
+        }
+    }
+
+    else if (strCommand == "nodhtproxy")
+    {
+        pfrom->fNoDhtProxy = true;
+    }
 
     else
     {

src/makefile.android

@@ -133,6 +133,7 @@ OBJS= \
     obj/leveldb.o \
     obj/txdb.o \
     obj/chainparams.o \
+    obj/dhtproxy.o \
     obj/twister.o \
     obj/twister_rss.o \
     obj/twister_utils.o

src/makefile.freebsd

@@ -148,6 +148,7 @@ OBJS= \
     obj/leveldb.o \
     obj/txdb.o \
     obj/chainparams.o \
+    obj/dhtproxy.o \
     obj/twister.o \
     obj/twister_rss.o \
     obj/twister_utils.o

src/makefile.osx

@@ -148,7 +148,9 @@ OBJS= \
     obj/leveldb.o \
     obj/txdb.o \
     obj/chainparams.o \
+    obj/dhtproxy.o \
     obj/twister.o \
+    obj/twister_rss.o \
     obj/twister_utils.o
 
 ifdef USE_SSE2

src/makefile.unix

@@ -150,6 +150,7 @@ OBJS= \
     obj/leveldb.o \
     obj/txdb.o \
     obj/chainparams.o \
+    obj/dhtproxy.o \
     obj/twister.o \
     obj/twister_rss.o \
     obj/twister_utils.o

src/net.h

@@ -203,6 +203,7 @@ public:
     // b) the peer may tell us in their version message that we should not relay tx invs
     //    until they have initialized their bloom filter.
     bool fRelayTxes;
+    bool fNoDhtProxy;
     CSemaphoreGrant grantOutbound;
     CCriticalSection cs_filter;
     CBloomFilter* pfilter;
@@ -266,6 +267,7 @@ public:
         fGetAddr = false;
         nMisbehavior = 0;
         fRelayTxes = false;
+        fNoDhtProxy = false;
         setInventoryKnown.max_size(SendBufferSize() / 1000);
         pfilter = NULL;
 

src/twister.cpp

@@ -1,6 +1,7 @@
 #include "twister.h"
 
 #include "twister_utils.h"
+#include "dhtproxy.h"
 
 #include "main.h"
 #include "init.h"
@@ -91,18 +92,6 @@ private:
 #define USER_DATA_FILE "user_data"
 #define GLOBAL_DATA_FILE "global_data"
 
-sha1_hash dhtTargetHash(std::string const &username, std::string const &resource, std::string const &type)
-{
-    entry target;
-    target["n"] = username;
-    target["r"] = resource;
-    target["t"] = type;
-
-    std::vector<char> buf;
-    bencode(std::back_inserter(buf), target);
-    return hasher(buf.data(), buf.size()).final();
-}
-
 void dhtgetMapAdd(sha1_hash &ih, alert_manager *am)
 {
     LOCK(cs_dhtgetMap);
@@ -337,7 +326,12 @@ void ThreadWaitExtIP()
         //dhts.restrict_routing_ips = false;
         //dhts.restrict_search_ips = false;
         ses->set_dht_settings(dhts);
-        ses->start_dht();
+        
+        if( !DhtProxy::fEnabled ) {
+            ses->start_dht();
+        } else {
+            ses->stop_dht();
+        }
     }
     
     session_settings settings;
@@ -495,7 +489,7 @@ void ThreadMaintainDHTNodes()
             vNodesSize = vNodes.size();
         }
 
-        if( !ses->is_paused() ) {
+        if( !ses->is_paused() && !DhtProxy::fEnabled ) {
             vector<CAddress> vAddr = addrman.GetAddr();
             int totalNodesCandidates = (int)(vNodesSize + vAddr.size());
             if( ((!dht_nodes && totalNodesCandidates) ||
@@ -630,6 +624,7 @@ void ThreadSessionAlerts()
                                     t && t->type() == entry::string_t) {
                                     sha1_hash ih = dhtTargetHash(n->string(), r->string(), t->string());
                                     dhtgetMapPost(ih,*rd);
+                                    DhtProxy::dhtgetPeerReqReply(ih,rd);
                                 }
                             }
                         }
@@ -675,7 +670,7 @@ void ThreadSessionAlerts()
                                                    t->string().c_str());
 #endif
                                             neighborCheck[ih] = false;
-                                            ses->dht_getData(n->string(), r->string(), t->string() == "m");
+                                            dhtGetData(n->string(), r->string(), t->string() == "m");
                                         } else if( neighborCheck[ih] ) {
                                             sha1_hash ihStatus = dhtTargetHash(n->string(), "status", "s");
 
@@ -686,7 +681,7 @@ void ThreadSessionAlerts()
                                                         n->string().c_str(), "status", "s");
 #endif
                                                 statusCheck[ihStatus] = GetTime();
-                                                ses->dht_getData(n->string(), "status", false);
+                                                dhtGetData(n->string(), "status", false);
                                             }
                                         }
                                     }
@@ -710,6 +705,7 @@ void ThreadSessionAlerts()
                     if( !dd->m_got_data ) {
                         // no data: post alert to return from wait_for_alert in dhtget()
                         dhtgetMapPost(ih,*dd);
+                        DhtProxy::dhtgetPeerReqReply(ih,dd);
                     }
 
                     if( neighborCheck.count(ih) ) {
@@ -721,7 +717,7 @@ void ThreadSessionAlerts()
 #endif
                             sha1_hash ihStatus = dhtTargetHash(dd->m_username, "status", "s");
                             statusCheck[ihStatus] = GetTime();
-                            ses->dht_getData(dd->m_username, "status", false);
+                            dhtGetData(dd->m_username, "status", false);
                         }
                     }
                     if( statusCheck.count(ih) ) {
@@ -765,6 +761,8 @@ void startSessionTorrent(boost::thread_group& threadGroup)
     m_noExpireResources["following"] = NumberedNoExpire;
     m_noExpireResources["status"] = SimpleNoExpire;
     m_noExpireResources["post"] = PostNoExpireRecent;
+    
+    DhtProxy::fEnabled = GetBoolArg("-dhtproxy", false);
 
     m_threadsToJoin = 0;
     threadGroup.create_thread(boost::bind(&ThreadWaitExtIP));
@@ -1334,16 +1332,24 @@ entry formatSpamPost(const string &msg, const string &username, uint64_t utcTime
 }
 
 
+void dhtGetData(std::string const &username, std::string const &resource, bool multi)
+{
+    if( DhtProxy::fEnabled ) {
+        printf("dhtGetData: not allowed - using proxy (bug!)\n");
+        return;
+    }
+    boost::shared_ptr<session> ses(m_ses);
+    if( !ses ) {
+        printf("dhtGetData: libtorrent session not ready\n");
+        return;
+    }
+    ses->dht_getData(username,resource,multi);
+}
+
 void dhtPutData(std::string const &username, std::string const &resource, bool multi,
                 entry const &value, std::string const &sig_user,
                 boost::int64_t timeutc, int seq)
 {
-    boost::shared_ptr<session> ses(m_ses);
-    if( !ses ) {
-        printf("dhtPutData: libtorrent session not ready\n");
-        return;
-    }
-    
     // construct p dictionary and sign it
     entry p;
     entry& target = p["target"];
@@ -1365,7 +1371,27 @@ void dhtPutData(std::string const &username, std::string const &resource, bool m
         return;
     }
 
-    ses->dht_putDataSigned(username,resource,multi,p,sig_p,sig_user, true);
+    if( !DhtProxy::fEnabled ) {
+        dhtPutDataSigned(username,resource,multi,p,sig_p,sig_user, true);
+    } else {
+        DhtProxy::dhtputRequest(username,resource,multi,str_p,sig_p,sig_user);
+    }
+}
+
+void dhtPutDataSigned(std::string const &username, std::string const &resource, bool multi,
+                libtorrent::entry const &p, std::string const &sig_p, std::string const &sig_user, bool local)
+{
+    if( DhtProxy::fEnabled ) {
+        printf("dhtputDataSigned: not allowed - using proxy (bug!)\n");
+        return;
+    }
+    boost::shared_ptr<session> ses(m_ses);
+    if( !ses ) {
+        printf("dhtPutData: libtorrent session not ready\n");
+        return;
+    }
+
+    ses->dht_putDataSigned(username,resource,multi,p,sig_p,sig_user, local);
 }
 
 Value dhtput(const Array& params, bool fHelp)
@@ -1441,9 +1467,15 @@ Value dhtget(const Array& params, bool fHelp)
 
     alert_manager am(10, alert::dht_notification);
     sha1_hash ih = dhtTargetHash(strUsername,strResource,strMulti);
-    dhtgetMapAdd(ih, &am);
+    
-
+    vector<CNode*> dhtProxyNodes;
-    ses->dht_getData(strUsername, strResource, multi);
+    if( !DhtProxy::fEnabled ) {
+        dhtgetMapAdd(ih, &am);
+        dhtGetData(strUsername, strResource, multi);
+    } else {
+        DhtProxy::dhtgetMapAdd(ih, &am);
+        dhtProxyNodes = DhtProxy::dhtgetStartRequest(strUsername, strResource, multi);
+    }
 
     Array ret;
     std::set<std::string> uniqueSigPs;
@@ -1488,7 +1520,12 @@ Value dhtget(const Array& params, bool fHelp)
         }
     }
 
-    dhtgetMapRemove(ih,&am);
+    if( !DhtProxy::fEnabled ) {
+        dhtgetMapRemove(ih,&am);
+    } else {
+        DhtProxy::dhtgetMapRemove(ih,&am);
+        DhtProxy::dhtgetStopRequest(dhtProxyNodes, strUsername, strResource, multi);
+    }
 
     return ret;
 }

src/twister.h

@@ -13,6 +13,9 @@
 #define BLOCK_AGE_TO_EXPIRE_DHT_ENTRY (2016)   // about 2 weeks
 #define BLOCK_AGE_TO_EXPIRE_DHT_POSTS (4320*2) // about 2 months
 
+namespace libtorrent {
+    class entry;
+}
 
 class twister
 {
@@ -41,4 +44,12 @@ int getDhtNodes(boost::int64_t *dht_global_nodes = NULL);
 
 void updateSeenHashtags(std::string &message, int64_t msgTime);
 
+// interface to dht api of the libtorrent current session
+void dhtGetData(std::string const &username, std::string const &resource, bool multi);
+void dhtPutData(std::string const &username, std::string const &resource, bool multi,
+                libtorrent::entry const &value, std::string const &sig_user,
+                boost::int64_t timeutc, int seq);
+void dhtPutDataSigned(std::string const &username, std::string const &resource, bool multi,
+                libtorrent::entry const &p, std::string const &sig_p, std::string const &sig_user, bool local);
+
 #endif // TWISTER_H

src/twister_utils.cpp

@@ -360,3 +360,16 @@ libtorrent::entry safeGetEntryDict(libtorrent::entry const &e, std::string const
     }
 }
 
+sha1_hash dhtTargetHash(std::string const &username, std::string const &resource, std::string const &type)
+{
+    entry target;
+    target["n"] = username;
+    target["r"] = resource;
+    target["t"] = type;
+
+    std::vector<char> buf;
+    bencode(std::back_inserter(buf), target);
+    return hasher(buf.data(), buf.size()).final();
+}
+
+

src/twister_utils.h

@@ -3,6 +3,7 @@
 
 #include "json/json_spirit.h"
 #include "libtorrent/entry.hpp"
+#include "libtorrent/peer_id.hpp"
 
 #include <string>
 #include <vector>
@@ -48,4 +49,6 @@ std::string safeGetEntryString(libtorrent::entry const &e, std::string const& ke
 int safeGetEntryInt(libtorrent::entry const &e, std::string const& key);
 libtorrent::entry safeGetEntryDict(libtorrent::entry const &e, std::string const& key);
 
+libtorrent::sha1_hash dhtTargetHash(std::string const &username, std::string const &resource, std::string const &type);
+
 #endif // TWISTER_UTILS_H

src/version.h

@@ -25,7 +25,7 @@ extern const std::string CLIENT_DATE;
 // network protocol versioning
 //
 
-static const int PROTOCOL_VERSION = 70002;
+static const int PROTOCOL_VERSION = 70003;
 
 // earlier versions not supported as of Feb 2012, and are disconnected
 static const int MIN_PROTO_VERSION = 209;
@@ -44,6 +44,9 @@ static const int BIP0031_VERSION = 60000;
 // soft checkpoint min version
 static const int SOFT_CHECKPOINT_VERSION = 70002;
 
+// dht proxy min version
+static const int DHT_PROXY_VERSION = 70003;
+
 // "mempool" command, enhanced "getdata" behavior starts with this version:
 static const int MEMPOOL_GD_VERSION = 60002;
 

twister-qt.pro

@@ -200,6 +200,7 @@ HEADERS +=  \
     src/limitedmap.h \
     src/scrypt.h \
     src/utf8core.h \
+    src/dhtproxy.h \
     src/twister.h \
     src/twister_rss.h \
     src/twister_utils.h
@@ -277,6 +278,7 @@ SOURCES += \ #src/qt/bitcoin.cpp \
     src/leveldb.cpp \
     src/txdb.cpp \
     src/scrypt.cpp \
+    src/dhtproxy.cpp \
     src/twister.cpp \
     src/twister_rss.cpp \
     src/twister_utils.cpp