net: Automatically create hidden service, listen on Tor

Starting with Tor version 0.2.7.1 it is possible, through Tor's control socket
API, to create and destroy 'ephemeral' hidden services programmatically.
https://stem.torproject.org/api/control.html#stem.control.Controller.create_ephemeral_hidden_service

This means that if Tor is running (and proper authorization is available),
bitcoin automatically creates a hidden service to listen on, without user
manual configuration. This will positively affect the number of available
.onion nodes.

- When the node is started, connect to Tor through control socket
- Send `ADD_ONION` command
- First time:
    - Make it create a hidden service key
    - Save the key in the data directory for later usage
- Make it redirect port 8333 to the local port 8333 (or whatever port we're listening on).
- Keep control socket connection open for as long node is running. The hidden service will
  (by default) automatically go away when the connection is closed.

Author: laanwj

src/Makefile.am

@@ -149,6 +149,7 @@ BITCOIN_CORE_H = \
   threadsafety.h \
   timedata.h \
   tinyformat.h \
+  torcontrol.h \
   txdb.h \
   txmempool.h \
   ui_interface.h \
@@ -206,6 +207,7 @@ libbitcoin_server_a_SOURCES = \
   rpcserver.cpp \
   script/sigcache.cpp \
   timedata.cpp \
+  torcontrol.cpp \
   txdb.cpp \
   txmempool.cpp \
   validationinterface.cpp \

src/init.cpp

@@ -28,6 +28,7 @@
 #include "scheduler.h"
 #include "txdb.h"
 #include "txmempool.h"
+#include "torcontrol.h"
 #include "ui_interface.h"
 #include "util.h"
 #include "utilmoneystr.h"
@@ -187,6 +188,7 @@ void Shutdown()
 #endif
     GenerateBitcoins(false, 0, Params());
     StopNode();
+    StopTorControl();
     UnregisterNodeSignals(GetNodeSignals());
 
     if (fFeeEstimatesInitialized)
@@ -347,6 +349,7 @@ std::string HelpMessage(HelpMessageMode mode)
     strUsage += HelpMessageOpt("-externalip=<ip>", _("Specify your own public address"));
     strUsage += HelpMessageOpt("-forcednsseed", strprintf(_("Always query for peer addresses via DNS lookup (default: %u)"), 0));
     strUsage += HelpMessageOpt("-listen", _("Accept connections from outside (default: 1 if no -proxy or -connect)"));
+    strUsage += HelpMessageOpt("-listenonion", strprintf(_("Automatically create Tor hidden service (default: %d)"), DEFAULT_LISTEN_ONION));
     strUsage += HelpMessageOpt("-maxconnections=<n>", strprintf(_("Maintain at most <n> connections to peers (default: %u)"), DEFAULT_MAX_PEER_CONNECTIONS));
     strUsage += HelpMessageOpt("-maxreceivebuffer=<n>", strprintf(_("Maximum per-connection receive buffer, <n>*1000 bytes (default: %u)"), 5000));
     strUsage += HelpMessageOpt("-maxsendbuffer=<n>", strprintf(_("Maximum per-connection send buffer, <n>*1000 bytes (default: %u)"), 1000));
@@ -358,6 +361,7 @@ std::string HelpMessage(HelpMessageMode mode)
     strUsage += HelpMessageOpt("-proxyrandomize", strprintf(_("Randomize credentials for every proxy connection. This enables Tor stream isolation (default: %u)"), 1));
     strUsage += HelpMessageOpt("-seednode=<ip>", _("Connect to a node to retrieve peer addresses, and disconnect"));
     strUsage += HelpMessageOpt("-timeout=<n>", strprintf(_("Specify connection timeout in milliseconds (minimum: 1, default: %d)"), DEFAULT_CONNECT_TIMEOUT));
+    strUsage += HelpMessageOpt("-torcontrol=<ip>:<port>", strprintf(_("Tor control port to use if onion listening enabled (default: %s)"), DEFAULT_TOR_CONTROL));
 #ifdef USE_UPNP
 #if USE_UPNP
     strUsage += HelpMessageOpt("-upnp", _("Use UPnP to map the listening port (default: 1 when listening and no -proxy)"));
@@ -777,6 +781,8 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
             LogPrintf("%s: parameter interaction: -listen=0 -> setting -upnp=0\n", __func__);
         if (SoftSetBoolArg("-discover", false))
             LogPrintf("%s: parameter interaction: -listen=0 -> setting -discover=0\n", __func__);
+        if (SoftSetBoolArg("-listenonion", false))
+            LogPrintf("%s: parameter interaction: -listen=0 -> setting -listenonion=0\n", __func__);
     }
 
     if (mapArgs.count("-externalip")) {
@@ -1567,6 +1573,9 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     LogPrintf("mapAddressBook.size() = %u\n",  pwalletMain ? pwalletMain->mapAddressBook.size() : 0);
 #endif
 
+    if (GetBoolArg("-listenonion", DEFAULT_LISTEN_ONION))
+        StartTorControl(threadGroup, scheduler);
+
     StartNode(threadGroup, scheduler);
 
     // Monitor the chain, and alert if we get blocks much quicker or slower than expected

src/main.cpp

@@ -4038,9 +4038,11 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
                 CAddress addr = GetLocalAddress(&pfrom->addr);
                 if (addr.IsRoutable())
                 {
+                    LogPrintf("ProcessMessages: advertizing address %s\n", addr.ToString());
                     pfrom->PushAddress(addr);
                 } else if (IsPeerAddrLocalGood(pfrom)) {
                     addr.SetIP(pfrom->addrLocal);
+                    LogPrintf("ProcessMessages: advertizing address %s\n", addr.ToString());
                     pfrom->PushAddress(addr);
                 }
             }

src/net.cpp

@@ -216,6 +216,7 @@ void AdvertizeLocal(CNode *pnode)
         }
         if (addrLocal.IsRoutable())
         {
+            LogPrintf("AdvertizeLocal: advertizing address %s\n", addrLocal.ToString());
             pnode->PushAddress(addrLocal);
         }
     }

src/netbase.cpp

@@ -227,10 +227,7 @@ bool LookupNumeric(const char *pszName, CService& addr, int portDefault)
     return Lookup(pszName, addr, portDefault, false);
 }
 
-/**
- * Convert milliseconds to a struct timeval for select.
- */
-struct timeval static MillisToTimeval(int64_t nTimeout)
+struct timeval MillisToTimeval(int64_t nTimeout)
 {
     struct timeval timeout;
     timeout.tv_sec  = nTimeout / 1000;

src/netbase.h

@@ -215,5 +215,9 @@ std::string NetworkErrorString(int err);
 bool CloseSocket(SOCKET& hSocket);
 /** Disable or enable blocking-mode for a socket */
 bool SetSocketNonBlocking(SOCKET& hSocket, bool fNonBlocking);
+/**
+ * Convert milliseconds to a struct timeval for e.g. select.
+ */
+struct timeval MillisToTimeval(int64_t nTimeout);
 
 #endif // BITCOIN_NETBASE_H