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.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/init.cpp b/src/init.cpp
index 5f2dc8bf2f..77837f85c3 100644
--- a/src/init.cpp
+++ b/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