Remove vfReachable and modify IsReachable to only use vfLimited.

This is a backport from bitcoin commit 110b62f
This should fix issue 373 and prevent some future net related issues
Original comment:
We do not know that a class of Network is reachable, only that it is not.

src/init.cpp

@@ -1222,6 +1222,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     // -proxy sets a proxy for all outgoing network traffic
     // -noproxy (or -proxy=0) as well as the empty string can be used to not set a proxy, this is the default
     std::string proxyArg = GetArg("-proxy", "");
+    SetLimited(NET_TOR);
     if (proxyArg != "" && proxyArg != "0") {
         CService proxyAddr;
         if (!Lookup(proxyArg.c_str(), proxyAddr, 9050, fNameLookup)) {
@@ -1236,7 +1237,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
         SetProxy(NET_IPV6, addrProxy);
         SetProxy(NET_TOR, addrProxy);
         SetNameProxy(addrProxy);
-        SetReachable(NET_TOR); // by default, -proxy sets onion as reachable, unless -noonion later
+        SetLimited(NET_TOR, false); // by default, -proxy sets onion as reachable, unless -noonion later
     }
 
     // -onion can be used to set only a proxy for .onion, or override normal proxy for .onion addresses
@@ -1245,7 +1246,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     std::string onionArg = GetArg("-onion", "");
     if (onionArg != "") {
         if (onionArg == "0") { // Handle -noonion/-onion=0
-            SetReachable(NET_TOR, false); // set onions as unreachable
+            SetLimited(NET_TOR); // set onions as unreachable
         } else {
             CService onionProxy;
             if (!Lookup(onionArg.c_str(), onionProxy, 9050, fNameLookup)) {
@@ -1255,7 +1256,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
             if (!addrOnion.IsValid())
                 return InitError(strprintf(_("Invalid -onion address or hostname: '%s'"), onionArg));
             SetProxy(NET_TOR, addrOnion);
-            SetReachable(NET_TOR);
+            SetLimited(NET_TOR, false);
         }
     }
 

src/net.cpp

@@ -78,7 +78,6 @@ bool fListen = true;
 uint64_t nLocalServices = NODE_NETWORK;
 CCriticalSection cs_mapLocalHost;
 map<CNetAddr, LocalServiceInfo> mapLocalHost;
-static bool vfReachable[NET_MAX] = {};
 static bool vfLimited[NET_MAX] = {};
 static CNode* pnodeLocalHost = NULL;
 uint64_t nLocalHostNonce = 0;
@@ -238,14 +237,6 @@ void AdvertizeLocal(CNode* pnode)
     }
 }
 
-void SetReachable(enum Network net, bool fFlag)
-{
-    LOCK(cs_mapLocalHost);
-    vfReachable[net] = fFlag;
-    if (net == NET_IPV6 && fFlag)
-        vfReachable[NET_IPV4] = true;
-}
-
 // learn a new local address
 bool AddLocal(const CService& addr, int nScore)
 {
@@ -268,7 +259,6 @@ bool AddLocal(const CService& addr, int nScore)
             info.nScore = nScore + (fAlready ? 1 : 0);
             info.nPort = addr.GetPort();
         }
-        SetReachable(addr.GetNetwork());
     }
 
     return true;
@@ -331,7 +321,7 @@ bool IsLocal(const CService& addr)
 bool IsReachable(enum Network net)
 {
     LOCK(cs_mapLocalHost);
-    return vfReachable[net] && !vfLimited[net];
+    return !vfLimited[net];
 }
 
 /** check whether a given address is in a network we can probably connect to */

src/net.h

@@ -119,7 +119,6 @@ bool IsLocal(const CService& addr);
 bool GetLocal(CService& addr, const CNetAddr* paddrPeer = NULL);
 bool IsReachable(enum Network net);
 bool IsReachable(const CNetAddr& addr);
-void SetReachable(enum Network net, bool fFlag = true);
 CAddress GetLocalAddress(const CNetAddr* paddrPeer = NULL);