Clean up use of commResetFD when socket incompatible with requested address

This patch backs out part of the patch for Bug #2222 and replaces it by
crudely cycling over the available addresses, trying to skip over
addresses not compatible with the current socket.

This solves issues seen when using tproxy or tcp_outgoing_address and
DNS of the requested host returns AAAA records in addition to A records.

This change is interim, waiting for the larger connection setup
overhaul, but seems to do the trick for now.

One effect of this change is that there will be no fallback to the other
IP generation if the socket is configured to a specific outgoing
address. Priory the code threw away the outgoing address and tried
again when encountering an incompatibility.

diff --git a/src/comm.cc b/src/comm.cc
index 00026672d52e2a0d4df4cbef9f027ed54b39da14..03a69e3c639dc4bfa0b714deafa8ba10d44df9dc 100644 (file)
--- a/src/comm.cc
+++ b/src/comm.cc
@@ -946,9 +946,6 @@ copyFDFlags(int to, fde *F)
 int
 ConnectStateData::commResetFD()
 {
-    struct addrinfo *AI = NULL;
-    Ip::Address nul;
-    int new_family = AF_UNSPEC;
 
 // XXX: do we have to check this?
 //
@@ -957,14 +954,13 @@ ConnectStateData::commResetFD()
 
     statCounter.syscalls.sock.sockets++;
 
-    /* setup a bare-bones addrinfo */
-    /* TODO INET6: for WinXP we may need to check the local_addr type and setup the family properly. */
-    nul.GetAddrInfo(AI);
-    new_family = AI->ai_family;
+    fde *F = &fd_table[fd];
 
-    int fd2 = socket(AI->ai_family, AI->ai_socktype, AI->ai_protocol);
+    struct addrinfo *AI = NULL;
+    F->local_addr.GetAddrInfo(AI);
+    int new_family = AI->ai_family;
 
-    nul.FreeAddrInfo(AI);
+    int fd2 = socket(new_family, AI->ai_socktype, AI->ai_protocol);
 
     if (fd2 < 0) {
         debugs(5, DBG_CRITICAL, HERE << "WARNING: FD " << fd2 << " socket failed to allocate: " << xstrerror());
@@ -972,6 +968,7 @@ ConnectStateData::commResetFD()
         if (ENFILE == errno || EMFILE == errno)
             fdAdjustReserved();
 
+        F->local_addr.FreeAddrInfo(AI);
         return 0;
     }
 
@@ -991,19 +988,20 @@ ConnectStateData::commResetFD()
 
         close(fd2);
 
+        F->local_addr.FreeAddrInfo(AI);
         return 0;
     }
     commResetSelect(fd);
 
     close(fd2);
-    fde *F = &fd_table[fd];
 
     debugs(50, 3, "commResetFD: Reset socket FD " << fd << "->" << fd2 << " : family=" << new_family );
 
     /* INET6: copy the new sockets family type to the FDE table */
-    fd_table[fd].sock_family = new_family;
+    F->sock_family = new_family;
+
+    F->flags.called_connect = 0;
 
-    fd_table[fd].flags.called_connect = 0;
     /*
      * yuck, this has assumptions about comm_open() arguments for
      * the original socket
@@ -1014,9 +1012,6 @@ ConnectStateData::commResetFD()
         comm_set_transparent(fd);
     }
 
-    AI = NULL;
-    F->local_addr.GetAddrInfo(AI);
-
     if (commBind(fd, *AI) != COMM_OK) {
         debugs(5, DBG_CRITICAL, "WARNING: Reset of FD " << fd << " for " << F->local_addr << " failed to bind: " << xstrerror());
         F->local_addr.FreeAddrInfo(AI);
@@ -1082,8 +1077,7 @@ ConnectStateData::defaults()
 void
 ConnectStateData::connect()
 {
-    if (S.IsAnyAddr())
-        defaults();
+    defaults();
 
     debugs(5,5, HERE << "to " << S);
 
@@ -1100,15 +1094,22 @@ ConnectStateData::connect()
         callCallback(COMM_OK, 0);
         break;
 
-#if USE_IPV6
     case COMM_ERR_PROTOCOL:
+        debugs(5, 5, HERE "FD " << fd << ": COMM_ERR_PROTOCOL - try again");
         /* problem using the desired protocol over this socket.
-         * count the connection attempt, reset the socket, and immediately try again */
+         * skip to the next address and hope it's more compatible
+         * but do not mark the current address as bad
+         */
         tries++;
-        commResetFD();
-        connect();
+        if (commRetryConnect()) {
+            /* Force an addr cycle to move forward to the next possible address */
+            ipcacheCycleAddr(host, NULL);
+            eventAdd("commReconnect", commReconnect, this, this->addrcount == 1 ? 0.05 : 0.0, 0);
+        } else {
+            debugs(5, 5, HERE << "FD " << fd << ": COMM_ERR_PROTOCOL - ERR tried too many times already.");
+            callCallback(COMM_ERR_CONNECT, errno);
+        }
         break;
-#endif
 
     default:
         debugs(5, 5, HERE "FD " << fd << ": * - try again");
@@ -1210,18 +1211,27 @@ comm_connect_addr(int sock, const Ip::Address &address)
 
     debugs(5, 9, "comm_connect_addr: connecting socket " << sock << " to " << address << " (want family: " << F->sock_family << ")");
 
-    /* BUG 2222 FIX: reset the FD when its found to be IPv4 in IPv6 mode */
-    /* inverse case of IPv4 failing to connect on IPv6 socket is handeld post-connect.
+    /* Handle IPv6 over IPv4-only socket case.
      * this case must presently be handled here since the GetAddrInfo asserts on bad mappings.
-     * eventually we want it to throw a Must() that gets handled there instead of this if.
-     * NP: because commresetFD is private to ConnStateData we have to return an error and
+     * NP: because commResetFD is private to ConnStateData we have to return an error and
      *     trust its handled properly.
      */
-#if USE_IPV6
     if (F->sock_family == AF_INET && !address.IsIPv4()) {
+        errno = ENETUNREACH;
+        return COMM_ERR_PROTOCOL;
+    }
+
+    /* Handle IPv4 over IPv6-only socket case.
+     * This case is presently handled here as it's both a known case and it's
+     * uncertain what error will be returned by the IPv6 stack in such case. It's
+     * possible this will also be handled by the errno checks below after connect()
+     * but needs carefull cross-platform verification, and verifying the address
+     * condition here is simple.
+     */
+    if (!F->local_addr.IsIPv4() && address.IsIPv4()) {
+        errno = ENETUNREACH;
         return COMM_ERR_PROTOCOL;
     }
-#endif
 
     address.GetAddrInfo(AI, F->sock_family);
 
@@ -1315,23 +1325,10 @@ comm_connect_addr(int sock, const Ip::Address &address)
         status = COMM_OK;
     else if (ignoreErrno(errno))
         status = COMM_INPROGRESS;
+    else if (errno == EAFNOSUPPORT || errno == EINVAL)
+        return COMM_ERR_PROTOCOL;
     else
-#if USE_IPV6
-        if ( F->sock_family == AF_INET6 && address.IsIPv4() ) {
-
-            /* failover to trying IPv4-only link if an IPv6 one fails */
-            /* to catch the edge case of apps listening on IPv4-localhost */
-            F->sock_family = AF_INET;
-            int res = comm_connect_addr(sock, address);
-
-            /* if that fails too, undo our temporary socktype hack so the repeat works properly. */
-            if (res == COMM_ERROR)
-                F->sock_family = AF_INET6;
-
-            return res;
-        } else
-#endif
-            return COMM_ERROR;
+        return COMM_ERROR;
 
     address.NtoA(F->ipaddr, MAX_IPSTRLEN);