Due to fears that an incompetent WinSock might allow localhost-

listening sockets to be talked to by non-local hosts, reinstate the
explicit peer address check on connection acceptance.

git-svn-id: svn://svn.tartarus.org/sgt/putty@1306 cda61777-01e9-0310-a592-d414129be87e

diff --git a/winnet.c b/winnet.c
index b671047..b68846f 100644 (file)
--- a/winnet.c
+++ b/winnet.c
@@ -68,6 +68,7 @@ struct Socket_tag {
     int frozen; /* this causes readability notifications to be ignored */
     int frozen_readable; /* this means we missed at least one readability
                          * notification while we were frozen */
+    int localhost_only;                       /* for listening sockets */
     char oobdata[1];
     int sending_oob;
     int oobinline;
@@ -410,6 +411,7 @@ Socket sk_register(void *sock, Plug plug)
     ret->sending_oob = 0;
     ret->frozen = 1;
     ret->frozen_readable = 0;
+    ret->localhost_only = 0;          /* unused, but best init anyway */
 
     ret->s = (SOCKET)sock;
 
@@ -469,6 +471,7 @@ Socket sk_new(SockAddr addr, int port, int privport, int oobinline,
     ret->sending_oob = 0;
     ret->frozen = 0;
     ret->frozen_readable = 0;
+    ret->localhost_only = 0;          /* unused, but best init anyway */
 
     /*
      * Open socket.
@@ -636,6 +639,7 @@ Socket sk_newlistener(int port, Plug plug, int local_host_only)
     ret->sending_oob = 0;
     ret->frozen = 0;
     ret->frozen_readable = 0;
+    ret->localhost_only = local_host_only;
 
     /*
      * Open socket.
@@ -963,11 +967,11 @@ int select_result(WPARAM wParam, LPARAM lParam)
        return open;
        case FD_ACCEPT:
        {
-           struct sockaddr isa;
-           int addrlen = sizeof(struct sockaddr);
+           struct sockaddr_in isa;
+           int addrlen = sizeof(struct sockaddr_in);
            SOCKET t;  /* socket of connection */
 
-           memset(&isa, 0, sizeof(struct sockaddr));
+           memset(&isa, 0, sizeof(struct sockaddr_in));
            err = 0;
            t = accept(s->s,&isa,&addrlen);
            if (t == INVALID_SOCKET)
@@ -977,7 +981,10 @@ int select_result(WPARAM wParam, LPARAM lParam)
                    break;
            }
 
-           if (plug_accepting(s->plug, (void*)t)) {
+           if (s->localhost_only &&
+               ntohl(isa.sin_addr.s_addr) != INADDR_LOOPBACK) {
+               closesocket(t);        /* dodgy WinSock let nonlocal through */
+           } else if (plug_accepting(s->plug, (void*)t)) {
                closesocket(t);        /* denied or error */
            }
        }