From 40a653f55539147855723cda0e2fbc1caa3016e3 Mon Sep 17 00:00:00 2001
From: Joel Martin <github@martintribe.org>
Date: Thu, 16 Dec 2010 14:04:16 -0600
Subject: [PATCH] wswrapper: fix preload path and interpose port.

Make path to ld preload library absolute so wswrapper works even if
path is changed before main program is executed (i.e. by the vncserver
wrapper script).

bind() was using the return value for the port number, but it's
actually the original port number that we should interpose on in the
bind() routine.
---
 utils/wswrap      |  2 +-
 utils/wswrapper.c | 30 ++++++++++++++++++------------
 2 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/utils/wswrap b/utils/wswrap
index 68b9307f..565d8ed3 100755
--- a/utils/wswrap
+++ b/utils/wswrap
@@ -9,7 +9,7 @@ usage() {
 }
 
 # Parameter defaults
-mydir=$(dirname ${0})
+mydir=$(readlink -f $(dirname ${0}))
 
 # Process parameters
 #while [ "${1}" != "${1#-}" ]; do
diff --git a/utils/wswrapper.c b/utils/wswrapper.c
index 0a4de4d5..ca4bd987 100644
--- a/utils/wswrapper.c
+++ b/utils/wswrapper.c
@@ -69,7 +69,7 @@ typedef struct {
  * matches WSWRAP_PORT, otherwise listen to the first socket fd that bind is
  * called on.
  */
-int              _WS_listen_fd  = 0;
+int              _WS_listen_fd  = -1;
 _WS_connection  *_WS_connections[65546];
 
 
@@ -560,40 +560,40 @@ int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen)
     static void * (*func)();
     struct sockaddr_in * addr_in = (struct sockaddr_in *)addr;
     char * WSWRAP_PORT, * end;
-    int fd, envport, bindport = htons(addr_in->sin_port);
+    int ret, envport, bindport = htons(addr_in->sin_port);
     if (!func) func = (void *(*)()) dlsym(RTLD_NEXT, "bind");
     DEBUG("bind(%d, _, %d) called\n", sockfd, addrlen);
 
-    fd = (int) func(sockfd, addr, addrlen);
+    ret = (int) func(sockfd, addr, addrlen);
 
     if (addr_in->sin_family != AF_INET) {
         // TODO: handle IPv6
         DEBUG("bind, ignoring non-IPv4 socket\n");
-        return fd;
+        return ret;
     }
 
     WSWRAP_PORT = getenv("WSWRAP_PORT");
     if ((! WSWRAP_PORT) || (*WSWRAP_PORT == '\0')) {
         // TODO: interpose on all sockets
         DEBUG("bind, not interposing: WSWRAP_PORT is not set\n");
-        return fd;
+        return ret;
     }
 
     envport = strtol(WSWRAP_PORT, &end, 10);
     if ((envport == 0) || (*end != '\0')) {
         MSG("bind, not interposing: WSWRAP_PORT is not a number\n");
-        return fd;
+        return ret;
     }
 
     if (envport != bindport) {
-        DEBUG("bind, not interposing on port %d\n", bindport);
-        return fd;
+        DEBUG("bind, not interposing on port: %d (fd %d)\n", bindport, sockfd);
+        return ret;
     }
 
-    MSG("bind, interposing on port: %d\n", envport);
-    _WS_listen_fd = envport;
+    MSG("bind, interposing on port: %d (fd %d)\n", envport, sockfd);
+    _WS_listen_fd = sockfd;
 
-    return fd;
+    return ret;
 }
 
 int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen)
@@ -605,11 +605,17 @@ int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen)
 
     fd = (int) func(sockfd, addr, addrlen);
 
-    if (_WS_listen_fd == 0) {
+    if (_WS_listen_fd == -1) {
         DEBUG("not interposing\n");
         return fd;
     }
 
+    if (_WS_listen_fd != sockfd) {
+        DEBUG("not interposing on fd %d\n", sockfd);
+        return fd;
+    }
+
+
     if (_WS_connections[fd]) {
         MSG("error, already interposing on fd %d\n", fd);
     } else {