* autoload.cc (rresvport): Remove.

	* net.cc (last_used_rrecvport): New global shared variable.
	(cygwin_rresvport): Implement rresvport without using rresvport from
	wsock32.

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 44cde4438f5d5b9a6a7dcdad555a3acd36479814..7290af8d4e5c198feab26801e9d8897dba70e7c5 100644 (file)
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,10 @@
+2006-01-18  Corinna Vinschen  <corinna@vinschen.de>
+
+       * autoload.cc (rresvport): Remove.
+       * net.cc (last_used_rrecvport): New global shared variable.
+       (cygwin_rresvport): Implement rresvport without using rresvport from
+       wsock32.
+
 2006-01-18  Corinna Vinschen  <corinna@vinschen.de>
 
        * include/cygwin/socket.h (struct sockaddr_storage): Fix typo in

diff --git a/winsup/cygwin/autoload.cc b/winsup/cygwin/autoload.cc
index 76f38a3b248d8afff7de901750ab2c2508b60aff..0d76ebeae9dd2e5fbbd752e757807eacedeff0c8 100644 (file)
--- a/winsup/cygwin/autoload.cc
+++ b/winsup/cygwin/autoload.cc
@@ -450,7 +450,6 @@ LoadDLLfunc (SetUserObjectSecurity, 12, user32)
 LoadDLLfunc (inet_network, 4, wsock32)
 LoadDLLfunc (rcmd, 24, wsock32)
 LoadDLLfunc (rexec, 24, wsock32)
-LoadDLLfunc (rresvport, 4, wsock32)
 
 LoadDLLfunc (accept, 12, ws2_32)
 LoadDLLfunc (bind, 12, ws2_32)

diff --git a/winsup/cygwin/net.cc b/winsup/cygwin/net.cc
index 1b3e4aca365570022dcd2275c08024005ae08f2f..3ec3cc1dcd2dbdcb09255b9e334911627ad770bd 100644 (file)
--- a/winsup/cygwin/net.cc
+++ b/winsup/cygwin/net.cc
@@ -18,6 +18,7 @@ details. */
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <iphlpapi.h>
+#include <syslog.h>
 
 #include <stdlib.h>
 #define gethostname cygwin_gethostname
@@ -1834,6 +1835,32 @@ cygwin_rcmd (char **ahost, unsigned short inport, char *locuser,
   return res;
 }
 
+/* The below implementation of rresvport looks pretty ugly, but there's
+   a problem in Winsock.  The bind(2) call does not fail if a local
+   address is still in TIME_WAIT state, and there's no way to get this
+   behaviour.  Unfortunately the first time when this is detected is when
+   the calling application tries to connect. 
+   
+   One (also not really foolproof) way around this problem would be to use
+   the iphlpapi function GetTcpTable and to check if the port in question is
+   in TIME_WAIT state and if so, choose another port number.  But this method
+   is as prone to races as the below one, or any other method using random
+   port numbers, etc.  The below method at least tries to avoid races between
+   multiple applications using rrecvport.
+
+   As for the question "why don't you just use the Winsock rresvport?"...
+   For some reason I do NOT understand, the call to WinSocks rresvport
+   corrupts the stack when Cygwin is built using -fomit-frame-pointers.
+   And then again, the Winsock rresvport function has the exact same
+   problem with reusing ports in the TIME_WAIT state as the socket/bind
+   method has.  So there's no gain in using that function. */
+
+#define PORT_LOW       (IPPORT_EFSSERVER + 1)
+#define PORT_HIGH      (IPPORT_RESERVED - 1)
+#define NUM_PORTS      (PORT_HIGH - PORT_LOW + 1)
+
+LONG last_used_rrecvport __attribute__((section (".cygwin_dll_common"), shared)) = IPPORT_RESERVED;
+
 /* exported as rresvport: standards? */
 extern "C" int
 cygwin_rresvport (int *port)
@@ -1845,7 +1872,38 @@ cygwin_rresvport (int *port)
   if (efault.faulted (EFAULT))
     return -1;
 
-  res = rresvport (port);
+  res = socket (AF_INET, SOCK_STREAM, 0);
+  if (res != (int) INVALID_SOCKET)
+    {
+      LONG myport;
+      int ret = SOCKET_ERROR;
+      struct sockaddr_in sin;
+      sin.sin_family = AF_INET;
+      sin.sin_addr.s_addr = INADDR_ANY;
+
+      for (int i = 0; i < NUM_PORTS; i++)
+       {
+         while ((myport = InterlockedExchange (&last_used_rrecvport, 0)) == 0)
+           low_priority_sleep (0);
+         if (--myport < PORT_LOW)
+           myport = PORT_HIGH;
+         InterlockedExchange (&last_used_rrecvport, myport);
+
+         sin.sin_port = htons (myport);
+         if (!(ret = bind (res, (struct sockaddr *) &sin, sizeof sin)))
+           break;
+         int err = WSAGetLastError ();
+         if (err != WSAEADDRINUSE && err != WSAEINVAL)
+           break;
+       }
+      if (ret == SOCKET_ERROR)
+       {
+         closesocket (res);
+         res = (int) INVALID_SOCKET;
+       }
+      else if (port)
+        *port = myport;
+    }
 
   if (res != (int) INVALID_SOCKET)
     {