merge core-8-branch

1 files changed, 519 insertions, 208 deletions

diff --git a/unix/tclUnixSock.c b/unix/tclUnixSock.c
index 9c3d7eb..2793d3b 100644
--- a/unix/tclUnixSock.c
+++ b/unix/tclUnixSock.c
@@ -19,6 +19,7 @@
 
 #define SET_BITS(var, bits)	((var) |= (bits))
 #define CLEAR_BITS(var, bits)	((var) &= ~(bits))
+#define GOT_BITS(var, bits)     (((var) & (bits)) != 0)
 
 /* "sock" + a pointer in hex + \0 */
 #define SOCK_CHAN_LENGTH        (4 + sizeof(void *) * 2 + 1)
@@ -52,9 +53,13 @@ typedef struct TcpFdList {
 
 struct TcpState {
     Tcl_Channel channel;	/* Channel associated with this file. */
+    int testFlags;              /* bit field for tests. Is set by testsocket
+                                 * test procedure */
     TcpFdList fds;		/* The file descriptors of the sockets. */
     int flags;			/* ORed combination of the bitfields defined
 				 * below. */
+    int interest;		/* Event types of interest */
+
     /*
      * Only needed for server sockets
      */
@@ -73,7 +78,7 @@ struct TcpState {
     struct addrinfo *myaddr;	/* Iterator over myaddrlist. */
     int filehandlers;           /* Caches FileHandlers that get set up while
                                  * an async socket is not yet connected. */
-    int status;                 /* Cache status of async socket. */
+    int connectError;           /* Cache SO_ERROR of async socket. */
     int cachedBlocking;         /* Cache blocking mode of async socket. */
 };
 
@@ -82,8 +87,22 @@ struct TcpState {
  * structure.
  */
 
-#define TCP_ASYNC_SOCKET	(1<<0)	/* Asynchronous socket. */
+#define TCP_NONBLOCKING		(1<<0)	/* Socket with non-blocking I/O */
 #define TCP_ASYNC_CONNECT	(1<<1)	/* Async connect in progress. */
+#define TCP_ASYNC_PENDING	(1<<4)	/* TcpConnect was called to
+					 * process an async connect. This
+					 * flag indicates that reentry is
+					 * still pending */
+#define TCP_ASYNC_FAILED	(1<<5)	/* An async connect finally failed */
+
+/*
+ * These bits may be ORed together into the "testFlags" field of a TcpState
+ * structure.
+ */
+
+#define TCP_ASYNC_TEST_MODE	(1<<0)	/* Async testing activated.  Do not
+					 * automatically continue connection
+					 * process. */
 
 /*
  * The following defines the maximum length of the listen queue. This is the
@@ -110,8 +129,7 @@ struct TcpState {
  * Static routines for this file:
  */
 
-static int		CreateClientSocket(Tcl_Interp *interp,
-                                           TcpState *state);
+static int		TcpConnect(Tcl_Interp *interp, TcpState *state);
 static void		TcpAccept(ClientData data, int mask);
 static int		TcpBlockModeProc(ClientData data, int mode);
 static int		TcpCloseProc(ClientData instanceData,
@@ -129,6 +147,7 @@ static int		TcpOutputProc(ClientData instanceData,
 			    const char *buf, int toWrite, int *errorCode);
 static void		TcpWatchProc(ClientData instanceData, int mask);
 static int		WaitForConnect(TcpState *statePtr, int *errorCodePtr);
+static void		WrapNotify(ClientData clientData, int mask);
 
 /*
  * This structure describes the channel type structure for TCP socket
@@ -163,8 +182,26 @@ static TclInitProcessGlobalValueProc InitializeHostName;
 static ProcessGlobalValue hostName =
 	{0, 0, NULL, NULL, InitializeHostName, NULL, NULL};
 
+#if 0
+/* printf debugging */
+void
+printaddrinfo(
+    struct addrinfo *addrlist,
+    char *prefix)
+{
+    char host[NI_MAXHOST], port[NI_MAXSERV];
+    struct addrinfo *ai;
+
+    for (ai = addrlist; ai != NULL; ai = ai->ai_next) {
+	getnameinfo(ai->ai_addr, ai->ai_addrlen,
+		host, sizeof(host), port, sizeof(port),
+		NI_NUMERICHOST|NI_NUMERICSERV);
+	fprintf(stderr,"%s: %s:%s\n", prefix, host, port);
+    }
+}
+#endif
 /*
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  *
  * InitializeHostName --
  *
@@ -174,13 +211,13 @@ static ProcessGlobalValue hostName =
  * Results:
  *	None.
  *
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  */
 
 static void
 InitializeHostName(
     char **valuePtr,
-    int *lengthPtr,
+    unsigned int *lengthPtr,
     Tcl_Encoding *encodingPtr)
 {
     const char *native = NULL;
@@ -217,7 +254,7 @@ InitializeHostName(
         }
     }
     if (native == NULL) {
-	native = tclEmptyStringRep;
+	native = &tclEmptyString;
     }
 #else /* !NO_UNAME */
     /*
@@ -248,12 +285,12 @@ InitializeHostName(
 
     *encodingPtr = Tcl_GetEncoding(NULL, NULL);
     *lengthPtr = strlen(native);
-    *valuePtr = ckalloc((*lengthPtr) + 1);
-    memcpy(*valuePtr, native, (size_t)(*lengthPtr)+1);
+    *valuePtr = ckalloc(*lengthPtr + 1);
+    memcpy(*valuePtr, native, *lengthPtr + 1);
 }
 
 /*
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  *
  * Tcl_GetHostName --
  *
@@ -267,7 +304,7 @@ InitializeHostName(
  * Side effects:
  *	Caches the name to return for future calls.
  *
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  */
 
 const char *
@@ -277,7 +314,7 @@ Tcl_GetHostName(void)
 }
 
 /*
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  *
  * TclpHasSockets --
  *
@@ -289,7 +326,7 @@ Tcl_GetHostName(void)
  * Side effects:
  *	None.
  *
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  */
 
 int
@@ -300,7 +337,7 @@ TclpHasSockets(
 }
 
 /*
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  *
  * TclpFinalizeSockets --
  *
@@ -312,7 +349,7 @@ TclpHasSockets(
  * Side effects:
  *	None.
  *
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  */
 
 void
@@ -322,7 +359,7 @@ TclpFinalizeSockets(void)
 }
 
 /*
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  *
  * TcpBlockModeProc --
  *
@@ -335,7 +372,7 @@ TclpFinalizeSockets(void)
  * Side effects:
  *	Sets the device into blocking or nonblocking mode.
  *
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  */
 
 	/* ARGSUSED */
@@ -349,11 +386,11 @@ TcpBlockModeProc(
     TcpState *statePtr = instanceData;
 
     if (mode == TCL_MODE_BLOCKING) {
-	CLEAR_BITS(statePtr->flags, TCP_ASYNC_SOCKET);
+	CLEAR_BITS(statePtr->flags, TCP_NONBLOCKING);
     } else {
-	SET_BITS(statePtr->flags, TCP_ASYNC_SOCKET);
+	SET_BITS(statePtr->flags, TCP_NONBLOCKING);
     }
-    if (statePtr->flags & TCP_ASYNC_CONNECT) {
+    if (GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT)) {
         statePtr->cachedBlocking = mode;
         return 0;
     }
@@ -364,17 +401,32 @@ TcpBlockModeProc(
 }
 
 /*
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  *
  * WaitForConnect --
  *
- *	Wait for a connection on an asynchronously opened socket to be
- *	completed.  In nonblocking mode, just test if the connection
- *	has completed without blocking.
+ *	Check the state of an async connect process. If a connection attempt
+ *	terminated, process it, which may finalize it or may start the next
+ *	attempt. If a connect error occures, it is saved in
+ *	statePtr->connectError to be reported by 'fconfigure -error'.
+ *
+ *	There are two modes of operation, defined by errorCodePtr:
+ *	 *  non-NULL: Called by explicite read/write command. Blocks if the
+ *	    socket is blocking.
+ *	    May return two error codes:
+ *	     *	EWOULDBLOCK: if connect is still in progress
+ *	     *	ENOTCONN: if connect failed. This would be the error message
+ *		of a rect or sendto syscall so this is emulated here.
+ *	 *  NULL: Called by a backround operation. Do not block and do not
+ *	    return any error code.
  *
  * Results:
- * 	0 if the connection has completed, -1 if still in progress
- * 	or there is an error.
+ * 	0 if the connection has completed, -1 if still in progress or there is
+ * 	an error.
+ *
+ * Side effects:
+ *	Processes socket events off the system queue. May process
+ *	asynchroneous connects.
  *
  *----------------------------------------------------------------------
  */
@@ -382,34 +434,67 @@ TcpBlockModeProc(
 static int
 WaitForConnect(
     TcpState *statePtr,		/* State of the socket. */
-    int *errorCodePtr)		/* Where to store errors? */
+    int *errorCodePtr)
 {
-    int timeOut;		/* How long to wait. */
-    int state;			/* Of calling TclWaitForFile. */
+    int timeout;
 
     /*
-     * If an asynchronous connect is in progress, attempt to wait for it to
-     * complete before reading.
+     * Check if an async connect failed already and error reporting is
+     * demanded, return the error ENOTCONN
      */
 
-    if (statePtr->flags & TCP_ASYNC_CONNECT) {
-	if (statePtr->flags & TCP_ASYNC_SOCKET) {
-	    timeOut = 0;
-	} else {
-	    timeOut = -1;
-	}
-	errno = 0;
-	state = TclUnixWaitForFile(statePtr->fds.fd,
-		TCL_WRITABLE | TCL_EXCEPTION, timeOut);
-	if (state & TCL_EXCEPTION) {
-	    return -1;
-	}
-	if (state & TCL_WRITABLE) {
-	    CLEAR_BITS(statePtr->flags, TCP_ASYNC_CONNECT);
-	} else if (timeOut == 0) {
-	    *errorCodePtr = errno = EWOULDBLOCK;
-	    return -1;
-	}
+    if (errorCodePtr != NULL && GOT_BITS(statePtr->flags, TCP_ASYNC_FAILED)) {
+	*errorCodePtr = ENOTCONN;
+	return -1;
+    }
+
+    /*
+     * Check if an async connect is running. If not return ok
+     */
+
+    if (!GOT_BITS(statePtr->flags, TCP_ASYNC_PENDING)) {
+	return 0;
+    }
+
+    /*
+     * In socket test mode do not continue with the connect.
+     * Exceptions are:
+     * - Call by recv/send and blocking socket
+     *   (errorCodePtr != NULL && !GOT_BITS(flags, TCP_NONBLOCKING))
+     */
+
+    if (GOT_BITS(statePtr->testFlags, TCP_ASYNC_TEST_MODE)
+            && !(errorCodePtr != NULL
+                    && !GOT_BITS(statePtr->flags, TCP_NONBLOCKING))) {
+	*errorCodePtr = EWOULDBLOCK;
+	return -1;
+    }
+
+    if (errorCodePtr == NULL || GOT_BITS(statePtr->flags, TCP_NONBLOCKING)) {
+        timeout = 0;
+    } else {
+        timeout = -1;
+    }
+    do {
+        if (TclUnixWaitForFile(statePtr->fds.fd,
+                TCL_WRITABLE | TCL_EXCEPTION, timeout) != 0) {
+            TcpConnect(NULL, statePtr);
+        }
+
+        /*
+         * Do this only once in the nonblocking case and repeat it until the
+         * socket is final when blocking.
+         */
+    } while (timeout == -1 && GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT));
+
+    if (errorCodePtr != NULL) {
+        if (GOT_BITS(statePtr->flags, TCP_ASYNC_PENDING)) {
+            *errorCodePtr = EAGAIN;
+            return -1;
+        } else if (statePtr->connectError != 0) {
+            *errorCodePtr = ENOTCONN;
+            return -1;
+        }
     }
     return 0;
 }
@@ -503,6 +588,7 @@ TcpOutputProc(
 	return -1;
     }
     written = send(statePtr->fds.fd, buf, (size_t) toWrite, 0);
+
     if (written > -1) {
 	return written;
     }
@@ -545,7 +631,7 @@ TcpCloseProc(
      * handlers are already deleted in the generic IO channel closing code
      * that called this function, so we do not have to delete them here.
      */
-    
+
     for (fds = &statePtr->fds; fds != NULL; fds = fds->next) {
 	if (fds->fd < 0) {
 	    continue;
@@ -554,12 +640,13 @@ TcpCloseProc(
 	if (close(fds->fd) < 0) {
 	    errorCode = errno;
 	}
-    
+
     }
     fds = statePtr->fds.next;
     while (fds != NULL) {
 	TcpFdList *next = fds->next;
-        ckfree(fds);
+
+	ckfree(fds);
 	fds = next;
     }
     if (statePtr->addrlist != NULL) {
@@ -629,10 +716,9 @@ TcpClose2Proc(
  *
  * TcpHostPortList --
  *
- *	This function is called by the -gethostname and -getpeername
- *	switches of TcpGetOptionProc() to add three list elements
- *	with the textual representation of the given address to the
- *	given DString.
+ *	This function is called by the -gethostname and -getpeername switches
+ *	of TcpGetOptionProc() to add three list elements with the textual
+ *	representation of the given address to the given DString.
  *
  * Results:
  *	None.
@@ -642,6 +728,37 @@ TcpClose2Proc(
  *
  *----------------------------------------------------------------------
  */
+
+#ifndef NEED_FAKE_RFC2553
+#if defined (__clang__) || ((__GNUC__)  && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 5))))
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstrict-aliasing"
+#endif
+static inline int
+IPv6AddressNeedsNumericRendering(
+    struct in6_addr addr)
+{
+    if (IN6_ARE_ADDR_EQUAL(&addr, &in6addr_any)) {
+        return 1;
+    }
+
+    /*
+     * The IN6_IS_ADDR_V4MAPPED macro has a problem with aliasing warnings on
+     * at least some versions of OSX.
+     */
+
+    if (!IN6_IS_ADDR_V4MAPPED(&addr)) {
+        return 0;
+    }
+
+    return (addr.s6_addr[12] == 0 && addr.s6_addr[13] == 0
+            && addr.s6_addr[14] == 0 && addr.s6_addr[15] == 0);
+}
+#if defined (__clang__) || ((__GNUC__)  && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 5))))
+#pragma GCC diagnostic pop
+#endif
+#endif /* NEED_FAKE_RFC2553 */
+
 static void
 TcpHostPortList(
     Tcl_Interp *interp,
@@ -653,40 +770,47 @@ TcpHostPortList(
     char host[NI_MAXHOST], nhost[NI_MAXHOST], nport[NI_MAXSERV];
     int flags = 0;
 
-    getnameinfo(&addr.sa, salen,
-                nhost, sizeof(nhost), nport, sizeof(nport),
-                NI_NUMERICHOST | NI_NUMERICSERV);
+    getnameinfo(&addr.sa, salen, nhost, sizeof(nhost), nport, sizeof(nport),
+            NI_NUMERICHOST | NI_NUMERICSERV);
     Tcl_DStringAppendElement(dsPtr, nhost);
+
     /*
-     * We don't want to resolve INADDR_ANY and sin6addr_any; they
-     * can sometimes cause problems (and never have a name).
+     * We don't want to resolve INADDR_ANY and sin6addr_any; they can
+     * sometimes cause problems (and never have a name).
      */
+
     if (addr.sa.sa_family == AF_INET) {
         if (addr.sa4.sin_addr.s_addr == INADDR_ANY) {
             flags |= NI_NUMERICHOST;
         }
 #ifndef NEED_FAKE_RFC2553
     } else if (addr.sa.sa_family == AF_INET6) {
-        if ((IN6_ARE_ADDR_EQUAL(&addr.sa6.sin6_addr,
-                                &in6addr_any))
-            || (IN6_IS_ADDR_V4MAPPED(&addr.sa6.sin6_addr) &&
-                addr.sa6.sin6_addr.s6_addr[12] == 0 &&
-                addr.sa6.sin6_addr.s6_addr[13] == 0 &&
-                addr.sa6.sin6_addr.s6_addr[14] == 0 &&
-                addr.sa6.sin6_addr.s6_addr[15] == 0)) {
+        if (IPv6AddressNeedsNumericRendering(addr.sa6.sin6_addr)) {
             flags |= NI_NUMERICHOST;
         }
 #endif /* NEED_FAKE_RFC2553 */
     }
-    /* Check if reverse DNS has been switched off globally */
-    if (interp != NULL && Tcl_GetVar(interp, SUPPRESS_RDNS_VAR, 0) != NULL) {
+
+    /*
+     * Check if reverse DNS has been switched off globally.
+     */
+
+    if (interp != NULL &&
+            Tcl_GetVar2(interp, SUPPRESS_RDNS_VAR, NULL, 0) != NULL) {
         flags |= NI_NUMERICHOST;
     }
-    if (getnameinfo(&addr.sa, salen, host, sizeof(host), NULL, 0, flags) == 0) {
-        /* Reverse mapping worked */
+    if (getnameinfo(&addr.sa, salen, host, sizeof(host), NULL, 0,
+            flags) == 0) {
+        /*
+         * Reverse mapping worked.
+         */
+
         Tcl_DStringAppendElement(dsPtr, host);
     } else {
-        /* Reverse mappong failed - use the numeric rep once more */
+        /*
+         * Reverse mapping failed - use the numeric rep once more.
+         */
+
         Tcl_DStringAppendElement(dsPtr, nhost);
     }
     Tcl_DStringAppendElement(dsPtr, nport);
@@ -726,6 +850,8 @@ TcpGetOptionProc(
     TcpState *statePtr = instanceData;
     size_t len = 0;
 
+    WaitForConnect(statePtr, NULL);
+
     if (optionName != NULL) {
 	len = strlen(optionName);
     }
@@ -733,30 +859,57 @@ TcpGetOptionProc(
     if ((len > 1) && (optionName[1] == 'e') &&
 	    (strncmp(optionName, "-error", len) == 0)) {
 	socklen_t optlen = sizeof(int);
-	int err, ret;
 
-        if (statePtr->status == 0) {
-            ret = getsockopt(statePtr->fds.fd, SOL_SOCKET, SO_ERROR,
-                    (char *) &err, &optlen);
-            if (ret < 0) {
-                err = errno;
-            }
+        if (GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT)) {
+            /*
+             * Suppress errors as long as we are not done.
+             */
+
+            errno = 0;
+        } else if (statePtr->connectError != 0) {
+            errno = statePtr->connectError;
+            statePtr->connectError = 0;
         } else {
-            err = statePtr->status;
-            statePtr->status = 0;
+            int err;
+
+            getsockopt(statePtr->fds.fd, SOL_SOCKET, SO_ERROR, (char *) &err,
+                    &optlen);
+            errno = err;
+        }
+        if (errno != 0) {
+	    Tcl_DStringAppend(dsPtr, Tcl_ErrnoMsg(errno), -1);
         }
-	if (err != 0) {
-	    Tcl_DStringAppend(dsPtr, Tcl_ErrnoMsg(err), -1);
-	}
 	return TCL_OK;
     }
 
+    if ((len > 1) && (optionName[1] == 'c') &&
+	    (strncmp(optionName, "-connecting", len) == 0)) {
+        Tcl_DStringAppend(dsPtr,
+                GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT) ? "1" : "0", -1);
+        return TCL_OK;
+    }
+
     if ((len == 0) || ((len > 1) && (optionName[1] == 'p') &&
 	    (strncmp(optionName, "-peername", len) == 0))) {
         address peername;
         socklen_t size = sizeof(peername);
 
-	if (getpeername(statePtr->fds.fd, &peername.sa, &size) >= 0) {
+	if (GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT)) {
+	    /*
+	     * In async connect output an empty string
+	     */
+
+	    if (len == 0) {
+		Tcl_DStringAppendElement(dsPtr, "-peername");
+		Tcl_DStringAppendElement(dsPtr, "");
+	    } else {
+		return TCL_OK;
+	    }
+	} else if (getpeername(statePtr->fds.fd, &peername.sa, &size) >= 0) {
+	    /*
+	     * Peername fetch succeeded - output list
+	     */
+
 	    if (len == 0) {
 		Tcl_DStringAppendElement(dsPtr, "-peername");
 		Tcl_DStringStartSublist(dsPtr);
@@ -796,11 +949,19 @@ TcpGetOptionProc(
 	    Tcl_DStringAppendElement(dsPtr, "-sockname");
 	    Tcl_DStringStartSublist(dsPtr);
 	}
-	for (fds = &statePtr->fds; fds != NULL; fds = fds->next) {
-	    size = sizeof(sockname);
-	    if (getsockname(fds->fd, &(sockname.sa), &size) >= 0) {
-		found = 1;
-                TcpHostPortList(interp, dsPtr, sockname, size);
+	if (GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT)) {
+	    /*
+	     * In async connect output an empty string
+	     */
+
+            found = 1;
+	} else {
+	    for (fds = &statePtr->fds; fds != NULL; fds = fds->next) {
+		size = sizeof(sockname);
+		if (getsockname(fds->fd, &(sockname.sa), &size) >= 0) {
+		    found = 1;
+		    TcpHostPortList(interp, dsPtr, sockname, size);
+		}
 	    }
 	}
         if (found) {
@@ -818,14 +979,15 @@ TcpGetOptionProc(
     }
 
     if (len > 0) {
-	return Tcl_BadChannelOption(interp, optionName, "peername sockname");
+	return Tcl_BadChannelOption(interp, optionName,
+                "connecting peername sockname");
     }
 
     return TCL_OK;
 }
 
 /*
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  *
  * TcpWatchProc --
  *
@@ -838,10 +1000,39 @@ TcpGetOptionProc(
  *	Sets up the notifier so that a future event on the channel will be
  *	seen by Tcl.
  *
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  */
 
 static void
+WrapNotify(
+    ClientData clientData,
+    int mask)
+{
+    TcpState *statePtr = (TcpState *) clientData;
+    int newmask = mask & statePtr->interest;
+
+    if (newmask == 0) {
+	/*
+	 * There was no overlap between the states the channel is interested
+	 * in notifications for, and the states that are reported present on
+	 * the file descriptor by select().  The only way that can happen is
+	 * when the channel is interested in a writable condition, and only a
+	 * readable state is reported present (see TcpWatchProc() below).  In
+	 * that case, signal back to the caller the writable state, which is
+	 * really an error condition.  As an extra check on that assumption,
+	 * check for a non-zero value of errno before reporting an artificial
+	 * writable state.
+	 */
+
+	if (errno == 0) {
+	    return;
+	}
+	newmask = TCL_WRITABLE;
+    }
+    Tcl_NotifyChannel(statePtr->channel, newmask);
+}
+
+static void
 TcpWatchProc(
     ClientData instanceData,	/* The socket state. */
     int mask)			/* Events of interest; an OR-ed combination of
@@ -856,23 +1047,48 @@ TcpWatchProc(
          * be readable or writable at the Tcl level. This keeps Tcl scripts
          * from interfering with the -accept behavior (bug #3394732).
          */
+
     	return;
     }
-     
-    if (statePtr->flags & TCP_ASYNC_CONNECT) {
-        /* Async sockets use a FileHandler internally while connecting, so we
-         * need to cache this request until the connection has succeeded. */
+
+    if (GOT_BITS(statePtr->flags, TCP_ASYNC_PENDING)) {
+        /*
+         * Async sockets use a FileHandler internally while connecting, so we
+         * need to cache this request until the connection has succeeded.
+         */
+
         statePtr->filehandlers = mask;
     } else if (mask) {
-        Tcl_CreateFileHandler(statePtr->fds.fd, mask,
-                (Tcl_FileProc *) Tcl_NotifyChannel, statePtr->channel);
+
+	/*
+	 * Whether it is a bug or feature or otherwise, it is a fact of life
+	 * that on at least some Linux kernels select() fails to report that a
+	 * socket file descriptor is writable when the other end of the socket
+	 * is closed.  This is in contrast to the guarantees Tcl makes that
+	 * its channels become writable and fire writable events on an error
+	 * conditon.  This has caused a leak of file descriptors in a state of
+	 * background flushing.  See Tcl ticket 1758a0b603.
+	 *
+	 * As a workaround, when our caller indicates an interest in writable
+	 * notifications, we must tell the notifier built around select() that
+	 * we are interested in the readable state of the file descriptor as
+	 * well, as that is the only reliable means to get notified of error
+	 * conditions.  Then it is the task of WrapNotify() above to untangle
+	 * the meaning of these channel states and report the chan events as
+	 * best it can.  We save a copy of the mask passed in to assist with
+	 * that.
+	 */
+
+	statePtr->interest = mask;
+        Tcl_CreateFileHandler(statePtr->fds.fd, mask|TCL_READABLE,
+                (Tcl_FileProc *) WrapNotify, statePtr);
     } else {
         Tcl_DeleteFileHandler(statePtr->fds.fd);
     }
 }
 
 /*
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  *
  * TcpGetHandleProc --
  *
@@ -886,7 +1102,7 @@ TcpWatchProc(
  * Side effects:
  *	None.
  *
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  */
 
 	/* ARGSUSED */
@@ -903,16 +1119,17 @@ TcpGetHandleProc(
 }
 
 /*
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  *
  * TcpAsyncCallback --
  *
- *	Called by the event handler that CreateClientSocket sets up
- *	internally for [socket -async] to get notified when the
- *	asyncronous connection attempt has succeeded or failed.
+ *	Called by the event handler that TcpConnect sets up internally for
+ *	[socket -async] to get notified when the asynchronous connection
+ *	attempt has succeeded or failed.
  *
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  */
+
 static void
 TcpAsyncCallback(
     ClientData clientData,	/* The socket state. */
@@ -920,13 +1137,13 @@ TcpAsyncCallback(
 				 * TCL_READABLE, TCL_WRITABLE and
 				 * TCL_EXCEPTION. */
 {
-    CreateClientSocket(NULL, clientData);
+    TcpConnect(NULL, clientData);
 }
 
 /*
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  *
- * CreateClientSocket --
+ * TcpConnect --
  *
  *	This function opens a new socket in client mode.
  *
@@ -940,7 +1157,7 @@ TcpAsyncCallback(
  *
  * Remarks:
  *	A single host name may resolve to more than one IP address, e.g. for
- *	an IPv4/IPv6 dual stack host. For handling asyncronously connecting
+ *	an IPv4/IPv6 dual stack host. For handling asynchronously connecting
  *	sockets in the background for such hosts, this function can act as a
  *	coroutine. On the first call, it sets up the control variables for the
  *	two nested loops over the local and remote addresses. Once the first
@@ -948,39 +1165,38 @@ TcpAsyncCallback(
  *	event handler for that socket, and returns. When the callback occurs,
  *	control is transferred to the "reenter" label, right after the initial
  *	return and the loops resume as if they had never been interrupted.
- *	For syncronously connecting sockets, the loops work the usual way.
+ *	For synchronously connecting sockets, the loops work the usual way.
  *
- *----------------------------------------------------------------------
+ * ----------------------------------------------------------------------
  */
 
 static int
-CreateClientSocket(
+TcpConnect(
     Tcl_Interp *interp,		/* For error reporting; can be NULL. */
-    TcpState *state)
+    TcpState *statePtr)
 {
     socklen_t optlen;
-    int async_callback = (state->addr != NULL);
-    int status;
-    int async = state->flags & TCP_ASYNC_CONNECT;
+    int async_callback = GOT_BITS(statePtr->flags, TCP_ASYNC_PENDING);
+    int ret = -1, error = EHOSTUNREACH;
+    int async = GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT);
 
     if (async_callback) {
         goto reenter;
     }
 
-    for (state->addr = state->addrlist; state->addr != NULL;
-            state->addr = state->addr->ai_next) {
-	status = -1;
+    for (statePtr->addr = statePtr->addrlist; statePtr->addr != NULL;
+            statePtr->addr = statePtr->addr->ai_next) {
+        for (statePtr->myaddr = statePtr->myaddrlist;
+                statePtr->myaddr != NULL;
+                statePtr->myaddr = statePtr->myaddr->ai_next) {
+            int reuseaddr = 1;
 
-        for (state->myaddr = state->myaddrlist; state->myaddr != NULL;
-                state->myaddr = state->myaddr->ai_next) {
-            int reuseaddr;
-            
 	    /*
 	     * No need to try combinations of local and remote addresses of
 	     * different families.
 	     */
 
-	    if (state->myaddr->ai_family != state->addr->ai_family) {
+	    if (statePtr->myaddr->ai_family != statePtr->addr->ai_family) {
 		continue;
 	    }
 
@@ -989,13 +1205,15 @@ CreateClientSocket(
              * iteration.
              */
 
-            if (state->fds.fd >= 0) {
-		close(state->fds.fd);
-		state->fds.fd = -1;
+            if (statePtr->fds.fd >= 0) {
+		close(statePtr->fds.fd);
+		statePtr->fds.fd = -1;
+                errno = 0;
 	    }
 
-	    state->fds.fd = socket(state->addr->ai_family, SOCK_STREAM, 0);
-	    if (state->fds.fd < 0) {
+	    statePtr->fds.fd = socket(statePtr->addr->ai_family, SOCK_STREAM,
+                    0);
+	    if (statePtr->fds.fd < 0) {
 		continue;
 	    }
 
@@ -1003,29 +1221,36 @@ CreateClientSocket(
 	     * Set the close-on-exec flag so that the socket will not get
 	     * inherited by child processes.
 	     */
-	    
-	    fcntl(state->fds.fd, F_SETFD, FD_CLOEXEC);
-	    
+
+	    fcntl(statePtr->fds.fd, F_SETFD, FD_CLOEXEC);
+
 	    /*
 	     * Set kernel space buffering
 	     */
-	    
-	    TclSockMinimumBuffers(INT2PTR(state->fds.fd), SOCKET_BUFSIZE);
-    
+
+	    TclSockMinimumBuffers(INT2PTR(statePtr->fds.fd), SOCKET_BUFSIZE);
+
 	    if (async) {
-		status = TclUnixSetBlockingMode(state->fds.fd,
+                ret = TclUnixSetBlockingMode(statePtr->fds.fd,
                         TCL_MODE_NONBLOCKING);
-		if (status < 0) {
+                if (ret < 0) {
                     continue;
-		}
-	    }
+                }
+            }
+
+            /*
+             * Must reset the error variable here, before we use it for the
+             * first time in this iteration.
+             */
+
+            error = 0;
 
-            reuseaddr = 1;
-            (void) setsockopt(state->fds.fd, SOL_SOCKET, SO_REUSEADDR,
+            (void) setsockopt(statePtr->fds.fd, SOL_SOCKET, SO_REUSEADDR,
                     (char *) &reuseaddr, sizeof(reuseaddr));
-            status = bind(state->fds.fd, state->myaddr->ai_addr,
-                    state->myaddr->ai_addrlen);
-            if (status < 0) {
+            ret = bind(statePtr->fds.fd, statePtr->myaddr->ai_addr,
+                    statePtr->myaddr->ai_addrlen);
+            if (ret < 0) {
+                error = errno;
                 continue;
             }
 
@@ -1035,16 +1260,23 @@ CreateClientSocket(
 	     * will set up a file handler on the socket if she is interested
 	     * in being informed when the connect completes.
 	     */
-	    
-	    status = connect(state->fds.fd, state->addr->ai_addr,
-                    state->addr->ai_addrlen);
-	    if (status < 0 && errno == EINPROGRESS) {
-                Tcl_CreateFileHandler(state->fds.fd,
-                        TCL_WRITABLE|TCL_EXCEPTION, TcpAsyncCallback, state);
+
+	    ret = connect(statePtr->fds.fd, statePtr->addr->ai_addr,
+                        statePtr->addr->ai_addrlen);
+            if (ret < 0) {
+                error = errno;
+            }
+	    if (ret < 0 && errno == EINPROGRESS) {
+                Tcl_CreateFileHandler(statePtr->fds.fd,
+                        TCL_WRITABLE | TCL_EXCEPTION, TcpAsyncCallback,
+                        statePtr);
+                errno = EWOULDBLOCK;
+                SET_BITS(statePtr->flags, TCP_ASYNC_PENDING);
                 return TCL_OK;
 
             reenter:
-                Tcl_DeleteFileHandler(state->fds.fd);
+                CLEAR_BITS(statePtr->flags, TCP_ASYNC_PENDING);
+                Tcl_DeleteFileHandler(statePtr->fds.fd);
 
                 /*
                  * Read the error state from the socket to see if the async
@@ -1054,26 +1286,31 @@ CreateClientSocket(
                  */
 
                 optlen = sizeof(int);
-                getsockopt(state->fds.fd, SOL_SOCKET, SO_ERROR,
-                        (char *) &status, &optlen);
-                state->status = status;
+
+                getsockopt(statePtr->fds.fd, SOL_SOCKET, SO_ERROR,
+                        (char *) &error, &optlen);
+                errno = error;
             }
-	    if (status == 0) {
-		CLEAR_BITS(state->flags, TCP_ASYNC_CONNECT);
+	    if (error == 0) {
 		goto out;
 	    }
 	}
     }
 
-out:
-
+  out:
+    statePtr->connectError = error;
+    CLEAR_BITS(statePtr->flags, TCP_ASYNC_CONNECT);
     if (async_callback) {
         /*
          * An asynchonous connection has finally succeeded or failed.
          */
 
-        TcpWatchProc(state, state->filehandlers);
-        TclUnixSetBlockingMode(state->fds.fd, state->cachedBlocking);
+        TcpWatchProc(statePtr, statePtr->filehandlers);
+        TclUnixSetBlockingMode(statePtr->fds.fd, statePtr->cachedBlocking);
+
+        if (error != 0) {
+            SET_BITS(statePtr->flags, TCP_ASYNC_FAILED);
+        }
 
         /*
          * We need to forward the writable event that brought us here, bcasue
@@ -1084,8 +1321,11 @@ out:
          * the event mechanism one roundtrip through select().
          */
 
-        Tcl_NotifyChannel(state->channel, TCL_WRITABLE);
-    } else if (status != 0) {
+	if (statePtr->cachedBlocking == TCL_MODE_NONBLOCKING) {
+	    Tcl_NotifyChannel(statePtr->channel, TCL_WRITABLE);
+	}
+    }
+    if (error != 0) {
         /*
          * Failure for either a synchronous connection, or an async one that
          * failed before it could enter background mode, e.g. because an
@@ -1093,6 +1333,7 @@ out:
          */
 
         if (interp != NULL) {
+            errno = error;
             Tcl_SetObjResult(interp, Tcl_ObjPrintf(
                     "couldn't open socket: %s", Tcl_PosixError(interp)));
         }
@@ -1129,9 +1370,9 @@ Tcl_OpenTcpClient(
 				 * connect. Otherwise we do a blocking
 				 * connect. */
 {
-    TcpState *state;
+    TcpState *statePtr;
     const char *errorMsg = NULL;
-    void *addrlist = NULL, *myaddrlist = NULL;
+    struct addrinfo *addrlist = NULL, *myaddrlist = NULL;
     char channelName[SOCK_CHAN_LENGTH];
 
     /*
@@ -1154,32 +1395,34 @@ Tcl_OpenTcpClient(
     /*
      * Allocate a new TcpState for this socket.
      */
-    state = ckalloc(sizeof(TcpState));
-    memset(state, 0, sizeof(TcpState));
-    state->flags = async ? TCP_ASYNC_CONNECT : 0;
-    state->cachedBlocking = TCL_MODE_BLOCKING;
-    state->addrlist = addrlist;
-    state->myaddrlist = myaddrlist;
-    state->fds.fd = -1;
+
+    statePtr = ckalloc(sizeof(TcpState));
+    memset(statePtr, 0, sizeof(TcpState));
+    statePtr->flags = async ? TCP_ASYNC_CONNECT : 0;
+    statePtr->cachedBlocking = TCL_MODE_BLOCKING;
+    statePtr->addrlist = addrlist;
+    statePtr->myaddrlist = myaddrlist;
+    statePtr->fds.fd = -1;
 
     /*
      * Create a new client socket and wrap it in a channel.
      */
-    if (CreateClientSocket(interp, state) != TCL_OK) {
-        TcpCloseProc(state, NULL);
+
+    if (TcpConnect(interp, statePtr) != TCL_OK) {
+        TcpCloseProc(statePtr, NULL);
         return NULL;
     }
 
-    sprintf(channelName, SOCK_TEMPLATE, (long) state);
+    sprintf(channelName, SOCK_TEMPLATE, (long) statePtr);
 
-    state->channel = Tcl_CreateChannel(&tcpChannelType, channelName, state,
-            (TCL_READABLE | TCL_WRITABLE));
-    if (Tcl_SetChannelOption(interp, state->channel, "-translation",
+    statePtr->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
+            statePtr, TCL_READABLE | TCL_WRITABLE);
+    if (Tcl_SetChannelOption(interp, statePtr->channel, "-translation",
 	    "auto crlf") == TCL_ERROR) {
-	Tcl_Close(NULL, state->channel);
+	Tcl_Close(NULL, statePtr->channel);
 	return NULL;
     }
-    return state->channel;
+    return statePtr->channel;
 }
 
 /*
@@ -1202,7 +1445,8 @@ Tcl_Channel
 Tcl_MakeTcpClientChannel(
     ClientData sock)		/* The socket to wrap up into a channel. */
 {
-    return (Tcl_Channel) TclpMakeTcpClientChannelMode(sock, (TCL_READABLE | TCL_WRITABLE));
+    return (Tcl_Channel) TclpMakeTcpClientChannelMode(sock,
+            TCL_READABLE | TCL_WRITABLE);
 }
 
 /*
@@ -1251,7 +1495,7 @@ TclpMakeTcpClientChannelMode(
 /*
  *----------------------------------------------------------------------
  *
- * Tcl_OpenTcpServer --
+ * Tcl_OpenTcpServerEx --
  *
  *	Opens a TCP server socket and creates a channel around it.
  *
@@ -1266,18 +1510,18 @@ TclpMakeTcpClientChannelMode(
  */
 
 Tcl_Channel
-Tcl_OpenTcpServer(
+Tcl_OpenTcpServerEx(
     Tcl_Interp *interp,		/* For error reporting - may be NULL. */
-    int port,			/* Port number to open. */
+    const char *service,	/* Port number to open. */
     const char *myHost,		/* Name of local host. */
+    unsigned int flags,		/* Flags. */
     Tcl_TcpAcceptProc *acceptProc,
 				/* Callback for accepting connections from new
 				 * clients. */
     ClientData acceptProcData)	/* Data for the callback. */
 {
-    int status = 0, sock = -1, reuseaddr = 1, chosenport = 0;
-    void *addrlist = NULL;
-    struct addrinfo *addrPtr;	/* socket address */
+    int status = 0, sock = -1, optvalue, port, chosenport;
+    struct addrinfo *addrlist = NULL, *addrPtr;	/* socket address */
     TcpState *statePtr = NULL;
     char channelName[SOCK_CHAN_LENGTH];
     const char *errorMsg = NULL;
@@ -1291,7 +1535,45 @@ Tcl_OpenTcpServer(
     enum { LOOKUP, SOCKET, BIND, LISTEN } howfar = LOOKUP;
     int my_errno = 0;
 
-    if (!TclCreateSocketAddress(interp, &addrlist, myHost, port, 1, &errorMsg)) {
+    /*
+     * If we were called with port 0 to listen on a random port number, we
+     * copy the port number from the first member of the addrinfo list to all
+     * subsequent members, so that IPv4 and IPv6 listen on the same port. This
+     * might fail to bind() with EADDRINUSE if a port is free on the first
+     * address family in the list but already used on the other. In this case
+     * we revert everything we've done so far and start from scratch hoping
+     * that next time we'll find a port number that is usable on all address
+     * families. We try this at most MAXRETRY times to avoid an endless loop
+     * if all ports are taken.
+     */
+
+    int retry = 0;
+#define MAXRETRY 10
+
+ repeat:
+    if (retry > 0) {
+        if (statePtr != NULL) {
+            TcpCloseProc(statePtr, NULL);
+            statePtr = NULL;
+        }
+        if (addrlist != NULL) {
+            freeaddrinfo(addrlist);
+            addrlist = NULL;
+        }
+        if (retry >= MAXRETRY) {
+            goto error;
+        }
+    }
+    retry++;
+    chosenport = 0;
+
+    if (TclSockGetPort(interp, service, "tcp", &port) != TCL_OK) {
+	errorMsg = "invalid port number";
+	goto error;
+    }
+
+    if (!TclCreateSocketAddress(interp, &addrlist, myHost, port, 1,
+            &errorMsg)) {
 	my_errno = errno;
 	goto error;
     }
@@ -1306,28 +1588,46 @@ Tcl_OpenTcpServer(
 	    }
 	    continue;
 	}
-	
+
 	/*
 	 * Set the close-on-exec flag so that the socket will not get
 	 * inherited by child processes.
 	 */
-	
+
 	fcntl(sock, F_SETFD, FD_CLOEXEC);
-	
+
 	/*
 	 * Set kernel space buffering
 	 */
-	
+
 	TclSockMinimumBuffers(INT2PTR(sock), SOCKET_BUFSIZE);
-	
+
 	/*
-	 * Set up to reuse server addresses automatically and bind to the
-	 * specified port.
+	 * Set up to reuse server addresses and/or ports if requested.
 	 */
-	
-	(void) setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, 
-		(char *) &reuseaddr, sizeof(reuseaddr));
-	
+
+	if (GOT_BITS(flags, TCL_TCPSERVER_REUSEADDR)) {
+	    optvalue = 1;
+	    (void) setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
+		    (char *) &optvalue, sizeof(optvalue));
+	}
+
+	if (GOT_BITS(flags, TCL_TCPSERVER_REUSEPORT)) {
+#ifndef SO_REUSEPORT
+	    /*
+	     * If the platform doesn't support the SO_REUSEPORT flag we can't
+	     * do much beside erroring out.
+	     */
+
+	    errorMsg = "SO_REUSEPORT isn't supported by this platform";
+	    goto error;
+#else
+	    optvalue = 1;
+	    (void) setsockopt(sock, SOL_SOCKET, SO_REUSEPORT,
+		    (char *) &optvalue, sizeof(optvalue));
+#endif
+	}
+
         /*
          * Make sure we use the same port number when opening two server
          * sockets for IPv4 and IPv6 on a random port.
@@ -1342,7 +1642,10 @@ Tcl_OpenTcpServer(
 	}
 
 #ifdef IPV6_V6ONLY
-	/* Missing on: Solaris 2.8 */
+	/*
+         * Missing on: Solaris 2.8
+         */
+
         if (addrPtr->ai_family == AF_INET6) {
             int v6only = 1;
 
@@ -1356,8 +1659,12 @@ Tcl_OpenTcpServer(
 	    if (howfar < BIND) {
 		howfar = BIND;
 		my_errno = errno;
-	    }       
+	    }
             close(sock);
+            sock = -1;
+            if (port == 0 && errno == EADDRINUSE) {
+                goto repeat;
+            }
             continue;
         }
         if (port == 0 && chosenport == 0) {
@@ -1380,13 +1687,17 @@ Tcl_OpenTcpServer(
 		my_errno = errno;
 	    }
             close(sock);
+            sock = -1;
+            if (port == 0 && errno == EADDRINUSE) {
+                goto repeat;
+            }
             continue;
         }
         if (statePtr == NULL) {
             /*
              * Allocate a new TcpState for this socket.
              */
-            
+
             statePtr = ckalloc(sizeof(TcpState));
             memset(statePtr, 0, sizeof(TcpState));
             statePtr->acceptProc = acceptProc;
@@ -1401,12 +1712,12 @@ Tcl_OpenTcpServer(
         newfds->fd = sock;
         newfds->statePtr = statePtr;
         fds = newfds;
-	
+
         /*
          * Set up the callback mechanism for accepting connections from new
          * clients.
          */
-        
+
         Tcl_CreateFileHandler(sock, TCL_READABLE, TcpAccept, fds);
     }
 
@@ -1465,7 +1776,7 @@ TcpAccept(
     socklen_t len;		/* For accept interface */
     char channelName[SOCK_CHAN_LENGTH];
     char host[NI_MAXHOST], port[NI_MAXSERV];
-    
+
     len = sizeof(addr);
     newsock = accept(fds->fd, &addr.sa, &len);
     if (newsock < 0) {
@@ -1486,7 +1797,7 @@ TcpAccept(
 
     sprintf(channelName, SOCK_TEMPLATE, (long) newSockState);
     newSockState->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
-	    newSockState, (TCL_READABLE | TCL_WRITABLE));
+	    newSockState, TCL_READABLE | TCL_WRITABLE);
 
     Tcl_SetChannelOption(NULL, newSockState->channel, "-translation",
 	    "auto crlf");