unixctl: Add support for Windows.

For Windows, use a kernel assigned localhost TCP port to listen for
runtime management connections and then write it into a file
so that a client can read it and then make a TCP connection.

Since we do not have the infrastructure to create pidfiles on
windows as of now, we create the *.ctl file without a pid. This
should be okay since we use different OVS_RUNDIR when we run
multiple copies of a daemon.

We do not generate man pages on Windows. But we still update them
for Windows so that anyone can read it elsewhere. Since we do not
generate it directly, we cannot dynamically show the configured
OVS_RUNDIR in windows. So, I have a not so nice \fIOVS_RUNDIR\fR
in the man page.

Signed-off-by: Gurucharan Shetty <[email protected]>
Acked-by: Ben Pfaff <[email protected]>

lib/unixctl.c

@@ -27,6 +27,7 @@
 #include "poll-loop.h"
 #include "shash.h"
 #include "stream.h"
+#include "stream-provider.h"
 #include "svec.h"
 #include "vlog.h"
 
@@ -177,19 +178,26 @@ unixctl_command_reply_error(struct unixctl_conn *conn, const char *error)
     unixctl_command_reply__(conn, false, error);
 }
 
-/* Creates a unixctl server listening on 'path', which may be:
+/* Creates a unixctl server listening on 'path', which for POSIX may be:
  *
  *      - NULL, in which case <rundir>/<program>.<pid>.ctl is used.
  *
- *      - "none", in which case the function will return successfully but
- *        no socket will actually be created.
- *
  *      - A name that does not start with '/', in which case it is put in
  *        <rundir>.
  *
  *      - An absolute path (starting with '/') that gives the exact name of
  *        the Unix domain socket to listen on.
  *
+ * For Windows, a kernel assigned TCP port is used and written in 'path'
+ * which may be:
+ *
+ *      - NULL, in which case <rundir>/<program>.ctl is used.
+ *
+ *      - An absolute path that gives the name of the file.
+ *
+ * For both POSIX and Windows, if the path is "none", the function will
+ * return successfully but no socket will actually be created.
+ *
  * A program that (optionally) daemonizes itself should call this function
  * *after* daemonization, so that the socket name contains the pid of the
  * daemon instead of the pid of the program that exited.  (Otherwise,
@@ -203,29 +211,59 @@ unixctl_server_create(const char *path, struct unixctl_server **serverp)
 {
     struct unixctl_server *server;
     struct pstream *listener;
-    char *punix_path;
+    char *punix_path, *abs_path = NULL;
     int error;
+#ifdef _WIN32
+    FILE *file;
+#endif
 
     *serverp = NULL;
     if (path && !strcmp(path, "none")) {
         return 0;
     }
 
+#ifndef _WIN32
     if (path) {
-        char *abs_path = abs_file_name(ovs_rundir(), path);
+        abs_path = abs_file_name(ovs_rundir(), path);
         punix_path = xasprintf("punix:%s", abs_path);
-        free(abs_path);
     } else {
         punix_path = xasprintf("punix:%s/%s.%ld.ctl", ovs_rundir(),
                                program_name, (long int) getpid());
     }
+#else
+    punix_path = xstrdup("ptcp:0:127.0.0.1");
+#endif
 
     error = pstream_open(punix_path, &listener, 0);
     if (error) {
         ovs_error(error, "could not initialize control socket %s", punix_path);
         goto exit;
     }
 
+#ifdef _WIN32
+    if (path) {
+        abs_path = xstrdup(path);
+    } else {
+        abs_path = xasprintf("%s/%s.ctl", ovs_rundir(), program_name);
+    }
+
+    file = fopen(abs_path, "w");
+    if (!file) {
+        error = errno;
+        ovs_error(error, "could not open %s", abs_path);
+        goto exit;
+    }
+
+    fprintf(file, "%d\n", ntohs(listener->bound_port));
+    if (fflush(file) == EOF) {
+        error = EIO;
+        ovs_error(error, "write failed for %s", abs_path);
+        fclose(file);
+        goto exit;
+    }
+    fclose(file);
+#endif
+
     unixctl_command_register("help", "", 0, 0, unixctl_help, NULL);
     unixctl_command_register("version", "", 0, 0, unixctl_version, NULL);
 
@@ -235,6 +273,9 @@ unixctl_server_create(const char *path, struct unixctl_server **serverp)
     *serverp = server;
 
 exit:
+    if (abs_path) {
+        free(abs_path);
+    }
     free(punix_path);
     return error;
 }
@@ -404,9 +445,12 @@ unixctl_server_destroy(struct unixctl_server *server)
     }
 }
 
-/* Connects to a unixctl server socket.  'path' should be the name of a unixctl
- * server socket.  If it does not start with '/', it will be prefixed with the
- * rundir (e.g. /usr/local/var/run/openvswitch).
+/* On POSIX based systems, connects to a unixctl server socket.  'path' should
+ * be the name of a unixctl server socket.  If it does not start with '/', it
+ * will be prefixed with the rundir (e.g. /usr/local/var/run/openvswitch).
+ *
+ * On Windows, connects to a localhost TCP port as written inside 'path'.
+ * 'path' should be an absolute path of the file.
  *
  * Returns 0 if successful, otherwise a positive errno value.  If successful,
  * sets '*client' to the new jsonrpc, otherwise to NULL. */
@@ -416,11 +460,35 @@ unixctl_client_create(const char *path, struct jsonrpc **client)
     char *abs_path, *unix_path;
     struct stream *stream;
     int error;
+#ifdef _WIN32
+    FILE *file;
+    int port;
+
+    abs_path = strdup(path);
+    file = fopen(abs_path, "r");
+    if (!file) {
+        int error = errno;
+        ovs_error(error, "could not open %s", abs_path);
+        free(abs_path);
+        return error;
+    }
 
-    *client = NULL;
+    error = fscanf(file, "%d", &port);
+    if (error != 1) {
+        ovs_error(errno, "failed to read port from %s", abs_path);
+        free(abs_path);
+        return EINVAL;
+    }
+    fclose(file);
 
+    unix_path = xasprintf("tcp:127.0.0.1:%d", port);
+#else
     abs_path = abs_file_name(ovs_rundir(), path);
     unix_path = xasprintf("unix:%s", abs_path);
+#endif
+
+    *client = NULL;
+
     error = stream_open_block(stream_open(unix_path, &stream, DSCP_DEFAULT),
                               &stream);
     free(unix_path);

lib/unixctl.man

@@ -6,5 +6,12 @@ interpreted as relative to \fB@RUNDIR@\fR.  If \fB\-\-unixctl\fR is
 not used at all, the default socket is
 \fB@RUNDIR@/\*(PN.\fIpid\fB.ctl\fR, where \fIpid\fR is \fB\*(PN\fR's
 process ID.
+.IP
+On Windows, uses a kernel chosen TCP port on the localhost to listen
+for runtime management commands.  The kernel chosen TCP port value is written
+in a file whose absolute path is pointed by \fIsocket\fR. If \fB\-\-unixctl\fR
+is not used at all, the file is created as \fB\*(PN.ctl\fR in the configured
+\fIOVS_RUNDIR\fR directory.
+.IP
 Specifying \fBnone\fR for \fIsocket\fR disables the control socket
 feature.