Extend RPC server to allow FD passing

The RPC server classes are extended to allow FDs to be received
from clients with calls. There is not currently any way for a
procedure to pass FDs back to the client with replies

* daemon/remote.c, src/rpc/gendispatch.pl: Change virNetMessageHeaderPtr
  param to virNetMessagePtr in dispatcher impls
* src/rpc/virnetserver.c, src/rpc/virnetserverclient.c,
  src/rpc/virnetserverprogram.c, src/rpc/virnetserverprogram.h:
  Extend to support FD passing

src/libvirt_private.syms

@@ -1191,6 +1191,7 @@ virNetClientHasPassFD;
 # virnetmessage.h
 virNetMessageClear;
 virNetMessageDecodeNumFDs;
+virNetMessageDupFD;
 virNetMessageEncodeHeader;
 virNetMessageEncodePayload;
 virNetMessageEncodeNumFDs;

src/remote/remote_protocol.x

@@ -2348,7 +2348,7 @@ enum remote_procedure {
     REMOTE_PROC_DOMAIN_GET_SCHEDULER_PARAMETERS = 57, /* skipgen autogen */
     REMOTE_PROC_DOMAIN_SET_SCHEDULER_PARAMETERS = 58, /* autogen autogen */
     REMOTE_PROC_GET_HOSTNAME = 59, /* autogen autogen priority:high */
-    REMOTE_PROC_SUPPORTS_FEATURE = 60, /* autogen autogen priority:high */
+    REMOTE_PROC_SUPPORTS_FEATURE = 60, /* skipgen autogen priority:high */
 
     REMOTE_PROC_DOMAIN_MIGRATE_PREPARE = 61, /* skipgen skipgen */
     REMOTE_PROC_DOMAIN_MIGRATE_PERFORM = 62, /* autogen autogen */

src/rpc/gendispatch.pl

@@ -298,7 +298,7 @@ elsif ($opt_b) {
 	print "static int ${name}(\n";
 	print "    virNetServerPtr server,\n";
 	print "    virNetServerClientPtr client,\n";
-	print "    virNetMessageHeaderPtr hdr,\n";
+	print "    virNetMessagePtr msg,\n";
 	print "    virNetMessageErrorPtr rerr";
 	if ($argtype ne "void") {
 	    print ",\n    $argtype *args";
@@ -315,13 +315,13 @@ elsif ($opt_b) {
 	print "static int ${name}Helper(\n";
 	print "    virNetServerPtr server,\n";
 	print "    virNetServerClientPtr client,\n";
-	print "    virNetMessageHeaderPtr hdr,\n";
+	print "    virNetMessagePtr msg,\n";
 	print "    virNetMessageErrorPtr rerr,\n";
 	print "    void *args$argann,\n";
 	print "    void *ret$retann)\n";
 	print "{\n";
-	print "  VIR_DEBUG(\"server=%p client=%p hdr=%p rerr=%p args=%p ret=%p\", server, client, hdr, rerr, args, ret);\n";
-	print "  return $name(server, client, hdr, rerr";
+	print "  VIR_DEBUG(\"server=%p client=%p msg=%p rerr=%p args=%p ret=%p\", server, client, msg, rerr, args, ret);\n";
+	print "  return $name(server, client, msg, rerr";
 	if ($argtype ne "void") {
 	    print ", args";
 	}
@@ -750,7 +750,7 @@ elsif ($opt_b) {
 	print "static int $name(\n";
 	print "    virNetServerPtr server ATTRIBUTE_UNUSED,\n";
 	print "    virNetServerClientPtr client,\n";
-	print "    virNetMessageHeaderPtr hdr ATTRIBUTE_UNUSED,\n";
+	print "    virNetMessagePtr msg ATTRIBUTE_UNUSED,\n";
 	print "    virNetMessageErrorPtr rerr";
         if ($argtype ne "void") {
 	    print ",\n    $argtype *args";
@@ -809,7 +809,7 @@ elsif ($opt_b) {
             print "    if (!(st = virStreamNew(priv->conn, VIR_STREAM_NONBLOCK)))\n";
             print "        goto cleanup;\n";
             print "\n";
-            print "    if (!(stream = daemonCreateClientStream(client, st, remoteProgram, hdr)))\n";
+            print "    if (!(stream = daemonCreateClientStream(client, st, remoteProgram, &msg->header)))\n";
             print "        goto cleanup;\n";
             print "\n";
         }

src/rpc/virnetserver.c

@@ -138,7 +138,8 @@ static void virNetServerHandleJob(void *jobOpaque, void *opaque)
          * message types are not expecting replies, so we
          * must just log it & drop them
          */
-        if (job->msg->header.type == VIR_NET_CALL) {
+        if (job->msg->header.type == VIR_NET_CALL ||
+            job->msg->header.type == VIR_NET_CALL_WITH_FDS) {
             if (virNetServerProgramUnknownError(job->client,
                                                 job->msg,
                                                 &job->msg->header) < 0)

src/rpc/virnetserverclient.c

@@ -770,6 +770,7 @@ readmore:
         /* Grab the completed message */
         virNetMessagePtr msg = virNetMessageQueueServe(&client->rx);
         virNetServerClientFilterPtr filter;
+        size_t i;
 
         /* Decode the header so we can use it for routing decisions */
         if (virNetMessageDecodeHeader(msg) < 0) {
@@ -778,6 +779,20 @@ readmore:
             return;
         }
 
+        if (msg->header.type == VIR_NET_CALL_WITH_FDS &&
+            virNetMessageDecodeNumFDs(msg) < 0) {
+            virNetMessageFree(msg);
+            client->wantClose = true;
+            return;
+        }
+        for (i = 0 ; i < msg->nfds ; i++) {
+            if ((msg->fds[i] = virNetSocketRecvFD(client->sock)) < 0) {
+                virNetMessageFree(msg);
+                client->wantClose = true;
+                return;
+            }
+        }
+
         PROBE(RPC_SERVER_CLIENT_MSG_RX,
               "client=%p len=%zu prog=%u vers=%u proc=%u type=%u status=%u serial=%u",
               client, msg->bufferLength,
@@ -883,6 +898,15 @@ virNetServerClientDispatchWrite(virNetServerClientPtr client)
 
         if (client->tx->bufferOffset == client->tx->bufferLength) {
             virNetMessagePtr msg;
+            size_t i;
+
+            for (i = 0 ; i < client->tx->nfds ; i++) {
+                if (virNetSocketSendFD(client->sock, client->tx->fds[i]) < 0) {
+                    client->wantClose = true;
+                    return;
+                }
+            }
+
 #if HAVE_SASL
             /* Completed this 'tx' operation, so now read for all
              * future rx/tx to be under a SASL SSF layer

src/rpc/virnetserverprogram.c

@@ -29,6 +29,7 @@
 #include "memory.h"
 #include "virterror_internal.h"
 #include "logging.h"
+#include "virfile.h"
 
 #define VIR_FROM_THIS VIR_FROM_RPC
 #define virNetError(code, ...)                                    \
@@ -284,6 +285,7 @@ int virNetServerProgramDispatch(virNetServerProgramPtr prog,
 
     switch (msg->header.type) {
     case VIR_NET_CALL:
+    case VIR_NET_CALL_WITH_FDS:
         ret = virNetServerProgramDispatchCall(prog, server, client, msg);
         break;
 
@@ -314,7 +316,8 @@ int virNetServerProgramDispatch(virNetServerProgramPtr prog,
     return ret;
 
 error:
-    if (msg->header.type == VIR_NET_CALL) {
+    if (msg->header.type == VIR_NET_CALL ||
+        msg->header.type == VIR_NET_CALL_WITH_FDS) {
         ret = virNetServerProgramSendReplyError(prog, client, msg, &rerr, &msg->header);
     } else {
         /* Send a dummy reply to free up 'msg' & unblock client rx */
@@ -355,6 +358,7 @@ virNetServerProgramDispatchCall(virNetServerProgramPtr prog,
     int rv = -1;
     virNetServerProgramProcPtr dispatcher;
     virNetMessageError rerr;
+    size_t i;
 
     memset(&rerr, 0, sizeof(rerr));
 
@@ -409,7 +413,20 @@ virNetServerProgramDispatchCall(virNetServerProgramPtr prog,
      *
      *   'args and 'ret'
      */
-    rv = (dispatcher->func)(server, client, &msg->header, &rerr, arg, ret);
+    rv = (dispatcher->func)(server, client, msg, &rerr, arg, ret);
+
+    /*
+     * Clear out the FDs we got from the client, we don't
+     * want to send them back !
+     *
+     * XXX we don't have a way to let dispatcher->func
+     * return any FDs. Fortunately we don't need this
+     * capability just yet
+     */
+    for (i = 0 ; i < msg->nfds ; i++)
+        VIR_FORCE_CLOSE(msg->fds[i]);
+    VIR_FREE(msg->fds);
+    msg->nfds = 0;
 
     xdr_free(dispatcher->arg_filter, arg);
 
@@ -421,7 +438,7 @@ virNetServerProgramDispatchCall(virNetServerProgramPtr prog,
     /*msg->header.prog = msg->header.prog;*/
     /*msg->header.vers = msg->header.vers;*/
     /*msg->header.proc = msg->header.proc;*/
-    msg->header.type = VIR_NET_REPLY;
+    msg->header.type = msg->nfds ? VIR_NET_REPLY_WITH_FDS : VIR_NET_REPLY;
     /*msg->header.serial = msg->header.serial;*/
     msg->header.status = VIR_NET_OK;
 
@@ -430,6 +447,12 @@ virNetServerProgramDispatchCall(virNetServerProgramPtr prog,
         goto error;
     }
 
+    if (msg->nfds &&
+        virNetMessageEncodeNumFDs(msg) < 0) {
+        xdr_free(dispatcher->ret_filter, ret);
+        goto error;
+    }
+
     if (virNetMessageEncodePayload(msg, dispatcher->ret_filter, ret) < 0) {
         xdr_free(dispatcher->ret_filter, ret);
         goto error;

src/rpc/virnetserverprogram.h

@@ -41,7 +41,7 @@ typedef virNetServerProgramProc *virNetServerProgramProcPtr;
 
 typedef int (*virNetServerProgramDispatchFunc)(virNetServerPtr server,
                                                virNetServerClientPtr client,
-                                               virNetMessageHeaderPtr hdr,
+                                               virNetMessagePtr msg,
                                                virNetMessageErrorPtr rerr,
                                                void *args,
                                                void *ret);