[libvirt] [PATCH 5/8] Extend RPC protocol to allow FD passing
Daniel P. Berrange
berrange at redhat.com
Fri Oct 21 12:55:57 UTC 2011
From: "Daniel P. Berrange" <berrange at redhat.com>
Define two new RPC message types VIR_NET_CALL_WITH_FDS and
VIR_NET_REPLY_WITH_FDS. These message types are equivalent
to VIR_NET_CALL and VIR_NET_REPLY, except that between the
message header, and payload there is a 32-bit integer field
specifying how many file descriptors have been passed.
The actual file descriptors are sent/recv'd out of band.
* src/rpc/virnetmessage.c, src/rpc/virnetmessage.h,
src/libvirt_private.syms: Add support for handling
passed file descriptors
* src/rpc/virnetprotocol.x: Extend protocol for FD
passing
---
src/libvirt_private.syms | 2 +
src/rpc/virnetmessage.c | 111 +++++++++++++++++++++++++++++++++++++++++++++-
src/rpc/virnetmessage.h | 9 ++++
src/rpc/virnetprotocol.x | 23 +++++++++-
4 files changed, 142 insertions(+), 3 deletions(-)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 0648e49..f798c4a 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1178,6 +1178,8 @@ virFileFdopen;
virNetMessageClear;
virNetMessageEncodeHeader;
virNetMessageEncodePayload;
+virNetMessageEncodeNumFDs;
+virNetMessageDecodeNumFDs;
virNetMessageFree;
virNetMessageNew;
virNetMessageQueuePush;
diff --git a/src/rpc/virnetmessage.c b/src/rpc/virnetmessage.c
index a1ae9c4..a833c90 100644
--- a/src/rpc/virnetmessage.c
+++ b/src/rpc/virnetmessage.c
@@ -21,11 +21,13 @@
#include <config.h>
#include <stdlib.h>
+#include <unistd.h>
#include "virnetmessage.h"
#include "memory.h"
#include "virterror_internal.h"
#include "logging.h"
+#include "virfile.h"
#define VIR_FROM_THIS VIR_FROM_RPC
#define virNetError(code, ...) \
@@ -51,6 +53,13 @@ virNetMessagePtr virNetMessageNew(bool tracked)
void virNetMessageClear(virNetMessagePtr msg)
{
bool tracked = msg->tracked;
+ size_t i;
+
+ VIR_DEBUG("msg=%p nfds=%zu", msg, msg->nfds);
+
+ for (i = 0 ; i < msg->nfds ; i++)
+ VIR_FORCE_CLOSE(msg->fds[i]);
+ VIR_FREE(msg->fds);
memset(msg, 0, sizeof(*msg));
msg->tracked = tracked;
}
@@ -58,14 +67,18 @@ void virNetMessageClear(virNetMessagePtr msg)
void virNetMessageFree(virNetMessagePtr msg)
{
+ size_t i;
if (!msg)
return;
+ VIR_DEBUG("msg=%p nfds=%zu cb=%p", msg, msg->nfds, msg->cb);
+
if (msg->cb)
msg->cb(msg, msg->opaque);
- VIR_DEBUG("msg=%p", msg);
-
+ for (i = 0 ; i < msg->nfds ; i++)
+ VIR_FORCE_CLOSE(msg->fds[i]);
+ VIR_FREE(msg->fds);
VIR_FREE(msg);
}
@@ -239,6 +252,78 @@ cleanup:
}
+int virNetMessageEncodeNumFDs(virNetMessagePtr msg)
+{
+ XDR xdr;
+ unsigned int numFDs = msg->nfds;
+ int ret = -1;
+
+ xdrmem_create(&xdr, msg->buffer + msg->bufferOffset,
+ msg->bufferLength - msg->bufferOffset, XDR_ENCODE);
+
+ if (numFDs > VIR_NET_MESSAGE_NUM_FDS_MAX) {
+ virNetError(VIR_ERR_RPC,
+ _("Too many FDs to send %d, expected %d maximum"),
+ numFDs, VIR_NET_MESSAGE_NUM_FDS_MAX);
+ goto cleanup;
+ }
+
+ if (!xdr_u_int(&xdr, &numFDs)) {
+ virNetError(VIR_ERR_RPC, "%s", _("Unable to encode number of FDs"));
+ goto cleanup;
+ }
+ msg->bufferOffset += xdr_getpos(&xdr);
+
+ VIR_DEBUG("Send %zu FDs to peer", msg->nfds);
+
+ ret = 0;
+
+cleanup:
+ xdr_destroy(&xdr);
+ return ret;
+}
+
+
+int virNetMessageDecodeNumFDs(virNetMessagePtr msg)
+{
+ XDR xdr;
+ unsigned int numFDs;
+ int ret = -1;
+ size_t i;
+
+ xdrmem_create(&xdr, msg->buffer + msg->bufferOffset,
+ msg->bufferLength - msg->bufferOffset, XDR_DECODE);
+ if (!xdr_u_int(&xdr, &numFDs)) {
+ virNetError(VIR_ERR_RPC, "%s", _("Unable to decode number of FDs"));
+ goto cleanup;
+ }
+ msg->bufferOffset += xdr_getpos(&xdr);
+
+ if (numFDs > VIR_NET_MESSAGE_NUM_FDS_MAX) {
+ virNetError(VIR_ERR_RPC,
+ _("Received too many FDs %d, expected %d maximum"),
+ numFDs, VIR_NET_MESSAGE_NUM_FDS_MAX);
+ goto cleanup;
+ }
+
+ msg->nfds = numFDs;
+ if (VIR_ALLOC_N(msg->fds, msg->nfds) < 0) {
+ virReportOOMError();
+ goto cleanup;
+ }
+ for (i = 0 ; i < msg->nfds ; i++)
+ msg->fds[i] = -1;
+
+ VIR_DEBUG("Got %zu FDs from peer", msg->nfds);
+
+ ret = 0;
+
+cleanup:
+ xdr_destroy(&xdr);
+ return ret;
+}
+
+
int virNetMessageEncodePayload(virNetMessagePtr msg,
xdrproc_t filter,
void *data)
@@ -403,3 +488,25 @@ void virNetMessageSaveError(virNetMessageErrorPtr rerr)
rerr->level = VIR_ERR_ERROR;
}
}
+
+
+int virNetMessageDupFD(virNetMessagePtr msg,
+ size_t slot)
+{
+ int fd;
+
+ if (slot >= msg->nfds) {
+ virNetError(VIR_ERR_INTERNAL_ERROR,
+ _("No FD available at slot %zu"), slot);
+ return -1;
+ }
+
+ if ((fd = dup(msg->fds[slot])) < 0) {
+ virReportSystemError(errno,
+ _("Unable to duplicate FD %d"),
+ msg->fds[slot]);
+ return -1;
+ }
+
+ return fd;
+}
diff --git a/src/rpc/virnetmessage.h b/src/rpc/virnetmessage.h
index 307a041..ad63409 100644
--- a/src/rpc/virnetmessage.h
+++ b/src/rpc/virnetmessage.h
@@ -46,6 +46,9 @@ struct _virNetMessage {
virNetMessageFreeCallback cb;
void *opaque;
+ size_t nfds;
+ int *fds;
+
virNetMessagePtr next;
};
@@ -78,6 +81,9 @@ int virNetMessageDecodePayload(virNetMessagePtr msg,
void *data)
ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(2) ATTRIBUTE_RETURN_CHECK;
+int virNetMessageEncodeNumFDs(virNetMessagePtr msg);
+int virNetMessageDecodeNumFDs(virNetMessagePtr msg);
+
int virNetMessageEncodePayloadRaw(virNetMessagePtr msg,
const char *buf,
size_t len)
@@ -88,4 +94,7 @@ int virNetMessageEncodePayloadEmpty(virNetMessagePtr msg)
void virNetMessageSaveError(virNetMessageErrorPtr rerr)
ATTRIBUTE_NONNULL(1);
+int virNetMessageDupFD(virNetMessagePtr msg,
+ size_t slot);
+
#endif /* __VIR_NET_MESSAGE_H__ */
diff --git a/src/rpc/virnetprotocol.x b/src/rpc/virnetprotocol.x
index 306fafa..4520e38 100644
--- a/src/rpc/virnetprotocol.x
+++ b/src/rpc/virnetprotocol.x
@@ -62,6 +62,11 @@ const VIR_NET_MESSAGE_LEN_MAX = 4;
*/
const VIR_NET_MESSAGE_STRING_MAX = 65536;
+/* Limit on number of File Descriptors allowed to be
+ * passed per message
+ */
+const VIR_NET_MESSAGE_NUM_FDS_MAX = 32;
+
/*
* RPC wire format
*
@@ -126,6 +131,18 @@ const VIR_NET_MESSAGE_STRING_MAX = 65536;
* remote_error error information
* * status == VIR_NET_OK
* <empty>
+ *
+ * - type == VIR_NET_CALL_WITH_FDS
+ * int8 - number of FDs
+ * XXX_args for procedure
+ *
+ * - type == VIR_NET_REPLY_WITH_FDS
+ * int8 - number of FDs
+ * * status == VIR_NET_OK
+ * XXX_ret for procedure
+ * * status == VIR_NET_ERROR
+ * remote_error Error information
+ *
*/
enum virNetMessageType {
/* client -> server. args from a method call */
@@ -135,7 +152,11 @@ enum virNetMessageType {
/* either direction. async notification */
VIR_NET_MESSAGE = 2,
/* either direction. stream data packet */
- VIR_NET_STREAM = 3
+ VIR_NET_STREAM = 3,
+ /* client -> server. args from a method call, with passed FDs */
+ VIR_NET_CALL_WITH_FDS = 4,
+ /* server -> client. reply/error from a method call, with passed FDs */
+ VIR_NET_REPLY_WITH_FDS = 5
};
enum virNetMessageStatus {
--
1.7.6.4
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