[libvirt] [PATCH 02/12] Provide a simple object for encoding/decoding RPC messages
Daniel P. Berrange
berrange at redhat.com
Fri Mar 18 18:54:17 UTC 2011
This provides a new struct that contains a buffer for the RPC
message header+payload, as well as a decoded copy of the message
header. There is an API for applying a XDR encoding & decoding
of the message headers and payloads. There are also APIs for
maintaining a simple FIFO queue of message instances.
Expected usage scenarios are:
To send a message
msg = virNetMessageNew()
...fill in msg->header fields..
virNetMessageEncodeHeader(msg)
...loook at msg->header fields to determine payload filter
virNetMessageEncodePayload(msg, xdrfilter, data)
...send msg->bufferLength worth of data from buffer
To receive a message
msg = virNetMessageNew()
...read VIR_NET_MESSAGE_LEN_MAX of data into buffer
virNetMessageDecodeLength(msg)
...read msg->bufferLength-msg->bufferOffset of data into buffer
virNetMessageDecodeHeader(msg)
...look at msg->header fields to determine payload filter
virNetMessageDecodePayload(msg, xdrfilter, data)
...run payload processor
* src/Makefile.am: Add to libvirt-net-rpc.la
* src/rpc/virnetmessage.c, src/rpc/virnetmessage.h: Internal
message handling API.
---
cfg.mk | 1 +
po/POTFILES.in | 1 +
src/Makefile.am | 1 +
src/rpc/virnetmessage.c | 365 +++++++++++++++++++++++++++++++++++++++++++++++
src/rpc/virnetmessage.h | 82 +++++++++++
5 files changed, 450 insertions(+), 0 deletions(-)
create mode 100644 src/rpc/virnetmessage.c
create mode 100644 src/rpc/virnetmessage.h
diff --git a/cfg.mk b/cfg.mk
index a7120e2..dc8ed01 100644
--- a/cfg.mk
+++ b/cfg.mk
@@ -114,6 +114,7 @@ useless_free_options = \
--name=virInterfaceProtocolDefFree \
--name=virJSONValueFree \
--name=virLastErrFreeData \
+ --name=virNetMessageFree \
--name=virNWFilterDefFree \
--name=virNWFilterEntryFree \
--name=virNWFilterHashTableFree \
diff --git a/po/POTFILES.in b/po/POTFILES.in
index 12adb3e..187d056 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -66,6 +66,7 @@ src/qemu/qemu_monitor_json.c
src/qemu/qemu_monitor_text.c
src/qemu/qemu_process.c
src/remote/remote_driver.c
+src/rpc/virnetmessage.c
src/secret/secret_driver.c
src/security/security_apparmor.c
src/security/security_dac.c
diff --git a/src/Makefile.am b/src/Makefile.am
index e575a61..0ddbf24 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1226,6 +1226,7 @@ EXTRA_DIST += $(LIBVIRT_QEMU_SYMBOL_FILE)
noinst_LTLIBRARIES += libvirt-net-rpc.la
libvirt_net_rpc_la_SOURCES = \
+ rpc/virnetmessage.h rpc/virnetmessage.c \
rpc/virnetprotocol.h rpc/virnetprotocol.c
libvirt_net_rpc_la_CFLAGS = \
$(AM_CFLAGS)
diff --git a/src/rpc/virnetmessage.c b/src/rpc/virnetmessage.c
new file mode 100644
index 0000000..04fb78b
--- /dev/null
+++ b/src/rpc/virnetmessage.c
@@ -0,0 +1,365 @@
+/*
+ * virnetmessage.c: basic RPC message encoding/decoding
+ *
+ * Copyright (C) 2010-2011 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <config.h>
+
+#include <stdlib.h>
+
+#include "virnetmessage.h"
+#include "memory.h"
+#include "virterror_internal.h"
+#include "logging.h"
+
+#define VIR_FROM_THIS VIR_FROM_RPC
+#define virNetError(code, ...) \
+ virReportErrorHelper(NULL, VIR_FROM_RPC, code, __FILE__, \
+ __FUNCTION__, __LINE__, __VA_ARGS__)
+
+virNetMessagePtr virNetMessageNew(void)
+{
+ virNetMessagePtr msg;
+
+ if (VIR_ALLOC(msg) < 0) {
+ virReportOOMError();
+ return NULL;
+ }
+
+ VIR_DEBUG("msg=%p", msg);
+
+ return msg;
+}
+
+void virNetMessageFree(virNetMessagePtr msg)
+{
+ if (!msg)
+ return;
+
+ VIR_DEBUG("msg=%p", msg);
+
+ VIR_FREE(msg);
+}
+
+void virNetMessageQueuePush(virNetMessagePtr *queue, virNetMessagePtr msg)
+{
+ virNetMessagePtr tmp = *queue;
+
+ if (tmp) {
+ while (tmp->next)
+ tmp = tmp->next;
+ tmp->next = msg;
+ } else {
+ *queue = msg;
+ }
+}
+
+
+virNetMessagePtr virNetMessageQueueServe(virNetMessagePtr *queue)
+{
+ virNetMessagePtr tmp = *queue;
+
+ if (tmp) {
+ *queue = tmp->next;
+ tmp->next = NULL;
+ }
+
+ return tmp;
+}
+
+
+int virNetMessageDecodeLength(virNetMessagePtr msg)
+{
+ XDR xdr;
+ unsigned int len;
+ int ret = -1;
+
+ xdrmem_create(&xdr, msg->buffer,
+ msg->bufferLength, XDR_DECODE);
+ if (!xdr_u_int(&xdr, &len)) {
+ virNetError(VIR_ERR_RPC, "%s", _("Unable to decode message length"));
+ goto cleanup;
+ }
+ msg->bufferOffset = xdr_getpos(&xdr);
+
+ if (len < VIR_NET_MESSAGE_LEN_MAX) {
+ virNetError(VIR_ERR_RPC, "%s",
+ _("packet received from server too small"));
+ goto cleanup;
+ }
+
+ /* Length includes length word - adjust to real length to read. */
+ len -= VIR_NET_MESSAGE_LEN_MAX;
+
+ if (len > VIR_NET_MESSAGE_MAX) {
+ virNetError(VIR_ERR_RPC, "%s",
+ _("packet received from server too large"));
+ goto cleanup;
+ }
+
+ /* Extend our declared buffer length and carry
+ on reading the header + payload */
+ msg->bufferLength += len;
+
+ VIR_DEBUG("Got length, now need %zu total (%u more)",
+ msg->bufferLength, len);
+
+ ret = 0;
+
+cleanup:
+ xdr_destroy(&xdr);
+ return ret;
+}
+
+
+/*
+ * @msg: the complete incoming message, whose header to decode
+ *
+ * Decodes the header part of the message, but does not
+ * validate the decoded fields in the header. It expects
+ * bufferLength to refer to length of the data packet. Upon
+ * return bufferOffset will refer to the amount of the packet
+ * consumed by decoding of the header.
+ *
+ * returns 0 if successfully decoded, -1 upon fatal error
+ */
+int virNetMessageDecodeHeader(virNetMessagePtr msg)
+{
+ XDR xdr;
+ int ret = -1;
+
+ msg->bufferOffset = VIR_NET_MESSAGE_LEN_MAX;
+
+ /* Parse the header. */
+ xdrmem_create(&xdr,
+ msg->buffer + msg->bufferOffset,
+ msg->bufferLength - msg->bufferOffset,
+ XDR_DECODE);
+
+ if (!xdr_virNetMessageHeader(&xdr, &msg->header)) {
+ virNetError(VIR_ERR_RPC, "%s", _("Unable to decode message header"));
+ goto cleanup;
+ }
+
+ msg->bufferOffset += xdr_getpos(&xdr);
+
+ ret = 0;
+
+cleanup:
+ xdr_destroy(&xdr);
+ return ret;
+}
+
+
+/*
+ * @msg: the outgoing message, whose header to encode
+ *
+ * Encodes the length word and header of the message, setting the
+ * message offset ready to encode the payload. Leaves space
+ * for the length field later. Upon return bufferLength will
+ * refer to the total available space for message, while
+ * bufferOffset will refer to current space used by header
+ *
+ * returns 0 if successfully encoded, -1 upon fatal error
+ */
+int virNetMessageEncodeHeader(virNetMessagePtr msg)
+{
+ XDR xdr;
+ int ret = -1;
+ unsigned int len = 0;
+
+ msg->bufferLength = sizeof(msg->buffer);
+ msg->bufferOffset = 0;
+
+ /* Format the header. */
+ xdrmem_create(&xdr,
+ msg->buffer,
+ msg->bufferLength,
+ XDR_ENCODE);
+
+ /* The real value is filled in shortly */
+ if (!xdr_u_int(&xdr, &len)) {
+ virNetError(VIR_ERR_RPC, "%s", _("Unable to encode message length"));
+ goto cleanup;
+ }
+
+ if (!xdr_virNetMessageHeader(&xdr, &msg->header)) {
+ virNetError(VIR_ERR_RPC, "%s", _("Unable to encode message header"));
+ goto cleanup;
+ }
+
+ len = xdr_getpos(&xdr);
+ xdr_setpos(&xdr, 0);
+
+ /* Fill in current length - may be re-written later
+ * if a payload is added
+ */
+ if (!xdr_u_int(&xdr, &len)) {
+ virNetError(VIR_ERR_RPC, "%s", _("Unable to re-encode message length"));
+ goto cleanup;
+ }
+
+ msg->bufferOffset += len;
+
+ ret = 0;
+
+cleanup:
+ xdr_destroy(&xdr);
+ return ret;
+}
+
+
+int virNetMessageEncodePayload(virNetMessagePtr msg,
+ xdrproc_t filter,
+ void *data)
+{
+ XDR xdr;
+ unsigned int msglen;
+
+ /* Serialise payload of the message. This assumes that
+ * virNetMessageEncodeHeader has already been run, so
+ * just appends to that data */
+ xdrmem_create(&xdr, msg->buffer + msg->bufferOffset,
+ msg->bufferLength - msg->bufferOffset, XDR_ENCODE);
+
+ if (!(*filter)(&xdr, data)) {
+ virNetError(VIR_ERR_RPC, "%s", _("Unable to encode message payload"));
+ goto error;
+ }
+
+ /* Get the length stored in buffer. */
+ msg->bufferOffset += xdr_getpos(&xdr);
+ xdr_destroy(&xdr);
+
+ /* Re-encode the length word. */
+ VIR_DEBUG("Encode length as %zu", msg->bufferOffset);
+ xdrmem_create(&xdr, msg->buffer, VIR_NET_MESSAGE_HEADER_XDR_LEN, XDR_ENCODE);
+ msglen = msg->bufferOffset;
+ if (!xdr_u_int(&xdr, &msglen)) {
+ virNetError(VIR_ERR_RPC, "%s", _("Unable to encode message length"));
+ goto error;
+ }
+ xdr_destroy(&xdr);
+
+ msg->bufferLength = msg->bufferOffset;
+ msg->bufferOffset = 0;
+ return 0;
+
+error:
+ xdr_destroy(&xdr);
+ return -1;
+}
+
+
+int virNetMessageDecodePayload(virNetMessagePtr msg,
+ xdrproc_t filter,
+ void *data)
+{
+ XDR xdr;
+
+ /* Deserialise payload of the message. This assumes that
+ * virNetMessageDecodeHeader has already been run, so
+ * just start from after that data */
+ xdrmem_create(&xdr, msg->buffer + msg->bufferOffset,
+ msg->bufferLength - msg->bufferOffset, XDR_DECODE);
+
+ if (!(*filter)(&xdr, data)) {
+ virNetError(VIR_ERR_RPC, "%s", _("Unable to decode message payload"));
+ goto error;
+ }
+
+ /* Get the length stored in buffer. */
+ msg->bufferLength += xdr_getpos(&xdr);
+ xdr_destroy(&xdr);
+ return 0;
+
+error:
+ xdr_destroy(&xdr);
+ return -1;
+}
+
+
+int virNetMessageEncodePayloadRaw(virNetMessagePtr msg,
+ const char *data,
+ size_t len)
+{
+ XDR xdr;
+ unsigned int msglen;
+
+ if ((msg->bufferLength - msg->bufferOffset) < len) {
+ virNetError(VIR_ERR_RPC,
+ _("Stream data too long to send (%zu bytes needed, %zu bytes available)"),
+ len, (msg->bufferLength - msg->bufferOffset));
+ return -1;
+ }
+
+ memcpy(msg->buffer + msg->bufferOffset, data, len);
+ msg->bufferOffset += len;
+
+ /* Re-encode the length word. */
+ VIR_DEBUG("Encode length as %zu", msg->bufferOffset);
+ xdrmem_create(&xdr, msg->buffer, VIR_NET_MESSAGE_HEADER_XDR_LEN, XDR_ENCODE);
+ msglen = msg->bufferOffset;
+ if (!xdr_u_int(&xdr, &msglen)) {
+ virNetError(VIR_ERR_RPC, "%s", _("Unable to encode message length"));
+ goto error;
+ }
+ xdr_destroy(&xdr);
+
+ msg->bufferLength = msg->bufferOffset;
+ msg->bufferOffset = 0;
+ return 0;
+
+error:
+ xdr_destroy(&xdr);
+ return -1;
+}
+
+
+void virNetMessageSaveError(virNetMessageErrorPtr rerr)
+{
+ /* This func may be called several times & the first
+ * error is the one we want because we don't want
+ * cleanup code overwriting the first one.
+ */
+ if (rerr->code != VIR_ERR_OK)
+ return;
+
+ virErrorPtr verr = virGetLastError();
+ if (verr) {
+ rerr->code = verr->code;
+ rerr->domain = verr->domain;
+ rerr->message = verr->message ? malloc(sizeof(char*)) : NULL;
+ if (rerr->message) *rerr->message = strdup(verr->message);
+ rerr->level = verr->level;
+ rerr->str1 = verr->str1 ? malloc(sizeof(char*)) : NULL;
+ if (rerr->str1) *rerr->str1 = strdup(verr->str1);
+ rerr->str2 = verr->str2 ? malloc(sizeof(char*)) : NULL;
+ if (rerr->str2) *rerr->str2 = strdup(verr->str2);
+ rerr->str3 = verr->str3 ? malloc(sizeof(char*)) : NULL;
+ if (rerr->str3) *rerr->str3 = strdup(verr->str3);
+ rerr->int1 = verr->int1;
+ rerr->int2 = verr->int2;
+ } else {
+ rerr->code = VIR_ERR_INTERNAL_ERROR;
+ rerr->domain = VIR_FROM_RPC;
+ rerr->message = malloc(sizeof(char*));
+ if (rerr->message) *rerr->message = strdup(_("Library function returned error but did not set virError"));
+ rerr->level = VIR_ERR_ERROR;
+ }
+}
diff --git a/src/rpc/virnetmessage.h b/src/rpc/virnetmessage.h
new file mode 100644
index 0000000..7473681
--- /dev/null
+++ b/src/rpc/virnetmessage.h
@@ -0,0 +1,82 @@
+/*
+ * virnetmessage.h: basic RPC message encoding/decoding
+ *
+ * Copyright (C) 2010-2011 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef __VIR_NET_MESSAGE_H__
+# define __VIR_NET_MESSAGE_H__
+
+# include <stdbool.h>
+
+# include "virnetprotocol.h"
+
+typedef struct virNetMessageHeader *virNetMessageHeaderPtr;
+typedef struct virNetMessageError *virNetMessageErrorPtr;
+
+typedef struct _virNetMessage virNetMessage;
+typedef virNetMessage *virNetMessagePtr;
+
+/* Never allocate this (huge) buffer on the stack. Always
+ * use virNetMessageNew() to allocate on the heap
+ */
+struct _virNetMessage {
+ char buffer[VIR_NET_MESSAGE_MAX + VIR_NET_MESSAGE_LEN_MAX];
+ size_t bufferLength;
+ size_t bufferOffset;
+
+ virNetMessageHeader header;
+
+ virNetMessagePtr next;
+};
+
+
+virNetMessagePtr virNetMessageNew(void);
+
+void virNetMessageFree(virNetMessagePtr msg);
+
+virNetMessagePtr virNetMessageQueueServe(virNetMessagePtr *queue)
+ ATTRIBUTE_NONNULL(1);
+void virNetMessageQueuePush(virNetMessagePtr *queue,
+ virNetMessagePtr msg)
+ ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
+
+int virNetMessageEncodeHeader(virNetMessagePtr msg)
+ ATTRIBUTE_NONNULL(1) ATTRIBUTE_RETURN_CHECK;
+int virNetMessageDecodeLength(virNetMessagePtr msg)
+ ATTRIBUTE_NONNULL(1) ATTRIBUTE_RETURN_CHECK;
+int virNetMessageDecodeHeader(virNetMessagePtr msg)
+ ATTRIBUTE_NONNULL(1) ATTRIBUTE_RETURN_CHECK;
+
+int virNetMessageEncodePayload(virNetMessagePtr msg,
+ xdrproc_t filter,
+ void *data)
+ ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(2) ATTRIBUTE_RETURN_CHECK;
+int virNetMessageDecodePayload(virNetMessagePtr msg,
+ xdrproc_t filter,
+ void *data)
+ ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(2) ATTRIBUTE_RETURN_CHECK;
+
+int virNetMessageEncodePayloadRaw(virNetMessagePtr msg,
+ const char *buf,
+ size_t len)
+ ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_RETURN_CHECK;
+
+void virNetMessageSaveError(virNetMessageErrorPtr rerr)
+ ATTRIBUTE_NONNULL(1);
+
+#endif /* __VIR_NET_MESSAGE_H__ */
--
1.7.4
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