[libvirt] [PATCH v4 1/5] util: introduce virNetlinkGetNeighbor to get neighbor table entry
From: Chen Hanxiao <chenhanxiao(a)gmail.com>
use RTM_GETNEIGH to query arp table entry by netlink socket
Signed-off-by: Chen Hanxiao <chenhanxiao(a)gmail.com>
---
v4:
use netlink to get arp table entry
src/libvirt_private.syms | 1 +
src/util/virnetlink.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++
src/util/virnetlink.h | 2 ++
3 files changed, 85 insertions(+)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 0bce0bbfb..d90eb3dde 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -2367,6 +2367,7 @@ virNetlinkEventServiceStart;
virNetlinkEventServiceStop;
virNetlinkEventServiceStopAll;
virNetlinkGetErrorCode;
+virNetlinkGetNeighbor;
virNetlinkShutdown;
virNetlinkStartup;
diff --git a/src/util/virnetlink.c b/src/util/virnetlink.c
index d732fe8cf..0f9b0f5d1 100644
--- a/src/util/virnetlink.c
+++ b/src/util/virnetlink.c
@@ -590,6 +590,88 @@ virNetlinkDelLink(const char *ifname, virNetlinkDelLinkFallback
fallback)
goto cleanup;
}
+/**
+ * virNetlinkGetNeighbor:
+ *
+ * @nlData: Gets a pointer to the raw data from netlink.
+ MUST BE FREED BY CALLER!
+ * @src_pid: pid used for nl_pid of the local end of the netlink message
+ * (0 == "use getpid()")
+ * @dst_pid: pid of destination nl_pid if the kernel
+ * is not the target of the netlink message but it is to be
+ * sent to another process (0 if sending to the kernel)
+ *
+ * Get neighbor table entry from netlink.
+ *
+ * Returns 0 on success, -1 on fatal error.
+ */
+int
+virNetlinkGetNeighbor(void **nlData, uint32_t src_pid, uint32_t dst_pid)
+{
+ int rc = -1;
+ struct nlmsghdr *resp = NULL;
+ struct nlmsgerr *err;
+ struct ndmsg ndinfo = {
+ .ndm_family = AF_UNSPEC,
+ };
+ unsigned int recvbuflen;
+ struct nl_msg *nl_msg;
+
+ nl_msg = nlmsg_alloc_simple(RTM_GETNEIGH, NLM_F_DUMP | NLM_F_REQUEST);
+ if (!nl_msg) {
+ virReportOOMError();
+ return -1;
+ }
+
+ if (nlmsg_append(nl_msg, &ndinfo, sizeof(ndinfo), NLMSG_ALIGNTO) < 0)
+ goto buffer_too_small;
+
+
+ if (virNetlinkCommand(nl_msg, &resp, &recvbuflen,
+ src_pid, dst_pid, NETLINK_ROUTE, 0) < 0)
+ goto cleanup;
+
+ if (recvbuflen < NLMSG_LENGTH(0) || resp == NULL)
+ goto malformed_resp;
+
+ switch (resp->nlmsg_type) {
+ case NLMSG_ERROR:
+ err = (struct nlmsgerr *)NLMSG_DATA(resp);
+ if (resp->nlmsg_len < NLMSG_LENGTH(sizeof(*err)))
+ goto malformed_resp;
+
+ if (err->error) {
+ virReportSystemError(-err->error,
+ "%s", _("error dumping"));
+ goto cleanup;
+ }
+ break;
+
+ case RTM_NEWNEIGH:
+ break;
+
+ default:
+ goto malformed_resp;
+ }
+ rc = recvbuflen;
+
+ cleanup:
+ nlmsg_free(nl_msg);
+ if (rc < 0)
+ VIR_FREE(resp);
+ *nlData = resp;
+ return rc;
+
+ malformed_resp:
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("malformed netlink response message"));
+ goto cleanup;
+
+ buffer_too_small:
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("allocated netlink buffer is too small"));
+ goto cleanup;
+}
int
virNetlinkGetErrorCode(struct nlmsghdr *resp, unsigned int recvbuflen)
diff --git a/src/util/virnetlink.h b/src/util/virnetlink.h
index 088b01343..2a9de0a57 100644
--- a/src/util/virnetlink.h
+++ b/src/util/virnetlink.h
@@ -71,6 +71,8 @@ int virNetlinkDumpLink(const char *ifname, int ifindex,
void **nlData, struct nlattr **tb,
uint32_t src_pid, uint32_t dst_pid)
ATTRIBUTE_RETURN_CHECK;
+int
+virNetlinkGetNeighbor(void **nlData, uint32_t src_pid, uint32_t dst_pid);
typedef void (*virNetlinkEventHandleCallback)(struct nlmsghdr *,
unsigned int length,
--
2.14.3