This patch adds a source module that implements RT netlink sockets
for the purpose of link monitoring. Unfortunately the netlink API
offers no possibility for per-port notification. Instead it
forces us to use a de-multiplexing pattern.
Signed-off-by: Richard Cochran <***@gmail.com>
---
makefile | 2 +-
rtnl.c | 161 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
rtnl.h | 54 +++++++++++++++++++++
3 files changed, 216 insertions(+), 1 deletion(-)
create mode 100644 rtnl.c
create mode 100644 rtnl.h
diff --git a/makefile b/makefile
index bcdbb92..44be067 100644
--- a/makefile
+++ b/makefile
@@ -25,7 +25,7 @@ LDLIBS = -lm -lrt $(EXTRA_LDFLAGS)
PRG = ptp4l pmc phc2sys hwstamp_ctl phc_ctl timemaster
OBJ = bmc.o clock.o clockadj.o clockcheck.o config.o fault.o \
filter.o fsm.o hash.o linreg.o mave.o mmedian.o msg.o ntpshm.o nullf.o phc.o \
- pi.o port.o print.o ptp4l.o raw.o servo.o sk.o stats.o tlv.o \
+ pi.o port.o print.o ptp4l.o raw.o rtnl.o servo.o sk.o stats.o tlv.o \
transport.o tsproc.o udp.o udp6.o uds.o util.o version.o
OBJECTS = $(OBJ) hwstamp_ctl.o phc2sys.o phc_ctl.o pmc.o pmc_common.o \
diff --git a/rtnl.c b/rtnl.c
new file mode 100644
index 0000000..cf11835
--- /dev/null
+++ b/rtnl.c
@@ -0,0 +1,161 @@
+/**
+ * @file rtnl.c
+ * @note Copyright (C) 2012 Richard Cochran <***@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#include <asm/types.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <net/if.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include "print.h"
+#include "rtnl.h"
+
+static int rtnl_len;
+static char *rtnl_buf;
+
+int rtnl_close(int fd)
+{
+ return close(fd);
+}
+
+int rtnl_link_query(int fd)
+{
+ struct sockaddr_nl sa;
+ struct msghdr msg;
+ struct iovec iov;
+ int cnt;
+
+ struct {
+ struct nlmsghdr hdr;
+ struct rtgenmsg gen;
+ } __attribute__((packed)) request;
+
+ memset(&sa, 0, sizeof(sa));
+ sa.nl_family = AF_NETLINK;
+
+ memset(&request, 0, sizeof(request));
+ request.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(request.gen));
+ request.hdr.nlmsg_type = RTM_GETLINK;
+ request.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
+ request.hdr.nlmsg_seq = 1;
+ request.hdr.nlmsg_pid = 0;
+ request.gen.rtgen_family = AF_UNSPEC;
+
+ iov.iov_base = &request;
+ iov.iov_len = sizeof(request);
+
+ memset(&msg, 0, sizeof(msg));
+ msg.msg_name = &sa;
+ msg.msg_namelen = sizeof(sa);
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+
+ cnt = sendmsg(fd, &msg, 0);
+ if (cnt < 0) {
+ pr_err("rtnl: sendmsg: %m");
+ return -1;
+ }
+ return 0;
+}
+
+int rtnl_link_status(int fd, rtnl_callback cb, void *ctx)
+{
+ int index, len;
+ struct iovec iov;
+ struct sockaddr_nl sa;
+ struct msghdr msg;
+ struct nlmsghdr *nh;
+ struct ifinfomsg *info = NULL;
+
+ if (!rtnl_buf) {
+ rtnl_len = 4096;
+ rtnl_buf = malloc(rtnl_len);
+ if (!rtnl_buf) {
+ pr_err("rtnl: low memory");
+ return -1;
+ }
+ }
+
+ iov.iov_base = rtnl_buf;
+ iov.iov_len = rtnl_len;
+ memset(&msg, 0, sizeof(msg));
+ msg.msg_name = &sa;
+ msg.msg_namelen = sizeof(sa);
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+
+ len = recvmsg(fd, &msg, MSG_PEEK | MSG_TRUNC);
+ if (len < 1) {
+ pr_err("rtnl: recvmsg: %m");
+ return -1;
+ }
+ if (len > rtnl_len) {
+ free(rtnl_buf);
+ rtnl_len = len;
+ rtnl_buf = malloc(len);
+ if (!rtnl_buf) {
+ pr_err("rtnl: failed to resize to %d bytes", len);
+ return -1;
+ }
+ iov.iov_base = rtnl_buf;
+ iov.iov_len = rtnl_len;
+ }
+
+ len = recvmsg(fd, &msg, 0);
+ if (len < 1) {
+ pr_err("rtnl: recvmsg: %m");
+ return -1;
+ }
+ nh = (struct nlmsghdr *) rtnl_buf;
+
+ for ( ; NLMSG_OK(nh, len); nh = NLMSG_NEXT(nh, len)) {
+ if (nh->nlmsg_type == RTM_NEWLINK) {
+ info = NLMSG_DATA(nh);
+ index = info->ifi_index;
+ pr_debug("interface index %d is %s", index,
+ info->ifi_flags & IFF_RUNNING ? "up" : "down");
+ cb(ctx, index, info->ifi_flags & IFF_RUNNING ? 1 : 0);
+ }
+ }
+ return 0;
+}
+
+int rtnl_open(void)
+{
+ int fd;
+ struct sockaddr_nl sa;
+
+ memset(&sa, 0, sizeof(sa));
+ sa.nl_family = AF_NETLINK;
+ sa.nl_groups = RTMGRP_LINK;
+
+ fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+ if (fd < 0) {
+ pr_err("failed to open netlink socket: %m");
+ return -1;
+ }
+ if (bind(fd, (struct sockaddr *) &sa, sizeof(sa))) {
+ pr_err("failed to bind netlink socket: %m");
+ return -1;
+ }
+ return fd;
+}
diff --git a/rtnl.h b/rtnl.h
new file mode 100644
index 0000000..f1871f2
--- /dev/null
+++ b/rtnl.h
@@ -0,0 +1,54 @@
+/**
+ * @file rtnl.h
+ * @brief Interface link status via RT netlink
+ * @note Copyright (C) 2012 Richard Cochran <***@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#ifndef HAVE_RTNL_H
+#define HAVE_RTNL_H
+
+typedef void (*rtnl_callback)(void *ctx, int index, int linkup);
+
+/**
+ * Close a RT netlink socket.
+ * @param fd A socket obtained via rtnl_open().
+ * @return Zero on success, non-zero otherwise.
+ */
+int rtnl_close(int fd);
+
+/**
+ * Request the link status from the kernel.
+ * @param fd A socket obtained via rtnl_open().
+ * @return Zero on success, non-zero otherwise.
+ */
+int rtnl_link_query(int fd);
+
+/**
+ * Read kernel messages looking for a link up/down events.
+ * @param fd Readable socket obtained via rtnl_open().
+ * @param cb Callback function to be invoked on each event.
+ * @param ctx Private context passed to the callback.
+ * @return Zero on success, non-zero otherwise.
+ */
+int rtnl_link_status(int fd, rtnl_callback cb, void *ctx);
+
+/**
+ * Open a RT netlink socket for monitoring link state.
+ * @return A valid socket, or -1 on error.
+ */
+int rtnl_open(void);
+
+#endif
--
2.1.4
------------------------------------------------------------------------------