From 0b3c045a4236f128ab4c1592e6cc91adc1cd6eb0 Mon Sep 17 00:00:00 2001 From: Richard Cochran Date: Sun, 31 Jul 2016 12:08:24 +0200 Subject: [PATCH] rtnl: Introduce RT netlink sockets. 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 --- makefile | 2 +- rtnl.c | 166 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ rtnl.h | 54 ++++++++++++++++++ 3 files changed, 221 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..7f5dc45 --- /dev/null +++ b/rtnl.c @@ -0,0 +1,166 @@ +/** + * @file rtnl.c + * @note Copyright (C) 2012 Richard Cochran + * + * 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 +#include +#include +#include +#include +#include +#include +#include +#include + +#include "print.h" +#include "rtnl.h" + +static int rtnl_len; +static char *rtnl_buf; + +int rtnl_close(int fd) +{ + if (rtnl_buf) { + free(rtnl_buf); + rtnl_buf = NULL; + rtnl_len = 0; + } + 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 + * + * 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