+++ /dev/null
-/******************************************************************************
- * xen_netwatch.c
- *
- * Watch for network interfaces changing state (IFF_UP), and call a standard
- * script '/etc/xen/netwatch <ifname> up|down'. Logging from the netwatch
- * daemon is written to '/var/xen/netwatch' -- other programs can therefore
- * watch that file to take action on interface state changes.
- *
- * Note that, apart from the names of the default action script and log file,
- * this program is not actually Xen-dependent.
- *
- * Copyright (c) 2003, K A Fraser
- */
-
-#include <asm/types.h>
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <sys/ioctl.h>
-#include <sys/resource.h>
-#include <sys/time.h>
-#include <sys/un.h>
-#include <sys/wait.h>
-#include <linux/netlink.h>
-#include <linux/rtnetlink.h>
-#include <linux/if.h>
-
-#include <errno.h>
-#include <signal.h>
-#include <stdio.h>
-#include <unistd.h>
-#include <time.h>
-
-#define DEFAULT_SCRIPT "/etc/xen/netwatch"
-#define DEFAULT_LOGFILE "/var/xen/netwatch"
-
-#define LOG(_f, _a...) \
- do { \
- time_t now = time(NULL); \
- char *tstr = ctime(&now); \
- char *p = strchr(tstr, '\n'); if (p) *p = '\0'; \
- fprintf(logfd, "%s: " _f "\n", tstr, ## _a); \
- fflush(logfd); \
- } while ( 0 )
-
-#define EXIT do { LOG("Exiting."); return 1; } while ( 0 )
-
-static void daemonise(void)
-{
- int i;
- struct rlimit rlim;
-
- /* Close all file handles we inherited from our parent. */
- if ( getrlimit(RLIMIT_NOFILE, &rlim) == 0 )
- for ( i = 0; i < rlim.rlim_cur; i++ )
- close(i);
-
- /* Lose the controlling tty. */
- setsid();
-}
-
-void handle_child_death(int dummy)
-{
- (void)waitpid(-1, NULL, WNOHANG);
-}
-
-int main(int argc, char **argv)
-{
- char *logfile = DEFAULT_LOGFILE;
- char *scriptfile = DEFAULT_SCRIPT;
- FILE *logfd;
- int i, nlfd, unixfd, bytes, last_index = ~0;
- unsigned int last_flags = ~0;
- char buffer[8192];
- struct sockaddr_nl nladdr;
- struct nlmsghdr *nlmsg;
- struct ifinfomsg *ifi;
- struct ifreq ifr;
- struct sigaction sigchld;
-
- for ( i = 1; i < argc; i++ )
- {
- if ( strncmp("-s", argv[i], 2) == 0 )
- {
- scriptfile = argv[i] + 2;
- }
- else if ( strncmp("-l", argv[i], 2) == 0 )
- {
- logfile = argv[i] + 2;
- }
- else
- {
- printf("Usage: %s [-s<script>] [-l<logfile>]\n", argv[0]);
- printf("Default script: %s\n", scriptfile);
- printf("Default log file: %s\n", logfile);
- return 0;
- }
- }
-
- /* Ensure that zombie children are reaped. */
- memset(&sigchld, 0, sizeof(sigchld));
- sigchld.sa_handler = handle_child_death;
- sigemptyset(&sigchld.sa_mask);
- sigchld.sa_flags = SA_NOCLDSTOP | SA_RESTART;
- (void)sigaction(SIGCHLD, &sigchld, NULL);
-
- /*
- * After child daemonises it can't display errors until it opens the log
- * file. Since it may be unable to open the log file, we test for that
- * possibility here.
- */
- if ( (logfd = fopen(logfile, "wb")) == NULL )
- {
- fprintf(stderr, "Could not open log file '%s' (%d)\n", logfile, errno);
- fprintf(stderr, "Exiting.\n");
- return 1;
- }
- fclose(logfd);
-
- switch ( fork() )
- {
- case 0:
- daemonise();
- break;
- case -1:
- fprintf(stderr, "Could not daemonize. (%d)\n", errno);
- fprintf(stderr, "Exiting.\n");
- return 1;
- default:
- goto out;
- }
-
- /* Silent error is forgiveable here, as our parent did a test for us. */
- if ( (logfd = fopen(logfile, "wb")) == NULL )
- return 1;
-
- if ( (nlfd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)) == -1 )
- {
- LOG("Could not open an rtnetlink socket. (%d)\n", errno);
- EXIT;
- }
-
- if ( (unixfd = socket(PF_UNIX, SOCK_DGRAM, 0)) == -1 )
- {
- LOG("Could not open UNIX socket. (%d)\n", errno);
- EXIT;
- }
-
- nladdr.nl_family = AF_NETLINK;
- nladdr.nl_pid = 0;
- nladdr.nl_groups = RTMGRP_LINK;
- if ( bind(nlfd, (struct sockaddr *)&nladdr, sizeof(nladdr)) == -1 )
- {
- LOG("Could not bind to kernel (%d)\n", errno);
- EXIT;
- }
-
- for ( ; ; )
- {
- memset(buffer, 0, sizeof(buffer));
-
- if ( (bytes = read(nlfd, buffer, sizeof(buffer))) == -1 )
- {
- if ( errno != EINTR )
- LOG("Error when reading from socket (%d)", errno);
- continue;
- }
-
- if ( bytes == 0 )
- continue;
-
- for ( nlmsg = (struct nlmsghdr *)buffer;
- !(nlmsg->nlmsg_flags & NLMSG_DONE);
- nlmsg = NLMSG_NEXT(nlmsg, bytes) )
- {
- /*
- * This termination condition works. NLMSG_DONE doesn't always.
- * This therefore works around a Linux bug.
- */
- if ( nlmsg->nlmsg_len == 0 )
- break;
-
- if ( nlmsg->nlmsg_type != RTM_NEWLINK )
- continue;
-
- ifi = NLMSG_DATA(nlmsg);
-
- ifr.ifr_ifindex = ifi->ifi_index;
- if ( ioctl(unixfd, SIOCGIFNAME, &ifr) == -1 )
- continue;
-
- if ( !(ifi->ifi_change & IFF_UP) )
- continue;
-
- /* Ignore duplicate messages. This works around a Linux bug.*/
- if ( (last_index == ifr.ifr_ifindex) &&
- (last_flags == ifi->ifi_flags) )
- continue;
- last_index = ifr.ifr_ifindex;
- last_flags = ifi->ifi_flags;
-
- LOG("Network %s event for interface %s",
- (ifi->ifi_flags & IFF_UP) ? "UP" : "DOWN",
- ifr.ifr_name);
-
- switch ( fork() )
- {
- case 0:
- execl(scriptfile,
- ifr.ifr_name,
- (ifi->ifi_flags & IFF_UP) ? "up" : "down");
- LOG("Error executing network script '%s %s %s'",
- scriptfile, ifr.ifr_name,
- (ifi->ifi_flags & IFF_UP) ? "up" : "down");
- return 1;
- case -1:
- LOG("Error forking to exec script");
- default:
- break;
- }
- }
- }
-
- out:
- return 0;
-}
projects / xen.git / commitdiff