release/src/router/hotplug2/hotplug2_utils.c

   1 #include <stdio.h>
   2 #include <string.h>
   3 #include <stdlib.h>
   4 #include <fcntl.h>
   5 #include <stdio.h>
   6 #include <unistd.h>
   7 #include <errno.h>
   8 #include <sys/socket.h>
   9 #include <sys/types.h>
  10 #include <sys/un.h>
  11 #include <sys/wait.h>
  12 #include <linux/types.h>
  13 #include <linux/netlink.h>
  14
  15 #include "hotplug2_utils.h"
  16
  17 /**
  18  * A trivial function that reads kernel seqnum from sysfs.
  19  *
  20  * Returns: Seqnum as read from sysfs
  21  */
  22 inline event_seqnum_t get_kernel_seqnum() {
  23         FILE *fp;
  24
  25         char filename[64];
  26         char seqnum[64];
  27
  28         strcpy(filename, sysfs_seqnum_path);
  29
  30         fp = fopen(filename, "r");
  31         if (fp == NULL)
  32                 return 0;
  33
  34         fread(seqnum, 1, 64, fp);
  35         fclose(fp);
  36
  37         return strtoull(seqnum, NULL, 0);
  38 }
  39
  40 /**
  41  * Opens a PF_NETLINK socket into the kernel, to read uevents.
  42  *
  43  * @1 Specifies type of socket (whether we bind or whether we connect)
  44  *
  45  * Returns: Socket fd if succesful, -1 otherwise.
  46  */
  47 inline int init_netlink_socket(int type) {
  48         int netlink_socket;
  49         struct sockaddr_nl snl;
  50         int buffersize = 16 * 1024 * 1024;
  51
  52         memset(&snl, 0x00, sizeof(struct sockaddr_nl));
  53         snl.nl_family = AF_NETLINK;
  54         snl.nl_pid = getpid();
  55         snl.nl_groups = 1;
  56         netlink_socket = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
  57         if (netlink_socket == -1) {
  58                 ERROR("opening netlink","Failed socket: %s.", strerror(errno));
  59                 return -1;
  60         }
  61
  62         /*
  63          * We're trying to override buffer size. If we fail, we attempt to set a big buffer and pray.
  64          */
  65         if (setsockopt(netlink_socket, SOL_SOCKET, SO_RCVBUFFORCE, &buffersize, sizeof(buffersize))) {
  66                 ERROR("opening netlink","Failed setsockopt: %s. (non-critical)", strerror(errno));
  67
  68                 /* Somewhat safe default. */
  69                 buffersize = 106496;
  70
  71                 if (setsockopt(netlink_socket, SOL_SOCKET, SO_RCVBUF, &buffersize, sizeof(buffersize))) {
  72                         ERROR("opening netlink","Failed setsockopt: %s. (critical)", strerror(errno));
  73                 }
  74         }
  75
  76         /*
  77          * hotplug2-dnode performs connect, while hotplug2 daemon binds
  78          */
  79         switch (type) {
  80                 case NETLINK_CONNECT:
  81                         if (connect(netlink_socket, (struct sockaddr *) &snl, sizeof(struct sockaddr_nl))) {
  82                                 ERROR("opening netlink","Failed connect: %s.", strerror(errno));
  83                                 close(netlink_socket);
  84                                 return -1;
  85                         }
  86
  87                 default:
  88                         if (bind(netlink_socket, (struct sockaddr *) &snl, sizeof(struct sockaddr_nl))) {
  89                                 ERROR("opening netlink","Failed bind: %s.", strerror(errno));
  90                                 close(netlink_socket);
  91                                 return -1;
  92                         }
  93         }
  94
  95         return netlink_socket;
  96 }