xio.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Copyright 2009, 2010 Daniel Borkmann.
   4  * Subject to the GPL, version 2.
   5  */
   6
   7 #define _GNU_SOURCE
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <unistd.h>
  11 #include <string.h>
  12 #include <errno.h>
  13 #include <fcntl.h>
  14 #include <signal.h>
  15 #include <syslog.h>
  16 #include <sys/types.h>
  17 #include <sys/stat.h>
  18 #include <sys/types.h>
  19 #include <sys/ioctl.h>
  20 #include <sys/socket.h>
  21 #include <linux/if.h>
  22 #include <linux/if_tun.h>
  23
  24 #include "die.h"
  25 #include "xio.h"
  26 #include "str.h"
  27 #include "xutils.h"
  28
  29 int open_or_die(const char *file, int flags)
  30 {
  31         int ret = open(file, flags);
  32         if (ret < 0)
  33                 panic("Cannot open file %s! %s.\n", file, strerror(errno));
  34
  35         return ret;
  36 }
  37
  38 int open_or_die_m(const char *file, int flags, mode_t mode)
  39 {
  40         int ret = open(file, flags, mode);
  41         if (ret < 0)
  42                 panic("Cannot open or create file %s! %s.", file, strerror(errno));
  43         return ret;
  44 }
  45
  46 void create_or_die(const char *file, mode_t mode)
  47 {
  48         int fd = open_or_die_m(file, O_WRONLY | O_CREAT, mode);
  49         close(fd);
  50 }
  51
  52 void pipe_or_die(int pipefd[2], int flags)
  53 {
  54         int ret = pipe2(pipefd, flags);
  55         if (ret < 0)
  56                 panic("Cannot create pipe2 event fd! %s.\n", strerror(errno));
  57 }
  58
  59 int tun_open_or_die(char *name, int type)
  60 {
  61         int fd, ret;
  62         short flags;
  63         struct ifreq ifr;
  64
  65         if (!name)
  66                 panic("No name provided for tundev!\n");
  67
  68         fd = open_or_die("/dev/net/tun", O_RDWR);
  69
  70         memset(&ifr, 0, sizeof(ifr));
  71         ifr.ifr_flags = type;
  72         strlcpy(ifr.ifr_name, name, IFNAMSIZ);
  73
  74         ret = ioctl(fd, TUNSETIFF, &ifr);
  75         if (ret < 0)
  76                 panic("ioctl screwed up! %s.\n", strerror(errno));
  77
  78         ret = fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);
  79         if (ret < 0)
  80                 panic("fctnl screwed up! %s.\n", strerror(errno));
  81
  82         flags = device_get_flags(name);
  83         flags |= IFF_UP | IFF_RUNNING;
  84         device_set_flags(name, flags);
  85
  86         return fd;
  87 }
  88
  89 ssize_t read_or_die(int fd, void *buf, size_t len)
  90 {
  91         ssize_t ret = read(fd, buf, len);
  92         if (ret < 0) {
  93                 if (errno == EPIPE)
  94                         die();
  95                 panic("Cannot read from descriptor! %s.\n", strerror(errno));
  96         }
  97
  98         return ret;
  99 }
 100
 101 ssize_t write_or_die(int fd, const void *buf, size_t len)
 102 {
 103         ssize_t ret = write(fd, buf, len);
 104         if (ret < 0) {
 105                 if (errno == EPIPE)
 106                         die();
 107                 panic("Cannot write to descriptor! %s.", strerror(errno));
 108         }
 109
 110         return ret;
 111 }
 112
 113 extern volatile sig_atomic_t sigint;
 114
 115 ssize_t read_exact(int fd, void *buf, size_t len, int mayexit)
 116 {
 117         ssize_t num = 0, written;
 118
 119         while (len > 0 && !sigint) {
 120                 if ((written = read(fd, buf, len)) < 0) {
 121                         if (errno == EAGAIN && num > 0)
 122                                 continue;
 123                         if (mayexit)
 124                                 return -1;
 125                         else
 126                                 continue;
 127                 }
 128                 if (!written)
 129                         return 0;
 130                 len -= written;
 131                 buf += written;
 132                 num += written;
 133         }
 134
 135         return num;
 136 }
 137
 138 ssize_t write_exact(int fd, void *buf, size_t len, int mayexit)
 139 {
 140         ssize_t num = 0, written;
 141
 142         while (len > 0 && !sigint) {
 143                 if ((written = write(fd, buf, len)) < 0) {
 144                         if (errno == EAGAIN && num > 0)
 145                                 continue;
 146                         if (mayexit)
 147                                 return -1;
 148                         else
 149                                 continue;
 150                 }
 151                 if (!written)
 152                         return 0;
 153                 len -= written;
 154                 buf += written;
 155                 num += written;
 156         }
 157
 158         return num;
 159 }