src/ifaces.c

   1 /* For terms of usage/redistribution/modification see the LICENSE file */
   2 /* For authors and contributors see the AUTHORS file */
   3
   4 /***
   5
   6 ifaces.c - routine that determines whether a given interface is supported
   7                 by IPTraf
   8
   9 ***/
  10
  11 #include "iptraf-ng-compat.h"
  12
  13 #include "error.h"
  14
  15 /*
  16  * Open /proc/net/dev and move file pointer past the two table header lines
  17  * at the top of the file.
  18  */
  19
  20 FILE *open_procnetdev(void)
  21 {
  22         FILE *fd;
  23         char buf[161];
  24
  25         fd = fopen("/proc/net/dev", "r");
  26
  27         /*
  28          * Read and discard the table header lines in the file
  29          */
  30
  31         if (fd != NULL) {
  32                 fgets(buf, 160, fd);
  33                 fgets(buf, 160, fd);
  34         }
  35
  36         return fd;
  37 }
  38
  39 /*
  40  * Get the next interface from /proc/net/dev.
  41  */
  42 int get_next_iface(FILE * fd, char *ifname, int n)
  43 {
  44         char buf[161];
  45
  46         strcpy(ifname, "");
  47
  48         if (!feof(fd)) {
  49                 strcpy(buf, "");
  50                 fgets(buf, 160, fd);
  51                 if (strcmp(buf, "") != 0) {
  52                         memset(ifname, 0, n);
  53                         strncpy(ifname, skip_whitespace(strtok(buf, ":")), n);
  54                         if (ifname[n - 1] != '\0')
  55                                 strcpy(ifname, "");
  56                         return 1;
  57                 }
  58         }
  59         return 0;
  60 }
  61
  62 int dev_up(char *iface)
  63 {
  64         int fd;
  65         int ir;
  66         struct ifreq ifr;
  67
  68         fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
  69
  70         strcpy(ifr.ifr_name, iface);
  71         ir = ioctl(fd, SIOCGIFFLAGS, &ifr);
  72
  73         close(fd);
  74
  75         if ((ir != 0) || (!(ifr.ifr_flags & IFF_UP)))
  76                 return 0;
  77
  78         return 1;
  79 }
  80
  81 void err_iface_down(void)
  82 {
  83         write_error("Specified interface not active");
  84 }
  85
  86 int dev_get_ifindex(const char *iface)
  87 {
  88         int fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
  89         if (fd == -1)
  90                 return fd;
  91
  92         struct ifreq ifr;
  93         strcpy(ifr.ifr_name, iface);
  94         int ir = ioctl(fd, SIOCGIFINDEX, &ifr);
  95
  96         /* need to preserve errno across call to close() */
  97         int saved_errno = errno;
  98
  99         close(fd);
 100
 101         /* bug out if ioctl() failed */
 102         if (ir != 0) {
 103                 errno = saved_errno;
 104                 return ir;
 105         }
 106
 107         return ifr.ifr_ifindex;
 108 }
 109
 110 int dev_get_mtu(const char *iface)
 111 {
 112         int fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
 113         if (fd == -1)
 114                 return fd;
 115
 116         struct ifreq ifr;
 117         strcpy(ifr.ifr_name, iface);
 118         int ir = ioctl(fd, SIOCGIFMTU, &ifr);
 119
 120         /* need to preserve errno across call to close() */
 121         int saved_errno = errno;
 122
 123         close(fd);
 124
 125         /* bug out if ioctl() failed */
 126         if (ir != 0) {
 127                 errno = saved_errno;
 128                 return ir;
 129         }
 130
 131         return ifr.ifr_mtu;
 132 }
 133
 134 int dev_get_flags(const char *iface)
 135 {
 136         int fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
 137         if (fd == -1)
 138                 return fd;
 139
 140         struct ifreq ifr;
 141         strcpy(ifr.ifr_name, iface);
 142         int ir = ioctl(fd, SIOCGIFFLAGS, &ifr);
 143
 144         /* need to preserve errno across call to close() */
 145         int saved_errno = errno;
 146
 147         close(fd);
 148
 149         /* bug out if ioctl() failed */
 150         if (ir != 0) {
 151                 errno = saved_errno;
 152                 return ir;
 153         }
 154
 155         return ifr.ifr_flags;
 156 }
 157
 158 int dev_set_flags(const char *iface, int flags)
 159 {
 160         int fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
 161         if (fd == -1)
 162                 return fd;
 163
 164         struct ifreq ifr;
 165         strcpy(ifr.ifr_name, iface);
 166         int ir = ioctl(fd, SIOCGIFFLAGS, &ifr);
 167         if (ir == -1)
 168                 goto err;
 169
 170         ifr.ifr_flags |= flags;
 171         ir = ioctl(fd, SIOCSIFFLAGS, &ifr);
 172
 173         int saved_errno;
 174 err:    /* need to preserve errno across call to close() */
 175         saved_errno = errno;
 176
 177         close(fd);
 178
 179         /* bug out if ioctl() failed */
 180         if (ir != 0)
 181                 errno = saved_errno;
 182
 183         return ir;
 184 }
 185
 186 int dev_clear_flags(const char *iface, int flags)
 187 {
 188         int fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
 189         if (fd == -1)
 190                 return fd;
 191
 192         struct ifreq ifr;
 193         strcpy(ifr.ifr_name, iface);
 194         int ir = ioctl(fd, SIOCGIFFLAGS, &ifr);
 195         if (ir == -1)
 196                 goto err;
 197
 198         ifr.ifr_flags &= ~flags;
 199         ir = ioctl(fd, SIOCSIFFLAGS, &ifr);
 200
 201         int saved_errno;
 202 err:    /* need to preserve errno across call to close() */
 203         saved_errno = errno;
 204
 205         close(fd);
 206
 207         /* bug out if ioctl() failed */
 208         if (ir != 0)
 209                 errno = saved_errno;
 210
 211         return ir;
 212 }
 213
 214 int dev_get_ifname(int ifindex, char *ifname)
 215 {
 216         int fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
 217         if (fd == -1)
 218                 return fd;
 219
 220         struct ifreq ifr = {
 221                 .ifr_ifindex = ifindex
 222         };
 223         int ir = ioctl(fd, SIOCGIFNAME, &ifr);
 224
 225         /* need to preserve errno across call to close() */
 226         int saved_errno = errno;
 227
 228         close(fd);
 229
 230         /* bug out if ioctl() failed */
 231         if (ir != 0) {
 232                 errno = saved_errno;
 233                 return ir;
 234         }
 235
 236         strncpy(ifname, ifr.ifr_name, IFNAMSIZ);
 237         return ir;
 238 }
 239
 240 static int dev_bind_ifindex(int fd, const int ifindex)
 241 {
 242         struct sockaddr_ll fromaddr;
 243         socklen_t addrlen = sizeof(fromaddr);
 244
 245         fromaddr.sll_family = AF_PACKET;
 246         fromaddr.sll_protocol = htons(ETH_P_ALL);
 247         fromaddr.sll_ifindex = ifindex;
 248         return bind(fd, (struct sockaddr *) &fromaddr, addrlen);
 249 }
 250
 251 int dev_bind_ifname(int fd, const char * const ifname)
 252 {
 253         int ifindex = 0;
 254
 255         if (ifname) {
 256                 int ir;
 257                 struct ifreq ifr;
 258
 259                 strcpy(ifr.ifr_name, ifname);
 260                 ir = ioctl(fd, SIOCGIFINDEX, &ifr);
 261                 if (ir)
 262                         return ir;
 263                 ifindex = ifr.ifr_ifindex;
 264         }
 265
 266         return dev_bind_ifindex(fd, ifindex);
 267 }
 268
 269 int dev_promisc_flag(const char *dev_name)
 270 {
 271         int flags = dev_get_flags(dev_name);
 272         if (flags < 0) {
 273                 write_error("Unable to obtain interface parameters for %s",
 274                             dev_name);
 275                 return -1;
 276         }
 277
 278         if (flags & IFF_PROMISC)
 279                 return -1;
 280
 281         return flags;
 282 }