utils/cegw/cegw.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include <sys/socket.h>
   5 #include <net/if.h>
   6 #include <arpa/inet.h>
   7 #include <linux/can.h>
   8 #include <limits.h>
   9 #include <unistd.h>
  10 #include <fcntl.h>
  11 #include <sys/ioctl.h>
  12 #include "canethgw.h"
  13
  14 unsigned int cegw_errno = 0;
  15
  16 enum
  17 {
  18         CEGW_ERR_UNKNOWN,
  19         CEGW_ERR_COLON,
  20         CEGW_ERR_UNEXLEN,
  21         CEGW_ERR_ATON,
  22         CEGW_ERR_PORT
  23 };
  24
  25 char* cegw_errlist[] =
  26 {
  27         [CEGW_ERR_UNKNOWN] = "",
  28         [CEGW_ERR_COLON  ] = "expected ':' (<ip>:<port>)",
  29         [CEGW_ERR_UNEXLEN] = "unexpected ip address length, please use dot notation"
  30                              " (eg. 127.0.0.1)",
  31         [CEGW_ERR_ATON   ] = "ip address mismatch",
  32         [CEGW_ERR_PORT   ] = "port number"
  33 };
  34
  35 static const char help_msg[] = "usage:\n"
  36                                "        %s <can_if> <udp_listen_addr>:<port> <udp_dest_addr>:<port>\n"
  37                                "                [list of additional udp recipients <addr:port>]\n"
  38                                "example:\n"
  39                                "        %s can0 192.168.0.1:10501 192.168.0.4:980 192.168.0.7:1160\n\n"
  40                                "        Executing this command will set the gateway so that it will\n"
  41                                "        listen for udp messages on 192.168.0.1:10501 and send them\n"
  42                                "        to can0. Simultaneously, it will send all messages from can0\n"
  43                                "        to 192.168.0.4:980 and 192.168.0.7:1160 via udp. The message is\n"
  44                                "        therefore cloned. Notice that there can be any number\n"
  45                                "        of udp recipients.\n";
  46
  47 static void perr(char* s)
  48 {
  49         if (s) {
  50                 if (cegw_errno == 0) {
  51                         fprintf(stderr, "error: %s\n", s);
  52
  53                 } else {
  54                         fprintf(stderr, "error: %s, %s\n", s, cegw_errlist[cegw_errno]);
  55                 }
  56                 return;
  57         }
  58
  59         fprintf(stderr, "error: %s\n", cegw_errlist[cegw_errno]);
  60 }
  61
  62 /**
  63  * read_addrport - parses @in for eth address.
  64  * Valid input is e.g. 127.0.0.1:10502. If parsing fails
  65  * the cause is stored in cegw_errno.
  66  *
  67  * @param[in]  in   string to search in
  68  * @param[out] addr ip address
  69  * @param[out] port transport layer port
  70  * @return 0 on success, -1 otherwise
  71  */
  72 int read_addrport(char* in, struct in_addr* addr, unsigned short* port)
  73 {
  74         char* delim = NULL;
  75         const int addrstr_len = 16;
  76         char addrstr[addrstr_len];
  77         int addrlen;
  78
  79         if ((delim = strchr(in, ':')) == NULL) {
  80                 cegw_errno = CEGW_ERR_COLON;
  81                 return -1;
  82         }
  83
  84         /* get address */
  85         addrlen = delim - in;
  86         if (addrlen > addrstr_len) {
  87                 cegw_errno = CEGW_ERR_UNEXLEN;
  88                 return -1;
  89         }
  90
  91         memcpy(addrstr, in, addrlen);
  92         addrstr[addrlen] = '\0';
  93         if (inet_aton(addrstr, addr) == 0) {
  94                 cegw_errno = CEGW_ERR_ATON;
  95                 return -1;
  96         }
  97
  98         /* get port */
  99         /* ToDo: handle overflow */
 100         if (sscanf(delim, ":%hu", port) != 1) {
 101                 cegw_errno = CEGW_ERR_PORT;
 102                 return -1;
 103         }
 104
 105         return 0;
 106 }
 107
 108 int main(int argc, char* argv[])
 109 {
 110         int i;
 111         int fd;
 112         int tmpi;
 113         int dstcnt;
 114         unsigned short port;
 115         int udp_sock, can_sock;
 116         struct sockaddr_in udp_addr;
 117         struct sockaddr_can can_addr;
 118         struct sockaddr_in* dst = NULL;
 119         struct cegw_ioctl* gwctl = NULL;
 120
 121         if (argc == 1)
 122         {
 123                 printf(help_msg, argv[0], argv[0]);
 124                 return 0;
 125         }
 126
 127         if (argc < 4) {
 128                 perr("not enought arguments");
 129                 printf(help_msg, argv[0], argv[0]);
 130                 /* ToDo: print usage */
 131                 return -1;
 132         }
 133
 134         dstcnt = argc-3;
 135         gwctl = (struct cegw_ioctl*)malloc(sizeof(*gwctl) + (dstcnt)*sizeof(struct sockaddr_in));
 136
 137         for (i=1; i<argc; i++) {
 138                 switch (i) {
 139                         case 1: /* can ifindex */
 140                                 can_addr.can_family = AF_CAN;
 141                                 tmpi = if_nametoindex(argv[i]);
 142                                 if (tmpi == 0) {
 143                                         perr("given can interface not found");
 144                                         free(gwctl);
 145                                         return -1;
 146                                 }
 147                                 can_addr.can_ifindex = tmpi;
 148                                 break;
 149                         case 2: /* listen addr */
 150                                 udp_addr.sin_family = AF_INET;
 151                                 if (read_addrport(argv[i], &udp_addr.sin_addr, &port) != 0) {
 152                                         perr("listening address mismatch");
 153                                         free(gwctl);
 154                                         return -1;
 155                                 }
 156                                 udp_addr.sin_port = htons(port);
 157                                 break;
 158                         default: /* udp destination */
 159                                 dst = &gwctl->udp_dst[i-3];
 160                                 dst->sin_family = AF_INET;
 161                                 if (read_addrport(argv[i], &dst->sin_addr, &port) != 0) {
 162                                         perr("udp destination mismatch");
 163                                         free(gwctl);
 164                                         return -1;
 165                                 }
 166                                 dst->sin_port = htons(port);
 167                                 break;
 168                 }
 169         }
 170
 171         /* prepare udp socket */
 172         udp_sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
 173         if (udp_sock == -1) {
 174                 fprintf(stderr, "error: udp socket(..) failed\n");
 175                 free(gwctl);
 176                 return -1;
 177         }
 178
 179         if (bind(udp_sock, (struct sockaddr *)&udp_addr, sizeof(struct sockaddr_in)) != 0) {
 180                 fprintf(stderr, "error: udp bind(..) failed\n");
 181                 free(gwctl);
 182                 return -1;
 183         }
 184
 185         /* prepare can socket */
 186         can_sock = socket(PF_CAN, SOCK_RAW, CAN_RAW);
 187         if (can_sock == -1) {
 188                 fprintf(stderr, "error: can socket(..) failed\n");
 189                 free(gwctl);
 190                 return -1;
 191         }
 192
 193         if (bind(can_sock, (struct sockaddr *)&can_addr, sizeof(struct sockaddr_can)) != 0) {
 194                 fprintf(stderr, "error: can bind(..) failed\n");
 195                 free(gwctl);
 196                 return -1;
 197         }
 198
 199         /* send it to kernel gateway */
 200         fd = open("/dev/cegw", O_RDONLY);
 201         if (fd == -1) {
 202                 fprintf(stderr, "error: could not open device file\n");
 203                 free(gwctl);
 204                 return -1;
 205         }
 206
 207         gwctl->can_sock = can_sock;
 208         gwctl->udp_sock = udp_sock;
 209         gwctl->udp_dstcnt = dstcnt;
 210         gwctl->udp_addrlen = sizeof(struct sockaddr_in);
 211
 212         if (ioctl(fd, CEGW_IOCTL_START, gwctl) != 0) {
 213                 perror(NULL);
 214                 free(gwctl);
 215                 return -1;
 216         }
 217         printf("gateway successfully set and running\n");
 218         free(gwctl);
 219
 220         /* sleep until someone kills me */
 221         while (1) {
 222                 sleep(UINT_MAX);
 223         }
 224
 225         return 0;
 226 }
 227