utils/cegw/cegw.c

   1 /*
   2  * Copyright: (c) 2012 Czech Technical University in Prague
   3  *
   4  * Authors:
   5  *      Radek Matějka <radek.matejka@gmail.com>
   6  *      Michal Sojka  <sojkam1@fel.cvut.cz>
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version
  11  * 2 of the License, or (at your option) any later version.
  12  */
  13
  14
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18 #include <sys/socket.h>
  19 #include <net/if.h>
  20 #include <arpa/inet.h>
  21 #include <linux/can.h>
  22 #include <limits.h>
  23 #include <unistd.h>
  24 #include <fcntl.h>
  25 #include <sys/ioctl.h>
  26 #include "canethgw.h"
  27
  28 unsigned int cegw_errno = 0;
  29
  30 enum
  31 {
  32         CEGW_ERR_UNKNOWN,
  33         CEGW_ERR_COLON,
  34         CEGW_ERR_UNEXLEN,
  35         CEGW_ERR_ATON,
  36         CEGW_ERR_PORT
  37 };
  38
  39 char* cegw_errlist[] =
  40 {
  41         [CEGW_ERR_UNKNOWN] = "",
  42         [CEGW_ERR_COLON  ] = "expected ':' (<ip>:<port>)",
  43         [CEGW_ERR_UNEXLEN] = "unexpected ip address length, please use dot notation"
  44                              " (eg. 127.0.0.1)",
  45         [CEGW_ERR_ATON   ] = "ip address mismatch",
  46         [CEGW_ERR_PORT   ] = "port number"
  47 };
  48
  49 static const char help_msg[] = "usage:\n"
  50                                "        %s <can_if> <udp_listen_addr>:<port> <udp_dest_addr>:<port>\n"
  51                                "                [list of additional udp recipients <addr:port>]\n"
  52                                "example:\n"
  53                                "        %s can0 192.168.0.1:10501 192.168.0.4:980 192.168.0.7:1160\n\n"
  54                                "        Executing this command will set the gateway so that it will\n"
  55                                "        listen for udp messages on 192.168.0.1:10501 and send them\n"
  56                                "        to can0. Simultaneously, it will send all messages from can0\n"
  57                                "        to 192.168.0.4:980 and 192.168.0.7:1160 via udp. The message is\n"
  58                                "        therefore cloned. Notice that there can be any number\n"
  59                                "        of udp recipients.\n";
  60
  61 static void perr(char* s)
  62 {
  63         if (s) {
  64                 if (cegw_errno == 0) {
  65                         fprintf(stderr, "error: %s\n", s);
  66
  67                 } else {
  68                         fprintf(stderr, "error: %s, %s\n", s, cegw_errlist[cegw_errno]);
  69                 }
  70                 return;
  71         }
  72
  73         fprintf(stderr, "error: %s\n", cegw_errlist[cegw_errno]);
  74 }
  75
  76 /**
  77  * read_addrport - parses @in for eth address.
  78  * Valid input is e.g. 127.0.0.1:10502. If parsing fails
  79  * the cause is stored in cegw_errno.
  80  *
  81  * @param[in]  in   string to search in
  82  * @param[out] addr ip address
  83  * @param[out] port transport layer port
  84  * @return 0 on success, -1 otherwise
  85  */
  86 int read_addrport(char* in, struct in_addr* addr, unsigned short* port)
  87 {
  88         char* delim = NULL;
  89         const int addrstr_len = 16;
  90         char addrstr[addrstr_len];
  91         int addrlen;
  92
  93         if ((delim = strchr(in, ':')) == NULL) {
  94                 cegw_errno = CEGW_ERR_COLON;
  95                 return -1;
  96         }
  97
  98         /* get address */
  99         addrlen = delim - in;
 100         if (addrlen > addrstr_len) {
 101                 cegw_errno = CEGW_ERR_UNEXLEN;
 102                 return -1;
 103         }
 104
 105         memcpy(addrstr, in, addrlen);
 106         addrstr[addrlen] = '\0';
 107         if (inet_aton(addrstr, addr) == 0) {
 108                 cegw_errno = CEGW_ERR_ATON;
 109                 return -1;
 110         }
 111
 112         /* get port */
 113         /* ToDo: handle overflow */
 114         if (sscanf(delim, ":%hu", port) != 1) {
 115                 cegw_errno = CEGW_ERR_PORT;
 116                 return -1;
 117         }
 118
 119         return 0;
 120 }
 121
 122 int main(int argc, char* argv[])
 123 {
 124         int i;
 125         int fd;
 126         int tmpi;
 127         int dstcnt;
 128         unsigned short port;
 129         int udp_sock, can_sock;
 130         struct sockaddr_in udp_addr;
 131         struct sockaddr_can can_addr;
 132         struct sockaddr_in* dst = NULL;
 133         struct cegw_ioctl* gwctl = NULL;
 134
 135         if (argc == 1)
 136         {
 137                 printf(help_msg, argv[0], argv[0]);
 138                 return 0;
 139         }
 140
 141         if (argc < 4) {
 142                 perr("not enought arguments");
 143                 printf(help_msg, argv[0], argv[0]);
 144                 /* ToDo: print usage */
 145                 return -1;
 146         }
 147
 148         dstcnt = argc-3;
 149         gwctl = (struct cegw_ioctl*)malloc(sizeof(*gwctl) + (dstcnt)*sizeof(struct sockaddr_in));
 150
 151         for (i=1; i<argc; i++) {
 152                 switch (i) {
 153                         case 1: /* can ifindex */
 154                                 can_addr.can_family = AF_CAN;
 155                                 tmpi = if_nametoindex(argv[i]);
 156                                 if (tmpi == 0) {
 157                                         perr("given can interface not found");
 158                                         free(gwctl);
 159                                         return -1;
 160                                 }
 161                                 can_addr.can_ifindex = tmpi;
 162                                 break;
 163                         case 2: /* listen addr */
 164                                 udp_addr.sin_family = AF_INET;
 165                                 if (read_addrport(argv[i], &udp_addr.sin_addr, &port) != 0) {
 166                                         perr("listening address mismatch");
 167                                         free(gwctl);
 168                                         return -1;
 169                                 }
 170                                 udp_addr.sin_port = htons(port);
 171                                 break;
 172                         default: /* udp destination */
 173                                 dst = &gwctl->udp_dst[i-3];
 174                                 dst->sin_family = AF_INET;
 175                                 if (read_addrport(argv[i], &dst->sin_addr, &port) != 0) {
 176                                         perr("udp destination mismatch");
 177                                         free(gwctl);
 178                                         return -1;
 179                                 }
 180                                 dst->sin_port = htons(port);
 181                                 break;
 182                 }
 183         }
 184
 185         /* prepare udp socket */
 186         udp_sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
 187         if (udp_sock == -1) {
 188                 fprintf(stderr, "error: udp socket(..) failed\n");
 189                 free(gwctl);
 190                 return -1;
 191         }
 192
 193         if (bind(udp_sock, (struct sockaddr *)&udp_addr, sizeof(struct sockaddr_in)) != 0) {
 194                 fprintf(stderr, "error: udp bind(..) failed\n");
 195                 free(gwctl);
 196                 return -1;
 197         }
 198
 199         /* prepare can socket */
 200         can_sock = socket(PF_CAN, SOCK_RAW, CAN_RAW);
 201         if (can_sock == -1) {
 202                 fprintf(stderr, "error: can socket(..) failed\n");
 203                 free(gwctl);
 204                 return -1;
 205         }
 206
 207         if (bind(can_sock, (struct sockaddr *)&can_addr, sizeof(struct sockaddr_can)) != 0) {
 208                 fprintf(stderr, "error: can bind(..) failed\n");
 209                 free(gwctl);
 210                 return -1;
 211         }
 212
 213         /* send it to kernel gateway */
 214         fd = open("/dev/cegw", O_RDONLY);
 215         if (fd == -1) {
 216                 fprintf(stderr, "error: could not open device file\n");
 217                 free(gwctl);
 218                 return -1;
 219         }
 220
 221         gwctl->can_sock = can_sock;
 222         gwctl->udp_sock = udp_sock;
 223         gwctl->udp_dstcnt = dstcnt;
 224         gwctl->udp_addrlen = sizeof(struct sockaddr_in);
 225
 226         if (ioctl(fd, CEGW_IOCTL_START, gwctl) != 0) {
 227                 perror(NULL);
 228                 free(gwctl);
 229                 return -1;
 230         }
 231         printf("gateway successfully set and running\n");
 232         free(gwctl);
 233
 234         /* sleep until someone kills me */
 235         while (1) {
 236                 sleep(UINT_MAX);
 237         }
 238
 239         return 0;
 240 }
 241