wrapper.c

   1 #include <sys/stat.h>
   2 #include <sys/types.h>
   3
   4 #include <err.h>
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <time.h>
   9 #include <unistd.h>
  10
  11 int
  12 main(int argc, char **argv)
  13 {
  14         const unsigned int uargc = (unsigned int)argc;
  15         char *init = NULL;
  16         size_t i, j, r, rv = 0, s;
  17         pid_t pid, sid;
  18
  19         if (uargc % 2 != 0 || uargc < 4) {
  20                 (void)fprintf(stderr, "usage: wrapper \"ii args\" host1 port1"
  21                     " [host2 port2 ...]\n");
  22                 exit(1);
  23         }
  24
  25         for (i = 0; i < strlen(argv[1]); i++)
  26                 if (argv[1][i] == '<' || argv[1][i] == '>'
  27                     || argv[1][i] == '|' || argv[1][i] == ';'
  28                     || argv[1][i] == '(' || argv[1][i] == ')'
  29                     || argv[1][i] == '&' || argv[1][i] == '"'
  30                     || argv[1][i] == '\'')
  31                         err(1, "sh(1) meta-characters and quotation marks are "
  32                             "not allowed in the `ii args'.\n");
  33
  34         for (i = 2; i < uargc; i++)
  35                 if (i % 2 == 1) {
  36                         /*
  37                          * Permit port numbers that are in the range 0 < p <
  38                          * 65535.
  39                          */
  40                         if (atoi(argv[i]) < 1 || atoi(argv[i]) > 65535)
  41                                 err(1, "Port number `%lu' is not in range.\n",
  42                                     (unsigned long)i / 2);
  43                         for (j = 0; j < strlen(argv[i]); j++)
  44                                 if (argv[i][j] < 0x30 || argv[i][j] > 0x39)
  45                                         err(1, "Character `%lu' in port `%lu'"
  46                                             " is not allowed.\n",
  47                                             (unsigned long)j + 1,
  48                                             (unsigned long)i / 2);
  49                 } else {
  50                         /*
  51                          * Permitted characters in the hostname fields:
  52                          *      a-z     (0x61 < c < 0x7a)
  53                          *      0-9     (0x30 < c < 0x39)
  54                          *      A-Z     (0x41 < c < 0x5a)
  55                          *      .-
  56                          */
  57                         for (j = 0; j < strlen(argv[i]); j++)
  58                                 if (((argv[i][j] < 0x61 || argv[i][j] > 0x7a)
  59                                     && (argv[i][j] < 0x30 || argv[i][j] > 0x39)
  60                                     && (argv[i][j] < 0x41 || argv[i][j] > 0x5a))
  61                                     && argv[i][j] != '.' && argv[i][j] != '-')
  62                                         err(1, "Character `%lu' in hostname"
  63                                             " `%lu' is not allowed.\n",
  64                                             (unsigned long)j + 1,
  65                                             (unsigned long)i / 2);
  66                 }
  67
  68         printf("arguments: `%s'\n", argv[1]);
  69         for (i = 2; i < uargc; i += 2)
  70                 printf("[%lu]: %s:%d\n", (unsigned long)(i - 1) / 2, argv[i],
  71                     atoi(argv[i + 1]));
  72
  73         pid = fork();
  74         if (pid < 0) {
  75                 rv = 1;
  76                 goto clean;
  77         } else if (pid > 0)
  78                 goto clean;
  79
  80         umask(0);
  81
  82         sid = setsid();
  83         if (sid < 0) {
  84                 rv = 1;
  85                 goto clean;
  86         }
  87
  88         if ((chdir("/")) < 0) {
  89                 rv = 1;
  90                 goto clean;
  91         }
  92
  93         close(STDIN_FILENO);
  94         close(STDOUT_FILENO);
  95         close(STDERR_FILENO);
  96
  97         srandom(time(NULL));
  98
  99         while (1) {
 100                 /*
 101                  * Calculate a random number in the range 0-(i/2 - 1).
 102                  * http://eternallyconfuzzled.com/arts/jsw_art_rand.aspx
 103                  */
 104                 r = random() * 1.0 / ( RAND_MAX + 1.0 ) * (i / 2 - 1);
 105
 106                 s = strlen(argv[1]) + strlen(argv[r * 2 + 2]) +
 107                     strlen(argv[r * 2 + 3]) + 10 + sizeof(EXECUTABLE);
 108
 109                 if ((init = calloc(s, 1)) == NULL) {
 110                         rv = 1;
 111                         goto clean;
 112                 }
 113                 strlcpy(init, EXECUTABLE" ", s);
 114                 strlcat(init, argv[1], s);
 115                 strlcat(init, " -s ", s);
 116                 strlcat(init, argv[r * 2 + 2], s);
 117                 strlcat(init, " -p ", s);
 118                 strlcat(init, argv[r * 2 + 3], s);
 119
 120                 system(init);
 121                 free(init);
 122         }
 123
 124 clean:
 125         if (init != NULL)
 126                 free(init);
 127         return rv;
 128 }