utils.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2022 Felix Fietkau <nbd@nbd.name>
   4  */
   5 #include <sys/types.h>
   6 #include <sys/socket.h>
   7 #include <arpa/inet.h>
   8 #include <netdb.h>
   9 #include "unetd.h"
  10
  11 int network_get_endpoint(union network_endpoint *dest, const char *str,
  12                          int default_port, int idx)
  13 {
  14         struct addrinfo hints = {
  15                 .ai_flags = AI_ADDRCONFIG,
  16                 .ai_family = AF_UNSPEC,
  17         };
  18         char *buf = strdup(str);
  19         char *host = buf, *port;
  20         struct addrinfo *ai, *ai_cur;
  21         int n_res;
  22         int ret = -1;
  23
  24         memset(dest, 0, sizeof(*dest));
  25
  26         if (*host == '[') {
  27                 host++;
  28                 port = strchr(host, ']');
  29                 if (!port)
  30                         goto out;
  31
  32                 *(port++) = 0;
  33                 if (!*port)
  34                         port = NULL;
  35                 else if (*port == ':')
  36                         port++;
  37                 else
  38                         goto out;
  39                 hints.ai_family = AF_INET6;
  40                 hints.ai_flags |= AI_NUMERICHOST;
  41         } else {
  42                 host = buf;
  43
  44                 port = strchr(host, ':');
  45                 if (port)
  46                         *(port++) = 0;
  47         }
  48
  49         if (getaddrinfo(host, port, &hints, &ai) || !ai)
  50                 goto out;
  51
  52         while (1) {
  53                 ai_cur = ai;
  54                 for (n_res = 0; ai_cur; ai_cur = ai_cur->ai_next, n_res++)
  55                         if (!idx--)
  56                                 goto found;
  57
  58                 idx %= n_res;
  59         }
  60
  61 found:
  62         if (ai_cur->ai_addrlen > sizeof(*dest))
  63                 goto free_ai;
  64
  65         memcpy(dest, ai_cur->ai_addr, ai_cur->ai_addrlen);
  66         if (!port)
  67                 dest->in.sin_port = htons(default_port);
  68         ret = 0;
  69
  70 free_ai:
  71         freeaddrinfo(ai_cur);
  72
  73 out:
  74         free(buf);
  75         return ret;
  76 }
  77
  78 int network_get_subnet(int af, union network_addr *addr, int *mask, const char *str)
  79 {
  80         char *buf = strdup(str);
  81         char *sep, *end;
  82         int ret = -1;
  83
  84         if (af == AF_INET6)
  85                 *mask = 128;
  86         else
  87                 *mask = 32;
  88
  89         sep = strchr(buf, '/');
  90         if (sep) {
  91                 unsigned long val;
  92
  93                 *(sep++) = 0;
  94
  95                 val = strtoul(sep, &end, 0);
  96                 if ((end && *end) || val > *mask)
  97                         goto out;
  98
  99                 *mask = val;
 100         }
 101
 102         if (inet_pton(af, buf, addr) == 1)
 103                 ret = 0;
 104
 105 out:
 106         free(buf);
 107         return ret;
 108 }
 109
 110 int network_get_local_addr(void *local, const union network_endpoint *target)
 111 {
 112         union network_endpoint ep = {};
 113         socklen_t len;
 114         int ret = -1;
 115         int fd;
 116
 117         memset(local, 0, sizeof(union network_addr));
 118         if (target->sa.sa_family == AF_INET6)
 119                 len = sizeof(ep.in6);
 120         else
 121                 len = sizeof(ep.in);
 122
 123         fd = socket(target->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
 124         if (fd < 0)
 125                 return -1;
 126
 127         if (connect(fd, (const struct sockaddr *)target, len))
 128                 goto out;
 129
 130         len = sizeof(ep);
 131         if (getsockname(fd, &ep.sa, &len))
 132                 goto out;
 133
 134         if (ep.sa.sa_family == AF_INET6)
 135                 memcpy(local, &ep.in6.sin6_addr, sizeof(ep.in6.sin6_addr));
 136         else
 137                 memcpy(local, &ep.in.sin_addr, sizeof(ep.in.sin_addr));
 138         ret = 0;
 139
 140 out:
 141         close(fd);
 142         return ret;
 143 }