src/network/gethostbyname2_r.c

   1 #define _GNU_SOURCE
   2
   3 #include <sys/socket.h>
   4 #include <netdb.h>
   5 #include <string.h>
   6 #include <netinet/in.h>
   7 #include <errno.h>
   8 #include <inttypes.h>
   9
  10 int gethostbyname2_r(const char *name, int af,
  11         struct hostent *h, char *buf, size_t buflen,
  12         struct hostent **res, int *err)
  13 {
  14         struct addrinfo hint = {
  15                 .ai_family = af==AF_INET6 ? af : AF_INET,
  16                 .ai_flags = AI_CANONNAME
  17         };
  18         struct addrinfo *ai, *p;
  19         int i;
  20         size_t need;
  21         const char *canon;
  22
  23         af = hint.ai_family;
  24
  25         /* Align buffer */
  26         i = (uintptr_t)buf & sizeof(char *)-1;
  27         if (i) {
  28                 if (buflen < sizeof(char *)-i) return ERANGE;
  29                 buf += sizeof(char *)-i;
  30                 buflen -= sizeof(char *)-i;
  31         }
  32
  33         switch (getaddrinfo(name, 0, &hint, &ai)) {
  34         case EAI_NONAME:
  35                 *err = HOST_NOT_FOUND;
  36                 return errno;
  37         case EAI_AGAIN:
  38                 *err = TRY_AGAIN;
  39                 return errno;
  40         default:
  41         case EAI_MEMORY:
  42         case EAI_SYSTEM:
  43         case EAI_FAIL:
  44                 *err = NO_RECOVERY;
  45                 return errno;
  46         case 0:
  47                 break;
  48         }
  49
  50         h->h_addrtype = af;
  51         h->h_length = af==AF_INET6 ? 16 : 4;
  52
  53         canon = ai->ai_canonname ? ai->ai_canonname : name;
  54         need = 4*sizeof(char *);
  55         for (i=0, p=ai; p; i++, p=p->ai_next)
  56                 need += sizeof(char *) + h->h_length;
  57         need += strlen(name)+1;
  58         need += strlen(canon)+1;
  59
  60         if (need > buflen) {
  61                 freeaddrinfo(ai);
  62                 return ERANGE;
  63         }
  64
  65         h->h_aliases = (void *)buf;
  66         buf += 3*sizeof(char *);
  67         h->h_addr_list = (void *)buf;
  68         buf += (i+1)*sizeof(char *);
  69
  70         h->h_name = h->h_aliases[0] = buf;
  71         strcpy(h->h_name, canon);
  72         buf += strlen(h->h_name)+1;
  73
  74         if (strcmp(h->h_name, name)) {
  75                 h->h_aliases[1] = buf;
  76                 strcpy(h->h_aliases[1], name);
  77                 buf += strlen(h->h_aliases[1])+1;
  78         } else h->h_aliases[1] = 0;
  79
  80         h->h_aliases[2] = 0;
  81
  82         for (i=0, p=ai; p; i++, p=p->ai_next) {
  83                 h->h_addr_list[i] = (void *)buf;
  84                 buf += h->h_length;
  85                 memcpy(h->h_addr_list[i],
  86                         &((struct sockaddr_in *)p->ai_addr)->sin_addr,
  87                         h->h_length);
  88         }
  89         h->h_addr_list[i] = 0;
  90
  91         *res = h;
  92         freeaddrinfo(ai);
  93         return 0;
  94 }