fusl/src/network/gethostbyname2_r.c

#define _GNU_SOURCE

#include <sys/socket.h>
#include <netdb.h>
#include <string.h>
#include <netinet/in.h>
#include <errno.h>
#include <stdint.h>
#include "lookup.h"

int gethostbyname2_r(const char* name,
                     int af,
                     struct hostent* h,
                     char* buf,
                     size_t buflen,
                     struct hostent** res,
                     int* err) {
  struct address addrs[MAXADDRS];
  char canon[256];
  int i, cnt;
  size_t align, need;

  *res = 0;
  cnt = __lookup_name(addrs, canon, name, af, AI_CANONNAME);
  if (cnt < 0)
    switch (cnt) {
      case EAI_NONAME:
        *err = HOST_NOT_FOUND;
        return ENOENT;
      case EAI_AGAIN:
        *err = TRY_AGAIN;
        return EAGAIN;
      default:
      case EAI_FAIL:
        *err = NO_RECOVERY;
        return EBADMSG;
      case EAI_MEMORY:
      case EAI_SYSTEM:
        *err = NO_RECOVERY;
        return errno;
      case 0:
        break;
    }

  h->h_addrtype = af;
  h->h_length = af == AF_INET6 ? 16 : 4;

  /* Align buffer */
  align = -(uintptr_t)buf & sizeof(char*) - 1;

  need = 4 * sizeof(char*);
  need += (cnt + 1) * (sizeof(char*) + h->h_length);
  need += strlen(name) + 1;
  need += strlen(canon) + 1;
  need += align;

  if (need > buflen)
    return ERANGE;

  buf += align;
  h->h_aliases = (void*)buf;
  buf += 3 * sizeof(char*);
  h->h_addr_list = (void*)buf;
  buf += (cnt + 1) * sizeof(char*);

  h->h_name = h->h_aliases[0] = buf;
  strcpy(h->h_name, canon);
  buf += strlen(h->h_name) + 1;

  if (strcmp(h->h_name, name)) {
    h->h_aliases[1] = buf;
    strcpy(h->h_aliases[1], name);
    buf += strlen(h->h_aliases[1]) + 1;
  } else
    h->h_aliases[1] = 0;

  h->h_aliases[2] = 0;

  for (i = 0; i < cnt; i++) {
    h->h_addr_list[i] = (void*)buf;
    buf += h->h_length;
    memcpy(h->h_addr_list[i], addrs[i].addr, h->h_length);
  }
  h->h_addr_list[i] = 0;

  *res = h;
  return 0;
}