cosmopolitan/libc/sock/inet_aton.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
╚──────────────────────────────────────────────────────────────────────────────╝
│                                                                              │
│  Musl Libc                                                                   │
│  Copyright © 2005-2014 Rich Felker, et al.                                   │
│                                                                              │
│  Permission is hereby granted, free of charge, to any person obtaining       │
│  a copy of this software and associated documentation files (the             │
│  "Software"), to deal in the Software without restriction, including         │
│  without limitation the rights to use, copy, modify, merge, publish,         │
│  distribute, sublicense, and/or sell copies of the Software, and to          │
│  permit persons to whom the Software is furnished to do so, subject to       │
│  the following conditions:                                                   │
│                                                                              │
│  The above copyright notice and this permission notice shall be              │
│  included in all copies or substantial portions of the Software.             │
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│  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,             │
│  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF          │
│  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.      │
│  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY        │
│  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,        │
│  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE           │
│  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                      │
│                                                                              │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/ctype.h"
#include "libc/fmt/conv.h"
#include "libc/sock/sock.h"
#include "libc/sock/struct/sockaddr.h"
#include "libc/str/str.h"
__static_yoink("musl_libc_notice");

/**
 * Converts dotted IPv4 address string to network order binary.
 */
int inet_aton(const char *s0, struct in_addr *dest) {
  const char *s = s0;
  unsigned char *d = (void *)dest;
  unsigned long a[4] = {0};
  char *z;
  int i;
  for (i = 0; i < 4; i++) {
    a[i] = strtoul(s, &z, 0);
    if (z == s || (*z && *z != '.') || !isdigit(*s))
      return 0;
    if (!*z)
      break;
    s = z + 1;
  }
  if (i == 4)
    return 0;
  switch (i) {
    case 0:
      a[1] = a[0] & 0xffffff;
      a[0] >>= 24;
    case 1:
      a[2] = a[1] & 0xffff;
      a[1] >>= 16;
    case 2:
      a[3] = a[2] & 0xff;
      a[2] >>= 8;
  }
  for (i = 0; i < 4; i++) {
    if (a[i] > 255)
      return 0;
    d[i] = a[i];
  }
  return 1;
}