libc-bottom-half/cloudlibc/src/libc/arpa/inet/inet_aton.c

   1 // Copyright (c) 2016 Nuxi, https://nuxi.nl/
   2 //
   3 // SPDX-License-Identifier: BSD-2-Clause
   4
   5 #include <arpa/inet.h>
   6
   7 #include <stdbool.h>
   8 #include <stdint.h>
   9
  10 int inet_aton(const char *cp, struct in_addr *inp) {
  11   uint32_t max = UINT32_MAX;
  12   uint32_t leading = 0;
  13   int shift = 24;
  14   for (;;) {
  15     // Parse next part of the IPv4 address.
  16     typedef uint32_t int_t;
  17     uint32_t min = 0;
  18     int base = 0;
  19     bool allow_negative = false;
  20 #define PEEK(n) cp[n]
  21 #define SKIP(n) \
  22   do {          \
  23     cp += (n);  \
  24   } while (0)
  25 #include <common/parser_strtoint.h>
  26 #undef PEEK
  27 #undef SKIP
  28     if (!have_number || have_overflow)
  29       return 0;
  30
  31     if (*cp == '\0') {
  32       // End of string. Return the IPv4 address, combining the
  33       // previously parsed leading bytes with the trailing number.
  34       inp->s_addr = htonl(leading | number);
  35       return 1;
  36     } else if (shift > 0 && number <= UINT8_MAX && *cp++ == '.') {
  37       // More components follow.
  38       leading |= number << shift;
  39       shift -= 8;
  40       max >>= 8;
  41     } else {
  42       // Parse error.
  43       return 0;
  44     }
  45   }
  46 }