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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include <arpa/inet.h>
     18 #include <netinet/in.h>
     19 #include <stdlib.h>
     20 
     21 #include "private/ErrnoRestorer.h"
     22 
     23 // The difference between inet_network(3) and inet_addr(3) is that
     24 // inet_network uses host order and inet_addr network order.
     25 in_addr_t inet_network(const char* cp) {
     26   in_addr_t network_order = inet_addr(cp);
     27   return ntohl(network_order);
     28 }
     29 
     30 in_addr_t inet_addr(const char* cp) {
     31   in_addr addr;
     32   return inet_aton(cp, &addr) ? addr.s_addr : INADDR_NONE;
     33 }
     34 
     35 int inet_aton(const char* cp, in_addr* addr) {
     36   ErrnoRestorer errno_restorer;
     37 
     38   unsigned long parts[4];
     39   size_t i;
     40   for (i = 0; i < 4; ++i) {
     41     char* end;
     42     errno = 0;
     43     parts[i] = strtoul(cp, &end, 0);
     44     if (errno != 0 || end == cp || (*end != '.' && *end != '\0')) return 0;
     45     if (*end == '\0') break;
     46     cp = end + 1;
     47   }
     48 
     49   uint32_t result = 0;
     50   if (i == 0) {
     51     // a (a 32-bit).
     52     if (parts[0] > 0xffffffff) return 0;
     53     result = parts[0];
     54   } else if (i == 1) {
     55     // a.b (b 24-bit).
     56     if (parts[0] > 0xff || parts[1] > 0xffffff) return 0;
     57     result = (parts[0] << 24) | parts[1];
     58   } else if (i == 2) {
     59     // a.b.c (c 16-bit).
     60     if (parts[0] > 0xff || parts[1] > 0xff || parts[2] > 0xffff) return 0;
     61     result = (parts[0] << 24) | (parts[1] << 16) | parts[2];
     62   } else if (i == 3) {
     63     // a.b.c.d (d 8-bit).
     64     if (parts[0] > 0xff || parts[1] > 0xff || parts[2] > 0xff || parts[3] > 0xff) return 0;
     65     result = (parts[0] << 24) | (parts[1] << 16) | (parts[2] << 8) | parts[3];
     66   } else {
     67     return 0;
     68   }
     69 
     70   if (addr != nullptr) addr->s_addr = htonl(result);
     71   return 1;
     72 }
     73