1// Copyright (c) 2011 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "net/base/dns_util.h"
6
7#include <cstring>
8
9namespace net {
10
11// Based on DJB's public domain code.
12bool DNSDomainFromDot(const base::StringPiece& dotted, std::string* out) {
13  const char* buf = dotted.data();
14  unsigned n = dotted.size();
15  char label[63];
16  unsigned int labellen = 0; /* <= sizeof label */
17  char name[255];
18  unsigned int namelen = 0; /* <= sizeof name */
19  char ch;
20
21  for (;;) {
22    if (!n)
23      break;
24    ch = *buf++;
25    --n;
26    if (ch == '.') {
27      if (labellen) {
28        if (namelen + labellen + 1 > sizeof name)
29          return false;
30        name[namelen++] = labellen;
31        memcpy(name + namelen, label, labellen);
32        namelen += labellen;
33        labellen = 0;
34      }
35      continue;
36    }
37    if (labellen >= sizeof label)
38      return false;
39    label[labellen++] = ch;
40  }
41
42  if (labellen) {
43    if (namelen + labellen + 1 > sizeof name)
44      return false;
45    name[namelen++] = labellen;
46    memcpy(name + namelen, label, labellen);
47    namelen += labellen;
48    labellen = 0;
49  }
50
51  if (namelen + 1 > sizeof name)
52    return false;
53  if (namelen == 0) // Empty names e.g. "", "." are not valid.
54    return false;
55  name[namelen++] = 0;  // This is the root label (of length 0).
56
57  *out = std::string(name, namelen);
58  return true;
59}
60
61std::string DNSDomainToString(const base::StringPiece& domain) {
62  std::string ret;
63
64  for (unsigned i = 0; i < domain.size() && domain[i]; i += domain[i] + 1) {
65#if CHAR_MIN < 0
66    if (domain[i] < 0)
67      return std::string();
68#endif
69    if (domain[i] > 63)
70      return std::string();
71
72    if (i)
73      ret += ".";
74
75    if (static_cast<unsigned>(domain[i]) + i + 1 > domain.size())
76      return std::string();
77
78    domain.substr(i + 1, domain[i]).AppendToString(&ret);
79  }
80  return ret;
81}
82
83std::string TrimEndingDot(const base::StringPiece& host) {
84  base::StringPiece host_trimmed = host;
85  size_t len = host_trimmed.length();
86  if (len > 1 && host_trimmed[len - 1] == '.') {
87    host_trimmed.remove_suffix(1);
88  }
89  return host_trimmed.as_string();
90}
91
92}  // namespace net
93