| // Copyright 2020 The Chromium OS Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "patchpanel/dns/dns_util.h" |
| |
| #include <errno.h> |
| #include <limits.h> |
| |
| #include <string> |
| |
| #include "base/optional.h" |
| |
| #include "patchpanel/dns/dns_protocol.h" |
| |
| namespace { |
| |
| // RFC 1035, section 2.3.4: labels 63 octets or less. |
| // Section 3.1: Each label is represented as a one octet length field followed |
| // by that number of octets. |
| const int kMaxLabelLength = 63; |
| |
| } // namespace |
| |
| #if defined(OS_POSIX) |
| #include <netinet/in.h> |
| #if !defined(OS_NACL) |
| #include <net/if.h> |
| #if !defined(OS_ANDROID) |
| #include <ifaddrs.h> |
| #endif // !defined(OS_ANDROID) |
| #endif // !defined(OS_NACL) |
| #endif // defined(OS_POSIX) |
| |
| #if defined(OS_ANDROID) |
| #include "net/android/network_library.h" |
| #endif |
| |
| namespace patchpanel { |
| namespace { |
| |
| // Based on DJB's public domain code. |
| bool DNSDomainFromDot(const base::StringPiece& dotted, |
| bool is_unrestricted, |
| std::string* out) { |
| const char* buf = dotted.data(); |
| size_t n = dotted.size(); |
| char label[kMaxLabelLength]; |
| size_t labellen = 0; /* <= sizeof label */ |
| char name[dns_protocol::kMaxNameLength]; |
| size_t namelen = 0; /* <= sizeof name */ |
| char ch; |
| |
| for (;;) { |
| if (!n) |
| break; |
| ch = *buf++; |
| --n; |
| if (ch == '.') { |
| // Don't allow empty labels per http://crbug.com/456391. |
| if (!labellen) |
| return false; |
| if (namelen + labellen + 1 > sizeof name) |
| return false; |
| name[namelen++] = static_cast<char>(labellen); |
| memcpy(name + namelen, label, labellen); |
| namelen += labellen; |
| labellen = 0; |
| continue; |
| } |
| if (labellen >= sizeof label) |
| return false; |
| if (!is_unrestricted && !IsValidHostLabelCharacter(ch, labellen == 0)) { |
| return false; |
| } |
| label[labellen++] = ch; |
| } |
| |
| // Allow empty label at end of name to disable suffix search. |
| if (labellen) { |
| if (namelen + labellen + 1 > sizeof name) |
| return false; |
| name[namelen++] = static_cast<char>(labellen); |
| memcpy(name + namelen, label, labellen); |
| namelen += labellen; |
| labellen = 0; |
| } |
| |
| if (namelen + 1 > sizeof name) |
| return false; |
| if (namelen == 0) // Empty names e.g. "", "." are not valid. |
| return false; |
| name[namelen++] = 0; // This is the root label (of length 0). |
| |
| *out = std::string(name, namelen); |
| return true; |
| } |
| |
| } // namespace |
| |
| bool DNSDomainFromDot(const base::StringPiece& dotted, std::string* out) { |
| return DNSDomainFromDot(dotted, false /* is_unrestricted */, out); |
| } |
| |
| bool IsValidHostLabelCharacter(char c, bool is_first_char) { |
| return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || |
| (c >= '0' && c <= '9') || (!is_first_char && c == '-') || c == '_'; |
| } |
| |
| base::Optional<std::string> DnsDomainToString(base::StringPiece domain) { |
| std::string ret; |
| |
| for (unsigned i = 0; i < domain.size() && domain[i]; i += domain[i] + 1) { |
| #if CHAR_MIN < 0 |
| if (domain[i] < 0) |
| return base::nullopt; |
| #endif |
| if (domain[i] > kMaxLabelLength) |
| return base::nullopt; |
| |
| if (i) |
| ret += "."; |
| |
| if (static_cast<unsigned>(domain[i]) + i + 1 > domain.size()) |
| return base::nullopt; |
| |
| ret.append(domain.data() + i + 1, domain[i]); |
| } |
| return ret; |
| } |
| |
| } // namespace patchpanel |