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| 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_response.h" | |
| 6 | |
| 7 #include "net/base/address_list.h" | |
| 8 #include "net/base/dns_util.h" | |
| 9 #include "net/base/net_errors.h" | |
| 10 | |
| 11 namespace net { | |
| 12 | |
| 13 // RFC 1035, section 4.2.1: Messages carried by UDP are restricted to 512 | |
| 14 // bytes (not counting the IP nor UDP headers). | |
| 15 static const int kMaxResponseSize = 512; | |
| 16 | |
| 17 DnsResponse::DnsResponse(DnsQuery* query) | |
| 18 : query_(query), | |
| 19 io_buffer_(new IOBufferWithSize(kMaxResponseSize + 1)) { | |
| 20 DCHECK(query_); | |
| 21 DCHECK(query_->IsValid()); | |
| 22 } | |
| 23 | |
| 24 int DnsResponse::Parse(int nbytes, AddressList* results) { | |
| 25 DCHECK(query_->IsValid()); | |
| 26 | |
| 27 // Response includes query, it should be at least that size. | |
| 28 if (nbytes < query_->io_buffer()->size() || nbytes > kMaxResponseSize) | |
| 29 return ERR_DNS_MALFORMED_RESPONSE; | |
| 30 | |
| 31 DnsResponseBuffer response(reinterpret_cast<uint8*>(io_buffer_->data()), | |
| 32 io_buffer_->size()); | |
| 33 uint16 id; | |
| 34 if (!response.U16(&id) || id != query_->id()) // Make sure IDs match. | |
| 35 return ERR_DNS_MALFORMED_RESPONSE; | |
| 36 | |
| 37 uint8 flags, rcode; | |
| 38 if (!response.U8(&flags) || !response.U8(&rcode)) | |
| 39 return ERR_DNS_MALFORMED_RESPONSE; | |
| 40 | |
| 41 if (flags & 2) // TC is set -- server wants TCP, we don't support it (yet?). | |
| 42 return ERR_DNS_SERVER_REQUIRES_TCP; | |
| 43 | |
| 44 rcode &= 0x0f; // 3 means NXDOMAIN, the rest means server failed. | |
| 45 if (rcode && (rcode != 3)) | |
| 46 return ERR_DNS_SERVER_FAILED; | |
| 47 | |
| 48 uint16 query_count, answer_count, authority_count, additional_count; | |
| 49 if (!response.U16(&query_count) || | |
| 50 !response.U16(&answer_count) || | |
| 51 !response.U16(&authority_count) || | |
| 52 !response.U16(&additional_count)) { | |
| 53 return ERR_DNS_MALFORMED_RESPONSE; | |
| 54 } | |
| 55 | |
| 56 if (query_count != 1) // Sent a single question, shouldn't have changed. | |
| 57 return ERR_DNS_MALFORMED_RESPONSE; | |
| 58 | |
| 59 std::string hostname; | |
| 60 uint16 qtype, qclass; | |
| 61 if (!response.DNSName(&hostname) || | |
| 62 !response.U16(&qtype) || | |
| 63 !response.U16(&qclass) || | |
| 64 hostname != query_->hostname() || // Make sure Question section | |
| 65 qtype != query_->qtype() || // echoed back. | |
| 66 qclass != kClassIN) { | |
| 67 return ERR_DNS_MALFORMED_RESPONSE; | |
| 68 } | |
| 69 | |
| 70 if (answer_count < 1) | |
| 71 return ERR_NAME_NOT_RESOLVED; | |
| 72 | |
| 73 std::vector<IPAddressNumber> rdatas; | |
| 74 while (answer_count--) { | |
| 75 uint32 ttl; | |
| 76 uint16 rdlength; | |
| 77 if (!response.DNSName(NULL) || | |
| 78 !response.U16(&qtype) || | |
| 79 !response.U16(&qclass) || | |
| 80 !response.U32(&ttl) || | |
| 81 !response.U16(&rdlength)) { | |
| 82 return ERR_DNS_MALFORMED_RESPONSE; | |
| 83 } | |
| 84 | |
| 85 if (qtype == query_->qtype() && | |
| 86 qclass == kClassIN && | |
| 87 (rdlength == kIPv4AddressSize || rdlength == kIPv6AddressSize)) { | |
| 88 base::StringPiece rdata; | |
| 89 if (!response.Block(&rdata, rdlength)) | |
| 90 return ERR_DNS_MALFORMED_RESPONSE; | |
| 91 rdatas.push_back(IPAddressNumber(rdata.begin(), rdata.end())); | |
| 92 } else if (!response.Skip(rdlength)) | |
| 93 return ERR_DNS_MALFORMED_RESPONSE; | |
| 94 } | |
| 95 | |
| 96 if (rdatas.empty()) | |
| 97 return ERR_NAME_NOT_RESOLVED; | |
| 98 | |
| 99 *results = AddressList::CreateFromIPAddressList(rdatas, query_->port()); | |
| 100 return OK; | |
| 101 } | |
| 102 | |
| 103 } // namespace net | |
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Chromium Code Reviews
Issue 7056050:
Revert 87809 - Added DnsQuery class (Closed)
Base URL: svn://svn.chromium.org/chrome/trunk/src/