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https://github.com/RGBCube/serenity
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LookupServer: Minor overhaul
- Break out request building into a DNSRequest class. - Break out response parsing into a DNSResponse class. A DNSRequest contains one or more DNSQuestion objects. A DNSResponse contains all the DNSQuestions asked, and a DNSAnswer object for each answer.
This commit is contained in:
Andreas Kling
parent
f24173b0f1
commit
871b6b4e1a
10 changed files with 343 additions and 181 deletions
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@ -25,10 +25,8 @@
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*/
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#include "LookupServer.h"
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#include "DNSPacket.h"
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#include "DNSRecord.h"
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#include <AK/BufferStream.h>
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#include <AK/ByteBuffer.h>
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#include "DNSRequest.h"
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#include "DNSResponse.h"
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#include <AK/HashMap.h>
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#include <AK/String.h>
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#include <AK/StringBuilder.h>
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@ -38,7 +36,6 @@
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#include <LibCore/CFile.h>
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#include <LibCore/CLocalServer.h>
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#include <LibCore/CLocalSocket.h>
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#include <LibCore/CSyscallUtils.h>
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#include <arpa/inet.h>
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#include <netinet/in.h>
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#include <stdio.h>
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@ -49,15 +46,6 @@
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#include <time.h>
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#include <unistd.h>
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#define T_A 1
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#define T_NS 2
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#define T_CNAME 5
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#define T_SOA 6
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#define T_PTR 12
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#define T_MX 15
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#define C_IN 1
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LookupServer::LookupServer()
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{
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auto config = CConfigFile::get_for_system("LookupServer");
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@ -72,7 +60,7 @@ LookupServer::LookupServer()
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socket->on_ready_to_read = [this, socket]() {
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service_client(socket);
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RefPtr<CLocalSocket> keeper = socket;
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const_cast<CLocalSocket&>(*socket).on_ready_to_read = []{};
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const_cast<CLocalSocket&>(*socket).on_ready_to_read = [] {};
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};
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};
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bool ok = m_local_server->take_over_from_system_server();
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@ -173,29 +161,6 @@ void LookupServer::service_client(RefPtr<CLocalSocket> socket)
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}
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}
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String LookupServer::parse_dns_name(const u8* data, int& offset, int max_offset)
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{
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Vector<char, 128> buf;
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while (offset < max_offset) {
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u8 ch = data[offset];
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if (ch == '\0') {
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++offset;
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break;
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}
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if ((ch & 0xc0) == 0xc0) {
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ASSERT_NOT_REACHED();
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// FIXME: Parse referential names.
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offset += 2;
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}
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for (int i = 0; i < ch; ++i) {
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buf.append(data[offset + i + 1]);
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}
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buf.append('.');
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offset += ch + 1;
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}
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return String::copy(buf);
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}
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Vector<String> LookupServer::lookup(const String& hostname, bool& did_timeout, unsigned short record_type)
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{
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if (auto it = m_lookup_cache.find(hostname); it != m_lookup_cache.end()) {
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@ -206,52 +171,16 @@ Vector<String> LookupServer::lookup(const String& hostname, bool& did_timeout, u
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m_lookup_cache.remove(it);
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}
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DNSPacket request_header;
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request_header.set_id(get_next_id());
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request_header.set_is_query();
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request_header.set_opcode(0);
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request_header.set_truncated(false);
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request_header.set_recursion_desired(true);
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request_header.set_question_count(1);
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DNSRequest request;
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request.add_question(hostname, record_type);
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auto buffer = ByteBuffer::create_uninitialized(1024);
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{
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BufferStream stream(buffer);
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stream << ByteBuffer::wrap(&request_header, sizeof(request_header));
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auto parts = hostname.split('.');
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for (auto& part : parts) {
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stream << (u8)part.length();
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stream << part;
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}
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stream << '\0';
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stream << htons(record_type);
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stream << htons(C_IN);
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stream.snip();
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}
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int fd = socket(AF_INET, SOCK_DGRAM, 0);
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if (fd < 0) {
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perror("socket");
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return {};
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}
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struct timeval timeout {
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1, 0
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};
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int rc = setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
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if (rc < 0) {
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perror("setsockopt");
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close(fd);
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return {};
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}
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auto buffer = request.to_byte_buffer();
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struct sockaddr_in dst_addr;
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memset(&dst_addr, 0, sizeof(dst_addr));
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dst_addr.sin_family = AF_INET;
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dst_addr.sin_port = htons(53);
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rc = inet_pton(AF_INET, m_dns_ip.characters(), &dst_addr.sin_addr);
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int fd = make_dns_request_socket(dst_addr);
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if (fd < 0)
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return {};
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int nsent = sendto(fd, buffer.data(), buffer.size(), 0, (const struct sockaddr*)&dst_addr, sizeof(dst_addr));
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if (nsent < 0) {
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@ -277,63 +206,62 @@ Vector<String> LookupServer::lookup(const String& hostname, bool& did_timeout, u
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response_buffer[nrecv] = '\0';
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if (nrecv < (int)sizeof(DNSPacket)) {
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dbgprintf("LookupServer: Response not big enough (%d) to be a DNS packet :(\n", nrecv);
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auto o_response = DNSResponse::from_raw_response(response_buffer, nrecv);
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if (!o_response.has_value())
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return {};
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}
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auto& response_header = *(DNSPacket*)(response_buffer);
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dbgprintf("Got response (ID: %u)\n", response_header.id());
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dbgprintf(" Question count: %u\n", response_header.question_count());
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dbgprintf(" Answer count: %u\n", response_header.answer_count());
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dbgprintf(" Authority count: %u\n", response_header.authority_count());
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dbgprintf("Additional count: %u\n", response_header.additional_count());
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auto& response = o_response.value();
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if (response_header.id() != request_header.id()) {
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dbgprintf("LookupServer: ID mismatch (%u vs %u) :(\n", response_header.id(), request_header.id());
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if (response.id() != request.id()) {
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dbgprintf("LookupServer: ID mismatch (%u vs %u) :(\n", response.id(), request.id());
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return {};
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}
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if (response_header.question_count() != 1) {
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dbgprintf("LookupServer: Question count (%u vs %u) :(\n", response_header.question_count(), request_header.question_count());
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if (response.question_count() != 1) {
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dbgprintf("LookupServer: Question count (%u vs %u) :(\n", response.question_count(), request.question_count());
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return {};
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}
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if (response_header.answer_count() < 1) {
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dbgprintf("LookupServer: Not enough answers (%u) :(\n", response_header.answer_count());
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if (response.answer_count() < 1) {
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dbgprintf("LookupServer: Not enough answers (%u) :(\n", response.answer_count());
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return {};
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}
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int offset = 0;
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auto question = parse_dns_name((const u8*)response_header.payload(), offset, nrecv);
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offset += 4;
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Vector<String> addresses;
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for (u16 i = 0; i < response_header.answer_count(); ++i) {
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auto& record = *(const DNSRecord*)(&((const u8*)response_header.payload())[offset]);
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dbgprintf("LookupServer: Answer #%u: (question: %s), type=%u, ttl=%u, length=%u, data=",
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i,
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question.characters(),
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record.type(),
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record.ttl(),
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record.data_length());
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offset += sizeof(DNSRecord) + record.data_length();
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if (record.type() == T_PTR) {
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int dummy = 0;
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auto name = parse_dns_name((const u8*)record.data(), dummy, record.data_length());
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dbgprintf("%s\n", name.characters());
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addresses.append(name);
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} else if (record.type() == T_A) {
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auto ipv4_address = IPv4Address((const u8*)record.data());
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dbgprintf("%s\n", ipv4_address.to_string().characters());
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addresses.append(ipv4_address.to_string());
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} else {
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dbgprintf("(unimplemented)\n");
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dbgprintf("LookupServer: FIXME: Handle record type %u\n", record.type());
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}
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// FIXME: Parse some other record types perhaps?
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for (auto& answer : response.answers()) {
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addresses.append(answer.record_data());
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}
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m_lookup_cache.set(hostname, { time(nullptr), record_type, addresses });
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return addresses;
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}
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int LookupServer::make_dns_request_socket(sockaddr_in& dst_addr)
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{
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int fd = socket(AF_INET, SOCK_DGRAM, 0);
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if (fd < 0) {
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perror("socket");
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return {};
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}
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struct timeval timeout {
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1, 0
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};
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int rc = setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
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if (rc < 0) {
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perror("setsockopt(SOL_SOCKET, SO_RCVTIMEO)");
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close(fd);
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return {};
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}
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memset(&dst_addr, 0, sizeof(dst_addr));
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dst_addr.sin_family = AF_INET;
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dst_addr.sin_port = htons(53);
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rc = inet_pton(AF_INET, m_dns_ip.characters(), &dst_addr.sin_addr);
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if (rc < 0) {
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perror("inet_pton");
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close(fd);
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return rc;
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}
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return fd;
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}
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