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https://github.com/RGBCube/serenity
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Rename DNSLookupServer => LookupServer.
This commit is contained in:
Andreas Kling
parent
67009cee8e
commit
9120b05a40
10 changed files with 21 additions and 22 deletions
283
Servers/LookupServer/main.cpp
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283
Servers/LookupServer/main.cpp
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/select.h>
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#include <sys/socket.h>
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#include <arpa/inet.h>
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#include <netinet/in.h>
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#include <unistd.h>
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#include <unistd.h>
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#include <Kernel/IPv4.h>
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#include <AK/AKString.h>
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#include <AK/HashMap.h>
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#include <AK/ByteBuffer.h>
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#include <AK/BufferStream.h>
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#include "DNSPacket.h"
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#include "DNSRecord.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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static Vector<IPv4Address> lookup(const String& hostname, bool& did_timeout);
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static String parse_dns_name(const byte*, int& offset, int max_offset);
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int main(int argc, char**argv)
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{
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(void)argc;
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(void)argv;
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unlink("/tmp/.LookupServer-socket");
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HashMap<String, IPv4Address> dns_cache;
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int server_fd = socket(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
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if (server_fd < 0) {
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perror("socket");
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return 1;
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}
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sockaddr_un address;
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address.sun_family = AF_LOCAL;
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strcpy(address.sun_path, "/tmp/.LookupServer-socket");
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int rc = bind(server_fd, (const sockaddr*)&address, sizeof(address));
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if (rc < 0) {
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perror("bind");
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return 1;
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}
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rc = listen(server_fd, 5);
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if (rc < 0) {
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perror("listen");
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return 1;
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}
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for (;;) {
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fd_set rfds;
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FD_ZERO(&rfds);
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FD_SET(server_fd, &rfds);
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rc = select(server_fd + 1, &rfds, nullptr, nullptr, nullptr);
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if (rc < 1) {
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perror("select");
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return 1;
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}
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sockaddr_un client_address;
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socklen_t client_address_size = sizeof(client_address);
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int client_fd = accept(server_fd, (sockaddr*)&client_address, &client_address_size);
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if (client_fd < 0) {
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perror("accept");
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continue;
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}
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FD_ZERO(&rfds);
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FD_SET(client_fd, &rfds);
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rc = select(client_fd + 1, &rfds, nullptr, nullptr, nullptr);
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if (rc < 1) {
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perror("select");
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return 1;
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}
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char client_buffer[1024];
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int nrecv = read(client_fd, client_buffer, sizeof(client_buffer) - 1);
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if (nrecv < 0) {
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perror("recv");
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close(client_fd);
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continue;
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}
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client_buffer[nrecv] = '\0';
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auto hostname = String(client_buffer, nrecv, Chomp);
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dbgprintf("LookupServer: Got request for '%s'\n", hostname.characters());
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Vector<IPv4Address> addresses;
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if (!hostname.is_empty()) {
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bool did_timeout;
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int retries = 3;
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do {
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did_timeout = false;
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addresses = lookup(hostname, did_timeout);
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if (!did_timeout)
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break;
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} while (--retries);
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if (did_timeout) {
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fprintf(stderr, "LookupServer: Out of retries :(\n");
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close(client_fd);
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continue;
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}
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}
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if (addresses.is_empty()) {
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int nsent = write(client_fd, "Not found.\n", sizeof("Not found.\n"));
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if (nsent < 0)
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perror("write");
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close(client_fd);
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continue;
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}
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for (auto& address : addresses) {
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auto line = String::format("%s\n", address.to_string().characters());
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int nsent = write(client_fd, line.characters(), line.length());
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if (nsent < 0) {
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perror("write");
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break;
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}
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}
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close(client_fd);
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}
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return 0;
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}
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static word get_next_id()
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{
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static word s_next_id = 0;
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return ++s_next_id;
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}
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Vector<IPv4Address> lookup(const String& hostname, bool& did_timeout)
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{
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// FIXME: First check if it's an IP address in a string!
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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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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 << (byte)part.length();
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stream << part;
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}
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stream << '\0';
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stream << htons(T_A);
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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 { 1, 0 };
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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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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, "172.20.10.1", &dst_addr.sin_addr);
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int nsent = sendto(fd, buffer.pointer(), buffer.size(), 0,(const struct sockaddr *)&dst_addr, sizeof(dst_addr));
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if (nsent < 0) {
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perror("sendto");
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return { };
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}
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ASSERT(nsent == buffer.size());
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struct sockaddr_in src_addr;
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socklen_t src_addr_len = sizeof(src_addr);
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byte response_buffer[4096];
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ssize_t nrecv = recvfrom(fd, response_buffer, sizeof(response_buffer) - 1, 0, (struct sockaddr*)&src_addr, &src_addr_len);
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if (nrecv < 0) {
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if (errno == EAGAIN) {
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did_timeout = true;
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} else {
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perror("recvfrom");
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}
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close(fd);
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return { };
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}
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close(fd);
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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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return { };
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}
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auto& response_header = *(DNSPacket*)(response_buffer);
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printf("Got response (ID: %u)\n", response_header.id());
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//printf(" Question count: %u\n", response_header.question_count());
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printf(" Answer count: %u\n", response_header.answer_count());
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//printf(" Authority count: %u\n", response_header.authority_count());
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//printf("Additional count: %u\n", response_header.additional_count());
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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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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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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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return { };
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}
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int offset = 0;
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auto question = parse_dns_name((const byte*)response_header.payload(), offset, nrecv);
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offset += 4;
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Vector<IPv4Address> addresses;
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for (word i = 0; i < response_header.answer_count(); ++i) {
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auto& record = *(const DNSRecord*)(&((const byte*)response_header.payload())[offset]);
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auto ipv4_address = IPv4Address((const byte*)record.data());
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dbgprintf("LookupServer: Answer #%u: (question: %s), ttl=%u, length=%u, data=%s\n",
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i,
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question.characters(),
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record.ttl(),
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record.data_length(),
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ipv4_address.to_string().characters());
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offset += sizeof(DNSRecord) + record.data_length();
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addresses.append(ipv4_address);
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}
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return addresses;
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}
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static String parse_dns_name(const byte* data, int& offset, int max_offset)
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{
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Vector<char> buf;
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while (offset < max_offset) {
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byte 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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// 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(buf.data(), buf.size());
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}
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