#include #include #include extern dns_tracker dns_udp_tracker; #ifdef _WIN32 #define wmin(x, y) (((x) < (y)) ? (x) : (y)) #define MIN wmin #endif constexpr size_t BUFFER_SIZE = 1500; ssize_t raw_sendto_dns_hook_func(void *sock, const struct sockaddr *from, ManagedBuffer buf) { int *fd = (int *)sock; // how do we get to these?? socklen_t addrLen = sizeof(struct sockaddr_in); return sendto(*fd, (const char *)buf.underlying.base, buf.underlying.sz, 0, from, addrLen); } ssize_t llarp_sendto_dns_hook_func(void *sock, const struct sockaddr *from, ManagedBuffer buf) { auto *udp = (struct llarp_udp_io *)sock; if(!udp) { llarp::LogWarn("couldnt cast to udp"); return 0; } // llarp::LogInfo("hook sending ", udp, " bytes: ", length); // udp seems ok // this call isn't calling the function... // llarp::ev_io * evio = static_cast< llarp::ev_io * >(udp->impl); // printf("ev_io[%x]\n", evio); return llarp_ev_udp_sendto(udp, from, buf.underlying); } void write404_dnss_response(const dnsd_question_request *request) { char buf[BUFFER_SIZE] = {0}; char *write_buffer = buf; char *bufferBegin = buf; // build header put16bits(write_buffer, request->hdr.id); // not found flag set put16bits(write_buffer, (1 << 15) | request->hdr.fields() | 3); put16bits(write_buffer, 1); // QD (number of questions) put16bits(write_buffer, 1); // AN (number of answers) put16bits(write_buffer, 0); // NS (number of auth RRs) put16bits(write_buffer, 0); // AR (number of Additional RRs) // code question code_domain(write_buffer, request->question.name); put16bits(write_buffer, request->question.type); put16bits(write_buffer, request->question.qClass); // code answer code_domain(write_buffer, request->question.name); // com, type=6, ttl=0 put16bits(write_buffer, request->question.type); put16bits(write_buffer, request->question.qClass); put32bits(write_buffer, 1); // ttl put16bits(write_buffer, 1); // rdLength *write_buffer++ = 0; // write a null byte uint32_t out_bytes = write_buffer - bufferBegin; llarp::LogDebug("Sending 404, ", out_bytes, " bytes"); // struct llarp_udp_io *udp = (struct llarp_udp_io *)request->user; request->sendto_hook(request->user, request->from, ManagedBuffer(llarp_buffer_t(buf, out_bytes))); } void writecname_dnss_response(std::string cname, const dnsd_question_request *request) { char buf[BUFFER_SIZE] = {0}; char *write_buffer = buf; char *bufferBegin = buf; // build header put16bits(write_buffer, request->hdr.id); // fields |= 1UL << 7; // RA recursion available // fields |= 1UL << 8; // RD recursion desired // fields |= 1UL << 9; // 9 is truncate, forces TCP put16bits(write_buffer, request->hdr.fields() | (1 << 15)); put16bits(write_buffer, 1); // QD (number of questions) put16bits(write_buffer, 1); // AN (number of answers) put16bits(write_buffer, 1); // NS (number of auth RRs) put16bits(write_buffer, 1); // AR (number of Additional RRs) // code question code_domain(write_buffer, request->question.name); put16bits(write_buffer, request->question.type); put16bits(write_buffer, request->question.qClass); // code answer code_domain(write_buffer, request->question.name); // com, type=6, ttl=0 put16bits(write_buffer, 5); // cname put16bits(write_buffer, request->question.qClass); put32bits(write_buffer, 1); // ttl put16bits(write_buffer, cname.length() + 2); // rdLength code_domain(write_buffer, cname); // // location of cname //*write_buffer++ = ip[0]; //*write_buffer++ = ip[1]; // write auth RR code_domain(write_buffer, cname); // com, type=6, ttl=0 put16bits(write_buffer, 2); // NS put16bits(write_buffer, request->question.qClass); put32bits(write_buffer, 1); // ttl std::string local("ns1.loki"); put16bits(write_buffer, local.length() + 2); // rdLength code_domain(write_buffer, local); // com, type=6, ttl=0 // write addl RR code_domain(write_buffer, local); // com, type=6, ttl=0 put16bits(write_buffer, 1); // A put16bits(write_buffer, request->question.qClass); put32bits(write_buffer, 1); // ttl put16bits(write_buffer, 4); // rdLength *write_buffer++ = 127; *write_buffer++ = 0; *write_buffer++ = 0; *write_buffer++ = 1; uint32_t out_bytes = write_buffer - bufferBegin; llarp::LogDebug("Sending cname, ", out_bytes, " bytes"); // struct llarp_udp_io *udp = (struct llarp_udp_io *)request->user; request->sendto_hook(request->user, request->from, ManagedBuffer(llarp_buffer_t(buf, out_bytes))); } void writesend_dnss_revresponse(std::string reverse, const dnsd_question_request *request) { char buf[BUFFER_SIZE] = {0}; char *write_buffer = buf; char *bufferBegin = buf; // build header put16bits(write_buffer, request->hdr.id); // response put16bits(write_buffer, request->hdr.fields() | (1 << 15) | (1 << 10)); put16bits(write_buffer, 1); // QD (number of questions) put16bits(write_buffer, 1); // AN (number of answers) put16bits(write_buffer, 0); // NS (number of auth RRs) put16bits(write_buffer, 0); // AR (number of Additional RRs) // code question code_domain(write_buffer, request->question.name); put16bits(write_buffer, request->question.type); put16bits(write_buffer, request->question.qClass); // code answer code_domain(write_buffer, request->question.name); // com, type=6, ttl=0 put16bits(write_buffer, request->question.type); put16bits(write_buffer, request->question.qClass); put32bits(write_buffer, 1); // ttl put16bits(write_buffer, reverse.size() + 2); // rdLength code_domain(write_buffer, reverse); uint32_t out_bytes = write_buffer - bufferBegin; llarp::LogDebug("Sending reverse: ", reverse, " ", out_bytes, " bytes"); // struct llarp_udp_io *udp = (struct llarp_udp_io *)request->user; request->sendto_hook(request->user, request->from, ManagedBuffer(llarp_buffer_t(buf, out_bytes))); } // FIXME: we need an DNS answer not a sockaddr // otherwise ttl, type and class can't be relayed correctly void writesend_dnss_response(llarp::huint32_t *hostRes, const dnsd_question_request *request) { // llarp::Addr test(*from); // llarp::LogInfo("from ", test); if(!hostRes) { llarp::LogWarn("Failed to resolve ", request->question.name); write404_dnss_response(request); return; } char buf[BUFFER_SIZE] = {0}; char *write_buffer = buf; char *bufferBegin = buf; // build header put16bits(write_buffer, request->hdr.id); put16bits(write_buffer, request->hdr.fields() | (1 << 15)); put16bits(write_buffer, 1); // QD (number of questions) put16bits(write_buffer, 1); // AN (number of answers) put16bits(write_buffer, 0); // NS (number of auth RRs) put16bits(write_buffer, 0); // AR (number of Additional RRs) // code question code_domain(write_buffer, request->question.name); put16bits(write_buffer, request->question.type); put16bits(write_buffer, request->question.qClass); // code answer llarp::LogDebug("Sending question name: ", request->question.name); code_domain(write_buffer, request->question.name); // com, type=6, ttl=0 put16bits(write_buffer, request->question.type); put16bits(write_buffer, request->question.qClass); put32bits(write_buffer, 1); // ttl put16bits(write_buffer, 4); // rdLength // put32bits(write_buffer, xhtonl(*hostRes).n); put32bits(write_buffer, hostRes->h); // has to be a string of 4 bytes /* struct sockaddr_in *sin = (struct sockaddr_in *)hostRes; unsigned char *ip = (unsigned char *)&sin->sin_addr.s_addr; put16bits(write_buffer, 4); // rdLength llarp::LogDebug("Sending ip: ", std::to_string(ip[0]), '.', std::to_string(ip[1]), '.', std::to_string(ip[2]), '.', std::to_string(ip[3])); *write_buffer++ = ip[0]; *write_buffer++ = ip[1]; *write_buffer++ = ip[2]; *write_buffer++ = ip[3]; */ uint32_t out_bytes = write_buffer - bufferBegin; llarp::LogDebug("Sending found, ", out_bytes, " bytes"); // struct llarp_udp_io *udp = (struct llarp_udp_io *)request->user; request->sendto_hook(request->user, request->from, ManagedBuffer(llarp_buffer_t(buf, out_bytes))); } void writesend_dnss_mxresponse(uint16_t priority, std::string mx, const struct sockaddr *from, dnsd_question_request *request) { char buf[BUFFER_SIZE] = {0}; char *write_buffer = buf; char *bufferBegin = buf; // build header put16bits(write_buffer, request->hdr.id); put16bits(write_buffer, request->hdr.fields() | (1 << 15)); put16bits(write_buffer, 1); // QD (number of questions) put16bits(write_buffer, 1); // AN (number of answers) put16bits(write_buffer, 0); // NS (number of auth RRs) put16bits(write_buffer, 0); // AR (number of Additional RRs) // code question code_domain(write_buffer, request->question.name); put16bits(write_buffer, request->question.type); put16bits(write_buffer, request->question.qClass); // code answer llarp::LogDebug("Sending question name: ", request->question.name); code_domain(write_buffer, request->question.name); // com, type=6, ttl=0 put16bits(write_buffer, request->question.type); put16bits(write_buffer, request->question.qClass); put32bits(write_buffer, 1); // ttl put16bits(write_buffer, 2 + (mx.size() + 2)); // rdLength put16bits(write_buffer, priority); // priority code_domain(write_buffer, mx); // uint32_t out_bytes = write_buffer - bufferBegin; llarp::LogDebug("Sending found, ", out_bytes, " bytes"); // struct llarp_udp_io *udp = (struct llarp_udp_io *)request->user; request->sendto_hook(request->user, from, ManagedBuffer(llarp_buffer_t(buf, out_bytes))); } void writesend_dnss_txtresponse(std::string txt, const struct sockaddr *from, dnsd_question_request *request) { char buf[BUFFER_SIZE] = {0}; char *write_buffer = buf; char *bufferBegin = buf; // build header put16bits(write_buffer, request->hdr.id); put16bits(write_buffer, request->hdr.fields() | (1 << 15)); put16bits(write_buffer, 1); // QD (number of questions) put16bits(write_buffer, 1); // AN (number of answers) put16bits(write_buffer, 0); // NS (number of auth RRs) put16bits(write_buffer, 0); // AR (number of Additional RRs) // code question code_domain(write_buffer, request->question.name); put16bits(write_buffer, request->question.type); put16bits(write_buffer, request->question.qClass); // code answer llarp::LogDebug("Sending question name: ", request->question.name); code_domain(write_buffer, request->question.name); // com, type=6, ttl=0 put16bits(write_buffer, request->question.type); put16bits(write_buffer, request->question.qClass); put32bits(write_buffer, 1); // ttl put16bits(write_buffer, txt.size() + 2); // rdLength *write_buffer = txt.size(); // write size write_buffer++; code_domain(write_buffer, txt); // uint32_t out_bytes = write_buffer - bufferBegin; llarp::LogDebug("Sending found, ", out_bytes, " bytes"); // struct llarp_udp_io *udp = (struct llarp_udp_io *)request->user; request->sendto_hook(request->user, from, ManagedBuffer(llarp_buffer_t(buf, out_bytes))); } void handle_dnsc_result(dnsc_answer_request *client_request) { auto *server_request = (dnsd_question_request *)client_request->user; if(!server_request) { llarp::LogError("Couldn't map client requser user to a server request"); return; } client_request->packet.header.id = server_request->hdr.id; // stomp ID std::vector< byte_t > test = packet2bytes(client_request->packet); // llarp::LogInfo("packet2bytes figures we should send ", test.size(), " // bytes"); server_request->sendto_hook(server_request->user, server_request->from, ManagedBuffer(llarp_buffer_t(test))); llarp_host_resolved(client_request); return; // llarp::LogDebug("handle_dnsc_result - client request question type", // std::to_string(client_request->question.type)); /* if(client_request->question.type == 12) { writesend_dnss_revresponse(client_request->revDNS, server_request->from, server_request); } else if(client_request->question.type == 15) { writesend_dnss_mxresponse(client_request->result.h, client_request->revDNS, server_request->from, server_request); } else if(client_request->question.type == 16) { llarp::LogInfo("Writing TXT ", client_request->revDNS); writesend_dnss_txtresponse(client_request->revDNS, server_request->from, server_request); } else { if(client_request->question.type != 1) { llarp::LogInfo("Returning type ", client_request->question.type, " as standard"); } llarp::huint32_t *useHostRes = nullptr; if(client_request->found) useHostRes = &client_request->result; writesend_dnss_response(useHostRes, server_request->from, server_request); } llarp_host_resolved(client_request); */ } // our generic version void handle_recvfrom(llarp_buffer_t *buffer, dnsd_question_request *request) { const size_t HDR_OFFSET = 12; const char *p_buffer = (const char *)buffer->base; int rcode = (buffer->base[3] & 0x0F); llarp::LogDebug("dnsd rcode ", rcode); if(!decode_hdr(buffer, &request->hdr)) { llarp::LogError("failed to decode dns header"); return; } p_buffer += HDR_OFFSET; std::string m_qName = ""; int length = *p_buffer++; while(length != 0) { for(int i = 0; i < length; i++) { char c = *p_buffer++; m_qName.append(1, c); } length = *p_buffer++; if(length != 0) m_qName.append(1, '.'); } request->question.name = m_qName; request->question.type = get16bits(p_buffer); request->question.qClass = get16bits(p_buffer); llarp::LogDebug("qName ", request->question.name); llarp::LogDebug("qType ", request->question.type); llarp::LogDebug("qClass ", request->question.qClass); /* llarp::Addr test(*request->from); llarp::LogInfo("DNS request from ", test); llarp::Addr test2(from); llarp::LogInfo("DNS request from ", test2); */ // sockaddr *fromCopy = new sockaddr(*from); // make our own sockaddr that // won't get cleaned up if(!request) { llarp::LogError("request is not configured"); return; } if(!request->context) { llarp::LogError("request context is not configured"); return; } if(request->context->intercept) { // llarp::Addr test(*from); // llarp::LogInfo("from ", test); dnsd_query_hook_response *intercept = request->context->intercept(request->question.name, request); // if(!forward_dns_request(m_qName)) if(intercept != nullptr) { llarp::LogDebug("hook returned a response"); if(intercept->dontSendResponse) { llarp::LogDebug("HOOKED: Not sending a response"); return; } if(intercept->dontLookUp && intercept->returnThis.h) { llarp::LogDebug("HOOKED: sending an immediate override"); // told that hook will handle overrides writesend_dnss_response(&intercept->returnThis, request); return; } } } // FIXME: check request and context's client if(!request->context) { llarp::LogError("dnsd request context was not a dnsd context"); writesend_dnss_response(nullptr, request); return; } /* struct dns_tracker *tracker = (struct dns_tracker *)request->context->tracker; if (!tracker) { llarp::LogError("dnsd request context tracker was not a dns_tracker"); sockaddr *fromCopy = new sockaddr(*from); writesend_dnss_response(nullptr, fromCopy, request); return; } dnsd_context *dnsd = tracker->dnsd; if (!dnsd) { llarp::LogError("tracker dnsd was not a dnsd context"); sockaddr *fromCopy = new sockaddr(*from); writesend_dnss_response(nullptr, fromCopy, request); return; } */ // delete fromCopy; // call DNSc if(request->llarp) { // make async request llarp_resolve_host(&request->context->client, m_qName.c_str(), &handle_dnsc_result, (void *)request, request->question.type); } else { // make raw/sync request raw_resolve_host(&request->context->client, m_qName.c_str(), &handle_dnsc_result, (void *)request, request->question.type); } } void llarp_handle_dnsd_recvfrom(struct llarp_udp_io *udp, const struct sockaddr *saddr, ManagedBuffer buf) { if(!dns_udp_tracker.dnsd) { llarp::LogError("No tracker set in dnsd context"); return; } // create new request auto *llarp_dns_request = new dnsd_question_request; llarp_dns_request->context = dns_udp_tracker.dnsd; // set context llarp_dns_request->from = new sockaddr(*saddr); // make a copy of the sockaddr llarp_dns_request->user = (void *)udp; llarp_dns_request->llarp = true; llarp_dns_request->sendto_hook = &llarp_sendto_dns_hook_func; // set sock hook // llarp::LogInfo("Server request's UDP ", llarp_dns_request->user); handle_recvfrom(&buf.underlying, llarp_dns_request); } void raw_handle_recvfrom(int *sockfd, const struct sockaddr *saddr, ManagedBuffer buffer) { if(!dns_udp_tracker.dnsd) { llarp::LogError("No tracker set in dnsd context"); return; } auto *llarp_dns_request = new dnsd_question_request; llarp_dns_request->context = dns_udp_tracker.dnsd; // set context llarp_dns_request->from = new sockaddr(*saddr); // make a copy of the sockaddr llarp_dns_request->user = (void *)sockfd; llarp_dns_request->llarp = false; llarp_dns_request->sendto_hook = &raw_sendto_dns_hook_func; handle_recvfrom(&buffer.underlying, llarp_dns_request); } bool llarp_dnsd_init(struct dnsd_context *const dnsd, llarp::Logic *const logic, struct llarp_ev_loop *const netloop, const llarp::Addr &dnsd_sockaddr, const llarp::Addr &dnsc_sockaddr) { // struct sockaddr_in bindaddr; /* llarp::Addr dnsd_addr; bool ifRes = GetIFAddr(std::string(dnsd_ifname), dnsd_addr, AF_INET); if (!ifRes) { llarp::LogError("Couldn't init dns server, can't resolve interface: ", dnsd_ifname); return false; } llarp::LogInfo("DNSd interface ip ", dnsd_addr); */ /* bindaddr.sin_addr.s_addr = inet_addr("127.0.0.1"); // network byte bindaddr.sin_family = AF_INET; bindaddr.sin_port = htons(dnsd_port); */ dnsd->udp.user = &dns_udp_tracker; dnsd->udp.recvfrom = &llarp_handle_dns_recvfrom; dnsd->udp.tick = nullptr; dns_udp_tracker.dnsd = dnsd; dnsd->tracker = &dns_udp_tracker; // register global tracker with context dnsd->intercept = nullptr; // set default intercepter // set up fresh socket dnsd->client.udp = new llarp_udp_io; dnsd->client.udp->user = &dns_udp_tracker; dnsd->client.udp->recvfrom = &llarp_handle_dns_recvfrom; dnsd->client.udp->tick = nullptr; // configure dns client // llarp::LogInfo("DNSd setting relay to ", dnsc_sockaddr); if(!llarp_dnsc_init(&dnsd->client, logic, netloop, dnsc_sockaddr)) { llarp::LogError("Couldnt init dns client"); return false; } if(netloop) { llarp::LogInfo("DNSd binding to ", dnsd_sockaddr); return llarp_ev_add_udp(netloop, &dnsd->udp, (const sockaddr *)dnsd_sockaddr) != -1; } return true; }