#include #include "dnsd.hpp" #include #include #include "ev.hpp" #include "llarp/net.hpp" #include "logger.hpp" extern dns_tracker dns_udp_tracker; #ifdef _WIN32 #define wmin(x, y) (((x) < (y)) ? (x) : (y)) #define MIN wmin #endif ssize_t raw_sendto_dns_hook_func(void *sock, const struct sockaddr *from, const void *buffer, size_t length) { int *fd = (int *)sock; // how do we get to these?? socklen_t addrLen = sizeof(struct sockaddr_in); #ifdef _WIN32 return sendto(*fd, (const char *)buffer, length, 0, from, addrLen); #else return sendto(*fd, (const char *)buffer, length, 0, from, addrLen); #endif } ssize_t llarp_sendto_dns_hook_func(void *sock, const struct sockaddr *from, const void *buffer, size_t length) { struct llarp_udp_io *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, buffer, length); } void write404_dnss_response(const struct sockaddr *from, dnsd_question_request *request) { const size_t BUFFER_SIZE = 1024 + (request->question.name.size() * 2); char buf[BUFFER_SIZE]; memset(buf, 0, BUFFER_SIZE); char *write_buffer = buf; char *bufferBegin = buf; // build header put16bits(write_buffer, request->id); int fields = (1 << 15); // QR => message type, 1 = response fields += (0 << 14); // I think opcode is always 0 fields += 3; // response code (3 => not found, 0 = Ok) put16bits(write_buffer, fields); 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, ""); // 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 uint 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, from, buf, out_bytes); } void writecname_dnss_response(std::string cname, const struct sockaddr *from, dnsd_question_request *request) { const size_t BUFFER_SIZE = 1024 + (request->question.name.size() * 2); char buf[BUFFER_SIZE]; memset(buf, 0, BUFFER_SIZE); char *write_buffer = buf; char *bufferBegin = buf; // build header put16bits(write_buffer, request->id); int fields = (1 << 15); // QR => message type, 1 = response fields += (0 << 14); // I think opcode is always 0 fields += 0; // response code (3 => not found, 0 = Ok) //fields |= 1UL << 7; // RA recursion available //fields |= 1UL << 8; // RD recursion desired //fields |= 1UL << 9; // 9 is truncate, forces TCP put16bits(write_buffer, fields); 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); // com, type=6, ttl=0 // 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; uint 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, from, 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(struct sockaddr *hostRes, const struct sockaddr *from, dnsd_question_request *request) { //llarp::Addr test(*from); //llarp::LogInfo("from ", test); if(!hostRes) { llarp::LogWarn("Failed to resolve"); write404_dnss_response(from, request); return; } const size_t BUFFER_SIZE = 1024 + (request->question.name.size() * 2); char buf[BUFFER_SIZE]; memset(buf, 0, BUFFER_SIZE); char *write_buffer = buf; char *bufferBegin = buf; // build header put16bits(write_buffer, request->id); int fields = (1 << 15); // QR => message type, 1 = response fields += (0 << 14); // I think opcode is always 0 fields += 0; // response code (3 => not found, 0 = Ok) put16bits(write_buffer, fields); 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 // 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 *write_buffer++ = ip[0]; *write_buffer++ = ip[1]; *write_buffer++ = ip[2]; *write_buffer++ = ip[3]; uint 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, buf, out_bytes); } void handle_dnsc_result(dnsc_answer_request *client_request) { dnsd_question_request *server_request = (dnsd_question_request *)client_request->user; if (!server_request) { llarp::LogError("Couldn't map client requser user to a server request"); return; } writesend_dnss_response( client_request->found ? &client_request->result : nullptr, server_request->from, server_request); llarp_host_resolved(client_request); } // our generic version void handle_recvfrom(const char *buffer, ssize_t nbytes, const struct sockaddr *from, dnsd_question_request *request) { const size_t HDR_OFFSET = 12; const char *p_buffer = buffer; int rcode = (buffer[3] & 0x0F); llarp::LogDebug("dnsd rcode ", rcode); dns_msg_header *msg = decode_hdr(p_buffer); p_buffer += HDR_OFFSET; request->id = msg->id; 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->context->intercept) { //llarp::Addr test(*from); //llarp::LogInfo("from ", test); dnsd_query_hook_response *intercept = request->context->intercept(request->question.name, fromCopy, request); if(intercept != nullptr) { llarp::LogDebug("hook returned a response"); if (intercept->dontSendResponse) { llarp::LogDebug("HOOKED: Not sending a response"); return; } if (intercept->dontLookUp == true && intercept->returnThis) { llarp::LogDebug("HOOKED: sending an immediate override"); // told that hook will handle overrides writesend_dnss_response(intercept->returnThis, fromCopy, 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, fromCopy, 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; } */ if(request->llarp) { // make async request llarp_resolve_host(&request->context->client, m_qName.c_str(), &handle_dnsc_result, (void *)request); } else { // make raw/sync request raw_resolve_host(&request->context->client, m_qName.c_str(), &handle_dnsc_result, (void *)request); } } void llarp_handle_dnsd_recvfrom(struct llarp_udp_io *udp, const struct sockaddr *saddr, const void *buf, ssize_t sz) { if (!dns_udp_tracker.dnsd) { llarp::LogError("No tracker set in dnsd context"); return; } // create new request dnsd_question_request *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((char *)buf, sz, llarp_dns_request->from, llarp_dns_request); } void raw_handle_recvfrom(int *sockfd, const struct sockaddr *saddr, const void *buf, ssize_t sz) { if (!dns_udp_tracker.dnsd) { llarp::LogError("No tracker set in dnsd context"); return; } dnsd_question_request *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((char *)buf, sz, llarp_dns_request->from, llarp_dns_request); } bool llarp_dnsd_init(struct dnsd_context *dnsd, struct llarp_ev_loop *netloop, struct llarp_logic *logic, const char *dnsd_ifname, uint16_t dnsd_port, const char *dnsc_hostname, uint16_t dnsc_port) { struct sockaddr_in bindaddr; bindaddr.sin_addr.s_addr = inet_addr("0.0.0.0"); 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->logic = logic; // set logic worker for timers dnsd->intercept = nullptr; // set default intercepter // configure dns client if(!llarp_dnsc_init(&dnsd->client, &dnsd->udp, dnsc_hostname, dnsc_port)) { llarp::LogError("Couldnt init dns client"); return false; } if (netloop) { return llarp_ev_add_udp(netloop, &dnsd->udp, (const sockaddr *)&bindaddr) != -1; } else { return true; } }