#include #include // for llarp::Addr #include #ifndef _WIN32 #include #include /* getaddrinfo, getnameinfo */ #include #include #include /* close */ #endif #include /* exit */ #include /* memset */ #include #include // for std::find_if #include // sprintf #define MIN(X, Y) (((X) < (Y)) ? (X) : (Y)) dns_tracker dns_udp_tracker; /* #define DNC_BUF_SIZE 512 /// a question to be asked remotely (the actual bytes to send on the wire) // header, question struct dns_query { uint16_t length; // char *url; unsigned char request[DNC_BUF_SIZE]; // uint16_t reqType; }; */ /// build a DNS question packet struct dns_query * build_dns_packet(char *url, uint16_t id, uint16_t reqType) { dns_query *dnsQuery = new dns_query; dnsQuery->length = 12; // ID // buffer[0] = (value & 0xFF00) >> 8; // buffer[1] = value & 0xFF; llarp::LogDebug("building request ", id); dnsQuery->request[0] = (id & 0xFF00) >> 8; dnsQuery->request[1] = (id & 0x00FF) >> 0; // field dnsQuery->request[2] = 0x01; dnsQuery->request[3] = 0x00; // questions dnsQuery->request[4] = 0x00; dnsQuery->request[5] = 0x01; // answers dnsQuery->request[6] = 0x00; dnsQuery->request[7] = 0x00; // ns dnsQuery->request[8] = 0x00; dnsQuery->request[9] = 0x00; // ar dnsQuery->request[10] = 0x00; dnsQuery->request[11] = 0x00; char *word; // llarp::LogDebug("Asking DNS server %s about %s", SERVER, dnsQuery->url); char *strTemp = strdup(url); word = strtok(strTemp, "."); while(word) { // llarp::LogDebug("parsing hostname: \"%s\" is %zu characters", word, // strlen(word)); dnsQuery->request[dnsQuery->length++] = strlen(word); for(unsigned int i = 0; i < strlen(word); i++) { dnsQuery->request[dnsQuery->length++] = word[i]; } word = strtok(nullptr, "."); } free(strTemp); dnsQuery->request[dnsQuery->length++] = 0x00; // End of the host name dnsQuery->request[dnsQuery->length++] = 0x00; // 0x0001 - Query is a Type A query (host address) dnsQuery->request[dnsQuery->length++] = reqType; dnsQuery->request[dnsQuery->length++] = 0x00; // 0x0001 - Query is class IN (Internet address) dnsQuery->request[dnsQuery->length++] = 0x01; return dnsQuery; } dns_query * answer_request_alloc(struct dnsc_context *dnsc, void *sock, const char *url, dnsc_answer_hook_func resolved, void *user, uint16_t type) { std::unique_ptr< dnsc_answer_request > request(new dnsc_answer_request); if(!request) { llarp::LogError("Couldn't make dnsc request"); return nullptr; } request->sock = sock; request->user = user; request->resolved = resolved; request->found = false; request->context = dnsc; char *sUrl = strdup(url); request->question.name = (char *)sUrl; // since it's a std::String // we can nuke sUrl now free(sUrl); // leave 256 bytes available if(request->question.name.size() > 255) { // size_t diff = request->question.name.size() - 255; // request->question.name = request->question.name.substr(diff); // get the // rightmost 255 bytes llarp::LogWarn("dnsc request question too long"); return nullptr; } request->question.type = type; request->question.qClass = 1; // register our self with the tracker dns_tracker *tracker = request->context->tracker; if(!tracker) { llarp::LogError("no tracker in DNSc context"); return nullptr; } uint16_t id = ++tracker->c_requests; if(id == 65535) id = 0; // conflict: do we need this? // tracker->client_request[id] = std::unique_ptr< dnsc_answer_request // >(request); dns_query *dns_packet = build_dns_packet( (char *)request->question.name.c_str(), id, request->question.type); tracker->client_request[id] = std::move(request); return dns_packet; } // FIXME: make first a std_unique /// generic dnsc handler void generic_handle_dnsc_recvfrom(dnsc_answer_request *request, const llarp_buffer_t &buffer, dns_msg_header *hdr) { if(!request) { llarp::LogError( "User data to DNS Client response not a dnsc_answer_request"); // we can't call back the hook return; } // llarp::LogInfo("got a response, udp user is ", udp->user); // unsigned char *castBuf = (unsigned char *)buf; // const char *const castBufc = (const char *)buf; // auto buffer = llarp::StackBuffer< decltype(castBuf) >(castBuf); size_t sz = buffer.sz; llarp::LogDebug("Header got client responses for id: ", hdr->id); // llarp_dnsc_unbind(request); // unsigned char *castBuf = (unsigned char *)buf; // auto buffer = llarp::StackBuffer< decltype(castBuf) >(castBuf); // hexdump("received packet", &buffer, ret); /* uint16_t QDCOUNT; // No. of items in Question Section uint16_t ANCOUNT; // No. of items in Answer Section uint16_t NSCOUNT; // No. of items in Authority Section uint16_t ARCOUNT; // No. of items in Additional Section uint16_t QCLASS; // Specifies the class of the query uint16_t ATYPE; // Specifies the meaning of the data in the RDATA field uint16_t ACLASS; // Specifies the class of the data in the RDATA field uint32_t TTL; // The number of seconds the results can be cached uint16_t RDLENGTH; // The length of the RDATA field uint16_t MSGID; */ uint8_t rcode; // int length; // struct dns_query *dnsQuery = &request->query; // rcode = (buffer[3] & 0x0F); // llarp::LogInfo("dnsc rcode ", rcode); // dns_msg_header *msg = decode_hdr((const char *)castBuf); // dns_msg_header *msg = hdr; // castBuf += 12; llarp::LogDebug("msg id ", hdr->id); uint8_t qr = hdr->qr; llarp::LogDebug("msg qr ", qr); uint8_t opcode = hdr->opcode; llarp::LogDebug("msg op ", opcode); rcode = hdr->rcode; llarp::LogDebug("msg rc ", rcode); llarp::LogDebug("msg qdc ", hdr->qdCount); llarp::LogDebug("msg anc ", hdr->anCount); llarp::LogDebug("msg nsc ", hdr->nsCount); llarp::LogDebug("msg arc ", hdr->arCount); // FIXME: only handling one atm uint32_t pos = 12; // just set after header dns_msg_question *question = nullptr; for(uint32_t i = 0; i < hdr->qdCount; i++) { question = decode_question((char *)buffer.base, &pos); request->packet.questions.emplace_back(question); // llarp::LogDebug("Read a question, now at ", std::to_string(pos)); // 1 dot: 1 byte for length + length // 4 bytes for class/type // castBuf += question->name.length() + 1 + 4; // castBuf += 2; // skip answer label } if(question) { llarp::LogDebug("Question ", std::to_string(question->type), " ", question->name); } // FIXME: only handling one atm std::vector< dns_msg_answer * > answers; dns_msg_answer *answer = nullptr; for(uint32_t i = 0; i < hdr->anCount; i++) { // pos = 0; // reset pos answer = decode_answer((char *)buffer.base, &pos); answers.push_back(answer); request->packet.answers.emplace_back(answer); /* llarp::LogDebug("Read an answer ", answer->type, " for ", request->question.name, ", now at ", std::to_string(pos)); */ // llarp::LogInfo("Read an answer. Label Len: ", answer->name.length(), " // rdLen: ", answer->rdLen); // name + Type (2) + Class (2) + TTL (4) + rdLen (2) + rdData + skip next // answer label (1) first 2 was answer->name.length() if lbl is ref and type // 1: it should be 16 bytes long l0 + t2 + c2 + t4 + l2 + rd4 (14) + l2 // (2) /* castBuf += 0 + 2 + 2 + 4 + 2 + answer->rdLen; castBuf += 2; // skip answer label uint8_t first = *castBuf; if(first != 0) { llarp::LogDebug("next byte isnt 12, skipping ahead one byte. ", std::to_string(first)); castBuf++; } */ // prevent reading past the end of the packet /* auto diff = castBuf - (unsigned char *)buf; llarp::LogDebug("Read answer, bytes left ", diff); if(diff > sz) { // llarp::LogWarn("Would read past end of dns packet. for ", // request->question.name); break; } */ if(pos > (size_t)sz) { llarp::LogWarn("Would read past end of dns packet. for ", request->question.name); break; } /* uint8_t first = castBufc[pos]; if(first != 0) { llarp::LogInfo("next byte isnt 12, skipping ahead one byte. ", std::to_string(first)); pos++; } */ } // handle authority records (usually no answers with these, so we'll just // stomp) usually NS records tho for(uint32_t i = 0; i < hdr->nsCount; i++) { // pos = 0; // reset pos answer = decode_answer((char *)buffer.base, &pos); request->packet.answers.emplace_back(answer); // answers.push_back(answer); /* llarp::LogDebug("Read an authority for ", request->question.name, " at ", std::to_string(pos)); */ // castBuf += answer->name.length() + 4 + 4 + 4 + answer->rdLen; if((size_t)pos > sz) { llarp::LogWarn("Would read past end of dns packet. for ", request->question.name); break; } } for(uint32_t i = 0; i < hdr->arCount; i++) { answer = decode_answer((char *)buffer.base, &pos); request->packet.answers.emplace_back(answer); /* llarp::LogDebug("Read an addl RR for ", request->question.name, " at ", std::to_string(pos)); */ // castBuf += answer->name.length() + 4 + 4 + 4 + answer->rdLen; if((size_t)pos > sz) { llarp::LogWarn("Would read past end of dns packet. for ", request->question.name); break; } } /* size_t i = 0; for(auto it = answers.begin(); it != answers.end(); ++it) { llarp::LogInfo("Answer #", i, " class: [", (*it)->aClass, "] type: [", (*it)->type, "] rdlen[", (*it)->rdLen, "]"); i++; } */ // dns_msg_answer *answer2 = decode_answer((const char*)castBuf); // castBuf += answer->name.length() + 4 + 4 + 4 + answer->rdLen; // llarp::LogDebug("query type: %u\n", dnsQuery->reqType); /* QCLASS = (uint16_t)dnsQuery->request[dnsQuery->length - 2] * 0x100 + dnsQuery->request[dnsQuery->length - 1]; llarp::LogInfo("query class: ", QCLASS); length = dnsQuery->length + 1; // to skip 0xc00c // printf("length [%d] from [%d]\n", length, buffer.base); ATYPE = (uint16_t)buffer[length + 1] * 0x100 + buffer[length + 2]; llarp::LogInfo("answer type: ", ATYPE); ACLASS = (uint16_t)buffer[length + 3] * 0x100 + buffer[length + 4]; llarp::LogInfo("answer class: ", ACLASS); TTL = (uint32_t)buffer[length + 5] * 0x1000000 + buffer[length + 6] * 0x10000 + buffer[length + 7] * 0x100 + buffer[length + 8]; llarp::LogInfo("seconds to cache: ", TTL); RDLENGTH = (uint16_t)buffer[length + 9] * 0x100 + buffer[length + 10]; llarp::LogInfo("bytes in answer: ", RDLENGTH); MSGID = (uint16_t)buffer[0] * 0x100 + buffer[1]; // llarp::LogDebug("answer msg id: %u\n", MSGID); */ llarp::Addr upstreamAddr = request->context->resolvers[0]; if(answer == nullptr) { llarp::LogWarn("nameserver ", upstreamAddr, " didnt return any answers for ", question ? question->name : "null question"); request->resolved(request); return; } if(answer->type == 5 || answer->type == 2) { llarp::LogDebug("Last answer is a cname/NS, reverting to first"); answer = answers.front(); } if(question) { llarp::LogDebug("qus type ", question->type); } llarp::LogDebug("ans class ", answer->aClass); llarp::LogDebug("ans type ", answer->type); llarp::LogDebug("ans ttl ", answer->ttl); llarp::LogDebug("ans rdlen ", answer->rdLen); /* llarp::LogInfo("ans2 class ", answer2->aClass); llarp::LogInfo("ans2 type ", answer2->type); llarp::LogInfo("ans2 ttl ", answer2->ttl); llarp::LogInfo("ans2 rdlen ", answer2->rdLen); */ // llarp::LogDebug("rcode ", std::to_string(rcode)); if(rcode == 2) { llarp::LogWarn("nameserver ", upstreamAddr, " returned SERVFAIL:"); llarp::LogWarn( " the name server was unable to process this query due to a problem " "with the name server."); request->resolved(request); return; } else if(rcode == 3) { llarp::LogWarn("nameserver ", upstreamAddr, " returned NXDOMAIN for: ", request->question.name); llarp::LogWarn(" the domain name referenced in the query does not exist"); request->resolved(request); return; } int ip = 0; // if no answer, just bail now if(!answer) { request->found = false; request->resolved(request); return; } /* search for and print IPv4 addresses */ // if(dnsQuery->reqType == 0x01) /* llarp::LogDebug("request question type: ", std::to_string(request->question.type)); */ // lets detect this for a bit if(answer->type != question->type) { llarp::LogWarn("Answer type [", std::to_string(answer->type), "] doesn't match question type[", std::to_string(question->type), "]"); } // check this assumption if(request->question.type != question->type) { llarp::LogWarn("Request qtype [", std::to_string(request->question.type), "] doesn't match response qtype[", std::to_string(question->type), "]"); } if(answer->type == 1) { // llarp::LogInfo("DNS server's answer is: (type#=", ATYPE, "):"); llarp::LogDebug("IPv4 address(es) for ", request->question.name, ":"); // llarp::LogDebug("Answer rdLen ", std::to_string(answer->rdLen)); if(answer->rdLen == 4) { /* request->result.sa_family = AF_INET; #if((__APPLE__ && __MACH__) || __FreeBSD__) request->result.sa_len = sizeof(in_addr); #endif struct in_addr *addr = &((struct sockaddr_in *)&request->result)->sin_addr; unsigned char *ip = (unsigned char *)&(addr->s_addr); ip[0] = answer->rData[0]; ip[1] = answer->rData[1]; ip[2] = answer->rData[2]; ip[3] = answer->rData[3]; */ /* request->result.from_4int(answer->rData[0], answer->rData[1], answer->rData[2], answer->rData[3]); */ // llarp::LogDebug("Passing back IPv4: ", // std::to_string(answer->rData[3]), ".", // std::to_string(answer->rData[2]), // ".", std::to_string(answer->rData[1]), ".", // std::to_string(answer->rData[0])); /* request->result = llarp::ipaddr_ipv4_bits(answer->rData[3], answer->rData[2], answer->rData[1], answer->rData[0]); */ // llarp::Addr test(request->result); // llarp::LogDebug(request->result); request->found = true; request->resolved(request); return; } if(!ip) { llarp::LogWarn(" No IPv4 address found in the DNS answer!"); request->resolved(request); return; } } else if(answer->type == 12) { llarp::LogDebug("Resolving PTR"); // llarp::dns::type_12ptr *record = dynamic_cast< llarp::dns::type_12ptr * // >(answer->record.get()); request->found = true; // request->revDNS = std::string((char *)answer->rData.data(), // answer->rData.size()); // request->revDNS = record->revname; request->resolved(request); return; } else if(answer->type == 15) { llarp::dns::type_15mx *record = dynamic_cast< llarp::dns::type_15mx * >(answer->record.get()); llarp::LogDebug("Resolving MX ", record->mx, "@", record->priority); request->found = true; // request->result.h = record->priority; // request->revDNS = std::string((char *)answer->rData.data(), // answer->rData.size()); // request->revDNS = record->mx; request->resolved(request); return; } else if(answer->type == 16) { llarp::LogDebug("Resolving TXT"); request->found = true; // request->revDNS = std::string((char *)answer->rData.data(), // answer->rData.size()); request->resolved(request); return; } else if(answer->type == 28) { llarp::LogDebug("Resolving AAAA"); return; } llarp::LogWarn("Unhandled question type ", request->question.type); // should we let it timeout? lets try sending 404 asap request->resolved(request); } void raw_resolve_host(struct dnsc_context *const dnsc, const char *url, dnsc_answer_hook_func resolved, void *const user, uint16_t type) { if(strstr(url, "in-addr.arpa") != nullptr) { type = 12; } dns_query *dns_packet = answer_request_alloc(dnsc, nullptr, url, resolved, user, type); if(!dns_packet) { llarp::LogError("Couldn't make dnsc packet"); return; } // char *word; llarp::Addr upstreamAddr = dnsc->resolvers[0]; llarp::LogDebug("Asking DNS server ", upstreamAddr, " about ", url); struct sockaddr_in addr; ssize_t ret; socklen_t size; // int length; unsigned char buffer[DNC_BUF_SIZE]; #ifndef _WIN32 int sockfd; #else SOCKET sockfd; #endif sockfd = socket(AF_INET, SOCK_DGRAM, 0); if(!(sockfd > 0)) { llarp::LogWarn("Error creating socket!\n"); delete dns_packet; return; } // socket = sockfd; sockaddr_in *dnscSock = ((sockaddr_in *)dnsc->resolvers[0].addr4()); memset(&addr, 0, sizeof(addr)); addr.sin_family = AF_INET; addr.sin_addr.s_addr = dnscSock->sin_addr.s_addr; addr.sin_port = dnscSock->sin_port; size = sizeof(addr); // hexdump("sending packet", &dnsQuery.request, dnsQuery.length); ret = sendto(sockfd, (const char *)dns_packet->request, dns_packet->length, 0, (struct sockaddr *)&addr, size); delete dns_packet; if(ret < 0) { llarp::LogWarn("Error Sending Request"); return; } llarp::LogInfo("Sent"); memset(&buffer, 0, DNC_BUF_SIZE); llarp::LogInfo("Waiting for recv"); // Timeout? ret = recvfrom(sockfd, (char *)buffer, DNC_BUF_SIZE, 0, (struct sockaddr *)&addr, &size); llarp::LogInfo("recv done ", size); if(ret < 0) { llarp::LogWarn("Error Receiving Response"); return; } llarp::LogInfo("closing new socket\n"); if(!size) { llarp::LogWarn("Error Receiving DNS Client Response"); return; } // hexdump("received packet", &buffer, ret); #ifndef _WIN32 close(sockfd); #else closesocket(sockfd); #endif llarp_buffer_t lbuffer; lbuffer.base = (byte_t *)buffer; lbuffer.cur = lbuffer.base; lbuffer.sz = size; // unsigned char *castBuf = (unsigned char *)buffer; // auto buffer = llarp::StackBuffer< decltype(castBuf) >(castBuf); dns_msg_header hdr; if(!decode_hdr(&lbuffer, &hdr)) { llarp::LogError("failed to decode dns header"); return; } llarp::LogInfo("response header says it belongs to id #", hdr.id); // if we sent this out, then there's an id struct dns_tracker *tracker = (struct dns_tracker *)dnsc->tracker; struct dnsc_answer_request *request = tracker->client_request[hdr.id].get(); if(request) { request->packet.header = hdr; generic_handle_dnsc_recvfrom(tracker->client_request[hdr.id].get(), lbuffer, &hdr); } else { llarp::LogWarn("Ignoring multiple responses on ID #", hdr.id); } } /// intermediate udp_io handler void llarp_handle_dnsc_recvfrom(struct llarp_udp_io *const udp, const struct sockaddr *saddr, ManagedBuffer buf) { if(!saddr) { llarp::LogWarn("saddr isnt set"); } // auto buffer = llarp::StackBuffer< decltype(castBuf) >(castBuf); dns_msg_header hdr; if(!decode_hdr(&buf.underlying, &hdr)) { llarp::LogError("failed to decode dns header"); return; } buf.underlying.cur = buf.underlying.base; // reset cursor to beginning llarp::LogDebug("Header got client responses for id: ", hdr.id); // if we sent this out, then there's an id struct dns_tracker *tracker = (struct dns_tracker *)udp->user; struct dnsc_answer_request *request = tracker->client_request[hdr.id].get(); // sometimes we'll get double responses if(request) { generic_handle_dnsc_recvfrom(request, buf, &hdr); } else { llarp::LogWarn("Ignoring multiple responses on ID #", hdr.id); } } bool llarp_resolve_host(struct dnsc_context *const dnsc, const char *url, dnsc_answer_hook_func resolved, void *const user, uint16_t type) { // FIXME: probably can be stack allocated /* if (strstr(url, "in-addr.arpa") != nullptr) { type = 12; } */ dns_query *dns_packet = answer_request_alloc(dnsc, &dnsc->udp, url, resolved, user, type); if(!dns_packet) { llarp::LogError("Couldn't make dnsc packet"); return false; } // register request with udp response tracker // dns_tracker *tracker = (dns_tracker *)dnsc->udp->user; /* uint16_t length = 0; dns_msg_header header; header.id = htons(id); header.qr = 0; header.opcode = 0; header.aa = 0; header.tc = 0; header.rd = 1; header.ra = 0; header.rcode = 0; header.qdCount = htons(1); header.anCount = 0; header.nsCount = 0; header.arCount = 0; length += 12; //request->question.name = sUrl; request->question.type = htons(1); request->question.qClass = htons(1); uint16_t qLen = request->question.name.length() + 8; length += qLen; unsigned char bytes[length]; // memcpy isn't going to fix the network endian issue // encode header into bytes memcpy(bytes, &header, 12); // encode question into bytes memcpy(bytes + 12, &request->question, qLen); */ // uint16_t id = ++tracker->c_requests; // tracker->client_request[id] = request; // llarp::LogInfo("Sending request #", tracker->c_requests, " ", length, " // bytes"); // ssize_t ret = llarp_ev_udp_sendto(dnsc->udp, dnsc->server, bytes, length); ssize_t ret = llarp_ev_udp_sendto( dnsc->udp, dnsc->resolvers[0], llarp_buffer_t(dns_packet->request, dns_packet->length)); delete dns_packet; if(ret < 0) { llarp::LogWarn("Error Sending Request"); return false; } return true; } void llarp_host_resolved(dnsc_answer_request *const request) { dns_tracker *tracker = (dns_tracker *)request->context->tracker; auto val = std::find_if( tracker->client_request.begin(), tracker->client_request.end(), [request]( std::pair< const uint32_t, std::unique_ptr< dnsc_answer_request > > &element) { return element.second.get() == request; }); if(val != tracker->client_request.end()) { tracker->client_request[val->first].reset(); } else { llarp::LogWarn("Couldn't disable ", request); } } bool llarp_dnsc_init(struct dnsc_context *const dnsc, llarp::Logic *const logic, struct llarp_ev_loop *const netloop, const llarp::Addr &dnsc_sockaddr) { // create client socket if(netloop) { if(!dnsc->udp) { llarp::LogError("DNSc udp isn't set"); return false; } llarp::Addr dnsc_srcsockaddr(0, 0, 0, 0, 0); // just find a public udp port int bind_res = llarp_ev_add_udp(netloop, dnsc->udp, (const sockaddr *)dnsc_srcsockaddr); if(bind_res == -1) { llarp::LogError("Couldn't bind to ", dnsc_srcsockaddr); return false; } } llarp::LogInfo("DNSc adding relay ", dnsc_sockaddr); dnsc->resolvers.push_back(dnsc_sockaddr); dnsc->tracker = &dns_udp_tracker; dnsc->logic = logic; return true; } bool llarp_dnsc_stop(ABSL_ATTRIBUTE_UNUSED struct dnsc_context *const dnsc) { // delete(sockaddr_in *)dnsc->server; // deallocation return true; }