// why dnsd? what do you need from that? #include "dnsd.hpp" #include "buffer.hpp" #include #include #include /* getaddrinfo, getnameinfo */ #include /* exit */ #include /* memset */ #include /* close */ #include #include #include "logger.hpp" #include #include "net.hpp" // for llarp::Addr #include "net.hpp" // for llarp::Addr // FIXME: make configurable #define SERVER "8.8.8.8" #define PORT 53 struct sockaddr *resolveHost(const char *url) { char* sUrl = strdup(url); struct dns_query dnsQuery; dnsQuery.length = 12; dnsQuery.url = sUrl; dnsQuery.reqType = 0x01; // dnsQuery.request = { 0xDB, 0x42, 0x01, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; dnsQuery.request[ 0] = 0xDB; dnsQuery.request[ 1] = 0x42; dnsQuery.request[ 2] = 0x01; dnsQuery.request[ 3] = 0x00; dnsQuery.request[ 4] = 0x00; dnsQuery.request[ 5] = 0x01; dnsQuery.request[ 6] = 0x00; dnsQuery.request[ 7] = 0x00; dnsQuery.request[ 8] = 0x00; dnsQuery.request[ 9] = 0x00; dnsQuery.request[10] = 0x00; dnsQuery.request[11] = 0x00; char * word; unsigned int i; llarp::LogDebug("Asking DNS server %s about %s\n", SERVER, url); //dnsQuery.reqType = 0x01; word = strtok(sUrl, "."); while (word) { llarp::LogDebug("parsing hostname: \"%s\" is %zu characters\n", word, strlen(word)); dnsQuery.request[dnsQuery.length++] = strlen(word); for (i = 0; i < strlen(word); i++) { dnsQuery.request[dnsQuery.length++] = word[i]; } word = strtok(NULL, "."); } 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++] = dnsQuery.reqType; dnsQuery.request[dnsQuery.length++] = 0x00; // 0x0001 - Query is class IN (Internet address) dnsQuery.request[dnsQuery.length++] = 0x01; struct sockaddr_in addr; //int socket; ssize_t ret; int rcode; socklen_t size; int ip = 0; int length; unsigned char buffer[DNC_BUF_SIZE]; //unsigned char tempBuf[3]; 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; int sockfd; sockfd = socket(AF_INET, SOCK_DGRAM, 0); if (sockfd < 0) { llarp::LogWarn("Error creating socket!\n"); return nullptr; } //socket = sockfd; memset(&addr, 0, sizeof(addr)); addr.sin_family = AF_INET; addr.sin_addr.s_addr = inet_addr(SERVER); addr.sin_port = htons(PORT); size = sizeof(addr); //hexdump("sending packet", &dnsQuery.request, dnsQuery.length); ret = sendto(sockfd, dnsQuery.request, dnsQuery.length, 0, (struct sockaddr*)&addr, size); if (ret < 0) { llarp::LogWarn("Error Sending Request"); return nullptr; } //printf("Sent\n"); memset(&buffer, 0, DNC_BUF_SIZE); ret = recvfrom(sockfd, buffer, DNC_BUF_SIZE, 0, (struct sockaddr*)&addr, &size); if (ret < 0) { llarp::LogWarn("Error Receiving Response"); return nullptr; } //hexdump("received packet", &buffer, ret); close(sockfd); rcode = (buffer[3] & 0x0F); //tempBuf[0] = buffer[4]; //tempBuf[1] = buffer[5]; //tempBuf[2] = '\0'; //printf("%0x %0x %0x %0x\n", buffer[4], buffer[5], tempBuf[0], tempBuf[1]); //QDCOUNT = (uint16_t) strtol(tempBuf, NULL, 16); QDCOUNT = (uint16_t) buffer[4] * 0x100 + buffer[5]; llarp::LogDebug("entries in question section: %u\n", QDCOUNT); ANCOUNT = (uint16_t) buffer[6] * 0x100 + buffer[7]; llarp::LogDebug("records in answer section: %u\n", ANCOUNT); NSCOUNT = (uint16_t) buffer[8] * 0x100 + buffer[9]; llarp::LogDebug("name server resource record count: %u\n", NSCOUNT); ARCOUNT = (uint16_t) buffer[10] * 0x100 + buffer[11]; llarp::LogDebug("additional records count: %u\n", ARCOUNT); llarp::LogDebug("query type: %u\n", dnsQuery.reqType); QCLASS = (uint16_t) dnsQuery.request[dnsQuery.length - 2] * 0x100 + dnsQuery.request[dnsQuery.length - 1]; llarp::LogDebug("query class: %u\n", QCLASS); length = dnsQuery.length + 1; // to skip 0xc00c ATYPE = (uint16_t) buffer[length + 1] * 0x100 + buffer[length + 2]; llarp::LogDebug("answer type: %u\n", ATYPE); ACLASS = (uint16_t) buffer[length + 3] * 0x100 + buffer[length + 4]; llarp::LogDebug("answer class: %u\n", ACLASS); TTL = (uint32_t) buffer[length + 5] * 0x1000000 + buffer[length + 6] * 0x10000 + buffer[length + 7] * 0x100 + buffer[length + 8]; llarp::LogDebug("seconds to cache: %u\n", TTL); RDLENGTH = (uint16_t) buffer[length + 9] * 0x100 + buffer[length + 10]; llarp::LogDebug("bytes in answer: %u\n", RDLENGTH); MSGID = (uint16_t) buffer[0] * 0x100 + buffer[1]; llarp::LogDebug("answer msg id: %u\n", MSGID); if (rcode == 2) { llarp::LogWarn("nameserver %s returned SERVFAIL:\n", SERVER); llarp::LogWarn(" the name server was unable to process this query due to a\n problem with the name server.\n"); return nullptr; } else if (rcode == 3) { llarp::LogWarn("nameserver %s returned NXDOMAIN for %s:\n", SERVER, dnsQuery.url); llarp::LogWarn(" the domain name referenced in the query does not exist\n"); return nullptr; } /* search for and print IPv4 addresses */ if (dnsQuery.reqType == 0x01) { llarp::LogDebug("DNS server's answer is: (type#=%u):", ATYPE); //printf("IPv4 address(es) for %s:\n", dnsQuery.url); for (i = 0 ; i < ret ; i++) { if (buffer[i] == 0xC0 && buffer[i+3] == 0x01) { ip++; i += 12; /* ! += buf[i+1]; */ llarp::LogDebug(" %u.%u.%u.%u\n", buffer[i], buffer[i+1], buffer[i+2], buffer[i+3]); struct sockaddr *g_addr = new sockaddr; g_addr->sa_family = AF_INET; g_addr->sa_len = sizeof(in_addr); struct in_addr *addr = &((struct sockaddr_in *)g_addr)->sin_addr; unsigned char * ip; //have ip point to s_addr ip = (unsigned char *) &(addr->s_addr); ip[0]=buffer[i + 0]; ip[1]=buffer[i + 1]; ip[2]=buffer[i + 2]; ip[3]=buffer[i + 3]; return g_addr; } } if (!ip) { llarp::LogWarn(" No IPv4 address found in the DNS response!\n"); return nullptr; } } return nullptr; } void llarp_handle_dnsclient_recvfrom(struct llarp_udp_io *udp, const struct sockaddr *saddr, const void *buf, ssize_t sz) { //llarp::LogInfo("got a response, udp user is ", udp->user); struct dns_client_request *request = (struct dns_client_request *)udp->user; if (!request) { llarp::LogError("User data to DNS Client response not a dns_client_request"); // we can't call back the hook return; } llarp_dnsc_unbind(request); if (sz < 0) { llarp::LogWarn("Error Receiving DNS Client Response"); request->resolved(request); return; } 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; int rcode; int length; struct dns_query *dnsQuery = &request->query; rcode = (buffer[3] & 0x0F); //tempBuf[0] = buffer[4]; //tempBuf[1] = buffer[5]; //tempBuf[2] = '\0'; //printf("%0x %0x %0x %0x\n", buffer[4], buffer[5], tempBuf[0], tempBuf[1]); //QDCOUNT = (uint16_t) strtol(tempBuf, NULL, 16); QDCOUNT = (uint16_t) buffer[4] * 0x100 + buffer[5]; //llarp::LogDebug("entries in question section: %u\n", QDCOUNT); ANCOUNT = (uint16_t) buffer[6] * 0x100 + buffer[7]; //llarp::LogDebug("records in answer section: %u\n", ANCOUNT); NSCOUNT = (uint16_t) buffer[8] * 0x100 + buffer[9]; //llarp::LogDebug("name server resource record count: %u\n", NSCOUNT); ARCOUNT = (uint16_t) buffer[10] * 0x100 + buffer[11]; //llarp::LogDebug("additional records count: %u\n", ARCOUNT); //llarp::LogDebug("query type: %u\n", dnsQuery->reqType); QCLASS = (uint16_t) dnsQuery->request[dnsQuery->length - 2] * 0x100 + dnsQuery->request[dnsQuery->length - 1]; //llarp::LogDebug("query class: %u\n", QCLASS); length = dnsQuery->length + 1; // to skip 0xc00c ATYPE = (uint16_t) buffer[length + 1] * 0x100 + buffer[length + 2]; //llarp::LogDebug("answer type: %u\n", ATYPE); ACLASS = (uint16_t) buffer[length + 3] * 0x100 + buffer[length + 4]; //llarp::LogDebug("answer class: %u\n", ACLASS); TTL = (uint32_t) buffer[length + 5] * 0x1000000 + buffer[length + 6] * 0x10000 + buffer[length + 7] * 0x100 + buffer[length + 8]; //llarp::LogDebug("seconds to cache: %u\n", TTL); RDLENGTH = (uint16_t) buffer[length + 9] * 0x100 + buffer[length + 10]; //llarp::LogDebug("bytes in answer: %u\n", RDLENGTH); MSGID = (uint16_t) buffer[0] * 0x100 + buffer[1]; //llarp::LogDebug("answer msg id: %u\n", MSGID); if (rcode == 2) { llarp::LogWarn("nameserver %s returned SERVFAIL:\n", SERVER); llarp::LogWarn(" the name server was unable to process this query due to a\n problem with the name server.\n"); request->resolved(request); return; } else if (rcode == 3) { llarp::LogWarn("nameserver %s returned NXDOMAIN for %s:\n", SERVER, dnsQuery->url); llarp::LogWarn(" the domain name referenced in the query does not exist\n"); request->resolved(request); return; } int ip = 0; /* search for and print IPv4 addresses */ if (dnsQuery->reqType == 0x01) { llarp::LogInfo("DNS server's answer is: (type#=%u):", ATYPE); printf("IPv4 address(es) for %s:\n", dnsQuery->url); for (unsigned int i = 0 ; i < sz ; i++) { if (buffer[i] == 0xC0 && buffer[i+3] == 0x01) { ip++; i += 12; /* ! += buf[i+1]; */ //llarp::LogInfo(" %u.%u.%u.%u\n", buffer[i], buffer[i+1], buffer[i+2], buffer[i+3]); /* struct sockaddr *g_addr = new sockaddr; g_addr->sa_family = AF_INET; g_addr->sa_len = sizeof(in_addr); struct in_addr *addr = &((struct sockaddr_in *)g_addr)->sin_addr; */ unsigned char * ip; //have ip point to s_addr request->result.sa_family = AF_INET; request->result.sa_len = sizeof(in_addr); struct in_addr *addr = &((struct sockaddr_in *) &request->result)->sin_addr; //ip = (unsigned char *) &request->result.sa_data; ip = (unsigned char *) &(addr->s_addr); ip[0]=buffer[i + 0]; ip[1]=buffer[i + 1]; ip[2]=buffer[i + 2]; ip[3]=buffer[i + 3]; llarp::Addr test(request->result); llarp::LogInfo("IP Address ", test); //return g_addr; //request->result = g_addr; request->found = true; request->resolved(request); return; } } if (!ip) { llarp::LogWarn(" No IPv4 address found in the DNS response!\n"); request->resolved(request); return; } } } void build_dns_query(struct dns_query *dnsQuery) { dnsQuery->length = 12; dnsQuery->reqType = 0x01; dnsQuery->request[ 0] = 0xDB; dnsQuery->request[ 1] = 0x42; dnsQuery->request[ 2] = 0x01; dnsQuery->request[ 3] = 0x00; dnsQuery->request[ 4] = 0x00; dnsQuery->request[ 5] = 0x01; dnsQuery->request[ 6] = 0x00; dnsQuery->request[ 7] = 0x00; dnsQuery->request[ 8] = 0x00; dnsQuery->request[ 9] = 0x00; dnsQuery->request[10] = 0x00; dnsQuery->request[11] = 0x00; char * word; //llarp::LogDebug("Asking DNS server %s about %s\n", SERVER, dnsQuery->url); char * strTemp = strdup(dnsQuery->url); word = strtok(strTemp, "."); while (word) { //llarp::LogDebug("parsing hostname: \"%s\" is %zu characters\n", 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(NULL, "."); } 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++] = dnsQuery->reqType; dnsQuery->request[dnsQuery->length++] = 0x00; // 0x0001 - Query is class IN (Internet address) dnsQuery->request[dnsQuery->length++] = 0x01; } bool llarp_resolve_host(struct dnsc_context *dnsc, const char *url, resolve_dns_hook_func resolved, void *user) { dns_client_request *request = new dns_client_request; request->sock = (void *)&request->udp; request->user = user; // configure query request->query.url = strdup(url); request->resolved = resolved; request->found = false; // request address holds through the packet recv request->udp.user = request; // finish setting up our query struct dns_query *dnsQuery = &request->query; build_dns_query(dnsQuery); // build a socket per request because we're multithreaded and will have many inflight if (!llarp_dnsc_bind(dnsc->netloop, request)) { llarp::LogWarn("Error binding"); return false; } ssize_t ret = llarp_ev_udp_sendto(&request->udp, dnsc->server, dnsQuery->request, dnsQuery->length); if (ret < 0) { llarp::LogWarn("Error Sending Request"); return false; } return true; } void llarp_host_resolved(dns_client_request *request) { delete request; } bool llarp_dnsc_bind(struct llarp_ev_loop *netloop, struct dns_client_request *request) { // just grab a random open port struct sockaddr_in srcaddr; srcaddr.sin_addr.s_addr = inet_addr("0.0.0.0"); srcaddr.sin_family = AF_INET; // we'll need to make sure the port is >1024 if not root request->udp.user = request; request->udp.recvfrom = &llarp_handle_dnsclient_recvfrom; request->udp.tick = nullptr; // create new listener for this request return llarp_ev_add_udp(netloop, &request->udp, (const sockaddr *)&srcaddr) != -1; } // FIXME: drop the bool bool llarp_dnsc_unbind(struct dns_client_request *request) { llarp_ev_close_udp(&request->udp); // stop listening return true; } bool llarp_dnsc_init(struct dnsc_context *dnsc, struct llarp_ev_loop *netloop, const char *dnsc_hostname, uint16_t dnsc_port) { sockaddr_in *trgaddr = new sockaddr_in; trgaddr->sin_addr.s_addr = inet_addr(dnsc_hostname); trgaddr->sin_port = htons(dnsc_port); trgaddr->sin_family = AF_INET; dnsc->server = (sockaddr *)trgaddr; dnsc->netloop = netloop; return true; } bool llarp_dnsc_stop(struct dnsc_context *dnsc) { //llarp_ev_close_udp(&dnsc->udp); // stop listening delete (sockaddr_in *)dnsc->server; // deallocation return true; }