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482 lines
15 KiB
C++
482 lines
15 KiB
C++
#include "dnsd.hpp"
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#include <netdb.h> /* getaddrinfo, getnameinfo */
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#include <stdlib.h> /* exit */
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#include <string.h> /* memset */
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#include <sys/socket.h>
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#include <sys/types.h>
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#include <unistd.h> /* close */
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#include <arpa/inet.h>
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#include <netinet/in.h>
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#include <llarp/dns.h>
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#include "logger.hpp"
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// FIXME: make configurable
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#define SERVER "8.8.8.8"
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#define PORT 53
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struct sockaddr *
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resolveHost(const char *url)
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{
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char *sUrl = strdup(url);
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struct dns_query dnsQuery;
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dnsQuery.length = 12;
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dnsQuery.url = sUrl;
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dnsQuery.reqType = 0x01;
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// dnsQuery.request = { 0xDB, 0x42, 0x01, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
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// 0x00, 0x00, 0x00 };
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dnsQuery.request[0] = 0xDB;
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dnsQuery.request[1] = 0x42;
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dnsQuery.request[2] = 0x01;
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dnsQuery.request[3] = 0x00;
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dnsQuery.request[4] = 0x00;
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dnsQuery.request[5] = 0x01;
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dnsQuery.request[6] = 0x00;
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dnsQuery.request[7] = 0x00;
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dnsQuery.request[8] = 0x00;
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dnsQuery.request[9] = 0x00;
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dnsQuery.request[10] = 0x00;
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dnsQuery.request[11] = 0x00;
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char *word;
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unsigned int i;
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llarp::LogDebug("Asking DNS server %s about %s\n", SERVER, url);
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// dnsQuery.reqType = 0x01;
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word = strtok(sUrl, ".");
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while(word)
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{
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llarp::LogDebug("parsing hostname: \"%s\" is %zu characters\n", word,
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strlen(word));
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dnsQuery.request[dnsQuery.length++] = strlen(word);
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for(i = 0; i < strlen(word); i++)
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{
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dnsQuery.request[dnsQuery.length++] = word[i];
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}
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word = strtok(NULL, ".");
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}
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dnsQuery.request[dnsQuery.length++] = 0x00; // End of the host name
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dnsQuery.request[dnsQuery.length++] =
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0x00; // 0x0001 - Query is a Type A query (host address)
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dnsQuery.request[dnsQuery.length++] = dnsQuery.reqType;
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dnsQuery.request[dnsQuery.length++] =
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0x00; // 0x0001 - Query is class IN (Internet address)
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dnsQuery.request[dnsQuery.length++] = 0x01;
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struct sockaddr_in addr;
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// int socket;
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ssize_t ret;
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int rcode;
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socklen_t size;
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int ip = 0;
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int length;
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unsigned char buffer[DNC_BUF_SIZE];
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// unsigned char tempBuf[3];
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uint16_t QDCOUNT; // No. of items in Question Section
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uint16_t ANCOUNT; // No. of items in Answer Section
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uint16_t NSCOUNT; // No. of items in Authority Section
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uint16_t ARCOUNT; // No. of items in Additional Section
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uint16_t QCLASS; // Specifies the class of the query
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uint16_t ATYPE; // Specifies the meaning of the data in the RDATA field
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uint16_t ACLASS; // Specifies the class of the data in the RDATA field
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uint32_t TTL; // The number of seconds the results can be cached
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uint16_t RDLENGTH; // The length of the RDATA field
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uint16_t MSGID;
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int sockfd;
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sockfd = socket(AF_INET, SOCK_DGRAM, 0);
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if(sockfd < 0)
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{
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llarp::LogWarn("Error creating socket!\n");
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return nullptr;
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}
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// socket = sockfd;
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memset(&addr, 0, sizeof(addr));
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addr.sin_family = AF_INET;
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addr.sin_addr.s_addr = inet_addr(SERVER);
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addr.sin_port = htons(PORT);
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size = sizeof(addr);
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// hexdump("sending packet", &dnsQuery.request, dnsQuery.length);
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ret = sendto(sockfd, dnsQuery.request, dnsQuery.length, 0,
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(struct sockaddr *)&addr, size);
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if(ret < 0)
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{
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llarp::LogWarn("Error Sending Request");
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return nullptr;
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}
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// printf("Sent\n");
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memset(&buffer, 0, DNC_BUF_SIZE);
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ret = recvfrom(sockfd, buffer, DNC_BUF_SIZE, 0, (struct sockaddr *)&addr,
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&size);
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if(ret < 0)
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{
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llarp::LogWarn("Error Receiving Response");
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return nullptr;
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}
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// hexdump("received packet", &buffer, ret);
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close(sockfd);
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rcode = (buffer[3] & 0x0F);
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// tempBuf[0] = buffer[4];
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// tempBuf[1] = buffer[5];
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// tempBuf[2] = '\0';
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// printf("%0x %0x %0x %0x\n", buffer[4], buffer[5], tempBuf[0], tempBuf[1]);
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// QDCOUNT = (uint16_t) strtol(tempBuf, NULL, 16);
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QDCOUNT = (uint16_t)buffer[4] * 0x100 + buffer[5];
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llarp::LogDebug("entries in question section: %u\n", QDCOUNT);
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ANCOUNT = (uint16_t)buffer[6] * 0x100 + buffer[7];
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llarp::LogDebug("records in answer section: %u\n", ANCOUNT);
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NSCOUNT = (uint16_t)buffer[8] * 0x100 + buffer[9];
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llarp::LogDebug("name server resource record count: %u\n", NSCOUNT);
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ARCOUNT = (uint16_t)buffer[10] * 0x100 + buffer[11];
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llarp::LogDebug("additional records count: %u\n", ARCOUNT);
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llarp::LogDebug("query type: %u\n", dnsQuery.reqType);
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QCLASS = (uint16_t)dnsQuery.request[dnsQuery.length - 2] * 0x100
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+ dnsQuery.request[dnsQuery.length - 1];
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llarp::LogDebug("query class: %u\n", QCLASS);
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length = dnsQuery.length + 1; // to skip 0xc00c
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ATYPE = (uint16_t)buffer[length + 1] * 0x100 + buffer[length + 2];
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llarp::LogDebug("answer type: %u\n", ATYPE);
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ACLASS = (uint16_t)buffer[length + 3] * 0x100 + buffer[length + 4];
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llarp::LogDebug("answer class: %u\n", ACLASS);
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TTL = (uint32_t)buffer[length + 5] * 0x1000000 + buffer[length + 6] * 0x10000
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+ buffer[length + 7] * 0x100 + buffer[length + 8];
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llarp::LogDebug("seconds to cache: %u\n", TTL);
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RDLENGTH = (uint16_t)buffer[length + 9] * 0x100 + buffer[length + 10];
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llarp::LogDebug("bytes in answer: %u\n", RDLENGTH);
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MSGID = (uint16_t)buffer[0] * 0x100 + buffer[1];
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llarp::LogDebug("answer msg id: %u\n", MSGID);
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if(rcode == 2)
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{
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llarp::LogWarn("nameserver %s returned SERVFAIL:\n", SERVER);
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llarp::LogWarn(
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" the name server was unable to process this query due to a\n "
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"problem with the name server.\n");
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return nullptr;
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}
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else if(rcode == 3)
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{
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llarp::LogWarn("nameserver %s returned NXDOMAIN for %s:\n", SERVER,
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dnsQuery.url);
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llarp::LogWarn(
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" the domain name referenced in the query does not exist\n");
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return nullptr;
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}
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/* search for and print IPv4 addresses */
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if(dnsQuery.reqType == 0x01)
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{
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llarp::LogDebug("DNS server's answer is: (type#=%u):", ATYPE);
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// printf("IPv4 address(es) for %s:\n", dnsQuery.url);
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for(i = 0; i < ret; i++)
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{
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if(buffer[i] == 0xC0 && buffer[i + 3] == 0x01)
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{
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ip++;
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i += 12; /* ! += buf[i+1]; */
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llarp::LogDebug(" %u.%u.%u.%u\n", buffer[i], buffer[i + 1],
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buffer[i + 2], buffer[i + 3]);
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struct sockaddr *g_addr = new sockaddr;
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g_addr->sa_family = AF_INET;
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// g_addr->sa_len = sizeof(in_addr);
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struct in_addr *addr = &((struct sockaddr_in *)g_addr)->sin_addr;
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unsigned char *ip;
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// have ip point to s_addr
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ip = (unsigned char *)&(addr->s_addr);
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ip[0] = buffer[i + 0];
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ip[1] = buffer[i + 1];
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ip[2] = buffer[i + 2];
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ip[3] = buffer[i + 3];
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return g_addr;
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}
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}
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if(!ip)
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{
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llarp::LogWarn(" No IPv4 address found in the DNS response!\n");
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return nullptr;
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}
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}
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return nullptr;
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}
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void
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llarp_handle_dnsclient_recvfrom(struct llarp_udp_io *udp,
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const struct sockaddr *saddr, const void *buf,
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ssize_t sz)
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{
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struct dns_client_request *request = (struct dns_client_request *)udp->user;
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if(!request)
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{
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llarp::LogError(
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"User data to DNS Client response not a dns_client_request");
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// we can't call back the hook
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return;
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}
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// it's corrupt by here...
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dns_request *server_request = (dns_request *)request->user;
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// unsigned char buffer[DNC_BUF_SIZE];
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unsigned char *buffer = (unsigned char *)buf;
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// memset(&buffer, 0, DNC_BUF_SIZE);
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// ret = recvfrom(sockfd, buffer, BUF_SIZE, 0, (struct sockaddr*)&addr,
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// &size);
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if(sz < 0)
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{
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llarp::LogWarn("Error Receiving DNS Client Response");
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request->resolved(request, nullptr);
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return;
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}
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// hexdump("received packet", &buffer, ret);
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llarp_ev_close_udp(udp);
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uint16_t QDCOUNT; // No. of items in Question Section
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uint16_t ANCOUNT; // No. of items in Answer Section
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uint16_t NSCOUNT; // No. of items in Authority Section
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uint16_t ARCOUNT; // No. of items in Additional Section
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uint16_t QCLASS; // Specifies the class of the query
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uint16_t ATYPE; // Specifies the meaning of the data in the RDATA field
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uint16_t ACLASS; // Specifies the class of the data in the RDATA field
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uint32_t TTL; // The number of seconds the results can be cached
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uint16_t RDLENGTH; // The length of the RDATA field
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uint16_t MSGID;
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int rcode;
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int length;
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struct dns_query *dnsQuery = &request->query;
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rcode = (buffer[3] & 0x0F);
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// tempBuf[0] = buffer[4];
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// tempBuf[1] = buffer[5];
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// tempBuf[2] = '\0';
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// printf("%0x %0x %0x %0x\n", buffer[4], buffer[5], tempBuf[0], tempBuf[1]);
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// QDCOUNT = (uint16_t) strtol(tempBuf, NULL, 16);
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QDCOUNT = (uint16_t)buffer[4] * 0x100 + buffer[5];
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llarp::LogDebug("entries in question section: %u\n", QDCOUNT);
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ANCOUNT = (uint16_t)buffer[6] * 0x100 + buffer[7];
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llarp::LogDebug("records in answer section: %u\n", ANCOUNT);
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NSCOUNT = (uint16_t)buffer[8] * 0x100 + buffer[9];
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llarp::LogDebug("name server resource record count: %u\n", NSCOUNT);
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ARCOUNT = (uint16_t)buffer[10] * 0x100 + buffer[11];
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llarp::LogDebug("additional records count: %u\n", ARCOUNT);
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llarp::LogDebug("query type: %u\n", dnsQuery->reqType);
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QCLASS = (uint16_t)dnsQuery->request[dnsQuery->length - 2] * 0x100
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+ dnsQuery->request[dnsQuery->length - 1];
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llarp::LogDebug("query class: %u\n", QCLASS);
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length = dnsQuery->length + 1; // to skip 0xc00c
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ATYPE = (uint16_t)buffer[length + 1] * 0x100 + buffer[length + 2];
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llarp::LogDebug("answer type: %u\n", ATYPE);
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ACLASS = (uint16_t)buffer[length + 3] * 0x100 + buffer[length + 4];
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llarp::LogDebug("answer class: %u\n", ACLASS);
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TTL = (uint32_t)buffer[length + 5] * 0x1000000 + buffer[length + 6] * 0x10000
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+ buffer[length + 7] * 0x100 + buffer[length + 8];
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llarp::LogDebug("seconds to cache: %u\n", TTL);
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RDLENGTH = (uint16_t)buffer[length + 9] * 0x100 + buffer[length + 10];
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llarp::LogDebug("bytes in answer: %u\n", RDLENGTH);
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MSGID = (uint16_t)buffer[0] * 0x100 + buffer[1];
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llarp::LogDebug("answer msg id: %u\n", MSGID);
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if(rcode == 2)
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{
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llarp::LogWarn("nameserver %s returned SERVFAIL:\n", SERVER);
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llarp::LogWarn(
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" the name server was unable to process this query due to a\n "
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"problem with the name server.\n");
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request->resolved(request, nullptr);
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return;
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}
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else if(rcode == 3)
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{
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llarp::LogWarn("nameserver %s returned NXDOMAIN for %s:\n", SERVER,
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dnsQuery->url);
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llarp::LogWarn(
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" the domain name referenced in the query does not exist\n");
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request->resolved(request, nullptr);
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return;
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}
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int ip = 0;
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/* search for and print IPv4 addresses */
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if(dnsQuery->reqType == 0x01)
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{
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llarp::LogInfo("DNS server's answer is: (type#=%u):", ATYPE);
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printf("IPv4 address(es) for %s:\n", dnsQuery->url);
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for(unsigned int i = 0; i < sz; i++)
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{
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if(buffer[i] == 0xC0 && buffer[i + 3] == 0x01)
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{
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ip++;
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i += 12; /* ! += buf[i+1]; */
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llarp::LogDebug(" %u.%u.%u.%u\n", buffer[i], buffer[i + 1],
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buffer[i + 2], buffer[i + 3]);
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struct sockaddr *g_addr = new sockaddr;
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g_addr->sa_family = AF_INET;
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// g_addr->sa_len = sizeof(in_addr);
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struct in_addr *addr = &((struct sockaddr_in *)g_addr)->sin_addr;
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unsigned char *ip;
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// have ip point to s_addr
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ip = (unsigned char *)&(addr->s_addr);
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ip[0] = buffer[i + 0];
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ip[1] = buffer[i + 1];
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ip[2] = buffer[i + 2];
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ip[3] = buffer[i + 3];
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// return g_addr;
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request->resolved(request, g_addr);
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return;
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}
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}
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if(!ip)
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{
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llarp::LogWarn(" No IPv4 address found in the DNS response!\n");
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request->resolved(request, nullptr);
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return;
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}
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}
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}
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void
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build_dns_query(struct dns_query *dnsQuery)
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{
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dnsQuery->length = 12;
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// dnsQuery->url = sUrl;
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dnsQuery->reqType = 0x01;
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// dnsQuery.request = { 0xDB, 0x42, 0x01, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
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// 0x00, 0x00, 0x00 };
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dnsQuery->request[0] = 0xDB;
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dnsQuery->request[1] = 0x42;
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dnsQuery->request[2] = 0x01;
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dnsQuery->request[3] = 0x00;
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dnsQuery->request[4] = 0x00;
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dnsQuery->request[5] = 0x01;
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dnsQuery->request[6] = 0x00;
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dnsQuery->request[7] = 0x00;
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dnsQuery->request[8] = 0x00;
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dnsQuery->request[9] = 0x00;
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dnsQuery->request[10] = 0x00;
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dnsQuery->request[11] = 0x00;
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char *word;
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llarp::LogDebug("Asking DNS server %s about %s\n", SERVER, dnsQuery->url);
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char *strTemp = strdup(dnsQuery->url);
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word = strtok(strTemp, ".");
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while(word)
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{
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llarp::LogDebug("parsing hostname: \"%s\" is %zu characters\n", word,
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strlen(word));
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dnsQuery->request[dnsQuery->length++] = strlen(word);
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for(unsigned int i = 0; i < strlen(word); i++)
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{
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dnsQuery->request[dnsQuery->length++] = word[i];
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}
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word = strtok(NULL, ".");
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}
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dnsQuery->request[dnsQuery->length++] = 0x00; // End of the host name
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dnsQuery->request[dnsQuery->length++] =
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0x00; // 0x0001 - Query is a Type A query (host address)
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dnsQuery->request[dnsQuery->length++] = dnsQuery->reqType;
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dnsQuery->request[dnsQuery->length++] =
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0x00; // 0x0001 - Query is class IN (Internet address)
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dnsQuery->request[dnsQuery->length++] = 0x01;
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}
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bool
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llarp_dns_resolve(dns_client_request *request)
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{
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struct dns_query *dnsQuery = &request->query;
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build_dns_query(dnsQuery);
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struct sockaddr_in addr;
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// int socket;
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ssize_t ret;
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socklen_t size;
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// unsigned char tempBuf[3];
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memset(&addr, 0, sizeof(addr));
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addr.sin_family = AF_INET;
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addr.sin_addr.s_addr = inet_addr(SERVER);
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addr.sin_port = htons(PORT);
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size = sizeof(addr);
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llarp_udp_io *udp = (llarp_udp_io *)request->sock;
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// llarp::LogDebug("dns client set to use ");
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// XXX: udp user pointer should be set before binding to socket and once
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udp->user = request;
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// hexdump("sending packet", &dnsQuery.request, dnsQuery.length);
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// ret = sendto(sockfd, dnsQuery.request, dnsQuery.length, 0, (struct
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// sockaddr*)&addr, size);
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ret = llarp_ev_udp_sendto(udp, (sockaddr *)&addr, dnsQuery->request,
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dnsQuery->length);
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if(ret < 0)
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{
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llarp::LogWarn("Error Sending Request");
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return false;
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}
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dns_request *test = (dns_request *)request->user;
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// printf("Sent\n");
|
|
llarp::LogInfo("Request sent, awaiting response");
|
|
return true;
|
|
}
|
|
|
|
bool
|
|
llarp_resolve_host(struct llarp_ev_loop *netloop, const char *url,
|
|
resolve_dns_hook_func resolved, void *user)
|
|
{
|
|
struct sockaddr_in s_addr;
|
|
s_addr.sin_family = AF_INET;
|
|
s_addr.sin_addr.s_addr = inet_addr("0.0.0.0");
|
|
|
|
llarp_udp_io *udp = new llarp_udp_io;
|
|
udp->tick = nullptr;
|
|
udp->user = nullptr;
|
|
udp->impl = nullptr;
|
|
udp->parent = netloop; // add_udp will do this...
|
|
// llarp::LogDebug("dns client set to use ");
|
|
udp->recvfrom = &llarp_handle_dnsclient_recvfrom;
|
|
|
|
if(llarp_ev_add_udp(netloop, udp, (sockaddr *)&s_addr) == -1)
|
|
{
|
|
llarp::LogError("failed to bind resolver to");
|
|
return false;
|
|
}
|
|
|
|
dns_client_request *request = new dns_client_request;
|
|
request->sock = (void *)udp;
|
|
request->user = user;
|
|
request->query.url = strdup(url);
|
|
request->resolved = resolved;
|
|
llarp_dns_resolve(request);
|
|
return true;
|
|
}
|