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lokinet/llarp/dnsc.cpp

565 lines
18 KiB
C++

// why dnsd? what do you need from that?
#include "dnsd.hpp"
#include "buffer.hpp"
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h> /* getaddrinfo, getnameinfo */
#include <stdlib.h> /* exit */
#include <string.h> /* memset */
#include <unistd.h> /* close */
#include <netinet/in.h>
#include <arpa/inet.h>
#include "logger.hpp"
#include <llarp/dns.h>
#include "net.hpp" // for llarp::Addr
#include "net.hpp" // for llarp::Addr
// FIXME: make configurable
#define SERVER "8.8.8.8"
#define PORT 53
mtx_t m_dnsc_Mutex;
mtx_t m_dnsc2_Mutex;
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 ", SERVER, " about ", 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;
}
//llarp::LogInfo("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)
{
lock_t lock(m_dnsc_Mutex);
//llarp::LogInfo("got a response, udp user is ", udp->user);
unsigned char *castBuf = (unsigned char *)buf;
auto buffer = llarp::StackBuffer< decltype(castBuf) >(castBuf);
dns_msg_header *hdr = decode_hdr((const char*)castBuf);
llarp::LogInfo("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 dns_client_request *request = tracker->client_request[hdr->id];
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);
llarp::LogInfo("dnsc rcode ", rcode);
dns_msg_header *msg = decode_hdr((const char*)castBuf);
castBuf += 12;
llarp::LogInfo("msg id ", msg->id);
llarp::LogInfo("msg qr ", msg->qr);
llarp::LogInfo("msg op ", msg->opcode);
llarp::LogInfo("msg rc ", msg->rcode);
//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::LogInfo("entries in question section: ", QDCOUNT);
ANCOUNT = (uint16_t) buffer[6] * 0x100 + buffer[7];
llarp::LogInfo("records in answer section: ", ANCOUNT);
NSCOUNT = (uint16_t) buffer[8] * 0x100 + buffer[9];
llarp::LogInfo("name server resource record count: ", NSCOUNT);
ARCOUNT = (uint16_t) buffer[10] * 0x100 + buffer[11];
llarp::LogInfo("additional records count: ", ARCOUNT);
llarp::LogInfo("msg qdc ", msg->qdCount);
llarp::LogInfo("msg anc ", msg->anCount);
llarp::LogInfo("msg nsc ", msg->nsCount);
llarp::LogInfo("msg arc ", msg->arCount);
// we may need to parse question first
dns_msg_question *question = decode_question((const char*)castBuf);
llarp::LogInfo("que name ", question->name);
castBuf += question->name.length() + 8;
dns_msg_answer *answer = decode_answer((const char*)castBuf);
castBuf += answer->name.length() + 4 + 4 + 4 + answer->rdLen;
//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::LogInfo("ans class ", answer->aClass);
llarp::LogInfo("ans type ", answer->type);
llarp::LogInfo("ans ttl ", answer->ttl);
llarp::LogInfo("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);
*/
if (rcode == 2) {
llarp::LogWarn("nameserver ", SERVER, " 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 ", SERVER, " returned NXDOMAIN for: ", dnsQuery->url);
llarp::LogWarn(" the domain name referenced in the query does not exist");
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#=", ATYPE, "):");
llarp::LogInfo("IPv4 address(es) for ", 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(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!");
request->resolved(request);
return;
}
}
}
void
llarp_handle_dns_recvfrom(struct llarp_udp_io *udp, const struct sockaddr *saddr,
const void *buf, ssize_t sz)
{
unsigned char *castBuf = (unsigned char *)buf;
//auto buffer = llarp::StackBuffer< decltype(castBuf) >(castBuf);
dns_msg_header *hdr = decode_hdr((const char*)castBuf);
//castBuf += 12;
llarp::LogInfo("msg id ", hdr->id);
llarp::LogInfo("msg qr ", hdr->qr);
if (hdr->qr)
{
llarp_handle_dnsclient_recvfrom(udp, saddr, buf, sz);
} else {
llarp_handle_recvfrom(udp, saddr, buf, sz);
}
/*
llarp::LogInfo("msg op ", hdr->opcode);
llarp::LogInfo("msg rc ", hdr->rcode);
for(uint i = 0; i < hdr->qdCount; i++)
{
dns_msg_question *question = decode_question((const char*)castBuf);
llarp::LogInfo("Read a question");
castBuf += question->name.length() + 8;
}
for(uint i = 0; i < hdr->anCount; i++)
{
dns_msg_answer *answer = decode_answer((const char*)castBuf);
llarp::LogInfo("Read an answer");
castBuf += answer->name.length() + 4 + 4 + 4 + answer->rdLen;
}
*/
}
void build_dns_query(struct dns_query *dnsQuery, uint id)
{
dnsQuery->length = 12;
dnsQuery->reqType = 0x01;
// ID
//buffer[0] = (value & 0xFF00) >> 8;
//buffer[1] = value & 0xFF;
llarp::LogInfo("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(dnsQuery->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(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;
dns_tracker *tracker = (dns_tracker *)dnsc->udp->user;
build_dns_query(dnsQuery, ++tracker->c_requests);
// 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;
}
*/
tracker->client_request[tracker->c_requests] = request;
ssize_t ret = llarp_ev_udp_sendto(dnsc->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)
{
lock_t lock(m_dnsc2_Mutex);
// 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
//llarp::LogInfo("outgoing port check ", ntohs(srcaddr.sin_port));
if (ntohs(srcaddr.sin_port) < 1024)
srcaddr.sin_port = htons(ntohs(srcaddr.sin_port) + 1024);
request->udp.user = request;
request->udp.recvfrom = &llarp_handle_dns_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_udp_io *udp,
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->udp = udp;
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;
}