mirror of
https://github.com/oxen-io/lokinet.git
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308 lines
8.5 KiB
C++
308 lines
8.5 KiB
C++
#include <llarp/endian.h>
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#include <llarp/dnsd.hpp> // for llarp_handle_dnsd_recvfrom, dnsc
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#include <llarp/logger.hpp>
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/*
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<domain-name> is a domain name represented as a series of labels, and
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terminated by a label with zero length. <character-string> is a single
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length octet followed by that number of characters. <character-string>
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is treated as binary information, and can be up to 256 characters in
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length (including the length octet).
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*/
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std::string
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getDNSstring(const char *buffer)
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{
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std::string str = "";
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uint8_t length = *buffer++;
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// printf("dnsStringLen[%d]\n", length);
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// llarp::LogInfo("dnsStringLen ", length);
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if(!length)
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return str;
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while(length != 0)
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{
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for(int i = 0; i < length; i++)
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{
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char c = *buffer++;
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str.append(1, c);
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}
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length = *buffer++;
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if(length != 0)
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str.append(1, '.');
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}
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return str;
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}
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void
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code_domain(char *&buffer, const std::string &domain) throw()
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{
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std::string::size_type start(0);
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std::string::size_type end; // indexes
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// llarp::LogInfo("domain [", domain, "]");
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while((end = domain.find('.', start)) != std::string::npos)
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{
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*buffer++ = end - start; // label length octet
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for(std::string::size_type i = start; i < end; i++)
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{
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*buffer++ = domain[i]; // label octets
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// llarp::LogInfo("Writing ", domain[i], " at ", i);
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}
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start = end + 1; // Skip '.'
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}
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// llarp::LogInfo("start ", start, " domain size ", domain.size());
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*buffer++ = domain.size() - start; // last label length octet
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for(size_t i = start; i < domain.size(); i++)
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{
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*buffer++ = domain[i]; // last label octets
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// llarp::LogInfo("Writing ", domain[i], " at ", i);
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}
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*buffer++ = 0;
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}
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// lets just remove uint
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#ifdef _WIN32
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#define uint UINT
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#endif
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extern "C"
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{
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uint16_t
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get16bits(const char *&buffer) throw()
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{
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uint16_t value = bufbe16toh(buffer);
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buffer += 2;
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return value;
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}
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uint32_t
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get32bits(const char *&buffer) throw()
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{
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uint32_t value = bufbe32toh(buffer);
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buffer += 4;
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return value;
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}
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dns_msg_header *
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decode_hdr(const char *buffer)
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{
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dns_msg_header *hdr = new dns_msg_header;
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hdr->id = get16bits(buffer);
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uint16_t fields = get16bits(buffer);
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uint8_t lFields = (fields & 0x00FF) >> 0;
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uint8_t hFields = (fields & 0xFF00) >> 8;
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// hdr->qr = fields & 0x8000;
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hdr->qr = (hFields >> 7) & 0x1;
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hdr->opcode = fields & 0x7800;
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hdr->aa = fields & 0x0400;
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hdr->tc = fields & 0x0200;
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hdr->rd = fields & 0x0100;
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hdr->ra = (lFields >> 7) & 0x1;
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hdr->z = (lFields >> 6) & 0x1;
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hdr->ad = (lFields >> 5) & 0x1;
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hdr->cd = (lFields >> 4) & 0x1;
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hdr->rcode = lFields & 0xf;
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hdr->qdCount = get16bits(buffer);
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hdr->anCount = get16bits(buffer);
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hdr->nsCount = get16bits(buffer);
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hdr->arCount = get16bits(buffer);
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return hdr;
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}
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dns_msg_question *
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decode_question(const char *buffer)
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{
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// char *start = (char *)buffer;
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dns_msg_question *question = new dns_msg_question;
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std::string m_qName = getDNSstring(buffer);
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buffer += m_qName.length() + 2; // + length byte & ending terminator
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// printf("Now0 at [%d]\n", buffer - start);
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// buffer += m_qName.size() + 1;
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/*
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std::string m_qName = "";
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int length = *buffer++;
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// llarp::LogInfo("qNamLen", length);
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while(length != 0)
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{
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for(int i = 0; i < length; i++)
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{
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char c = *buffer++;
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m_qName.append(1, c);
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}
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length = *buffer++;
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if(length != 0)
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m_qName.append(1, '.');
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}
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*/
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question->name = m_qName;
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question->type = get16bits(buffer);
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// printf("Now1 at [%d]\n", buffer - start);
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question->qClass = get16bits(buffer);
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// printf("Now2 at [%d]\n", buffer - start);
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return question;
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}
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dns_msg_answer *
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decode_answer(const char *buffer)
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{
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dns_msg_answer *answer = new dns_msg_answer;
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// skip for now until we can handle compressed labels
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/*
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std::string aName = getDNSstring((char *)buffer);
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buffer += aName.size() + 1;
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*/
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/*
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llarp_buffer_t bob;
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bob.base = (unsigned char *)buffer;
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bob.sz = 12;
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llarp::DumpBuffer(bob);
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*/
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char hex_buffer[12 * 3 + 1];
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hex_buffer[12 * 3] = 0;
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for(unsigned int j = 0; j < 10; j++)
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sprintf(&hex_buffer[3 * j], "%02X ", buffer[j]);
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llarp::LogDebug("First 12 bytes: ", hex_buffer);
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uint8_t first = *buffer++;
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// llarp::LogInfo("decode - first", std::to_string(first));
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// SOA hack
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if(first != 12 && first != 14) // 0x0c (c0 0c) 0
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{
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llarp::LogDebug("decode - first isnt 12, stepping back");
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buffer--; // rewind buffer one byte
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}
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answer->type = get16bits(buffer);
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// assert(answer->type < 259);
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if(answer->type > 259)
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{
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llarp::LogWarn("Answer type is off the charts");
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}
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answer->aClass = get16bits(buffer);
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answer->ttl = get32bits(buffer);
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answer->rdLen = get16bits(buffer);
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if(answer->rdLen == 4)
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{
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answer->rData = new uint8_t[answer->rdLen];
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memcpy(answer->rData, buffer, answer->rdLen);
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buffer += answer->rdLen; // advance the length
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}
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else
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{
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llarp::LogDebug("Got type ", answer->type);
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switch(answer->type)
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{
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case 5:
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buffer += answer->rdLen; // advance the length
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break;
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case 6: // type 6 = SOA
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{
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// 2 names, then 4x 32bit
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// why risk any crashes
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if(answer->rdLen < 24)
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{
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llarp::LogWarn("Weird SOA is less than 24 bytes: ", answer->rdLen);
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}
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/*
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std::string mname = getDNSstring((char *)buffer);
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std::string rname = getDNSstring((char *)buffer);
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uint32_t serial = get32bits(buffer);
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uint32_t refresh = get32bits(buffer);
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uint32_t retry = get32bits(buffer);
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uint32_t expire = get32bits(buffer);
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uint32_t minimum = get32bits(buffer);
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llarp::LogInfo("mname : ", mname);
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llarp::LogInfo("rname : ", rname);
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llarp::LogDebug("serial : ", serial);
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llarp::LogDebug("refresh : ", refresh);
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llarp::LogDebug("retry : ", retry);
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llarp::LogDebug("expire : ", expire);
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llarp::LogDebug("minimum : ", minimum);
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*/
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}
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break;
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case 12:
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{
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std::string revname = getDNSstring((char *)buffer);
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llarp::LogInfo("revDNSname: ", revname);
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answer->rData = new uint8_t[answer->rdLen + 1];
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memcpy(answer->rData, revname.c_str(), answer->rdLen);
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}
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break;
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default:
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buffer += answer->rdLen; // advance the length
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llarp::LogWarn("Unknown Type ", answer->type);
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break;
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}
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}
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return answer;
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}
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void
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put16bits(char *&buffer, uint16_t value) throw()
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{
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htobe16buf(buffer, value);
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buffer += 2;
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}
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void
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put32bits(char *&buffer, uint32_t value) throw()
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{
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htobe32buf(buffer, value);
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buffer += 4;
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}
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void
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llarp_handle_dns_recvfrom(struct llarp_udp_io *udp,
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const struct sockaddr *addr, const void *buf,
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ssize_t sz)
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{
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unsigned char *castBuf = (unsigned char *)buf;
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// auto buffer = llarp::StackBuffer< decltype(castBuf) >(castBuf);
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dns_msg_header *hdr = decode_hdr((const char *)castBuf);
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// castBuf += 12;
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llarp::LogDebug("msg id ", hdr->id);
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llarp::LogDebug("msg qr ", (uint8_t)hdr->qr);
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if(!udp)
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{
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llarp::LogError("no udp passed in to handler");
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}
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if(!addr)
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{
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llarp::LogError("no source addr passed in to handler");
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}
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if(hdr->qr)
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{
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llarp::LogDebug("handling as dnsc answer");
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llarp_handle_dnsc_recvfrom(udp, addr, buf, sz);
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}
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else
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{
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llarp::LogDebug("handling as dnsd question");
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llarp_handle_dnsd_recvfrom(udp, addr, buf, sz);
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}
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/*
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llarp::LogInfo("msg op ", hdr->opcode);
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llarp::LogInfo("msg rc ", hdr->rcode);
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for(uint8_t i = 0; i < hdr->qdCount; i++)
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{
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dns_msg_question *question = decode_question((const char*)castBuf);
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llarp::LogInfo("Read a question");
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castBuf += question->name.length() + 8;
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}
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for(uint8_t i = 0; i < hdr->anCount; i++)
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{
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dns_msg_answer *answer = decode_answer((const char*)castBuf);
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llarp::LogInfo("Read an answer");
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castBuf += answer->name.length() + 4 + 4 + 4 + answer->rdLen;
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}
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*/
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}
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}
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