2018-12-12 00:58:08 +00:00
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#include <dns/server.hpp>
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2018-12-03 22:22:59 +00:00
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namespace llarp
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{
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namespace dns
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{
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Proxy::Proxy(llarp_ev_loop* loop, IQueryHandler* h)
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: m_Loop(loop), m_QueryHandler(h)
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{
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2018-12-04 16:35:25 +00:00
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m_Client.user = this;
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m_Server.user = this;
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m_Client.tick = nullptr;
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m_Server.tick = nullptr;
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m_Client.recvfrom = &HandleUDPRecv_client;
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m_Server.recvfrom = &HandleUDPRecv_server;
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2018-12-03 22:22:59 +00:00
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}
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void
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Proxy::Stop()
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{
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}
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bool
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Proxy::Start(const llarp::Addr& addr,
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const std::vector< llarp::Addr >& resolvers)
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{
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m_Resolvers.clear();
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m_Resolvers = resolvers;
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if(m_Resolvers.size() == 0)
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{
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llarp::LogError("no upstream dns provide specified");
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return false;
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}
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2018-12-04 16:35:25 +00:00
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llarp::Addr any("0.0.0.0", 0);
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return llarp_ev_add_udp(m_Loop, &m_Server, addr) == 0
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2018-12-04 16:37:15 +00:00
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&& llarp_ev_add_udp(m_Loop, &m_Client, any) == 0;
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2018-12-03 22:22:59 +00:00
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}
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void
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2018-12-04 16:35:25 +00:00
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Proxy::HandleUDPRecv_server(llarp_udp_io* u, const sockaddr* from,
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llarp_buffer_t buf)
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2018-12-03 22:22:59 +00:00
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{
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2018-12-04 16:35:25 +00:00
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static_cast< Proxy* >(u->user)->HandlePktServer(*from, &buf);
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}
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void
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Proxy::HandleUDPRecv_client(llarp_udp_io* u, const sockaddr* from,
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llarp_buffer_t buf)
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{
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static_cast< Proxy* >(u->user)->HandlePktClient(*from, &buf);
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2018-12-03 22:22:59 +00:00
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}
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llarp::Addr
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Proxy::PickRandomResolver() const
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{
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size_t sz = m_Resolvers.size();
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if(sz == 0)
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2018-12-04 16:37:15 +00:00
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return llarp::Addr("1.1.1.1", 53);
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2018-12-03 22:22:59 +00:00
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if(sz == 1)
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return m_Resolvers[0];
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auto itr = m_Resolvers.begin();
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2018-12-11 00:53:11 +00:00
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std::advance(itr, llarp::randint() % sz);
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2018-12-03 22:22:59 +00:00
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return *itr;
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}
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void
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Proxy::HandleTick(llarp_udp_io*)
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{
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}
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void
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Proxy::SendMessageTo(llarp::Addr to, Message msg)
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{
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byte_t tmp[1500] = {0};
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auto buf = llarp::StackBuffer< decltype(tmp) >(tmp);
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if(msg.Encode(&buf))
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{
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buf.sz = buf.cur - buf.base;
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buf.cur = buf.base;
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2018-12-04 16:35:25 +00:00
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llarp_ev_udp_sendto(&m_Server, to, buf);
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2018-12-03 22:22:59 +00:00
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}
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else
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llarp::LogWarn("failed to encode dns message when sending");
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}
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void
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2018-12-04 16:35:25 +00:00
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Proxy::HandlePktClient(llarp::Addr from, llarp_buffer_t* pkt)
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2018-12-03 22:22:59 +00:00
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{
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2018-12-04 16:16:43 +00:00
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MessageHeader hdr;
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if(!hdr.Decode(pkt))
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{
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llarp::LogWarn("failed to parse dns header from ", from);
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return;
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}
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TX tx = {hdr.id, from};
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auto itr = m_Forwarded.find(tx);
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if(itr != m_Forwarded.end())
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{
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llarp_buffer_t buf;
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buf.sz = pkt->sz;
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buf.base = pkt->base;
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buf.cur = buf.base;
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2018-12-04 16:35:25 +00:00
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// forward reply
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llarp_ev_udp_sendto(&m_Server, itr->second, buf);
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2018-12-04 16:16:43 +00:00
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// remove pending
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m_Forwarded.erase(itr);
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}
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2018-12-04 16:35:25 +00:00
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}
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2018-12-04 16:16:43 +00:00
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2018-12-04 16:35:25 +00:00
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void
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Proxy::HandlePktServer(llarp::Addr from, llarp_buffer_t* pkt)
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{
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MessageHeader hdr;
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if(!hdr.Decode(pkt))
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{
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llarp::LogWarn("failed to parse dns header from ", from);
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return;
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}
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TX tx = {hdr.id, from};
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auto itr = m_Forwarded.find(tx);
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2018-12-04 16:16:43 +00:00
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Message msg(hdr);
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2018-12-03 22:22:59 +00:00
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if(!msg.Decode(pkt))
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{
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2018-12-04 16:16:43 +00:00
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llarp::LogWarn("failed to parse dns message from ", from);
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2018-12-03 22:22:59 +00:00
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return;
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}
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2018-12-04 16:16:43 +00:00
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2018-12-03 22:22:59 +00:00
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if(m_QueryHandler && m_QueryHandler->ShouldHookDNSMessage(msg))
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{
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if(!m_QueryHandler->HandleHookedDNSMessage(
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2018-12-04 16:16:43 +00:00
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std::move(msg),
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2018-12-03 22:22:59 +00:00
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std::bind(&Proxy::SendMessageTo, this, from,
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std::placeholders::_1)))
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{
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llarp::LogWarn("failed to handle hooked dns");
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}
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return;
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}
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2018-12-04 16:16:43 +00:00
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else if(itr == m_Forwarded.end())
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2018-12-03 22:22:59 +00:00
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{
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// new forwarded query
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tx.from = PickRandomResolver();
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m_Forwarded[tx] = from;
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2018-12-04 16:16:43 +00:00
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llarp_buffer_t buf;
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buf.sz = pkt->sz;
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buf.base = pkt->base;
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buf.cur = buf.base;
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// do query
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2018-12-04 16:35:25 +00:00
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llarp_ev_udp_sendto(&m_Client, tx.from, buf);
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2018-12-03 22:22:59 +00:00
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}
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else
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{
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2018-12-04 16:16:43 +00:00
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// drop (?)
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2018-12-03 22:22:59 +00:00
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}
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}
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} // namespace dns
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} // namespace llarp
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