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252 lines
10 KiB
C++
252 lines
10 KiB
C++
#pragma once
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#include "address.hpp"
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#include "connection.hpp"
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#include "io_result.hpp"
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#include "null_crypto.hpp"
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#include "packet.hpp"
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#include "stream.hpp"
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#include <llarp/net/ip_packet.hpp>
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#include <chrono>
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#include <map>
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#include <memory>
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#include <queue>
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#include <unordered_map>
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#include <vector>
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#include <uvw/async.h>
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#include <uvw/timer.h>
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namespace llarp
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{
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class EndpointBase;
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} // namespace llarp
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namespace llarp::quic
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{
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using namespace std::literals;
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inline constexpr auto IDLE_TIMEOUT = 5min;
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inline constexpr std::byte CLIENT_TO_SERVER{1};
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inline constexpr std::byte SERVER_TO_CLIENT{2};
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/// QUIC Tunnel Endpoint; this is the class that implements either end of a quic tunnel for both
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/// servers and clients.
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class Endpoint
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{
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public:
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/// Called from tun code via TunnelManager to deliver an incoming packet to us.
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///
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/// \param src - the source address; this may be a tun interface address, or may be a fake IPv6
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/// address based on the convo tag. The port is not used.
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/// \param ecn - the packet ecn parameter
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void
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receive_packet(const SockAddr& src, uint8_t ecn, bstring_view data);
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/// Returns a shared pointer to the uvw loop.
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std::shared_ptr<uvw::Loop>
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get_loop();
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protected:
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/// the service endpoint we are owned by
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EndpointBase& service_endpoint;
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/// local "address" is the IPv6 unspecified address since we don't have (or care about) the
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/// actual local address for building quic packets. The port of this address must be set to our
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/// local pseudo-port, for clients, and 0 for a server.
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Address local_addr{in6addr_any};
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std::shared_ptr<uvw::TimerHandle> expiry_timer;
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std::vector<std::byte> buf;
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// Max theoretical size of a UDP packet is 2^16-1 minus IP/UDP header overhead
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static constexpr size_t max_buf_size = 64 * 1024;
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// Max size of a UDP packet that we'll send
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static constexpr size_t max_pkt_size_v4 = NGTCP2_MAX_PKTLEN_IPV4;
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static constexpr size_t max_pkt_size_v6 = NGTCP2_MAX_PKTLEN_IPV6;
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using primary_conn_ptr = std::shared_ptr<Connection>;
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using alias_conn_ptr = std::weak_ptr<Connection>;
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// Connections. When a client establishes a new connection it chooses its own source connection
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// ID and a destination connection ID and sends them to the server.
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//
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// This container stores the primary Connection instance as a shared_ptr, and any connection
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// aliases as weak_ptrs referencing the primary instance (so that we don't have to double a
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// double-hash lookup on incoming packets, since those frequently use aliases).
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//
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// The destination connection ID should be entirely random and can be up to 160 bits, but the
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// source connection ID does not have to be (i.e. it can encode some information, if desired).
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//
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// The server is going to include in the response:
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// - destination connection ID equal to the client's source connection ID
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// - a new random source connection ID. (We don't use the client's destination ID but generate
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// our own). Like the clients source ID, this can contain embedded info.
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//
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// The client stores this, and so we end up with client-scid == server-dcid, and client-dcid ==
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// server-scid, where each side chose its own source connection ID.
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//
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// Ultimately, we store here our own {source connection ID -> Connection} pairs (or
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// equivalently, on incoming packets, the key will be the packet's dest conn ID).
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std::unordered_map<ConnectionID, std::variant<primary_conn_ptr, alias_conn_ptr>> conns;
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using conns_iterator = decltype(conns)::iterator;
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// Connections that are draining (i.e. we are dropping, but need to keep around for a while
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// to catch and drop lagged packets). The time point is the scheduled removal time.
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std::queue<std::pair<ConnectionID, std::chrono::steady_clock::time_point>> draining;
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NullCrypto null_crypto;
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// Random data that we hash together with a CID to make a stateless reset token
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std::array<std::byte, 32> static_secret;
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friend class Connection;
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explicit Endpoint(EndpointBase& service_endpoint_);
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virtual ~Endpoint();
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// Version & connection id info that we can potentially extract when decoding a packet
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struct version_info
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{
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uint32_t version;
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const uint8_t* dcid;
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size_t dcid_len;
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const uint8_t* scid;
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size_t scid_len;
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};
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// Called to handle an incoming packet
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void
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handle_packet(const Packet& p);
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// Internal method: handles initial common packet decoding, returns the connection ID or nullopt
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// if decoding failed.
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std::optional<ConnectionID>
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handle_packet_init(const Packet& p);
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// Internal method: handles a packet sent to the given connection
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void
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handle_conn_packet(Connection& c, const Packet& p);
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// Accept a new incoming connection, i.e. pre-handshake. Returns a nullptr if the connection
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// can't be created (e.g. because of invalid initial data), or if incoming connections are not
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// accepted by this endpoint (i.e. because it is not a Server instance, or because there are no
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// registered listen handlers). The base class default returns nullptr.
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virtual std::shared_ptr<Connection>
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accept_initial_connection(const Packet&)
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{
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return nullptr;
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}
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// Reads a packet and handles various error conditions. Returns an io_result. Note that it is
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// possible for the conn_it to be erased from `conns` if the error code is anything other than
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// success (0) or NGTCP2_ERR_RETRY.
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io_result
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read_packet(const Packet& p, Connection& conn);
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// Writes the lokinet packet header to the beginning of `buf_`; the header is prepend to quic
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// packets to identify which quic server the packet should be delivered to and consists of:
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// - type [1 byte]: 1 for client->server packets; 2 for server->client packets (other values
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// reserved)
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// - port [2 bytes, network order]: client pseudoport (i.e. either a source or destination port
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// depending on type)
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// - ecn value [1 byte]: provided by ngtcp2. (Only the lower 2 bits are actually used).
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//
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// \param psuedo_port - the remote's pseudo-port (will be 0 if the remote is a server, > 0 for
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// a client remote)
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// \param ecn - the ecn value from ngtcp2
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//
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// Returns the number of bytes written to buf_.
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virtual size_t
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write_packet_header(nuint16_t pseudo_port, uint8_t ecn) = 0;
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// Sends a packet to `to` containing `data`. Returns a non-error io_result on success,
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// an io_result with .error_code set to the errno of the failure on failure.
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io_result
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send_packet(const Address& to, bstring_view data, uint8_t ecn);
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// Wrapper around the above that takes a regular std::string_view (i.e. of chars) and recasts
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// it to an string_view of std::bytes.
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io_result
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send_packet(const Address& to, std::string_view data, uint8_t ecn)
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{
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return send_packet(
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to, bstring_view{reinterpret_cast<const std::byte*>(data.data()), data.size()}, ecn);
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}
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// Another wrapper taking a vector
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io_result
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send_packet(const Address& to, const std::vector<std::byte>& data, uint8_t ecn)
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{
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return send_packet(to, bstring_view{data.data(), data.size()}, ecn);
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}
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void
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send_version_negotiation(const version_info& vi, const Address& source);
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// Looks up a connection. Returns a shared_ptr (either copied for a primary connection, or
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// locked from an alias's weak pointer) if the connection was found or nullptr if not; and a
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// bool indicating whether this connection ID was an alias (true) or not (false). [Note: the
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// alias value can be true even if the shared_ptr is null in the case of an expired alias that
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// hasn't yet been cleaned up].
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std::pair<std::shared_ptr<Connection>, bool>
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get_conn(const ConnectionID& cid);
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// Called to start closing (or continue closing) a connection by sending a connection close
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// response to any incoming packets.
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//
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// Takes the iterator to the connection pair from `conns` and optional error parameters: if
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// `application` is false (the default) then we do a hard connection close because of transport
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// error, if true we do a graceful application close. For application closes the code is
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// application-defined; for hard closes the code should be one of the NGTCP2_*_ERROR values.
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void
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close_connection(Connection& conn, uint64_t code = NGTCP2_NO_ERROR, bool application = false);
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/// Puts a connection into draining mode (i.e. after getting a connection close). This will
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/// keep the connection registered for the recommended 3*Probe Timeout, during which we drop
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/// packets that use the connection id and after which we will forget about it.
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void
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start_draining(Connection& conn);
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void
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check_timeouts();
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/// Deletes a connection from `conns`; if the connecion is a primary connection shared pointer
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/// then it is removed and clean_alias_conns() is immediately called to remove any aliases to
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/// the connection. If the given connection is an alias connection then it is removed but no
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/// cleanup is performed. Returns true if something was removed, false if the connection was
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/// not found.
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bool
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delete_conn(const ConnectionID& cid);
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/// Removes any connection id aliases that no longer have associated Connections.
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void
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clean_alias_conns();
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/// Creates a new, unused connection ID alias for the given connection; adds the alias to
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/// `conns` and returns the ConnectionID.
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ConnectionID
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add_connection_id(Connection& conn, size_t cid_length = ConnectionID::max_size());
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public:
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// Makes a deterministic stateless reset token for the given connection ID. Writes it to dest
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// (which must have NGTCP2_STATELESS_RESET_TOKENLEN bytes available).
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void
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make_stateless_reset_token(const ConnectionID& cid, unsigned char* dest);
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// Default stream buffer size for streams opened through this endpoint.
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size_t default_stream_buffer_size = 64 * 1024;
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// Packet buffer we use when constructing custom packets to fire over lokinet
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std::array<std::byte, net::IPPacket::MaxSize> buf_;
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// Non-copyable, non-movable
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Endpoint(const Endpoint&) = delete;
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Endpoint(Endpoint&&) = delete;
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};
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} // namespace llarp::quic
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