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239 lines
9.2 KiB
C++
239 lines
9.2 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 <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 <variant>
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#include <vector>
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#include <uvw/loop.h>
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#include <uvw/poll.h>
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#include <uvw/timer.h>
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// True if we support recvmmsg/sendmmsg
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#if defined(__linux__) && !defined(LOKINET_NO_RECVMMSG)
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#define LOKINET_HAVE_RECVMMSG
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#endif
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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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class Endpoint
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{
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protected:
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// Address we are listening on
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Address local;
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// The current outgoing IP ecn value for the socket
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uint8_t ecn_curr = 0;
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std::shared_ptr<uvw::PollHandle> poll;
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std::shared_ptr<uvw::TimerHandle> expiry_timer;
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std::shared_ptr<uvw::Loop> loop;
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// How many messages (at most) we recv per callback:
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static constexpr int N_msgs = 8;
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#ifdef LOKINET_HAVE_RECVMMSG
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static constexpr int N_mmsg = N_msgs;
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std::array<mmsghdr, N_mmsg> msgs;
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#else
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static constexpr int N_mmsg = 1;
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std::array<msghdr, N_mmsg> msgs;
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#endif
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std::array<iovec, N_mmsg> msgs_iov;
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std::array<sockaddr_any, N_mmsg> msgs_addr;
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std::array<std::array<uint8_t, CMSG_SPACE(1)>, N_mmsg> msgs_cmsg;
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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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// Wires up an endpoint connection.
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//
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// `bind` - address we should bind to. Required for a server, optional for a client. If
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// omitted, no explicit bind is performed (which means the socket will be implicitly bound to
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// some OS-determined random high bind port).
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// `loop` - the uv loop pointer managing polling of this endpoint
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Endpoint(std::optional<Address> bind, std::shared_ptr<uvw::Loop> loop);
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virtual ~Endpoint();
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int
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socket_fd() const;
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void
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on_readable();
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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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virtual void
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handle_packet(const Packet& p) = 0;
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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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// 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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// Sets up the ECN IP field (IP_TOS for IPv4) for the next outgoing packet sent via
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// send_packet(). This does the actual syscall (if ECN is different than currently set), and is
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// typically called implicitly via send_packet().
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void
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update_ecn(uint32_t ecn);
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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, uint32_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, uint32_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, uint32_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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// Gets a reference to the UV event loop
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uvw::Loop&
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get_loop()
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{
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return *loop;
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}
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};
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} // namespace llarp::quic
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