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#pragma once
#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
#if HAVE_OPENSSL && NODE_OPENSSL_HAS_QUIC
#include <memory_tracker.h>
#include <ngtcp2/ngtcp2.h>
#include <string>
namespace node {
namespace quic {
// CIDS are used to identify endpoints participating in a QUIC session.
// Once created, CID instances are immutable.
//
// CIDs contain between 1 to 20 bytes. Most typically they are selected
// randomly but there is a spec for creating "routable" CIDs that encode
// a specific structure that is meaningful only to the side that creates
// the CID. For most purposes, CIDs should be treated as opaque tokens.
//
// Each peer in a QUIC session generates one or more CIDs that the *other*
// peer will use to identify the session. When a QUIC client initiates a
// brand new session, it will initially generates a CID of its own (its
// source CID) and a random placeholder CID for the server (the original
// destination CID). When the server receives the initial packet, it will
// generate its own source CID and use the clients source CID as the
// server's destination CID.
//
// Client Server
// -------------------------------------------
// Source CID <====> Destination CID
// Destination CID <====> Source CID
//
// While the connection is being established, it is possible for either
// peer to generate additional CIDs that are also associated with the
// connection.
class CID final : public MemoryRetainer {
public:
static constexpr size_t kMinLength = NGTCP2_MIN_CIDLEN;
static constexpr size_t kMaxLength = NGTCP2_MAX_CIDLEN;
// Copy the given ngtcp2_cid.
explicit CID(const ngtcp2_cid& cid);
// Copy the given buffer as a CID. The len must be within
// kMinLength and kMaxLength.
explicit CID(const uint8_t* data, size_t len);
// Wrap the given ngtcp2_cid. The CID does not take ownership
// of the underlying ngtcp2_cid.
explicit CID(const ngtcp2_cid* cid);
CID(const CID& other);
CID(CID&& other) = delete;
CID& operator=(const CID& other);
struct Hash final {
size_t operator()(const CID& cid) const;
};
bool operator==(const CID& other) const noexcept;
bool operator!=(const CID& other) const noexcept;
operator const uint8_t*() const;
operator const ngtcp2_cid&() const;
operator const ngtcp2_cid*() const;
// True if the CID length is at least kMinLength;
operator bool() const;
size_t length() const;
std::string ToString() const;
SET_NO_MEMORY_INFO()
SET_MEMORY_INFO_NAME(CID)
SET_SELF_SIZE(CID)
template <typename T>
using Map = std::unordered_map<CID, T, CID::Hash>;
// A CID::Factory, as the name suggests, is used to create new CIDs.
// Per https://datatracker.ietf.org/doc/draft-ietf-quic-load-balancers/, QUIC
// implementations MAY use the Connection ID associated with a QUIC session
// as a routing mechanism, with each CID instance securely encoding the
// routing information. By default, our implementation creates CIDs randomly
// but will allow user code to provide their own CID::Factory implementation.
class Factory;
static CID kInvalid;
// The default constructor creates an empty, zero-length CID.
// Zero-length CIDs are not usable. We use them as a placeholder
// for a missing or empty CID value. This is public only because
// it is required for the CID::Map implementation. It should not
// be used. Use kInvalid instead.
CID();
private:
ngtcp2_cid cid_;
const ngtcp2_cid* ptr_;
friend struct Hash;
};
class CID::Factory {
public:
virtual ~Factory() = default;
// Generate a new CID. The length_hint must be between CID::kMinLength
// and CID::kMaxLength. The implementation can choose to ignore the length.
virtual CID Generate(size_t length_hint = CID::kMaxLength) const = 0;
// Generate a new CID into the given ngtcp2_cid. This variation of
// Generate should be used far less commonly. It is provided largely
// for a couple of internal cases.
virtual void GenerateInto(ngtcp2_cid* cid,
size_t length_hint = CID::kMaxLength) const = 0;
// The default random CID generator instance.
static const Factory& random();
// TODO(@jasnell): This will soon also include additional implementations
// of CID::Factory that implement the QUIC Load Balancers spec.
};
} // namespace quic
} // namespace node
#endif // HAVE_OPENSSL && NODE_OPENSSL_HAS_QUIC
#endif // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
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