github.com/noisysockets/noisysockets@v0.21.2-0.20240515114641-7f467e651c90/internal/conn/conn.go

// SPDX-License-Identifier: MPL-2.0
/*
 * Copyright (C) 2024 The Noisy Sockets Authors.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Portions of this file are based on code originally from wireguard-go,
 *
 * Copyright (C) 2017-2023 WireGuard LLC. All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

// Package conn implements WireGuard's network connections.
package conn

import (
	"errors"
	"fmt"
	"net/netip"
	"reflect"
	"runtime"
	"strings"
)

const (
	IdealBatchSize = 128 // maximum number of packets handled per read and write
)

// A ReceiveFunc receives at least one packet from the network and writes them
// into packets. On a successful read it returns the number of elements of
// sizes, packets, and endpoints that should be evaluated. Some elements of
// sizes may be zero, and callers should ignore them. Callers must pass a sizes
// and eps slice with a length greater than or equal to the length of packets.
// These lengths must not exceed the length of the associated Bind.BatchSize().
type ReceiveFunc func(packets [][]byte, sizes []int, eps []Endpoint) (n int, err error)

// A Bind listens on a port for both IPv6 and IPv4 UDP traffic.
//
// A Bind interface may also be a PeekLookAtSocketFd or BindSocketToInterface,
// depending on the platform-specific implementation.
type Bind interface {
	// Open puts the Bind into a listening state on a given port and reports the actual
	// port that it bound to. Passing zero results in a random selection.
	// fns is the set of functions that will be called to receive packets.
	Open(port uint16) (fns []ReceiveFunc, actualPort uint16, err error)

	// Close closes the Bind listener.
	// All fns returned by Open must return net.ErrClosed after a call to Close.
	Close() error

	// Send writes one or more packets in bufs to address ep. The length of
	// bufs must not exceed BatchSize().
	Send(bufs [][]byte, ep Endpoint) error

	// ParseEndpoint creates a new endpoint from a string.
	ParseEndpoint(s string) (Endpoint, error)

	// BatchSize is the number of buffers expected to be passed to
	// the ReceiveFuncs, and the maximum expected to be passed to SendBatch.
	BatchSize() int
}

// An Endpoint maintains the source/destination caching for a peer.
//
//	dst: the remote address of a peer ("endpoint" in uapi terminology)
//	src: the local address from which datagrams originate going to the peer
type Endpoint interface {
	DstToString() string // returns the destination address (ip:port)
	DstToBytes() []byte  // used for mac2 cookie calculations
	DstIP() netip.Addr
}

var (
	ErrBindAlreadyOpen   = errors.New("bind is already open")
	ErrWrongEndpointType = errors.New("endpoint type does not correspond with bind type")
)

func (fn ReceiveFunc) PrettyName() string {
	name := runtime.FuncForPC(reflect.ValueOf(fn).Pointer()).Name()
	// 0. cheese/taco.beansIPv6.func12.func21218-fm
	name = strings.TrimSuffix(name, "-fm")
	// 1. cheese/taco.beansIPv6.func12.func21218
	if idx := strings.LastIndexByte(name, '/'); idx != -1 {
		name = name[idx+1:]
		// 2. taco.beansIPv6.func12.func21218
	}
	for {
		var idx int
		for idx = len(name) - 1; idx >= 0; idx-- {
			if name[idx] < '0' || name[idx] > '9' {
				break
			}
		}
		if idx == len(name)-1 {
			break
		}
		const dotFunc = ".func"
		if !strings.HasSuffix(name[:idx+1], dotFunc) {
			break
		}
		name = name[:idx+1-len(dotFunc)]
		// 3. taco.beansIPv6.func12
		// 4. taco.beansIPv6
	}
	if idx := strings.LastIndexByte(name, '.'); idx != -1 {
		name = name[idx+1:]
		// 5. beansIPv6
	}
	if name == "" {
		return fmt.Sprintf("%p", fn)
	}
	if strings.HasSuffix(name, "IPv4") {
		return "v4"
	}
	if strings.HasSuffix(name, "IPv6") {
		return "v6"
	}
	return name
}