feat: Waku v2 bridge

Issue #12610

vendor/github.com/pion/transport/packetio/buffer.go

@@ -0,0 +1,347 @@
+// Package packetio provides packet buffer
+package packetio
+
+import (
+	"errors"
+	"io"
+	"sync"
+	"time"
+
+	"github.com/pion/transport/deadline"
+)
+
+var errPacketTooBig = errors.New("packet too big")
+
+// BufferPacketType allow the Buffer to know which packet protocol is writing.
+type BufferPacketType int
+
+const (
+	// RTPBufferPacket indicates the Buffer that is handling RTP packets
+	RTPBufferPacket BufferPacketType = 1
+	// RTCPBufferPacket indicates the Buffer that is handling RTCP packets
+	RTCPBufferPacket BufferPacketType = 2
+)
+
+// Buffer allows writing packets to an intermediate buffer, which can then be read form.
+// This is verify similar to bytes.Buffer but avoids combining multiple writes into a single read.
+type Buffer struct {
+	mutex sync.Mutex
+
+	// this is a circular buffer.  If head <= tail, then the useful
+	// data is in the interval [head, tail[.  If tail < head, then
+	// the useful data is the union of [head, len[ and [0, tail[.
+	// In order to avoid ambiguity when head = tail, we always leave
+	// an unused byte in the buffer.
+	data       []byte
+	head, tail int
+
+	notify chan struct{}
+	subs   bool
+	closed bool
+
+	count                 int
+	limitCount, limitSize int
+
+	readDeadline *deadline.Deadline
+}
+
+const (
+	minSize    = 2048
+	cutoffSize = 128 * 1024
+	maxSize    = 4 * 1024 * 1024
+)
+
+// NewBuffer creates a new Buffer.
+func NewBuffer() *Buffer {
+	return &Buffer{
+		notify:       make(chan struct{}),
+		readDeadline: deadline.New(),
+	}
+}
+
+// available returns true if the buffer is large enough to fit a packet
+// of the given size, taking overhead into account.
+func (b *Buffer) available(size int) bool {
+	available := b.head - b.tail
+	if available <= 0 {
+		available += len(b.data)
+	}
+	// we interpret head=tail as empty, so always keep a byte free
+	if size+2+1 > available {
+		return false
+	}
+
+	return true
+}
+
+// grow increases the size of the buffer.  If it returns nil, then the
+// buffer has been grown.  It returns ErrFull if hits a limit.
+func (b *Buffer) grow() error {
+	var newsize int
+	if len(b.data) < cutoffSize {
+		newsize = 2 * len(b.data)
+	} else {
+		newsize = 5 * len(b.data) / 4
+	}
+	if newsize < minSize {
+		newsize = minSize
+	}
+	if (b.limitSize <= 0 || sizeHardlimit) && newsize > maxSize {
+		newsize = maxSize
+	}
+
+	// one byte slack
+	if b.limitSize > 0 && newsize > b.limitSize+1 {
+		newsize = b.limitSize + 1
+	}
+
+	if newsize <= len(b.data) {
+		return ErrFull
+	}
+
+	newdata := make([]byte, newsize)
+
+	var n int
+	if b.head <= b.tail {
+		// data was contiguous
+		n = copy(newdata, b.data[b.head:b.tail])
+	} else {
+		// data was discontiguous
+		n = copy(newdata, b.data[b.head:])
+		n += copy(newdata[n:], b.data[:b.tail])
+	}
+	b.head = 0
+	b.tail = n
+	b.data = newdata
+
+	return nil
+}
+
+// Write appends a copy of the packet data to the buffer.
+// Returns ErrFull if the packet doesn't fit.
+//
+// Note that the packet size is limited to 65536 bytes since v0.11.0 due to the internal data structure.
+func (b *Buffer) Write(packet []byte) (int, error) {
+	if len(packet) >= 0x10000 {
+		return 0, errPacketTooBig
+	}
+
+	b.mutex.Lock()
+
+	if b.closed {
+		b.mutex.Unlock()
+		return 0, io.ErrClosedPipe
+	}
+
+	if (b.limitCount > 0 && b.count >= b.limitCount) ||
+		(b.limitSize > 0 && b.size()+2+len(packet) > b.limitSize) {
+		b.mutex.Unlock()
+		return 0, ErrFull
+	}
+
+	// grow the buffer until the packet fits
+	for !b.available(len(packet)) {
+		err := b.grow()
+		if err != nil {
+			b.mutex.Unlock()
+			return 0, err
+		}
+	}
+
+	var notify chan struct{}
+
+	if b.subs {
+		// readers are waiting.  Prepare to notify, but only
+		// actually do it after we release the lock.
+		notify = b.notify
+		b.notify = make(chan struct{})
+		b.subs = false
+	}
+
+	// store the length of the packet
+	b.data[b.tail] = uint8(len(packet) >> 8)
+	b.tail++
+	if b.tail >= len(b.data) {
+		b.tail = 0
+	}
+	b.data[b.tail] = uint8(len(packet))
+	b.tail++
+	if b.tail >= len(b.data) {
+		b.tail = 0
+	}
+
+	// store the packet
+	n := copy(b.data[b.tail:], packet)
+	b.tail += n
+	if b.tail >= len(b.data) {
+		// we reached the end, wrap around
+		m := copy(b.data, packet[n:])
+		b.tail = m
+	}
+	b.count++
+	b.mutex.Unlock()
+
+	if notify != nil {
+		close(notify)
+	}
+
+	return len(packet), nil
+}
+
+// Read populates the given byte slice, returning the number of bytes read.
+// Blocks until data is available or the buffer is closed.
+// Returns io.ErrShortBuffer is the packet is too small to copy the Write.
+// Returns io.EOF if the buffer is closed.
+func (b *Buffer) Read(packet []byte) (n int, err error) {
+	// Return immediately if the deadline is already exceeded.
+	select {
+	case <-b.readDeadline.Done():
+		return 0, &netError{ErrTimeout, true, true}
+	default:
+	}
+
+	for {
+		b.mutex.Lock()
+
+		if b.head != b.tail {
+			// decode the packet size
+			n1 := b.data[b.head]
+			b.head++
+			if b.head >= len(b.data) {
+				b.head = 0
+			}
+			n2 := b.data[b.head]
+			b.head++
+			if b.head >= len(b.data) {
+				b.head = 0
+			}
+			count := int((uint16(n1) << 8) | uint16(n2))
+
+			// determine the number of bytes we'll actually copy
+			copied := count
+			if copied > len(packet) {
+				copied = len(packet)
+			}
+
+			// copy the data
+			if b.head+copied < len(b.data) {
+				copy(packet, b.data[b.head:b.head+copied])
+			} else {
+				k := copy(packet, b.data[b.head:])
+				copy(packet[k:], b.data[:copied-k])
+			}
+
+			// advance head, discarding any data that wasn't copied
+			b.head += count
+			if b.head >= len(b.data) {
+				b.head -= len(b.data)
+			}
+
+			if b.head == b.tail {
+				// the buffer is empty, reset to beginning
+				// in order to improve cache locality.
+				b.head = 0
+				b.tail = 0
+			}
+
+			b.count--
+
+			b.mutex.Unlock()
+
+			if copied < count {
+				return copied, io.ErrShortBuffer
+			}
+			return copied, nil
+		}
+
+		if b.closed {
+			b.mutex.Unlock()
+			return 0, io.EOF
+		}
+
+		notify := b.notify
+		b.subs = true
+		b.mutex.Unlock()
+
+		select {
+		case <-b.readDeadline.Done():
+			return 0, &netError{ErrTimeout, true, true}
+		case <-notify:
+		}
+	}
+}
+
+// Close the buffer, unblocking any pending reads.
+// Data in the buffer can still be read, Read will return io.EOF only when empty.
+func (b *Buffer) Close() (err error) {
+	b.mutex.Lock()
+
+	if b.closed {
+		b.mutex.Unlock()
+		return nil
+	}
+
+	notify := b.notify
+	b.closed = true
+
+	b.mutex.Unlock()
+
+	close(notify)
+
+	return nil
+}
+
+// Count returns the number of packets in the buffer.
+func (b *Buffer) Count() int {
+	b.mutex.Lock()
+	defer b.mutex.Unlock()
+	return b.count
+}
+
+// SetLimitCount controls the maximum number of packets that can be buffered.
+// Causes Write to return ErrFull when this limit is reached.
+// A zero value will disable this limit.
+func (b *Buffer) SetLimitCount(limit int) {
+	b.mutex.Lock()
+	defer b.mutex.Unlock()
+
+	b.limitCount = limit
+}
+
+// Size returns the total byte size of packets in the buffer, including
+// a small amount of administrative overhead.
+func (b *Buffer) Size() int {
+	b.mutex.Lock()
+	defer b.mutex.Unlock()
+
+	return b.size()
+}
+
+func (b *Buffer) size() int {
+	size := b.tail - b.head
+	if size < 0 {
+		size += len(b.data)
+	}
+	return size
+}
+
+// SetLimitSize controls the maximum number of bytes that can be buffered.
+// Causes Write to return ErrFull when this limit is reached.
+// A zero value means 4MB since v0.11.0.
+//
+// User can set packetioSizeHardlimit build tag to enable 4MB hardlimit.
+// When packetioSizeHardlimit build tag is set, SetLimitSize exceeding
+// the hardlimit will be silently discarded.
+func (b *Buffer) SetLimitSize(limit int) {
+	b.mutex.Lock()
+	defer b.mutex.Unlock()
+
+	b.limitSize = limit
+}
+
+// SetReadDeadline sets the deadline for the Read operation.
+// Setting to zero means no deadline.
+func (b *Buffer) SetReadDeadline(t time.Time) error {
+	b.readDeadline.Set(t)
+	return nil
+}