Class PacketUtil

Namespace

VpnHood.Net.Packets

Assembly

VpnHood.Net.Packets.dll

Provides helpers to read an IP packet's length and to compute Internet checksums.

public static class PacketUtil

Inheritance

object

PacketUtil

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Methods

ComputeChecksum(ReadOnlySpan<byte>)

Computes the Internet checksum (RFC 1071) of some bytes. The same as ComputeChecksum(ReadOnlySpan<byte>).

public static ushort ComputeChecksum(ReadOnlySpan<byte> data)

Parameters

data ReadOnlySpan<byte>

The bytes to sum, with any checksum field among them zero.

Returns

ushort

The checksum, as a number to write in network byte order.

ComputeChecksum(ReadOnlySpan<byte>, ReadOnlySpan<byte>)

Computes the Internet checksum (RFC 1071) of a pseudo-header followed by some bytes. The same as ComputeChecksum(ReadOnlySpan<byte>, ReadOnlySpan<byte>).

public static ushort ComputeChecksum(ReadOnlySpan<byte> pseudoHeader, ReadOnlySpan<byte> data)

Parameters

pseudoHeader ReadOnlySpan<byte>

The bytes summed first, such as an IP pseudo-header; may be empty.

data ReadOnlySpan<byte>

The bytes summed after them, with any checksum field among them zero.

Returns

ushort

The checksum, as a number to write in network byte order.

ComputeChecksum(ReadOnlySpan<byte>, ReadOnlySpan<byte>, byte, ReadOnlySpan<byte>)

Computes the checksum of a TCP, UDP or ICMPv6 packet: the Internet checksum of its IP pseudo-header and its bytes.

public static ushort ComputeChecksum(ReadOnlySpan<byte> sourceAddress, ReadOnlySpan<byte> destinationAddress, byte protocol, ReadOnlySpan<byte> data)

Parameters

sourceAddress ReadOnlySpan<byte>

The source address of the IP packet: 4 bytes for IPv4, 16 for IPv6.

destinationAddress ReadOnlySpan<byte>

The destination address of the IP packet, of the same length.

protocol byte

The protocol number the pseudo-header carries, such as 6 for TCP.

data ReadOnlySpan<byte>

The upper-layer packet, header and payload, with its checksum field zero.

Returns

ushort

The checksum, as a number to write in network byte order.

Exceptions

ArgumentException

The addresses are not both 4 or both 16 bytes long.

ReadPacketLength(ReadOnlySpan<byte>)

Reads an IP packet's total length from its header, without parsing the rest.

public static int ReadPacketLength(ReadOnlySpan<byte> buffer)

Parameters

buffer ReadOnlySpan<byte>

The packet's first bytes: at least 4 for IPv4 and 6 for IPv6.

Returns

int

The packet's length in bytes, header included.

Exceptions

ArgumentException

buffer is too short to hold the length.

IndexOutOfRangeException

buffer is empty.

NotSupportedException

The packet is neither IPv4 nor IPv6.