diff options
Diffstat (limited to 'test/packetimpact/testbench/layers.go')
| -rw-r--r-- | test/packetimpact/testbench/layers.go | 93 |
1 files changed, 53 insertions, 40 deletions
diff --git a/test/packetimpact/testbench/layers.go b/test/packetimpact/testbench/layers.go index ff800377e..b467c15cc 100644 --- a/test/packetimpact/testbench/layers.go +++ b/test/packetimpact/testbench/layers.go @@ -172,27 +172,46 @@ func NetworkProtocolNumber(v tcpip.NetworkProtocolNumber) *tcpip.NetworkProtocol return &v } +// LayerParser parses the input bytes and returns a Layer along with the next +// LayerParser to run. If there is no more parsing to do, the returned +// LayerParser is nil. +type LayerParser func([]byte) (Layer, LayerParser) + +// Parse parses bytes starting with the first LayerParser and using successive +// LayerParsers until all the bytes are parsed. +func Parse(parser LayerParser, b []byte) Layers { + var layers Layers + for { + var layer Layer + layer, parser = parser(b) + layers = append(layers, layer) + if parser == nil { + break + } + b = b[layer.length():] + } + layers.linkLayers() + return layers +} + // ParseEther parses the bytes assuming that they start with an ethernet header // and continues parsing further encapsulations. -func ParseEther(b []byte) (Layers, error) { +func ParseEther(b []byte) (Layer, LayerParser) { h := header.Ethernet(b) ether := Ether{ SrcAddr: LinkAddress(h.SourceAddress()), DstAddr: LinkAddress(h.DestinationAddress()), Type: NetworkProtocolNumber(h.Type()), } - layers := Layers{ðer} + var nextParser LayerParser switch h.Type() { case header.IPv4ProtocolNumber: - moreLayers, err := ParseIPv4(b[ether.length():]) - if err != nil { - return nil, err - } - return append(layers, moreLayers...), nil + nextParser = ParseIPv4 default: - // TODO(b/150301488): Support more protocols, like IPv6. - return nil, fmt.Errorf("ethernet header's type field is unrecognized: %#04x", h.Type()) + // Assume that the rest is a payload. + nextParser = ParsePayload } + return ðer, nextParser } func (l *Ether) match(other Layer) bool { @@ -313,7 +332,7 @@ func Address(v tcpip.Address) *tcpip.Address { // ParseIPv4 parses the bytes assuming that they start with an ipv4 header and // continues parsing further encapsulations. -func ParseIPv4(b []byte) (Layers, error) { +func ParseIPv4(b []byte) (Layer, LayerParser) { h := header.IPv4(b) tos, _ := h.TOS() ipv4 := IPv4{ @@ -329,22 +348,17 @@ func ParseIPv4(b []byte) (Layers, error) { SrcAddr: Address(h.SourceAddress()), DstAddr: Address(h.DestinationAddress()), } - layers := Layers{&ipv4} + var nextParser LayerParser switch h.TransportProtocol() { case header.TCPProtocolNumber: - moreLayers, err := ParseTCP(b[ipv4.length():]) - if err != nil { - return nil, err - } - return append(layers, moreLayers...), nil + nextParser = ParseTCP case header.UDPProtocolNumber: - moreLayers, err := ParseUDP(b[ipv4.length():]) - if err != nil { - return nil, err - } - return append(layers, moreLayers...), nil + nextParser = ParseUDP + default: + // Assume that the rest is a payload. + nextParser = ParsePayload } - return nil, fmt.Errorf("ipv4 header's protocol field is unrecognized: %#02x", h.Protocol()) + return &ipv4, nextParser } func (l *IPv4) match(other Layer) bool { @@ -470,7 +484,7 @@ func Uint32(v uint32) *uint32 { // ParseTCP parses the bytes assuming that they start with a tcp header and // continues parsing further encapsulations. -func ParseTCP(b []byte) (Layers, error) { +func ParseTCP(b []byte) (Layer, LayerParser) { h := header.TCP(b) tcp := TCP{ SrcPort: Uint16(h.SourcePort()), @@ -483,12 +497,7 @@ func ParseTCP(b []byte) (Layers, error) { Checksum: Uint16(h.Checksum()), UrgentPointer: Uint16(h.UrgentPointer()), } - layers := Layers{&tcp} - moreLayers, err := ParsePayload(b[tcp.length():]) - if err != nil { - return nil, err - } - return append(layers, moreLayers...), nil + return &tcp, ParsePayload } func (l *TCP) match(other Layer) bool { @@ -557,8 +566,8 @@ func setUDPChecksum(h *header.UDP, udp *UDP) error { } // ParseUDP parses the bytes assuming that they start with a udp header and -// continues parsing further encapsulations. -func ParseUDP(b []byte) (Layers, error) { +// returns the parsed layer and the next parser to use. +func ParseUDP(b []byte) (Layer, LayerParser) { h := header.UDP(b) udp := UDP{ SrcPort: Uint16(h.SourcePort()), @@ -566,12 +575,7 @@ func ParseUDP(b []byte) (Layers, error) { Length: Uint16(h.Length()), Checksum: Uint16(h.Checksum()), } - layers := Layers{&udp} - moreLayers, err := ParsePayload(b[udp.length():]) - if err != nil { - return nil, err - } - return append(layers, moreLayers...), nil + return &udp, ParsePayload } func (l *UDP) match(other Layer) bool { @@ -603,11 +607,11 @@ func (l *Payload) String() string { // ParsePayload parses the bytes assuming that they start with a payload and // continue to the end. There can be no further encapsulations. -func ParsePayload(b []byte) (Layers, error) { +func ParsePayload(b []byte) (Layer, LayerParser) { payload := Payload{ Bytes: b, } - return Layers{&payload}, nil + return &payload, nil } func (l *Payload) toBytes() ([]byte, error) { @@ -625,15 +629,24 @@ func (l *Payload) length() int { // Layers is an array of Layer and supports similar functions to Layer. type Layers []Layer -func (ls *Layers) toBytes() ([]byte, error) { +// linkLayers sets the linked-list ponters in ls. +func (ls *Layers) linkLayers() { for i, l := range *ls { if i > 0 { l.setPrev((*ls)[i-1]) + } else { + l.setPrev(nil) } if i+1 < len(*ls) { l.setNext((*ls)[i+1]) + } else { + l.setNext(nil) } } +} + +func (ls *Layers) toBytes() ([]byte, error) { + ls.linkLayers() outBytes := []byte{} for _, l := range *ls { layerBytes, err := l.toBytes() |