Add full-duplex raw-Ethernet 10G cable stress tester

frame.go

@@ -0,0 +1,175 @@
+package main
+
+import (
+	"encoding/binary"
+	"fmt"
+	"hash/crc32"
+	"math/rand/v2"
+)
+
+const (
+	etherType = 0x88b5
+	ethHdrLen = 14
+	hdrLen    = 24
+	hdrMagic  = 0x43424c54
+	minFrame  = ethHdrLen + hdrLen
+	maxFrame  = 9216
+)
+
+var crcTable = crc32.MakeTable(crc32.Castagnoli)
+
+type pattern struct {
+	name string
+	fill func([]byte)
+}
+
+var patterns = []pattern{
+	{"zeros", func(b []byte) { clear(b) }},
+	{"ones", func(b []byte) {
+		for i := range b {
+			b[i] = 0xff
+		}
+	}},
+	{"alt", func(b []byte) {
+		for i := range b {
+			if i%2 == 0 {
+				b[i] = 0x55
+			} else {
+				b[i] = 0xaa
+			}
+		}
+	}},
+	{"incr", func(b []byte) {
+		for i := range b {
+			b[i] = byte(i)
+		}
+	}},
+	{"prbs", func(b []byte) {
+		s := uint64(0x0123456789abcdef)
+		for i := range b {
+			s ^= s << 13
+			s ^= s >> 7
+			s ^= s << 17
+			b[i] = byte(s)
+		}
+	}},
+	{"random", func(b []byte) {
+		r := rand.New(rand.NewPCG(0xc0ffee, 0x5eed))
+		for i := range b {
+			b[i] = byte(r.Uint32())
+		}
+	}},
+}
+
+func patternIndex(name string) (int, error) {
+	for i, p := range patterns {
+		if p.name == name {
+			return i, nil
+		}
+	}
+	names := make([]string, len(patterns))
+	for i, p := range patterns {
+		names[i] = p.name
+	}
+	return 0, fmt.Errorf("unknown pattern %q (have %v)", name, names)
+}
+
+type frameSpec struct {
+	patIdx  int
+	ref     []byte
+	crcFor  map[int]uint32
+	dstMAC  [6]byte
+	srcMAC  [6]byte
+	sizes   []int
+	maxSize int
+}
+
+func newFrameSpec(patIdx int, dst, src [6]byte, sizes []int) *frameSpec {
+	maxSize := 0
+	for _, s := range sizes {
+		if s > maxSize {
+			maxSize = s
+		}
+	}
+	ref := make([]byte, maxSize-minFrame)
+	patterns[patIdx].fill(ref)
+	crcFor := make(map[int]uint32, len(sizes))
+	for _, s := range sizes {
+		crcFor[s] = crc32.Checksum(ref[:s-minFrame], crcTable)
+	}
+	return &frameSpec{
+		patIdx:  patIdx,
+		ref:     ref,
+		crcFor:  crcFor,
+		dstMAC:  dst,
+		srcMAC:  src,
+		sizes:   sizes,
+		maxSize: maxSize,
+	}
+}
+
+func (f *frameSpec) prefill(buf []byte) {
+	copy(buf[0:6], f.dstMAC[:])
+	copy(buf[6:12], f.srcMAC[:])
+	binary.BigEndian.PutUint16(buf[12:14], etherType)
+	copy(buf[minFrame:], f.ref)
+}
+
+func putHeader(buf []byte, patIdx int, stream uint16, seq uint64, payLen int, crc uint32) {
+	h := buf[ethHdrLen:]
+	binary.BigEndian.PutUint32(h[0:4], hdrMagic)
+	h[4] = 1
+	h[5] = byte(patIdx)
+	binary.BigEndian.PutUint16(h[6:8], stream)
+	binary.BigEndian.PutUint64(h[8:16], seq)
+	binary.BigEndian.PutUint16(h[16:18], uint16(payLen))
+	binary.BigEndian.PutUint16(h[18:20], 0)
+	binary.BigEndian.PutUint32(h[20:24], crc)
+}
+
+type parsed struct {
+	patIdx int
+	stream uint16
+	seq    uint64
+	payLen int
+	crc    uint32
+}
+
+func parseHeader(buf []byte) (parsed, bool) {
+	var p parsed
+	if len(buf) < minFrame {
+		return p, false
+	}
+	h := buf[ethHdrLen:]
+	if binary.BigEndian.Uint32(h[0:4]) != hdrMagic {
+		return p, false
+	}
+	p.patIdx = int(h[5])
+	p.stream = binary.BigEndian.Uint16(h[6:8])
+	p.seq = binary.BigEndian.Uint64(h[8:16])
+	p.payLen = int(binary.BigEndian.Uint16(h[16:18]))
+	p.crc = binary.BigEndian.Uint32(h[20:24])
+	if minFrame+p.payLen > len(buf) {
+		return p, false
+	}
+	return p, true
+}
+
+func firstDiff(got, want []byte) (int, int) {
+	n := len(got)
+	if len(want) < n {
+		n = len(want)
+	}
+	for i := 0; i < n; i++ {
+		if got[i] != want[i] {
+			bits := 0
+			x := got[i] ^ want[i]
+			for x != 0 {
+				bits += int(x & 1)
+				x >>= 1
+			}
+			return i, bits
+		}
+	}
+	return -1, 0
+}