fix looptable index

cmd/debug_jupv6/main.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"encoding/hex"
+	"fmt"
+	"os"
+)
+
+func main() {
+	hexData := "bb64facc31c4af14be34e6edcc0000006f03a4df67000000b903320000000300000064342100024b00000000dc0500026310270203"
+	b, err := hex.DecodeString(hexData)
+	if err != nil {
+		panic(err)
+	}
+	payload := b[8:]
+
+	off := 0
+	read := func(n int) []byte {
+		if off+n > len(payload) {
+			fmt.Printf("OOB read: off=%d n=%d len=%d\n", off, n, len(payload))
+			os.Exit(1)
+		}
+		out := payload[off : off+n]
+		off += n
+		return out
+	}
+	u8 := func() uint8 { return read(1)[0] }
+	leU16 := func() uint16 {
+		b := read(2)
+		return uint16(b[0]) | uint16(b[1])<<8
+	}
+	leU32 := func() uint32 {
+		b := read(4)
+		return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+	}
+	leU64 := func() uint64 {
+		b := read(8)
+		return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+			uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+	}
+
+	fmt.Printf("payload len=%d\n", len(payload))
+	amountIn := leU64()
+	quotedOut := leU64()
+	slippage := leU16()
+	platform := leU16()
+	posSlip := leU16()
+	fmt.Printf("in=%d out=%d slip=%d plat=%d pos=%d\n", amountIn, quotedOut, slippage, platform, posSlip)
+
+	planLen := leU32()
+	fmt.Printf("planLen=%d\n", planLen)
+	for i := uint32(0); i < planLen; i++ {
+		swapTag := u8()
+		fmt.Printf("step[%d] swapTag=%d (0x%02x) off=%d\n", i, swapTag, swapTag, off)
+		// payload depends on swapTag; we don't know, so just print next few bytes and stop
+		bps := leU16()
+		inIdx := u8()
+		outIdx := u8()
+		fmt.Printf("  bps=%d inIdx=%d outIdx=%d off=%d\n", bps, inIdx, outIdx, off)
+	}
+	fmt.Printf("done off=%d\n", off)
+}