cmd/devp2p: add eth protocol test suite (ethereum#21598)

This change adds a test framework for the "eth" protocol and some basic
tests. The tests can be run using the './devp2p rlpx eth-test' command.

cmd/devp2p/internal/ethtest/chain.go

@@ -0,0 +1,113 @@
+package ethtest
+
+import (
+	"compress/gzip"
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"math/big"
+	"os"
+	"strings"
+
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/forkid"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/rlp"
+)
+
+type Chain struct {
+	blocks      []*types.Block
+	chainConfig *params.ChainConfig
+}
+
+func (c *Chain) WriteTo(writer io.Writer) error {
+	for _, block := range c.blocks {
+		if err := rlp.Encode(writer, block); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Len returns the length of the chain.
+func (c *Chain) Len() int {
+	return len(c.blocks)
+}
+
+// TD calculates the total difficulty of the chain.
+func (c *Chain) TD(height int) *big.Int { // TODO later on channge scheme so that the height is included in range
+	sum := big.NewInt(0)
+	for _, block := range c.blocks[:height] {
+		sum.Add(sum, block.Difficulty())
+	}
+	return sum
+}
+
+// ForkID gets the fork id of the chain.
+func (c *Chain) ForkID() forkid.ID {
+	return forkid.NewID(c.chainConfig, c.blocks[0].Hash(), uint64(c.Len()))
+}
+
+// Shorten returns a copy chain of a desired height from the imported
+func (c *Chain) Shorten(height int) *Chain {
+	blocks := make([]*types.Block, height)
+	copy(blocks, c.blocks[:height])
+
+	config := *c.chainConfig
+	return &Chain{
+		blocks:      blocks,
+		chainConfig: &config,
+	}
+}
+
+// Head returns the chain head.
+func (c *Chain) Head() *types.Block {
+	return c.blocks[c.Len()-1]
+}
+
+// loadChain takes the given chain.rlp file, and decodes and returns
+// the blocks from the file.
+func loadChain(chainfile string, genesis string) (*Chain, error) {
+	// Open the file handle and potentially unwrap the gzip stream
+	fh, err := os.Open(chainfile)
+	if err != nil {
+		return nil, err
+	}
+	defer fh.Close()
+
+	var reader io.Reader = fh
+	if strings.HasSuffix(chainfile, ".gz") {
+		if reader, err = gzip.NewReader(reader); err != nil {
+			return nil, err
+		}
+	}
+	stream := rlp.NewStream(reader, 0)
+	var blocks []*types.Block
+	for i := 0; ; i++ {
+		var b types.Block
+		if err := stream.Decode(&b); err == io.EOF {
+			break
+		} else if err != nil {
+			return nil, fmt.Errorf("at block %d: %v", i, err)
+		}
+		blocks = append(blocks, &b)
+	}
+
+	// Open the file handle and potentially unwrap the gzip stream
+	chainConfig, err := ioutil.ReadFile(genesis)
+	if err != nil {
+		return nil, err
+	}
+	var gen core.Genesis
+	if err := json.Unmarshal(chainConfig, &gen); err != nil {
+		return nil, err
+	}
+
+	return &Chain{
+		blocks:      blocks,
+		chainConfig: gen.Config,
+	}, nil
+}