path: root/les/handler_test.go

// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package les

import (
    "encoding/binary"
    "math/big"
    "math/rand"
    "testing"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/common/mclock"
    "github.com/ethereum/go-ethereum/consensus/ethash"
    "github.com/ethereum/go-ethereum/core"
    "github.com/ethereum/go-ethereum/core/rawdb"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/crypto"
    "github.com/ethereum/go-ethereum/eth/downloader"
    "github.com/ethereum/go-ethereum/light"
    "github.com/ethereum/go-ethereum/p2p"
    "github.com/ethereum/go-ethereum/params"
    "github.com/ethereum/go-ethereum/rlp"
    "github.com/ethereum/go-ethereum/trie"
)

func expectResponse(r p2p.MsgReader, msgcode, reqID, bv uint64, data interface{}) error {
    type resp struct {
        ReqID, BV uint64
        Data      interface{}
    }
    return p2p.ExpectMsg(r, msgcode, resp{reqID, bv, data})
}

// Tests that block headers can be retrieved from a remote chain based on user queries.
func TestGetBlockHeadersLes2(t *testing.T) { testGetBlockHeaders(t, 2) }

func testGetBlockHeaders(t *testing.T, protocol int) {
    server, tearDown := newServerEnv(t, downloader.MaxHashFetch+15, protocol, nil)
    defer tearDown()
    bc := server.pm.blockchain.(*core.BlockChain)

    // Create a "random" unknown hash for testing
    var unknown common.Hash
    for i := range unknown {
        unknown[i] = byte(i)
    }
    // Create a batch of tests for various scenarios
    limit := uint64(MaxHeaderFetch)
    tests := []struct {
        query  *getBlockHeadersData // The query to execute for header retrieval
        expect []common.Hash        // The hashes of the block whose headers are expected
    }{
        // A single random block should be retrievable by hash and number too
        {
            &getBlockHeadersData{Origin: hashOrNumber{Hash: bc.GetBlockByNumber(limit / 2).Hash()}, Amount: 1},
            []common.Hash{bc.GetBlockByNumber(limit / 2).Hash()},
        }, {
            &getBlockHeadersData{Origin: hashOrNumber{Number: limit / 2}, Amount: 1},
            []common.Hash{bc.GetBlockByNumber(limit / 2).Hash()},
        },
        // Multiple headers should be retrievable in both directions
        {
            &getBlockHeadersData{Origin: hashOrNumber{Number: limit / 2}, Amount: 3},
            []common.Hash{
                bc.GetBlockByNumber(limit / 2).Hash(),
                bc.GetBlockByNumber(limit/2 + 1).Hash(),
                bc.GetBlockByNumber(limit/2 + 2).Hash(),
            },
        }, {
            &getBlockHeadersData{Origin: hashOrNumber{Number: limit / 2}, Amount: 3, Reverse: true},
            []common.Hash{
                bc.GetBlockByNumber(limit / 2).Hash(),
                bc.GetBlockByNumber(limit/2 - 1).Hash(),
                bc.GetBlockByNumber(limit/2 - 2).Hash(),
            },
        },
        // Multiple headers with skip lists should be retrievable
        {
            &getBlockHeadersData{Origin: hashOrNumber{Number: limit / 2}, Skip: 3, Amount: 3},
            []common.Hash{
                bc.GetBlockByNumber(limit / 2).Hash(),
                bc.GetBlockByNumber(limit/2 + 4).Hash(),
                bc.GetBlockByNumber(limit/2 + 8).Hash(),
            },
        }, {
            &getBlockHeadersData{Origin: hashOrNumber{Number: limit / 2}, Skip: 3, Amount: 3, Reverse: true},
            []common.Hash{
                bc.GetBlockByNumber(limit / 2).Hash(),
                bc.GetBlockByNumber(limit/2 - 4).Hash(),
                bc.GetBlockByNumber(limit/2 - 8).Hash(),
            },
        },
        // The chain endpoints should be retrievable
        {
            &getBlockHeadersData{Origin: hashOrNumber{Number: 0}, Amount: 1},
            []common.Hash{bc.GetBlockByNumber(0).Hash()},
        }, {
            &getBlockHeadersData{Origin: hashOrNumber{Number: bc.CurrentBlock().NumberU64()}, Amount: 1},
            []common.Hash{bc.CurrentBlock().Hash()},
        },
        // Ensure protocol limits are honored
        /*{
            &getBlockHeadersData{Origin: hashOrNumber{Number: bc.CurrentBlock().NumberU64() - 1}, Amount: limit + 10, Reverse: true},
            bc.GetBlockHashesFromHash(bc.CurrentBlock().Hash(), limit),
        },*/
        // Check that requesting more than available is handled gracefully
        {
            &getBlockHeadersData{Origin: hashOrNumber{Number: bc.CurrentBlock().NumberU64() - 4}, Skip: 3, Amount: 3},
            []common.Hash{
                bc.GetBlockByNumber(bc.CurrentBlock().NumberU64() - 4).Hash(),
                bc.GetBlockByNumber(bc.CurrentBlock().NumberU64()).Hash(),
            },
        }, {
            &getBlockHeadersData{Origin: hashOrNumber{Number: 4}, Skip: 3, Amount: 3, Reverse: true},
            []common.Hash{
                bc.GetBlockByNumber(4).Hash(),
                bc.GetBlockByNumber(0).Hash(),
            },
        },
        // Check that requesting more than available is handled gracefully, even if mid skip
        {
            &getBlockHeadersData{Origin: hashOrNumber{Number: bc.CurrentBlock().NumberU64() - 4}, Skip: 2, Amount: 3},
            []common.Hash{
                bc.GetBlockByNumber(bc.CurrentBlock().NumberU64() - 4).Hash(),
                bc.GetBlockByNumber(bc.CurrentBlock().NumberU64() - 1).Hash(),
            },
        }, {
            &getBlockHeadersData{Origin: hashOrNumber{Number: 4}, Skip: 2, Amount: 3, Reverse: true},
            []common.Hash{
                bc.GetBlockByNumber(4).Hash(),
                bc.GetBlockByNumber(1).Hash(),
            },
        },
        // Check that non existing headers aren't returned
        {
            &getBlockHeadersData{Origin: hashOrNumber{Hash: unknown}, Amount: 1},
            []common.Hash{},
        }, {
            &getBlockHeadersData{Origin: hashOrNumber{Number: bc.CurrentBlock().NumberU64() + 1}, Amount: 1},
            []common.Hash{},
        },
    }
    // Run each of the tests and verify the results against the chain
    var reqID uint64
    for i, tt := range tests {
        // Collect the headers to expect in the response
        headers := []*types.Header{}
        for _, hash := range tt.expect {
            headers = append(headers, bc.GetHeaderByHash(hash))
        }
        // Send the hash request and verify the response
        reqID++
        cost := server.tPeer.GetRequestCost(GetBlockHeadersMsg, int(tt.query.Amount))
        sendRequest(server.tPeer.app, GetBlockHeadersMsg, reqID, cost, tt.query)
        if err := expectResponse(server.tPeer.app, BlockHeadersMsg, reqID, testBufLimit, headers); err != nil {
            t.Errorf("test %d: headers mismatch: %v", i, err)
        }
    }
}

// Tests that block contents can be retrieved from a remote chain based on their hashes.
func TestGetBlockBodiesLes2(t *testing.T) { testGetBlockBodies(t, 2) }

func testGetBlockBodies(t *testing.T, protocol int) {
    server, tearDown := newServerEnv(t, downloader.MaxBlockFetch+15, protocol, nil)
    defer tearDown()
    bc := server.pm.blockchain.(*core.BlockChain)

    // Create a batch of tests for various scenarios
    limit := MaxBodyFetch
    tests := []struct {
        random    int           // Number of blocks to fetch randomly from the chain
        explicit  []common.Hash // Explicitly requested blocks
        available []bool        // Availability of explicitly requested blocks
        expected  int           // Total number of existing blocks to expect
    }{
        {1, nil, nil, 1},         // A single random block should be retrievable
        {10, nil, nil, 10},       // Multiple random blocks should be retrievable
        {limit, nil, nil, limit}, // The maximum possible blocks should be retrievable
        //{limit + 1, nil, nil, limit},                                  // No more than the possible block count should be returned
        {0, []common.Hash{bc.Genesis().Hash()}, []bool{true}, 1},      // The genesis block should be retrievable
        {0, []common.Hash{bc.CurrentBlock().Hash()}, []bool{true}, 1}, // The chains head block should be retrievable
        {0, []common.Hash{{}}, []bool{false}, 0},                      // A non existent block should not be returned

        // Existing and non-existing blocks interleaved should not cause problems
        {0, []common.Hash{
            {},
            bc.GetBlockByNumber(1).Hash(),
            {},
            bc.GetBlockByNumber(10).Hash(),
            {},
            bc.GetBlockByNumber(100).Hash(),
            {},
        }, []bool{false, true, false, true, false, true, false}, 3},
    }
    // Run each of the tests and verify the results against the chain
    var reqID uint64
    for i, tt := range tests {
        // Collect the hashes to request, and the response to expect
        hashes, seen := []common.Hash{}, make(map[int64]bool)
        bodies := []*types.Body{}

        for j := 0; j < tt.random; j++ {
            for {
                num := rand.Int63n(int64(bc.CurrentBlock().NumberU64()))
                if !seen[num] {
                    seen[num] = true

                    block := bc.GetBlockByNumber(uint64(num))
                    hashes = append(hashes, block.Hash())
                    if len(bodies) < tt.expected {
                        bodies = append(bodies, &types.Body{Transactions: block.Transactions(), Uncles: block.Uncles()})
                    }
                    break
                }
            }
        }
        for j, hash := range tt.explicit {
            hashes = append(hashes, hash)
            if tt.available[j] && len(bodies) < tt.expected {
                block := bc.GetBlockByHash(hash)
                bodies = append(bodies, &types.Body{Transactions: block.Transactions(), Uncles: block.Uncles()})
            }
        }
        reqID++
        // Send the hash request and verify the response
        cost := server.tPeer.GetRequestCost(GetBlockBodiesMsg, len(hashes))
        sendRequest(server.tPeer.app, GetBlockBodiesMsg, reqID, cost, hashes)
        if err := expectResponse(server.tPeer.app, BlockBodiesMsg, reqID, testBufLimit, bodies); err != nil {
            t.Errorf("test %d: bodies mismatch: %v", i, err)
        }
    }
}

// Tests that the contract codes can be retrieved based on account addresses.
func TestGetCodeLes2(t *testing.T) { testGetCode(t, 2) }

func testGetCode(t *testing.T, protocol int) {
    // Assemble the test environment
    server, tearDown := newServerEnv(t, 4, protocol, nil)
    defer tearDown()
    bc := server.pm.blockchain.(*core.BlockChain)

    var codereqs []*CodeReq
    var codes [][]byte

    for i := uint64(0); i <= bc.CurrentBlock().NumberU64(); i++ {
        header := bc.GetHeaderByNumber(i)
        req := &CodeReq{
            BHash:  header.Hash(),
            AccKey: crypto.Keccak256(testContractAddr[:]),
        }
        codereqs = append(codereqs, req)
        if i >= testContractDeployed {
            codes = append(codes, testContractCodeDeployed)
        }
    }

    cost := server.tPeer.GetRequestCost(GetCodeMsg, len(codereqs))
    sendRequest(server.tPeer.app, GetCodeMsg, 42, cost, codereqs)
    if err := expectResponse(server.tPeer.app, CodeMsg, 42, testBufLimit, codes); err != nil {
        t.Errorf("codes mismatch: %v", err)
    }
}

// Tests that the transaction receipts can be retrieved based on hashes.
func TestGetReceiptLes2(t *testing.T) { testGetReceipt(t, 2) }

func testGetReceipt(t *testing.T, protocol int) {
    // Assemble the test environment
    server, tearDown := newServerEnv(t, 4, protocol, nil)
    defer tearDown()
    bc := server.pm.blockchain.(*core.BlockChain)

    // Collect the hashes to request, and the response to expect
    hashes, receipts := []common.Hash{}, []types.Receipts{}
    for i := uint64(0); i <= bc.CurrentBlock().NumberU64(); i++ {
        block := bc.GetBlockByNumber(i)

        hashes = append(hashes, block.Hash())
        receipts = append(receipts, rawdb.ReadRawReceipts(server.db, block.Hash(), block.NumberU64()))
    }
    // Send the hash request and verify the response
    cost := server.tPeer.GetRequestCost(GetReceiptsMsg, len(hashes))
    sendRequest(server.tPeer.app, GetReceiptsMsg, 42, cost, hashes)
    if err := expectResponse(server.tPeer.app, ReceiptsMsg, 42, testBufLimit, receipts); err != nil {
        t.Errorf("receipts mismatch: %v", err)
    }
}

// Tests that trie merkle proofs can be retrieved
func TestGetProofsLes2(t *testing.T) { testGetProofs(t, 2) }

func testGetProofs(t *testing.T, protocol int) {
    // Assemble the test environment
    server, tearDown := newServerEnv(t, 4, protocol, nil)
    defer tearDown()
    bc := server.pm.blockchain.(*core.BlockChain)

    var proofreqs []ProofReq
    proofsV2 := light.NewNodeSet()

    accounts := []common.Address{testBankAddress, acc1Addr, acc2Addr, {}}
    for i := uint64(0); i <= bc.CurrentBlock().NumberU64(); i++ {
        header := bc.GetHeaderByNumber(i)
        root := header.Root
        trie, _ := trie.New(root, trie.NewDatabase(server.db))

        for _, acc := range accounts {
            req := ProofReq{
                BHash: header.Hash(),
                Key:   crypto.Keccak256(acc[:]),
            }
            proofreqs = append(proofreqs, req)
            trie.Prove(crypto.Keccak256(acc[:]), 0, proofsV2)
        }
    }
    // Send the proof request and verify the response
    cost := server.tPeer.GetRequestCost(GetProofsV2Msg, len(proofreqs))
    sendRequest(server.tPeer.app, GetProofsV2Msg, 42, cost, proofreqs)
    if err := expectResponse(server.tPeer.app, ProofsV2Msg, 42, testBufLimit, proofsV2.NodeList()); err != nil {
        t.Errorf("proofs mismatch: %v", err)
    }
}

// Tests that CHT proofs can be correctly retrieved.
func TestGetCHTProofsLes2(t *testing.T) { testGetCHTProofs(t, 2) }

func testGetCHTProofs(t *testing.T, protocol int) {
    config := light.TestServerIndexerConfig

    waitIndexers := func(cIndexer, bIndexer, btIndexer *core.ChainIndexer) {
        for {
            cs, _, _ := cIndexer.Sections()
            if cs >= 1 {
                break
            }
            time.Sleep(10 * time.Millisecond)
        }
    }
    server, tearDown := newServerEnv(t, int(config.ChtSize+config.ChtConfirms), protocol, waitIndexers)
    defer tearDown()
    bc := server.pm.blockchain.(*core.BlockChain)

    // Assemble the proofs from the different protocols
    header := bc.GetHeaderByNumber(config.ChtSize - 1)
    rlp, _ := rlp.EncodeToBytes(header)

    key := make([]byte, 8)
    binary.BigEndian.PutUint64(key, config.ChtSize-1)

    proofsV2 := HelperTrieResps{
        AuxData: [][]byte{rlp},
    }
    root := light.GetChtRoot(server.db, 0, bc.GetHeaderByNumber(config.ChtSize-1).Hash())
    trie, _ := trie.New(root, trie.NewDatabase(rawdb.NewTable(server.db, light.ChtTablePrefix)))
    trie.Prove(key, 0, &proofsV2.Proofs)
    // Assemble the requests for the different protocols
    requestsV2 := []HelperTrieReq{{
        Type:    htCanonical,
        TrieIdx: 0,
        Key:     key,
        AuxReq:  auxHeader,
    }}
    // Send the proof request and verify the response
    cost := server.tPeer.GetRequestCost(GetHelperTrieProofsMsg, len(requestsV2))
    sendRequest(server.tPeer.app, GetHelperTrieProofsMsg, 42, cost, requestsV2)
    if err := expectResponse(server.tPeer.app, HelperTrieProofsMsg, 42, testBufLimit, proofsV2); err != nil {
        t.Errorf("proofs mismatch: %v", err)
    }
}

// Tests that bloombits proofs can be correctly retrieved.
func TestGetBloombitsProofs(t *testing.T) {
    config := light.TestServerIndexerConfig

    waitIndexers := func(cIndexer, bIndexer, btIndexer *core.ChainIndexer) {
        for {
            bts, _, _ := btIndexer.Sections()
            if bts >= 1 {
                break
            }
            time.Sleep(10 * time.Millisecond)
        }
    }
    server, tearDown := newServerEnv(t, int(config.BloomTrieSize+config.BloomTrieConfirms), 2, waitIndexers)
    defer tearDown()
    bc := server.pm.blockchain.(*core.BlockChain)

    // Request and verify each bit of the bloom bits proofs
    for bit := 0; bit < 2048; bit++ {
        // Assemble the request and proofs for the bloombits
        key := make([]byte, 10)

        binary.BigEndian.PutUint16(key[:2], uint16(bit))
        // Only the first bloom section has data.
        binary.BigEndian.PutUint64(key[2:], 0)

        requests := []HelperTrieReq{{
            Type:    htBloomBits,
            TrieIdx: 0,
            Key:     key,
        }}
        var proofs HelperTrieResps

        root := light.GetBloomTrieRoot(server.db, 0, bc.GetHeaderByNumber(config.BloomTrieSize-1).Hash())
        trie, _ := trie.New(root, trie.NewDatabase(rawdb.NewTable(server.db, light.BloomTrieTablePrefix)))
        trie.Prove(key, 0, &proofs.Proofs)

        // Send the proof request and verify the response
        cost := server.tPeer.GetRequestCost(GetHelperTrieProofsMsg, len(requests))
        sendRequest(server.tPeer.app, GetHelperTrieProofsMsg, 42, cost, requests)
        if err := expectResponse(server.tPeer.app, HelperTrieProofsMsg, 42, testBufLimit, proofs); err != nil {
            t.Errorf("bit %d: proofs mismatch: %v", bit, err)
        }
    }
}

func TestTransactionStatusLes2(t *testing.T) {
    db := rawdb.NewMemoryDatabase()
    pm := newTestProtocolManagerMust(t, false, 0, nil, nil, nil, db, nil)
    chain := pm.blockchain.(*core.BlockChain)
    config := core.DefaultTxPoolConfig
    config.Journal = ""
    txpool := core.NewTxPool(config, params.TestChainConfig, chain)
    pm.txpool = txpool
    peer, _ := newTestPeer(t, "peer", 2, pm, true, 0)
    defer peer.close()

    var reqID uint64

    test := func(tx *types.Transaction, send bool, expStatus light.TxStatus) {
        reqID++
        if send {
            cost := peer.GetRequestCost(SendTxV2Msg, 1)
            sendRequest(peer.app, SendTxV2Msg, reqID, cost, types.Transactions{tx})
        } else {
            cost := peer.GetRequestCost(GetTxStatusMsg, 1)
            sendRequest(peer.app, GetTxStatusMsg, reqID, cost, []common.Hash{tx.Hash()})
        }
        if err := expectResponse(peer.app, TxStatusMsg, reqID, testBufLimit, []light.TxStatus{expStatus}); err != nil {
            t.Errorf("transaction status mismatch")
        }
    }

    signer := types.HomesteadSigner{}

    // test error status by sending an underpriced transaction
    tx0, _ := types.SignTx(types.NewTransaction(0, acc1Addr, big.NewInt(10000), params.TxGas, nil, nil), signer, testBankKey)
    test(tx0, true, light.TxStatus{Status: core.TxStatusUnknown, Error: core.ErrUnderpriced.Error()})

    tx1, _ := types.SignTx(types.NewTransaction(0, acc1Addr, big.NewInt(10000), params.TxGas, big.NewInt(100000000000), nil), signer, testBankKey)
    test(tx1, false, light.TxStatus{Status: core.TxStatusUnknown}) // query before sending, should be unknown
    test(tx1, true, light.TxStatus{Status: core.TxStatusPending})  // send valid processable tx, should return pending
    test(tx1, true, light.TxStatus{Status: core.TxStatusPending})  // adding it again should not return an error

    tx2, _ := types.SignTx(types.NewTransaction(1, acc1Addr, big.NewInt(10000), params.TxGas, big.NewInt(100000000000), nil), signer, testBankKey)
    tx3, _ := types.SignTx(types.NewTransaction(2, acc1Addr, big.NewInt(10000), params.TxGas, big.NewInt(100000000000), nil), signer, testBankKey)
    // send transactions in the wrong order, tx3 should be queued
    test(tx3, true, light.TxStatus{Status: core.TxStatusQueued})
    test(tx2, true, light.TxStatus{Status: core.TxStatusPending})
    // query again, now tx3 should be pending too
    test(tx3, false, light.TxStatus{Status: core.TxStatusPending})

    // generate and add a block with tx1 and tx2 included
    gchain, _ := core.GenerateChain(params.TestChainConfig, chain.GetBlockByNumber(0), ethash.NewFaker(), db, 1, func(i int, block *core.BlockGen) {
        block.AddTx(tx1)
        block.AddTx(tx2)
    })
    if _, err := chain.InsertChain(gchain); err != nil {
        panic(err)
    }
    // wait until TxPool processes the inserted block
    for i := 0; i < 10; i++ {
        if pending, _ := txpool.Stats(); pending == 1 {
            break
        }
        time.Sleep(100 * time.Millisecond)
    }
    if pending, _ := txpool.Stats(); pending != 1 {
        t.Fatalf("pending count mismatch: have %d, want 1", pending)
    }

    // check if their status is included now
    block1hash := rawdb.ReadCanonicalHash(db, 1)
    test(tx1, false, light.TxStatus{Status: core.TxStatusIncluded, Lookup: &rawdb.LegacyTxLookupEntry{BlockHash: block1hash, BlockIndex: 1, Index: 0}})
    test(tx2, false, light.TxStatus{Status: core.TxStatusIncluded, Lookup: &rawdb.LegacyTxLookupEntry{BlockHash: block1hash, BlockIndex: 1, Index: 1}})

    // create a reorg that rolls them back
    gchain, _ = core.GenerateChain(params.TestChainConfig, chain.GetBlockByNumber(0), ethash.NewFaker(), db, 2, func(i int, block *core.BlockGen) {})
    if _, err := chain.InsertChain(gchain); err != nil {
        panic(err)
    }
    // wait until TxPool processes the reorg
    for i := 0; i < 10; i++ {
        if pending, _ := txpool.Stats(); pending == 3 {
            break
        }
        time.Sleep(100 * time.Millisecond)
    }
    if pending, _ := txpool.Stats(); pending != 3 {
        t.Fatalf("pending count mismatch: have %d, want 3", pending)
    }
    // check if their status is pending again
    test(tx1, false, light.TxStatus{Status: core.TxStatusPending})
    test(tx2, false, light.TxStatus{Status: core.TxStatusPending})
}

func TestStopResumeLes3(t *testing.T) {
    db := rawdb.NewMemoryDatabase()
    clock := &mclock.Simulated{}
    testCost := testBufLimit / 10
    pm, err := newTestProtocolManager(false, 0, nil, nil, nil, db, nil, testCost, clock)
    if err != nil {
        t.Fatalf("Failed to create protocol manager: %v", err)
    }
    peer, _ := newTestPeer(t, "peer", 3, pm, true, testCost)
    defer peer.close()

    expBuf := testBufLimit
    var reqID uint64

    req := func() {
        reqID++
        sendRequest(peer.app, GetBlockHeadersMsg, reqID, testCost, &getBlockHeadersData{Origin: hashOrNumber{Hash: common.Hash{1}}, Amount: 1})
    }

    for i := 1; i <= 5; i++ {
        // send requests while we still have enough buffer and expect a response
        for expBuf >= testCost {
            req()
            expBuf -= testCost
            if err := expectResponse(peer.app, BlockHeadersMsg, reqID, expBuf, nil); err != nil {
                t.Errorf("expected response and failed: %v", err)
            }
        }
        // send some more requests in excess and expect a single StopMsg
        c := i
        for c > 0 {
            req()
            c--
        }
        if err := p2p.ExpectMsg(peer.app, StopMsg, nil); err != nil {
            t.Errorf("expected StopMsg and failed: %v", err)
        }
        // wait until the buffer is recharged by half of the limit
        wait := testBufLimit / testBufRecharge / 2
        clock.Run(time.Millisecond * time.Duration(wait))
        // expect a ResumeMsg with the partially recharged buffer value
        expBuf += testBufRecharge * wait
        if err := p2p.ExpectMsg(peer.app, ResumeMsg, expBuf); err != nil {
            t.Errorf("expected ResumeMsg and failed: %v", err)
        }
    }
}