指定md5校验下载失败

[wciq1208]

Bug report:

使用--digest参数指定摘要校验结果时下载失败，产生如下错误日志，可以看出是校验时没将用户输入的摘要类型前缀去除所导致

···
{"level":"warn","ts":"2022-03-25 18:29:25.626","caller":"digestutils/digest_reader.go:74","msg":"digest not match, desired: md5:965a9b47df62167a2a58e08463f965a6, actual: 965a9b47df62167a2a58e08463f965a6","peer":"10.144.237.247-658-0cad55ec-914f-49cb-b374-e9706d52d9d7-default","task":"dc1dafe7a2c51190715306d9527678a94a40dad221e788b1703ef699fc8c2b47","component":"PeerTask","stacktrace":"d7y.io/dragonfly/v2/pkg/util/digestutils.(*digestReader).Read\n\t/mnt/sdb1/Dragonfly2/pkg/util/digestutils/digest_reader.go:74\nd7y.io/dragonfly/v2/pkg/util/digestutils.(*digestReader).Read\n\t/mnt/sdb1/Dragonfly2/pkg/util/digestutils/digest_reader.go:64\nio.(*LimitedReader).Read\n\t/mnt/sdb1/tools/go/src/io/io.go:473\nio.copyBuffer\n\t/mnt/sdb1/tools/go/src/io/io.go:423\nio.Copy\n\t/mnt/sdb1/tools/go/src/io/io.go:382\nos.genericReadFrom\n\t/mnt/sdb1/tools/go/src/os/file.go:162\nos.(*File).ReadFrom\n\t/mnt/sdb1/tools/go/src/os/file.go:156\nio.copyBuffer\n\t/mnt/sdb1/tools/go/src/io/io.go:409\nio.Copy\n\t/mnt/sdb1/tools/go/src/io/io.go:382\nd7y.io/dragonfly/v2/client/daemon/storage.(*localTaskStore).WritePiece\n\t/mnt/sdb1/Dragonfly2/client/daemon/storage/local_storage.go:125\nd7y.io/dragonfly/v2/client/daemon/peer.(*pieceManager).processPieceFromSource\n\t/mnt/sdb1/Dragonfly2/client/daemon/peer/piece_manager.go:206\nd7y.io/dragonfly/v2/client/daemon/peer.(*pieceManager).downloadUnknownLengthSource\n\t/mnt/sdb1/Dragonfly2/client/daemon/peer/piece_manager.go:378\nd7y.io/dragonfly/v2/client/daemon/peer.(*pieceManager).DownloadSource\n\t/mnt/sdb1/Dragonfly2/client/daemon/peer/piece_manager.go:297\nd7y.io/dragonfly/v2/client/daemon/peer.(*peerTaskConductor).backSource\n\t/mnt/sdb1/Dragonfly2/client/daemon/peer/peertask_conductor.go:387\nd7y.io/dragonfly/v2/client/daemon/peer.(*peerTaskConductor).waitFirstPeerPacket\n\t/mnt/sdb1/Dragonfly2/client/daemon/peer/peertask_conductor.go:823\nd7y.io/dragonfly/v2/client/daemon/peer.(*peerTaskConductor).pullPiecesFromPeers\n\t/mnt/sdb1/Dragonfly2/client/daemon/peer/peertask_conductor.go:692"}
···

Expected behavior:

将
https://github.com/dragonflyoss/Dragonfly2/blob/v2.0.2-rc.25/pkg/util/digestutils/digest_reader.go#L63
该处Read函数改为下述代码后不再出错

func (dr *digestReader) Read(p []byte) (int, error) {
	n, err := dr.r.Read(p)
	if err != nil && err != io.EOF {
		return n, err
	}
	if n > 0 {
		dr.hash.Write(p[:n])
	}
	if err == io.EOF && dr.digest != "" {
		digest := dr.Digest()
		inputDigest := dr.digest
		if strings.Contains(inputDigest, ":") {
			digestInfo := strings.SplitN(inputDigest, ":", 2)
			inputDigest = digestInfo[1]
		}
		if digest != inputDigest {
			dr.Warnf("digest not match, desired: %s, actual: %s", inputDigest, digest)
			return n, ErrDigestNotMatch
		}
		dr.Debugf("digest match: %s", digest)
	}
	return n, err
}

How to reproduce it:

/dragonfly/bin/dfget --timeout 1027s --url hdfs://jssz-bigdata-cluster//department/ai/recsys/athena_data_export/shjd/mxnet2tf_v32/2c4b1fb1af9726ad05749fb348a8d4d6-1648224945-71470831/000000/slot-0.0.0.0-0-1648185845-47-47435/wdctr.data-00000-of-00001 --console --show-progress -O /dragonfly_cache/wdctr.data-00000-of-00001 -n --verbose --digest md5:290667593c3c39e71d99eaf9aa68434b --pattern p2p --config /etc/dragonfly/dfget.yaml

Environment:

• Dragonfly version:v2.0.2-rc.25
• OS:debian 10
• Kernel (e.g. uname -a):4.9.0-8-amd64 [WIP] Implement df daemon #1 SMP Debian 4.9.144-3 (2019-02-02) x86_64 GNU/Linux
• Others:

[gaius-qi]

@244372610

[gaius-qi]

Please try latest version.