Fix pserver checkpoint #5102
Fix pserver checkpoint #5102
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The pserver checkpoint before failed because the MD5 checksum is calculated incorrectly. Now changed to CRC32 checksum.
| var cptr (*C.uchar) | ||
| if len(c) > 0 { | ||
| cptr = (*C.uchar)(&c[0]) | ||
| } |
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Else output error log?
| h := md5.New() | ||
| md5 := hex.EncodeToString(h.Sum(content)) | ||
| if md5 != cpMeta.MD5 { | ||
| crc32 := crc32.ChecksumIEEE(content) |
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Curious why md5 will cause the error?
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@typhoonzero @Yancey1989 @dzhwinter
The problem was I think we used the md5 package incorrectly that generated a long string, causes etcd write error with "message too large". To show to error:
package main import ( "crypto/md5" "encoding/hex" "fmt" ) func main() { h := md5.New() md5 := hex.EncodeToString(h.Sum([]byte("hello this is some string"))) // Output: 68656c6c6f207468697320697320736f6d6520737472696e67d41d8cd98f00b204e9800998ecf8427e fmt.Println(md5) }The output is not a typical MD5 string, rather a very long one.
I think the correct way to get the MD5 string is here:
package main import ( "crypto/md5" "fmt" ) func main() { data := []byte("These pretzels are making me thirsty.") sum := fmt.Sprintf("%x", md5.Sum(data)) // Output: b0804ec967f48520697662a204f5fe72 fmt.Printf(sum) }The reason to switch to CRC32 is because it's faster, better for checksum, MD5 is slower, better for defending cracking.
| h := md5.New() | ||
| md5 := hex.EncodeToString(h.Sum(content)) | ||
| if md5 != cpMeta.MD5 { | ||
| crc32 := crc32.ChecksumIEEE(content) |
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one more question. Why we change MD5 to CRC, concern the speed?
| } | ||
| } | ||
| | ||
| if err != nil { |
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Maybe we would add some log here, sorry this is out of this PR code.
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The caller will handle it, here is one caller code:
err := s.checkpoint() if err != nil { log.Error("checkpoint error", log.Ctx{"error": err}) }I think in general the outer most caller should handle the error (either log or do something else), because it has the most information. If everyone prints log, it will be duplicating.
| h := md5.New() | ||
| md5 := hex.EncodeToString(h.Sum(content)) | ||
| if md5 != cpMeta.MD5 { | ||
| crc32 := crc32.ChecksumIEEE(content) |
4 participants
The pserver checkpoint before failed because the MD5 checksum is
calculated incorrectly. Now changed to CRC32 checksum.