sync-diff-inspector panics with nonstandard custom `server-version` in TiDB Server

[kennytm]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

1. Set the server-version of a TiDB server to 99.7.25-TiDB-v6.1
2. Run sync-diff-inspector with this server involved

2. What did you expect to see?

Sync-diff-inspector completes successfully.

3. What did you see instead?

Panicked on this line:

tidb-tools/sync_diff_inspector/utils/pd.go

Line 180 in 00998a9

versionStr = tidbVersionRegex.FindString(versionStr)[1:]

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?

5. which tool are you using?

sync-diff-inspector

6. what versionof tool are you using (pump -V or tidb-lightning -V or syncer -V)?

v6.1.1

[kennytm]

The problem should still exist on the master version.

tidb-tools/sync_diff_inspector/utils/pd.go

Lines 173 to 178 in 4572996

	// parse versino string to semver.Version
	func parseVersion(versionStr string) (*semver.Version, error) {
	versionStr = tidbVersionRegex.FindString(versionStr)[1:]
	versionStr = strings.TrimPrefix(versionStr, "v")
	return semver.NewVersion(versionStr)
	}

In our example, the customized version string only has 2 components ("-v6.1"), which does not match the required regexp

tidb-tools/sync_diff_inspector/utils/pd.go

Line 43 in 4572996

tidbVersionRegex = regexp.MustCompile(`-[v]?\d+\.\d+\.\d+([0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?`)

so tidbVersionRegex.FindString(versionStr) will return an empty slice and taking [1:] will crash the program.

Since this function is dealing with GC Safepoint with the PD API, it should ask PD for the version rather than TiDB. Or simply run UpdateServiceGCSafePoint directly and fallback to "unsupported" once we get codes.Unimplemented.