replication: Make ServerVersion a proper string (#930)

The ServerVersion is a slice of 50 bytes. If the ServerVersion was
"9.1.0" then the rest of they bytes would be 0x0.

This caused the printout of the FormatDescriptionEvent in go-mysqlbinlog
to look weird.

Before:

```
=== FormatDescriptionEvent ===
Date: 2024-10-24 14:42:04
Log position: 127
Event size: 123
Version: 4
Server version: 9.1.0^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@
Checksum algorithm: 1
```

After:

```
=== FormatDescriptionEvent ===
Date: 2024-10-24 14:42:04
Log position: 127
Event size: 123
Version: 4
Server version: 9.1.0
Checksum algorithm: 1
```

Co-authored-by: lance6716 <[email protected]>

Author: dveeden

replication/event.go

@@ -1,6 +1,7 @@
 package replication
 
 import (
+	"bytes"
 	"encoding/binary"
 	"encoding/hex"
 	"fmt"
@@ -145,9 +146,8 @@ func calcVersionProduct(server string) int {
 }
 
 type FormatDescriptionEvent struct {
-	Version uint16
-	//len = 50
-	ServerVersion          []byte
+	Version                uint16
+	ServerVersion          string
 	CreateTimestamp        uint32
 	EventHeaderLength      uint8
 	EventTypeHeaderLengths []byte
@@ -161,8 +161,8 @@ func (e *FormatDescriptionEvent) Decode(data []byte) error {
 	e.Version = binary.LittleEndian.Uint16(data[pos:])
 	pos += 2
 
-	e.ServerVersion = make([]byte, 50)
-	copy(e.ServerVersion, data[pos:])
+	serverVersionRaw := make([]byte, 50)
+	copy(serverVersionRaw, data[pos:])
 	pos += 50
 
 	e.CreateTimestamp = binary.LittleEndian.Uint32(data[pos:])
@@ -175,13 +175,18 @@ func (e *FormatDescriptionEvent) Decode(data []byte) error {
 		return errors.Errorf("invalid event header length %d, must 19", e.EventHeaderLength)
 	}
 
-	server := string(e.ServerVersion)
+	serverVersionLength := bytes.Index(serverVersionRaw, []byte{0x0})
+	if serverVersionLength < 0 {
+		e.ServerVersion = string(serverVersionRaw)
+	} else {
+		e.ServerVersion = string(serverVersionRaw[:serverVersionLength])
+	}
 	checksumProduct := checksumVersionProductMysql
-	if strings.Contains(strings.ToLower(server), "mariadb") {
+	if strings.Contains(strings.ToLower(e.ServerVersion), "mariadb") {
 		checksumProduct = checksumVersionProductMariaDB
 	}
 
-	if calcVersionProduct(string(e.ServerVersion)) >= checksumProduct {
+	if calcVersionProduct(e.ServerVersion) >= checksumProduct {
 		// here, the last 5 bytes is 1 byte check sum alg type and 4 byte checksum if exists
 		e.ChecksumAlgorithm = data[len(data)-5]
 		e.EventTypeHeaderLengths = data[pos : len(data)-5]

replication/parser_test.go

@@ -12,7 +12,7 @@ func TestIndexOutOfRange(t *testing.T) {
 
 	parser.format = &FormatDescriptionEvent{
 		Version:                0x4,
-		ServerVersion:          []uint8{0x35, 0x2e, 0x36, 0x2e, 0x32, 0x30, 0x2d, 0x6c, 0x6f, 0x67, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0},
+		ServerVersion:          "8.0.11",
 		CreateTimestamp:        0x0,
 		EventHeaderLength:      0x13,
 		EventTypeHeaderLengths: []uint8{0x38, 0xd, 0x0, 0x8, 0x0, 0x12, 0x0, 0x4, 0x4, 0x4, 0x4, 0x12, 0x0, 0x0, 0x5c, 0x0, 0x4, 0x1a, 0x8, 0x0, 0x0, 0x0, 0x8, 0x8, 0x8, 0x2, 0x0, 0x0, 0x0, 0xa, 0xa, 0xa, 0x19, 0x19, 0x0, 0x12, 0x34, 0x0, 0xa, 0x28, 0x0},
@@ -48,7 +48,7 @@ func TestParseEvent(t *testing.T) {
 	parser := NewBinlogParser()
 	parser.format = &FormatDescriptionEvent{
 		Version:                0x4,
-		ServerVersion:          []uint8{0x35, 0x2e, 0x36, 0x2e, 0x32, 0x30, 0x2d, 0x6c, 0x6f, 0x67, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0},
+		ServerVersion:          "8.0.11",
 		CreateTimestamp:        0x0,
 		EventHeaderLength:      0x13,
 		EventTypeHeaderLengths: []uint8{0x38, 0xd, 0x0, 0x8, 0x0, 0x12, 0x0, 0x4, 0x4, 0x4, 0x4, 0x12, 0x0, 0x0, 0x5c, 0x0, 0x4, 0x1a, 0x8, 0x0, 0x0, 0x0, 0x8, 0x8, 0x8, 0x2, 0x0, 0x0, 0x0, 0xa, 0xa, 0xa, 0x19, 0x19, 0x0, 0x12, 0x34, 0x0, 0xa, 0x28, 0x0},