Initial commit

session-dealer/mysql/util.go

@@ -0,0 +1,131 @@
+package mysql
+
+import (
+	"bytes"
+	"encoding/binary"
+)
+
+// parseHandshakeResponseHeader parses the common header of SSLRequest and HandshakeResponse41.
+func parseHandshakeResponseHeader(packet *handshakeResponse41, data []byte) (parsedBytes int, err error) {
+	// Ensure there are enough data to read:
+	// http://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::SSLRequest
+	if len(data) < 4+4+1+23 {
+		return 0, ErrMalformPacket
+	}
+
+	offset := 0
+	// capability
+	capability := binary.LittleEndian.Uint32(data[:4])
+	packet.Capability = capability
+	offset += 4
+	// skip max packet size
+	offset += 4
+	// charset, skip, if you want to use another charset, use set names
+	packet.Collation = data[offset]
+	offset++
+	// skip reserved 23[00]
+	offset += 23
+
+	return offset, nil
+}
+
+// parseHandshakeResponseBody parse the HandshakeResponse (except the common header part).
+func parseHandshakeResponseBody(packet *handshakeResponse41, data []byte, offset int) (err error) {
+	defer func() {
+		// Check malformat packet cause out of range is disgusting, but don't panic!
+		if r := recover(); r != nil {
+			err = ErrMalformPacket
+		}
+	}()
+	// user name
+	packet.User = string(data[offset : offset+bytes.IndexByte(data[offset:], 0)])
+	offset += len(packet.User) + 1
+
+	if packet.Capability&ClientPluginAuthLenencClientData > 0 {
+		// MySQL client sets the wrong capability, it will set this bit even server doesn't
+		// support ClientPluginAuthLenencClientData.
+		// https://github.com/mysql/mysql-server/blob/5.7/sql-common/client.c#L3478
+		num, null, off := parseLengthEncodedInt(data[offset:])
+		offset += off
+		if !null {
+			packet.Auth = data[offset : offset+int(num)]
+			offset += int(num)
+		}
+	} else if packet.Capability&ClientSecureConnection > 0 {
+		// auth length and auth
+		authLen := int(data[offset])
+		offset++
+		packet.Auth = data[offset : offset+authLen]
+		offset += authLen
+	} else {
+		packet.Auth = data[offset : offset+bytes.IndexByte(data[offset:], 0)]
+		offset += len(packet.Auth) + 1
+	}
+
+	if packet.Capability&ClientConnectWithDB > 0 {
+		if len(data[offset:]) > 0 {
+			idx := bytes.IndexByte(data[offset:], 0)
+			packet.DBName = string(data[offset : offset+idx])
+			offset = offset + idx + 1
+		}
+	}
+
+	if packet.Capability&ClientPluginAuth > 0 {
+		// TODO: Support mysql.ClientPluginAuth, skip it now
+		idx := bytes.IndexByte(data[offset:], 0)
+		offset = offset + idx + 1
+	}
+
+	if packet.Capability&ClientConnectAtts > 0 {
+		if len(data[offset:]) == 0 {
+			// Defend some ill-formated packet, connection attribute is not important and can be ignored.
+			return nil
+		}
+	}
+
+	return nil
+}
+
+func parseLengthEncodedInt(b []byte) (num uint64, isNull bool, n int) {
+	switch b[0] {
+	// 251: NULL
+	case 0xfb:
+		n = 1
+		isNull = true
+		return
+
+	// 252: value of following 2
+	case 0xfc:
+		num = uint64(b[1]) | uint64(b[2])<<8
+		n = 3
+		return
+
+	// 253: value of following 3
+	case 0xfd:
+		num = uint64(b[1]) | uint64(b[2])<<8 | uint64(b[3])<<16
+		n = 4
+		return
+
+	// 254: value of following 8
+	case 0xfe:
+		num = uint64(b[1]) | uint64(b[2])<<8 | uint64(b[3])<<16 |
+			uint64(b[4])<<24 | uint64(b[5])<<32 | uint64(b[6])<<40 |
+			uint64(b[7])<<48 | uint64(b[8])<<56
+		n = 9
+		return
+	}
+
+	// 0-250: value of first byte
+	num = uint64(b[0])
+	n = 1
+	return
+}
+
+func extractMysqlPayloadSize(payload []byte) int {
+	header := payload[:4]
+	return int(uint32(header[0]) | uint32(header[1])<<8 | uint32(header[2])<<16)
+}
+
+func bytesToInt(contents []byte) int {
+	return int(uint32(contents[0]) | uint32(contents[1])<<8 | uint32(contents[2])<<16 | uint32(contents[3])<<24)
+}