Add support for MySQL Connection Attributes

AUTHORS

@@ -94,6 +94,7 @@ Tan Jinhua <312841925 at qq.com>
 Thomas Wodarek <wodarekwebpage at gmail.com>
 Tim Ruffles <timruffles at gmail.com>
 Tom Jenkinson <tom at tjenkinson.me>
+Vasily Fedoseyev <vasilyfedoseyev at gmail.com>
 Vladimir Kovpak <cn007b at gmail.com>
 Vladyslav Zhelezniak <zhvladi at gmail.com>
 Xiangyu Hu <xiangyu.hu at outlook.com>

README.md

@@ -242,6 +242,16 @@ SELECT u.id FROM users as u
 
 will return `u.id` instead of just `id` if `columnsWithAlias=true`.
 
+##### `connectAttrs`
+
+```
+Type:           map
+Valid Values:   comma-separated list of attribute:value pairs
+Default:        empty
+```
+
+Allows setting of connection attributes, for example `connectAttrs=program_name:YourProgramName` will show `YourProgramName` in `Program` field of connections list of Mysql Workbench, if your server supports it (requires `performance_schema` to be supported and enabled).
+
 ##### `interpolateParams`
 
 ```

const.go

@@ -46,7 +46,7 @@ const (
 	clientIgnoreSIGPIPE
 	clientTransactions
 	clientReserved
-	clientSecureConn
+	clientSecureConn // reserved2 in 8.0
 	clientMultiStatements
 	clientMultiResults
 	clientPSMultiResults
@@ -56,6 +56,8 @@ const (
 	clientCanHandleExpiredPasswords
 	clientSessionTrack
 	clientDeprecateEOF
+	clientSslVerifyServerCert clientFlag = 1 << 30
+	clientRememberOptions     clientFlag = 1 << 31
 )
 
 const (

driver_test.go

@@ -2189,6 +2189,56 @@ func TestEmptyPassword(t *testing.T) {
 	}
 }
 
+func TestConnectAttrs(t *testing.T) {
+	if !available {
+		t.Skipf("MySQL server not running on %s", netAddr)
+	}
+
+	db, err := sql.Open("mysql", dsn+"&connectAttrs=program_name:GoTest,foo:bar")
+	if err != nil {
+		t.Fatalf("error connecting: %s", err.Error())
+	}
+	defer db.Close()
+	dbt := &DBTest{t, db}
+
+	rows := dbt.mustQuery("SHOW VARIABLES LIKE 'performance_schema'")
+	if rows.Next() {
+		var var_name, value string
+		rows.Scan(&var_name, &value)
+		if value != "ON" {
+			t.Skip("performance_schema is disabled")
+		}
+	} else {
+		t.Skip("no performance_schema variable in mysql")
+	}
+
+	rows, err = dbt.db.Query("SELECT attr_value FROM performance_schema.session_connect_attrs WHERE processlist_id=CONNECTION_ID() AND attr_name='program_name'")
+	if err != nil {
+		dbt.Skipf("server probably does not support performance_schema.session_connect_attrs: %s", err)
+	}
+
+	if rows.Next() {
+		var str string
+		rows.Scan(&str)
+		if "GoTest" != str {
+			dbt.Errorf("GoTest != %s", str)
+		}
+	} else {
+		dbt.Error("no data for program_name")
+	}
+
+	rows = dbt.mustQuery("SELECT attr_value FROM performance_schema.session_connect_attrs WHERE processlist_id=CONNECTION_ID() AND attr_name='foo'")
+	if rows.Next() {
+		var str string
+		rows.Scan(&str)
+		if "bar" != str {
+			dbt.Errorf("bar != %s", str)
+		}
+	} else {
+		dbt.Error("no data for custom attribute")
+	}
+}
+
 // static interface implementation checks of mysqlConn
 var (
 	_ driver.ConnBeginTx        = &mysqlConn{}

dsn.go

@@ -40,6 +40,7 @@ type Config struct {
 	Addr             string            // Network address (requires Net)
 	DBName           string            // Database name
 	Params           map[string]string // Connection parameters
+	ConnectAttrs     map[string]string // Connection attributes
 	Collation        string            // Connection collation
 	Loc              *time.Location    // Location for time.Time values
 	MaxAllowedPacket int               // Max packet size allowed
@@ -272,6 +273,30 @@ func (cfg *Config) FormatDSN() string {
 		writeDSNParam(&buf, &hasParam, "maxAllowedPacket", strconv.Itoa(cfg.MaxAllowedPacket))
 	}
 
+	if len(cfg.ConnectAttrs) > 0 {
+		// connectAttrs=program_name:Login Server,other_name:other
+		if hasParam {
+			buf.WriteString("&connectAttrs=")
+		} else {
+			hasParam = true
+			buf.WriteString("?connectAttrs=")
+		}
+
+		var attr_names []string
+		for attr_name := range cfg.ConnectAttrs {
+			attr_names = append(attr_names, attr_name)
+		}
+		sort.Strings(attr_names)
+		for index, attr_name := range attr_names {
+			if index > 0 {
+				buf.WriteByte(',')
+			}
+			buf.WriteString(attr_name)
+			buf.WriteByte(':')
+			buf.WriteString(url.QueryEscape(cfg.ConnectAttrs[attr_name]))
+		}
+	}
+
 	// other params
 	if cfg.Params != nil {
 		var params []string
@@ -536,6 +561,24 @@ func parseDSNParams(cfg *Config, params string) (err error) {
 			if err != nil {
 				return
 			}
+		case "connectAttrs":
+			if cfg.ConnectAttrs == nil {
+				cfg.ConnectAttrs = make(map[string]string)
+			}
+
+			var ConnectAttrs string
+			if ConnectAttrs, err = url.QueryUnescape(value); err != nil {
+				return
+			}
+
+			// program_name:Name,foo:bar
+			for _, attr_str := range strings.Split(ConnectAttrs, ",") {
+				attr := strings.SplitN(attr_str, ":", 2)
+				if len(attr) != 2 {
+					continue
+				}
+				cfg.ConnectAttrs[attr[0]] = attr[1]
+			}
 		default:
 			// lazy init
 			if cfg.Params == nil {

dsn_test.go

@@ -71,6 +71,9 @@ var testDSNs = []struct {
 }, {
 	"tcp(de:ad:be:ef::ca:fe)/dbname",
 	&Config{Net: "tcp", Addr: "[de:ad:be:ef::ca:fe]:3306", DBName: "dbname", Collation: "utf8mb4_general_ci", Loc: time.UTC, MaxAllowedPacket: defaultMaxAllowedPacket, AllowNativePasswords: true, CheckConnLiveness: true},
+}, {
+	"tcp(127.0.0.1)/dbname?connectAttrs=program_name:SomeService",
+	&Config{Net: "tcp", Addr: "127.0.0.1:3306", DBName: "dbname", ConnectAttrs: map[string]string{"program_name": "SomeService"}, Collation: "utf8mb4_general_ci", Loc: time.UTC, MaxAllowedPacket: defaultMaxAllowedPacket, AllowNativePasswords: true, CheckConnLiveness: true},
 },
 }
 
@@ -403,6 +406,20 @@ func TestNormalizeTLSConfig(t *testing.T) {
 	}
 }
 
+func TestAttributesAreSorted(t *testing.T) {
+	expected := "/dbname?connectAttrs=p1:v1,p2:v2"
+	cfg := NewConfig()
+	cfg.DBName = "dbname"
+	cfg.ConnectAttrs = map[string]string{
+		"p2": "v2",
+		"p1": "v1",
+	}
+	actual := cfg.FormatDSN()
+	if actual != expected {
+		t.Errorf("generic Config.ConnectAttrs were not sorted: want %#v, got %#v", expected, actual)
+	}
+}
+
 func BenchmarkParseDSN(b *testing.B) {
 	b.ReportAllocs()
 

packets.go

@@ -235,10 +235,15 @@ func (mc *mysqlConn) readHandshakePacket() (data []byte, plugin string, err erro
 	if len(data) > pos {
 		// character set [1 byte]
 		// status flags [2 bytes]
+		pos += 1 + 2
+
 		// capability flags (upper 2 bytes) [2 bytes]
+		mc.flags |= clientFlag(uint32(binary.LittleEndian.Uint16(data[pos:pos+2])) << 16)
+		pos += 2
+
 		// length of auth-plugin-data [1 byte]
 		// reserved (all [00]) [10 bytes]
-		pos += 1 + 2 + 2 + 1 + 10
+		pos += 1 + 10
 
 		// second part of the password cipher [mininum 13 bytes],
 		// where len=MAX(13, length of auth-plugin-data - 8)
@@ -305,16 +310,37 @@ func (mc *mysqlConn) writeHandshakeResponsePacket(authResp []byte, plugin string
 	var authRespLEIBuf [9]byte
 	authRespLen := len(authResp)
 	authRespLEI := appendLengthEncodedInteger(authRespLEIBuf[:0], uint64(authRespLen))
-	if len(authRespLEI) > 1 {
+	if len(authRespLEI) > 1 && clientFlags&clientSecureConn != 0 {
 		// if the length can not be written in 1 byte, it must be written as a
 		// length encoded integer
 		clientFlags |= clientPluginAuthLenEncClientData
 	}
 
 	pktLen := 4 + 4 + 1 + 23 + len(mc.cfg.User) + 1 + len(authRespLEI) + len(authResp) + 21 + 1
+	if clientFlags&clientSecureConn == 0 || clientFlags&clientPluginAuthLenEncClientData == 0 {
+		pktLen++
+	}
+
+	connectAttrsBuf := make([]byte, 0, 100)
+	if mc.flags&clientConnectAttrs != 0 {
+		clientFlags |= clientConnectAttrs
+		connectAttrsBuf = appendLengthEncodedString(connectAttrsBuf, []byte("_client_name"))
+		connectAttrsBuf = appendLengthEncodedString(connectAttrsBuf, []byte("go-mysql-driver"))
+
+		for k, v := range mc.cfg.ConnectAttrs {
+			if k == "_client_name" {
+				// do not allow overwriting reserved values
+				continue
+			}
+			connectAttrsBuf = appendLengthEncodedString(connectAttrsBuf, []byte(k))
+			connectAttrsBuf = appendLengthEncodedString(connectAttrsBuf, []byte(v))
+		}
+		connectAttrsBuf = appendLengthEncodedString(make([]byte, 0, 100), connectAttrsBuf)
+		pktLen += len(connectAttrsBuf)
+	}
 
 	// To specify a db name
-	if n := len(mc.cfg.DBName); n > 0 {
+	if n := len(mc.cfg.DBName); mc.flags&clientConnectWithDB != 0 && n > 0 {
 		clientFlags |= clientConnectWithDB
 		pktLen += n + 1
 	}
@@ -380,20 +406,39 @@ func (mc *mysqlConn) writeHandshakeResponsePacket(authResp []byte, plugin string
 	data[pos] = 0x00
 	pos++
 
-	// Auth Data [length encoded integer]
-	pos += copy(data[pos:], authRespLEI)
+	// Auth Data [length encoded integer + data] if clientPluginAuthLenEncClientData
+	// clientSecureConn => 1 byte len + data
+	// else null-terminated
+	if clientFlags&clientPluginAuthLenEncClientData != 0 {
+		pos += copy(data[pos:], authRespLEI)
+	} else if clientFlags&clientSecureConn != 0 {
+		data[pos] = uint8(len(authResp))
+		pos++
+	}
 	pos += copy(data[pos:], authResp)
+	if clientFlags&clientSecureConn == 0 && clientFlags&clientPluginAuthLenEncClientData == 0 {
+		data[pos] = 0x00
+		pos++
+	}
 
 	// Databasename [null terminated string]
-	if len(mc.cfg.DBName) > 0 {
+	if clientFlags&clientConnectWithDB != 0 {
 		pos += copy(data[pos:], mc.cfg.DBName)
 		data[pos] = 0x00
 		pos++
 	}
 
-	pos += copy(data[pos:], plugin)
-	data[pos] = 0x00
-	pos++
+	// auth plugin name [null terminated string]
+	if clientFlags&clientPluginAuth != 0 {
+		pos += copy(data[pos:], plugin)
+		data[pos] = 0x00
+		pos++
+	}
+
+	// connection attributes [lenenc-int total + lenenc-str key-value pairs]
+	if clientFlags&clientConnectAttrs != 0 {
+		pos += copy(data[pos:], connectAttrsBuf)
+	}
 
 	// Send Auth packet
 	return mc.writePacket(data[:pos])

utils.go

@@ -579,6 +579,12 @@ func skipLengthEncodedString(b []byte) (int, error) {
 	return n, io.EOF
 }
 
+// encodes a bytes slice with prepended length-encoded size and appends it to the given bytes slice
+func appendLengthEncodedString(b []byte, str []byte) []byte {
+	b = appendLengthEncodedInteger(b, uint64(len(str)))
+	return append(b, str...)
+}
+
 // returns the number read, whether the value is NULL and the number of bytes read
 func readLengthEncodedInteger(b []byte) (uint64, bool, int) {
 	// See issue #349