Add AllowFallbackToPlaintext and TLS to config (go-sql-driver#1370)

Author: lance6716

AUTHORS

@@ -61,6 +61,7 @@ Kamil Dziedzic <kamil at klecza.pl>
 Kei Kamikawa <x00.x7f.x86 at gmail.com>
 Kevin Malachowski <kevin at chowski.com>
 Kieron Woodhouse <kieron.woodhouse at infosum.com>
+Lance Tian <lance6716 at gmail.com>
 Lennart Rudolph <lrudolph at hmc.edu>
 Leonardo YongUk Kim <dalinaum at gmail.com>
 Linh Tran Tuan <linhduonggnu at gmail.com>

README.md

@@ -157,6 +157,17 @@ Default:        false
 
 `allowCleartextPasswords=true` allows using the [cleartext client side plugin](https://dev.mysql.com/doc/en/cleartext-pluggable-authentication.html) if required by an account, such as one defined with the [PAM authentication plugin](http://dev.mysql.com/doc/en/pam-authentication-plugin.html). Sending passwords in clear text may be a security problem in some configurations. To avoid problems if there is any possibility that the password would be intercepted, clients should connect to MySQL Server using a method that protects the password. Possibilities include [TLS / SSL](#tls), IPsec, or a private network.
 
+
+##### `allowFallbackToPlaintext`
+
+```
+Type:           bool
+Valid Values:   true, false
+Default:        false
+```
+
+`allowFallbackToPlaintext=true` acts like a `--ssl-mode=PREFERRED` MySQL client as described in [Command Options for Connecting to the Server](https://dev.mysql.com/doc/refman/5.7/en/connection-options.html#option_general_ssl-mode)
+
 ##### `allowNativePasswords`
 
 ```

auth.go

@@ -275,7 +275,7 @@ func (mc *mysqlConn) auth(authData []byte, plugin string) ([]byte, error) {
 		}
 		// unlike caching_sha2_password, sha256_password does not accept
 		// cleartext password on unix transport.
-		if mc.cfg.tls != nil {
+		if mc.cfg.TLS != nil {
 			// write cleartext auth packet
 			return append([]byte(mc.cfg.Passwd), 0), nil
 		}
@@ -351,7 +351,7 @@ func (mc *mysqlConn) handleAuthResult(oldAuthData []byte, plugin string) error {
 				}
 
 			case cachingSha2PasswordPerformFullAuthentication:
-				if mc.cfg.tls != nil || mc.cfg.Net == "unix" {
+				if mc.cfg.TLS != nil || mc.cfg.Net == "unix" {
 					// write cleartext auth packet
 					err = mc.writeAuthSwitchPacket(append([]byte(mc.cfg.Passwd), 0))
 					if err != nil {

auth_test.go

@@ -291,7 +291,7 @@ func TestAuthFastCachingSHA256PasswordFullSecure(t *testing.T) {
 
 	// Hack to make the caching_sha2_password plugin believe that the connection
 	// is secure
-	mc.cfg.tls = &tls.Config{InsecureSkipVerify: true}
+	mc.cfg.TLS = &tls.Config{InsecureSkipVerify: true}
 
 	// check written auth response
 	authRespStart := 4 + 4 + 4 + 1 + 23 + len(mc.cfg.User) + 1
@@ -663,7 +663,7 @@ func TestAuthFastSHA256PasswordSecure(t *testing.T) {
 
 	// hack to make the caching_sha2_password plugin believe that the connection
 	// is secure
-	mc.cfg.tls = &tls.Config{InsecureSkipVerify: true}
+	mc.cfg.TLS = &tls.Config{InsecureSkipVerify: true}
 
 	authData := []byte{6, 81, 96, 114, 14, 42, 50, 30, 76, 47, 1, 95, 126, 81,
 		62, 94, 83, 80, 52, 85}
@@ -676,7 +676,7 @@ func TestAuthFastSHA256PasswordSecure(t *testing.T) {
 	}
 
 	// unset TLS config to prevent the actual establishment of a TLS wrapper
-	mc.cfg.tls = nil
+	mc.cfg.TLS = nil
 
 	err = mc.writeHandshakeResponsePacket(authResp, plugin)
 	if err != nil {
@@ -866,7 +866,7 @@ func TestAuthSwitchCachingSHA256PasswordFullSecure(t *testing.T) {
 
 	// Hack to make the caching_sha2_password plugin believe that the connection
 	// is secure
-	mc.cfg.tls = &tls.Config{InsecureSkipVerify: true}
+	mc.cfg.TLS = &tls.Config{InsecureSkipVerify: true}
 
 	// auth switch request
 	conn.data = []byte{44, 0, 0, 2, 254, 99, 97, 99, 104, 105, 110, 103, 95,
@@ -1299,7 +1299,7 @@ func TestAuthSwitchSHA256PasswordSecure(t *testing.T) {
 
 	// Hack to make the caching_sha2_password plugin believe that the connection
 	// is secure
-	mc.cfg.tls = &tls.Config{InsecureSkipVerify: true}
+	mc.cfg.TLS = &tls.Config{InsecureSkipVerify: true}
 
 	// auth switch request
 	conn.data = []byte{38, 0, 0, 2, 254, 115, 104, 97, 50, 53, 54, 95, 112, 97,

dsn.go

@@ -46,22 +46,23 @@ type Config struct {
 	ServerPubKey     string            // Server public key name
 	pubKey           *rsa.PublicKey    // Server public key
 	TLSConfig        string            // TLS configuration name
-	tls              *tls.Config       // TLS configuration
+	TLS              *tls.Config       // TLS configuration, its priority is higher than TLSConfig
 	Timeout          time.Duration     // Dial timeout
 	ReadTimeout      time.Duration     // I/O read timeout
 	WriteTimeout     time.Duration     // I/O write timeout
 
-	AllowAllFiles           bool // Allow all files to be used with LOAD DATA LOCAL INFILE
-	AllowCleartextPasswords bool // Allows the cleartext client side plugin
-	AllowNativePasswords    bool // Allows the native password authentication method
-	AllowOldPasswords       bool // Allows the old insecure password method
-	CheckConnLiveness       bool // Check connections for liveness before using them
-	ClientFoundRows         bool // Return number of matching rows instead of rows changed
-	ColumnsWithAlias        bool // Prepend table alias to column names
-	InterpolateParams       bool // Interpolate placeholders into query string
-	MultiStatements         bool // Allow multiple statements in one query
-	ParseTime               bool // Parse time values to time.Time
-	RejectReadOnly          bool // Reject read-only connections
+	AllowAllFiles            bool // Allow all files to be used with LOAD DATA LOCAL INFILE
+	AllowCleartextPasswords  bool // Allows the cleartext client side plugin
+	AllowFallbackToPlaintext bool // Allows fallback to unencrypted connection if server does not support TLS
+	AllowNativePasswords     bool // Allows the native password authentication method
+	AllowOldPasswords        bool // Allows the old insecure password method
+	CheckConnLiveness        bool // Check connections for liveness before using them
+	ClientFoundRows          bool // Return number of matching rows instead of rows changed
+	ColumnsWithAlias         bool // Prepend table alias to column names
+	InterpolateParams        bool // Interpolate placeholders into query string
+	MultiStatements          bool // Allow multiple statements in one query
+	ParseTime                bool // Parse time values to time.Time
+	RejectReadOnly           bool // Reject read-only connections
 }
 
 // NewConfig creates a new Config and sets default values.
@@ -77,8 +78,8 @@ func NewConfig() *Config {
 
 func (cfg *Config) Clone() *Config {
 	cp := *cfg
-	if cp.tls != nil {
-		cp.tls = cfg.tls.Clone()
+	if cp.TLS != nil {
+		cp.TLS = cfg.TLS.Clone()
 	}
 	if len(cp.Params) > 0 {
 		cp.Params = make(map[string]string, len(cfg.Params))
@@ -119,24 +120,29 @@ func (cfg *Config) normalize() error {
 		cfg.Addr = ensureHavePort(cfg.Addr)
 	}
 
-	switch cfg.TLSConfig {
-	case "false", "":
-		// don't set anything
-	case "true":
-		cfg.tls = &tls.Config{}
-	case "skip-verify", "preferred":
-		cfg.tls = &tls.Config{InsecureSkipVerify: true}
-	default:
-		cfg.tls = getTLSConfigClone(cfg.TLSConfig)
-		if cfg.tls == nil {
-			return errors.New("invalid value / unknown config name: " + cfg.TLSConfig)
+	if cfg.TLS == nil {
+		switch cfg.TLSConfig {
+		case "false", "":
+			// don't set anything
+		case "true":
+			cfg.TLS = &tls.Config{}
+		case "skip-verify":
+			cfg.TLS = &tls.Config{InsecureSkipVerify: true}
+		case "preferred":
+			cfg.TLS = &tls.Config{InsecureSkipVerify: true}
+			cfg.AllowFallbackToPlaintext = true
+		default:
+			cfg.TLS = getTLSConfigClone(cfg.TLSConfig)
+			if cfg.TLS == nil {
+				return errors.New("invalid value / unknown config name: " + cfg.TLSConfig)
+			}
 		}
 	}
 
-	if cfg.tls != nil && cfg.tls.ServerName == "" && !cfg.tls.InsecureSkipVerify {
+	if cfg.TLS != nil && cfg.TLS.ServerName == "" && !cfg.TLS.InsecureSkipVerify {
 		host, _, err := net.SplitHostPort(cfg.Addr)
 		if err == nil {
-			cfg.tls.ServerName = host
+			cfg.TLS.ServerName = host
 		}
 	}
 
@@ -204,6 +210,10 @@ func (cfg *Config) FormatDSN() string {
 		writeDSNParam(&buf, &hasParam, "allowCleartextPasswords", "true")
 	}
 
+	if cfg.AllowFallbackToPlaintext {
+		writeDSNParam(&buf, &hasParam, "allowFallbackToPlaintext", "true")
+	}
+
 	if !cfg.AllowNativePasswords {
 		writeDSNParam(&buf, &hasParam, "allowNativePasswords", "false")
 	}
@@ -391,6 +401,14 @@ func parseDSNParams(cfg *Config, params string) (err error) {
 				return errors.New("invalid bool value: " + value)
 			}
 
+		// Allow fallback to unencrypted connection if server does not support TLS
+		case "allowFallbackToPlaintext":
+			var isBool bool
+			cfg.AllowFallbackToPlaintext, isBool = readBool(value)
+			if !isBool {
+				return errors.New("invalid bool value: " + value)
+			}
+
 		// Use native password authentication
 		case "allowNativePasswords":
 			var isBool bool

dsn_test.go

@@ -42,8 +42,8 @@ var testDSNs = []struct {
 	"user:password@/dbname?loc=UTC&timeout=30s&readTimeout=1s&writeTimeout=1s&allowAllFiles=1&clientFoundRows=true&allowOldPasswords=TRUE&collation=utf8mb4_unicode_ci&maxAllowedPacket=16777216&tls=false&allowCleartextPasswords=true&parseTime=true&rejectReadOnly=true",
 	&Config{User: "user", Passwd: "password", Net: "tcp", Addr: "127.0.0.1:3306", DBName: "dbname", Collation: "utf8mb4_unicode_ci", Loc: time.UTC, TLSConfig: "false", AllowCleartextPasswords: true, AllowNativePasswords: true, Timeout: 30 * time.Second, ReadTimeout: time.Second, WriteTimeout: time.Second, AllowAllFiles: true, AllowOldPasswords: true, CheckConnLiveness: true, ClientFoundRows: true, MaxAllowedPacket: 16777216, ParseTime: true, RejectReadOnly: true},
 }, {
-	"user:password@/dbname?allowNativePasswords=false&checkConnLiveness=false&maxAllowedPacket=0",
-	&Config{User: "user", Passwd: "password", Net: "tcp", Addr: "127.0.0.1:3306", DBName: "dbname", Collation: "utf8mb4_general_ci", Loc: time.UTC, MaxAllowedPacket: 0, AllowNativePasswords: false, CheckConnLiveness: false},
+	"user:password@/dbname?allowNativePasswords=false&checkConnLiveness=false&maxAllowedPacket=0&allowFallbackToPlaintext=true",
+	&Config{User: "user", Passwd: "password", Net: "tcp", Addr: "127.0.0.1:3306", DBName: "dbname", Collation: "utf8mb4_general_ci", Loc: time.UTC, MaxAllowedPacket: 0, AllowFallbackToPlaintext: true, AllowNativePasswords: false, CheckConnLiveness: false},
 }, {
 	"user:p@ss(word)@tcp([de:ad:be:ef::ca:fe]:80)/dbname?loc=Local",
 	&Config{User: "user", Passwd: "p@ss(word)", Net: "tcp", Addr: "[de:ad:be:ef::ca:fe]:80", DBName: "dbname", Collation: "utf8mb4_general_ci", Loc: time.Local, MaxAllowedPacket: defaultMaxAllowedPacket, AllowNativePasswords: true, CheckConnLiveness: true},
@@ -82,7 +82,7 @@ func TestDSNParser(t *testing.T) {
 		}
 
 		// pointer not static
-		cfg.tls = nil
+		cfg.TLS = nil
 
 		if !reflect.DeepEqual(cfg, tst.out) {
 			t.Errorf("%d. ParseDSN(%q) mismatch:\ngot  %+v\nwant %+v", i, tst.in, cfg, tst.out)
@@ -100,6 +100,7 @@ func TestDSNParserInvalid(t *testing.T) {
 		"User:pass@tcp(1.2.3.4:3306)",           // no trailing slash
 		"net()/",                                // unknown default addr
 		"user:pass@tcp(127.0.0.1:3306)/db/name", // invalid dbname
+		"user:password@/dbname?allowFallbackToPlaintext=PREFERRED", // wrong bool flag
 		//"/dbname?arg=/some/unescaped/path",
 	}
 
@@ -118,7 +119,7 @@ func TestDSNReformat(t *testing.T) {
 			t.Error(err.Error())
 			continue
 		}
-		cfg1.tls = nil // pointer not static
+		cfg1.TLS = nil // pointer not static
 		res1 := fmt.Sprintf("%+v", cfg1)
 
 		dsn2 := cfg1.FormatDSN()
@@ -127,7 +128,7 @@ func TestDSNReformat(t *testing.T) {
 			t.Error(err.Error())
 			continue
 		}
-		cfg2.tls = nil // pointer not static
+		cfg2.TLS = nil // pointer not static
 		res2 := fmt.Sprintf("%+v", cfg2)
 
 		if res1 != res2 {
@@ -203,7 +204,7 @@ func TestDSNWithCustomTLS(t *testing.T) {
 
 	if err != nil {
 		t.Error(err.Error())
-	} else if cfg.tls.ServerName != name {
+	} else if cfg.TLS.ServerName != name {
 		t.Errorf("did not get the correct TLS ServerName (%s) parsing DSN (%s).", name, tst)
 	}
 
@@ -214,7 +215,7 @@ func TestDSNWithCustomTLS(t *testing.T) {
 
 	if err != nil {
 		t.Error(err.Error())
-	} else if cfg.tls.ServerName != name {
+	} else if cfg.TLS.ServerName != name {
 		t.Errorf("did not get the correct ServerName (%s) parsing DSN (%s).", name, tst)
 	} else if tlsCfg.ServerName != "" {
 		t.Errorf("tlsCfg was mutated ServerName (%s) should be empty parsing DSN (%s).", name, tst)
@@ -229,23 +230,23 @@ func TestDSNTLSConfig(t *testing.T) {
 	if err != nil {
 		t.Error(err.Error())
 	}
-	if cfg.tls == nil {
+	if cfg.TLS == nil {
 		t.Error("cfg.tls should not be nil")
 	}
-	if cfg.tls.ServerName != expectedServerName {
-		t.Errorf("cfg.tls.ServerName should be %q, got %q (host with port)", expectedServerName, cfg.tls.ServerName)
+	if cfg.TLS.ServerName != expectedServerName {
+		t.Errorf("cfg.tls.ServerName should be %q, got %q (host with port)", expectedServerName, cfg.TLS.ServerName)
 	}
 
 	dsn = "tcp(example.com)/?tls=true"
 	cfg, err = ParseDSN(dsn)
 	if err != nil {
 		t.Error(err.Error())
 	}
-	if cfg.tls == nil {
+	if cfg.TLS == nil {
 		t.Error("cfg.tls should not be nil")
 	}
-	if cfg.tls.ServerName != expectedServerName {
-		t.Errorf("cfg.tls.ServerName should be %q, got %q (host without port)", expectedServerName, cfg.tls.ServerName)
+	if cfg.TLS.ServerName != expectedServerName {
+		t.Errorf("cfg.tls.ServerName should be %q, got %q (host without port)", expectedServerName, cfg.TLS.ServerName)
 	}
 }
 
@@ -262,7 +263,7 @@ func TestDSNWithCustomTLSQueryEscape(t *testing.T) {
 
 	if err != nil {
 		t.Error(err.Error())
-	} else if cfg.tls.ServerName != name {
+	} else if cfg.TLS.ServerName != name {
 		t.Errorf("did not get the correct TLS ServerName (%s) parsing DSN (%s).", name, dsn)
 	}
 }
@@ -335,12 +336,12 @@ func TestCloneConfig(t *testing.T) {
 		t.Errorf("Config.Clone did not create a separate config struct")
 	}
 
-	if cfg2.tls.ServerName != expectedServerName {
-		t.Errorf("cfg.tls.ServerName should be %q, got %q (host with port)", expectedServerName, cfg.tls.ServerName)
+	if cfg2.TLS.ServerName != expectedServerName {
+		t.Errorf("cfg.tls.ServerName should be %q, got %q (host with port)", expectedServerName, cfg.TLS.ServerName)
 	}
 
-	cfg2.tls.ServerName = "example2.com"
-	if cfg.tls.ServerName == cfg2.tls.ServerName {
+	cfg2.TLS.ServerName = "example2.com"
+	if cfg.TLS.ServerName == cfg2.TLS.ServerName {
 		t.Errorf("changed cfg.tls.Server name should not propagate to original Config")
 	}
 
@@ -384,20 +385,20 @@ func TestNormalizeTLSConfig(t *testing.T) {
 
 			cfg.normalize()
 
-			if cfg.tls == nil {
+			if cfg.TLS == nil {
 				if tc.want != nil {
 					t.Fatal("wanted a tls config but got nil instead")
 				}
 				return
 			}
 
-			if cfg.tls.ServerName != tc.want.ServerName {
+			if cfg.TLS.ServerName != tc.want.ServerName {
 				t.Errorf("tls.ServerName doesn't match (want: '%s', got: '%s')",
-					tc.want.ServerName, cfg.tls.ServerName)
+					tc.want.ServerName, cfg.TLS.ServerName)
 			}
-			if cfg.tls.InsecureSkipVerify != tc.want.InsecureSkipVerify {
+			if cfg.TLS.InsecureSkipVerify != tc.want.InsecureSkipVerify {
 				t.Errorf("tls.InsecureSkipVerify doesn't match (want: %T, got :%T)",
-					tc.want.InsecureSkipVerify, cfg.tls.InsecureSkipVerify)
+					tc.want.InsecureSkipVerify, cfg.TLS.InsecureSkipVerify)
 			}
 		})
 	}

packets.go

@@ -222,9 +222,9 @@ func (mc *mysqlConn) readHandshakePacket() (data []byte, plugin string, err erro
 	if mc.flags&clientProtocol41 == 0 {
 		return nil, "", ErrOldProtocol
 	}
-	if mc.flags&clientSSL == 0 && mc.cfg.tls != nil {
-		if mc.cfg.TLSConfig == "preferred" {
-			mc.cfg.tls = nil
+	if mc.flags&clientSSL == 0 && mc.cfg.TLS != nil {
+		if mc.cfg.AllowFallbackToPlaintext {
+			mc.cfg.TLS = nil
 		} else {
 			return nil, "", ErrNoTLS
 		}
@@ -292,7 +292,7 @@ func (mc *mysqlConn) writeHandshakeResponsePacket(authResp []byte, plugin string
 	}
 
 	// To enable TLS / SSL
-	if mc.cfg.tls != nil {
+	if mc.cfg.TLS != nil {
 		clientFlags |= clientSSL
 	}
 
@@ -356,14 +356,14 @@ func (mc *mysqlConn) writeHandshakeResponsePacket(authResp []byte, plugin string
 
 	// SSL Connection Request Packet
 	// http://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::SSLRequest
-	if mc.cfg.tls != nil {
+	if mc.cfg.TLS != nil {
 		// Send TLS / SSL request packet
 		if err := mc.writePacket(data[:(4+4+1+23)+4]); err != nil {
 			return err
 		}
 
 		// Switch to TLS
-		tlsConn := tls.Client(mc.netConn, mc.cfg.tls)
+		tlsConn := tls.Client(mc.netConn, mc.cfg.TLS)
 		if err := tlsConn.Handshake(); err != nil {
 			return err
 		}