Implement -J flag for server certificate pinning with strict encryption

.gitignore

@@ -32,3 +32,12 @@ darwin-arm64/sqlcmd
 linux-amd64/sqlcmd
 linux-arm64/sqlcmd
 linux-s390x/sqlcmd
+
+# Build artifacts in root
+/sqlcmd
+/sqlcmd_binary
+
+# certificates used for local testing
+*.der
+*.pem
+*.pfx

cmd/sqlcmd/sqlcmd.go

@@ -57,6 +57,7 @@ type SQLCmdArguments struct {
 	ApplicationIntent           string
 	EncryptConnection           string
 	HostNameInCertificate       string
+	ServerCertificate           string
 	DriverLoggingLevel          int
 	ExitOnError                 bool
 	ErrorSeverityLevel          uint8
@@ -127,6 +128,15 @@ const (
 	removeControlCharacters = "remove-control-characters"
 )
 
+func encryptConnectionAllowsTLS(value string) bool {
+	switch strings.ToLower(value) {
+	case "s", "strict", "m", "mandatory", "true", "t", "yes", "1":
+		return true
+	default:
+		return false
+	}
+}
+
 // Validate arguments for settings not describe
 func (a *SQLCmdArguments) Validate(c *cobra.Command) (err error) {
 	if a.ListServers != "" {
@@ -144,6 +154,8 @@ func (a *SQLCmdArguments) Validate(c *cobra.Command) (err error) {
 			err = mutuallyExclusiveError("-E", `-U/-P`)
 		case a.UseAad && len(a.AuthenticationMethod) > 0:
 			err = mutuallyExclusiveError("-G", "--authentication-method")
+		case len(a.HostNameInCertificate) > 0 && len(a.ServerCertificate) > 0:
+			err = mutuallyExclusiveError("-F", "-J")
 		case a.PacketSize != 0 && (a.PacketSize < 512 || a.PacketSize > 32767):
 			err = localizer.Errorf(`'-a %#v': Packet size has to be a number between 512 and 32767.`, a.PacketSize)
 		// Ignore 0 even though it's technically an invalid input
@@ -157,6 +169,8 @@ func (a *SQLCmdArguments) Validate(c *cobra.Command) (err error) {
 			err = rangeParameterError("-y", fmt.Sprint(*a.VariableTypeWidth), 0, 8000, true)
 		case a.QueryTimeout < 0 || a.QueryTimeout > 65534:
 			err = rangeParameterError("-t", fmt.Sprint(a.QueryTimeout), 0, 65534, true)
+		case a.ServerCertificate != "" && !encryptConnectionAllowsTLS(a.EncryptConnection):
+			err = localizer.Errorf("The -J parameter requires encryption to be enabled (-N true, -N mandatory, or -N strict).")
 		}
 	}
 	if err != nil {
@@ -429,6 +443,8 @@ func setFlags(rootCmd *cobra.Command, args *SQLCmdArguments) {
 	rootCmd.Flags().StringVarP(&args.ApplicationIntent, applicationIntent, "K", "default", localizer.Sprintf("Declares the application workload type when connecting to a server. The only currently supported value is ReadOnly. If %s is not specified, the sqlcmd utility will not support connectivity to a secondary replica in an Always On availability group", localizer.ApplicationIntentFlagShort))
 	rootCmd.Flags().StringVarP(&args.EncryptConnection, encryptConnection, "N", "default", localizer.Sprintf("This switch is used by the client to request an encrypted connection"))
 	rootCmd.Flags().StringVarP(&args.HostNameInCertificate, "host-name-in-certificate", "F", "", localizer.Sprintf("Specifies the host name in the server certificate."))
+	rootCmd.Flags().StringVarP(&args.ServerCertificate, "server-certificate", "J", "", localizer.Sprintf("Specifies the path to a server certificate file (PEM, DER, or CER) to match against the server's TLS certificate. Use when encryption is enabled (-N true, -N mandatory, or -N strict) for certificate pinning instead of standard certificate validation."))
+	rootCmd.MarkFlagsMutuallyExclusive("host-name-in-certificate", "server-certificate")
 	// Can't use NoOptDefVal until this fix: https://github.com/spf13/cobra/issues/866
 	//rootCmd.Flags().Lookup(encryptConnection).NoOptDefVal = "true"
 	rootCmd.Flags().BoolVarP(&args.Vertical, "vertical", "", false, localizer.Sprintf("Prints the output in vertical format. This option sets the sqlcmd scripting variable %s to '%s'. The default is false", sqlcmd.SQLCMDFORMAT, "vert"))
@@ -721,6 +737,7 @@ func setConnect(connect *sqlcmd.ConnectSettings, args *SQLCmdArguments, vars *sq
 		connect.Encrypt = args.EncryptConnection
 	}
 	connect.HostNameInCertificate = args.HostNameInCertificate
+	connect.ServerCertificate = args.ServerCertificate
 	connect.PacketSize = args.PacketSize
 	connect.WorkstationName = args.WorkstationName
 	connect.LogLevel = args.DriverLoggingLevel

cmd/sqlcmd/sqlcmd_test.go

@@ -111,6 +111,18 @@ func TestValidCommandLineToArgsConversion(t *testing.T) {
 		{[]string{"-N", "s", "-F", "myserver.domain.com"}, func(args SQLCmdArguments) bool {
 			return args.EncryptConnection == "s" && args.HostNameInCertificate == "myserver.domain.com"
 		}},
+		{[]string{"-N", "s", "-J", "/path/to/cert.pem"}, func(args SQLCmdArguments) bool {
+			return args.EncryptConnection == "s" && args.ServerCertificate == "/path/to/cert.pem"
+		}},
+		{[]string{"-N", "strict", "-J", "/path/to/cert.der"}, func(args SQLCmdArguments) bool {
+			return args.EncryptConnection == "strict" && args.ServerCertificate == "/path/to/cert.der"
+		}},
+		{[]string{"-N", "m", "-J", "/path/to/cert.cer"}, func(args SQLCmdArguments) bool {
+			return args.EncryptConnection == "m" && args.ServerCertificate == "/path/to/cert.cer"
+		}},
+		{[]string{"-N", "true", "-J", "/path/to/cert2.pem"}, func(args SQLCmdArguments) bool {
+			return args.EncryptConnection == "true" && args.ServerCertificate == "/path/to/cert2.pem"
+		}},
 	}
 
 	for _, test := range commands {
@@ -154,14 +166,18 @@ func TestInvalidCommandLine(t *testing.T) {
 		{[]string{"-E", "-U", "someuser"}, "The -E and the -U/-P options are mutually exclusive."},
 		{[]string{"-L", "-q", `"select 1"`}, "The -L parameter can not be used in combination with other parameters."},
 		{[]string{"-i", "foo.sql", "-q", `"select 1"`}, "The i and the -Q/-q options are mutually exclusive."},
-		{[]string{"-r", "5"}, `'-r 5': Unexpected argument. Argument value has to be one of [0 1].`},
+		{[]string{"-r", "5"}, "'-r 5': Unexpected argument. Argument value has to be one of [0 1]."},
 		{[]string{"-w", "x"}, "'-w x': value must be greater than 8 and less than 65536."},
 		{[]string{"-y", "111111"}, "'-y 111111': value must be greater than or equal to 0 and less than or equal to 8000."},
 		{[]string{"-Y", "-2"}, "'-Y -2': value must be greater than or equal to 0 and less than or equal to 8000."},
 		{[]string{"-P"}, "'-P': Missing argument. Enter '-?' for help."},
 		{[]string{"-;"}, "';': Unknown Option. Enter '-?' for help."},
 		{[]string{"-t", "-2"}, "'-t -2': value must be greater than or equal to 0 and less than or equal to 65534."},
 		{[]string{"-N", "invalid"}, "'-N invalid': Unexpected argument. Argument value has to be one of [m[andatory] yes 1 t[rue] disable o[ptional] no 0 f[alse] s[trict]]."},
+		{[]string{"-J", "/path/to/cert.pem"}, "The -J parameter requires encryption to be enabled (-N true, -N mandatory, or -N strict)."},
+		{[]string{"-N", "optional", "-J", "/path/to/cert.pem"}, "The -J parameter requires encryption to be enabled (-N true, -N mandatory, or -N strict)."},
+		{[]string{"-N", "disable", "-J", "/path/to/cert.pem"}, "The -J parameter requires encryption to be enabled (-N true, -N mandatory, or -N strict)."},
+		{[]string{"-N", "strict", "-F", "myserver.domain.com", "-J", "/path/to/cert.pem"}, "The -F and the -J options are mutually exclusive."},
 	}
 
 	for _, test := range commands {

go.mod

@@ -12,7 +12,7 @@ require (
 	github.com/docker/go-connections v0.4.0
 	github.com/golang-sql/sqlexp v0.1.0
 	github.com/google/uuid v1.6.0
-	github.com/microsoft/go-mssqldb v1.9.2
+	github.com/microsoft/go-mssqldb v1.9.6
 	github.com/opencontainers/image-spec v1.0.2
 	github.com/peterh/liner v1.2.2
 	github.com/pkg/errors v0.9.1
@@ -72,6 +72,7 @@ require (
 	github.com/prometheus/client_model v0.2.0 // indirect
 	github.com/prometheus/common v0.26.0 // indirect
 	github.com/prometheus/procfs v0.6.0 // indirect
+	github.com/shopspring/decimal v1.4.0 // indirect
 	github.com/spf13/afero v1.9.2 // indirect
 	github.com/spf13/cast v1.5.0 // indirect
 	github.com/spf13/jwalterweatherman v1.1.0 // indirect

go.sum

@@ -257,8 +257,8 @@ github.com/mattn/go-runewidth v0.0.3 h1:a+kO+98RDGEfo6asOGMmpodZq4FNtnGP54yps8Bz
 github.com/mattn/go-runewidth v0.0.3/go.mod h1:LwmH8dsx7+W8Uxz3IHJYH5QSwggIsqBzpuz5H//U1FU=
 github.com/matttproud/golang_protobuf_extensions v1.0.1 h1:4hp9jkHxhMHkqkrB3Ix0jegS5sx/RkqARlsWZ6pIwiU=
 github.com/matttproud/golang_protobuf_extensions v1.0.1/go.mod h1:D8He9yQNgCq6Z5Ld7szi9bcBfOoFv/3dc6xSMkL2PC0=
-github.com/microsoft/go-mssqldb v1.9.2 h1:nY8TmFMQOHpm2qVWo6y4I2mAmVdZqlGiMGAYt64Ibbs=
-github.com/microsoft/go-mssqldb v1.9.2/go.mod h1:GBbW9ASTiDC+mpgWDGKdm3FnFLTUsLYN3iFL90lQ+PA=
+github.com/microsoft/go-mssqldb v1.9.6 h1:1MNQg5UiSsokiPz3++K2KPx4moKrwIqly1wv+RyCKTw=
+github.com/microsoft/go-mssqldb v1.9.6/go.mod h1:yYMPDufyoF2vVuVCUGtZARr06DKFIhMrluTcgWlXpr4=
 github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=
 github.com/mitchellh/mapstructure v1.5.0/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
 github.com/moby/docker-image-spec v1.3.1 h1:jMKff3w6PgbfSa69GfNg+zN/XLhfXJGnEx3Nl2EsFP0=
@@ -320,6 +320,8 @@ github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFR
 github.com/rogpeppe/go-internal v1.13.1 h1:KvO1DLK/DRN07sQ1LQKScxyZJuNnedQ5/wKSR38lUII=
 github.com/rogpeppe/go-internal v1.13.1/go.mod h1:uMEvuHeurkdAXX61udpOXGD/AzZDWNMNyH2VO9fmH0o=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/shopspring/decimal v1.4.0 h1:bxl37RwXBklmTi0C79JfXCEBD1cqqHt0bbgBAGFp81k=
+github.com/shopspring/decimal v1.4.0/go.mod h1:gawqmDU56v4yIKSwfBSFip1HdCCXN8/+DMd9qYNcwME=
 github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
 github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE=
 github.com/sirupsen/logrus v1.6.0/go.mod h1:7uNnSEd1DgxDLC74fIahvMZmmYsHGZGEOFrfsX/uA88=

pkg/sqlcmd/connect.go

@@ -60,6 +60,8 @@ type ConnectSettings struct {
 	ChangePassword string
 	// The HostNameInCertificate is the name to use for the host in the certificate validation
 	HostNameInCertificate string
+	// ServerCertificate is the path to a certificate file to match against the server's TLS certificate
+	ServerCertificate string
 }
 
 func (c ConnectSettings) authenticationMethod() string {
@@ -150,6 +152,9 @@ func (connect ConnectSettings) ConnectionString() (connectionString string, err
 	if connect.HostNameInCertificate != "" {
 		query.Add(msdsn.HostNameInCertificate, connect.HostNameInCertificate)
 	}
+	if connect.ServerCertificate != "" {
+		query.Add(msdsn.ServerCertificate, connect.ServerCertificate)
+	}
 	if connect.LogLevel > 0 {
 		query.Add(msdsn.LogParam, fmt.Sprint(connect.LogLevel))
 	}