Add -N strict option (#459)

Co-authored-by: David Shiflet <david.shiflet@microsoft.com>

README.md

@@ -127,9 +127,10 @@ The `sqlcmd` project aims to be a complete port of the original ODBC sqlcmd to t
 The following switches have different behavior in this version of `sqlcmd` compared to the original ODBC based `sqlcmd`.
 - `-R` switch is ignored. The go runtime does not provide access to user locale information, and it's not readily available through syscall on all supported platforms.
 - `-I` switch is ignored; quoted identifiers are always set on. To disable quoted identifier behavior, add `SET QUOTED IDENTIFIER OFF` in your scripts.
-- `-N` now takes a string value that can be one of `true`, `false`, or `disable` to specify the encryption choice. 
+- `-N` now takes a string value that can be one of `strict`,`true`,`mandatory`,`yes`,`1`,`t`, `optional`, `no`, `0`, `f`, `false`, or `disable` to specify the encryption choice. 
   - If `-N` and `-C` are not provided, sqlcmd will negotiate authentication with the server without validating the server certificate.
   - If `-N` is provided but `-C` is not, sqlcmd will require validation of the server certificate. Note that a `false` value for encryption could still lead to encryption of the login packet.
+  - `-C` has no effect when `strict` value is specified for `-N`.
   - If both `-N` and `-C` are provided, sqlcmd will use their values for encryption negotiation.
   - More information about client/server encryption negotiation can be found at <https://docs.microsoft.com/openspecs/windows_protocols/ms-tds/60f56408-0188-4cd5-8b90-25c6f2423868>
 - `-u` The generated Unicode output file will have the UTF16 Little-Endian Byte-order mark (BOM) written to it.

cmd/sqlcmd/sqlcmd.go

@@ -455,10 +455,10 @@ func normalizeFlags(cmd *cobra.Command) error {
 		case encryptConnection:
 			value := strings.ToLower(v)
 			switch value {
-			case "false", "true", "disable":
+			case "mandatory", "yes", "1", "t", "true", "disable", "optional", "no", "0", "f", "false", "strict":
 				return pflag.NormalizedName(name)
 			default:
-				err = invalidParameterError("-N", v, "false", "true", "disable")
+				err = invalidParameterError("-N", v, "mandatory", "yes", "1", "t", "true", "disable", "optional", "no", "0", "f", "false", "strict")
 				return pflag.NormalizedName("")
 			}
 		case format:

cmd/sqlcmd/sqlcmd_test.go

@@ -150,6 +150,7 @@ func TestInvalidCommandLine(t *testing.T) {
 		{[]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 [mandatory yes 1 t true disable optional no 0 f false strict]."},
 	}
 
 	for _, test := range commands {