lib/httpserver: added tlsCipherSuites flag (#2468)

* lib/httpserver: added tlsCipherSuites flag

* lib/httpserver: compare lower case strings

* lib/httpserver: use EqualFold

* lib/httpserver: used flagutil.NewArray, supported only strings cipher suites

* lib/httpserver: updated flag description, added flag to documentation

* Update lib/httpserver/httpserver.go

Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>

lib/httpserver/httpserver_test.go

@@ -0,0 +1,78 @@
+package httpserver
+
+import (
+	"reflect"
+	"testing"
+)
+
+func Test_validateCipherSuites(t *testing.T) {
+	type args struct {
+		definedCipherSuites []string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    []uint16
+		wantErr bool
+	}{
+		{
+			name: "empty cipher suites",
+			args: args{definedCipherSuites: []string{}},
+			want: nil,
+		},
+		{
+			name:    "got wrong string",
+			args:    args{definedCipherSuites: []string{"word"}},
+			want:    nil,
+			wantErr: true,
+		},
+		{
+			name:    "got wrong number",
+			args:    args{definedCipherSuites: []string{"123"}},
+			want:    nil,
+			wantErr: true,
+		},
+		{
+			name:    "got correct string cipher suite",
+			args:    args{definedCipherSuites: []string{"TLS_RSA_WITH_AES_128_CBC_SHA", "TLS_RSA_WITH_AES_256_CBC_SHA"}},
+			want:    []uint16{0x2f, 0x35},
+			wantErr: false,
+		},
+		{
+			name:    "got correct string with different cases (upper and lower) cipher suite",
+			args:    args{definedCipherSuites: []string{"tls_rsa_with_aes_128_cbc_sha", "TLS_RSA_WITH_AES_256_CBC_SHA"}},
+			want:    []uint16{0x2f, 0x35},
+			wantErr: false,
+		},
+		{
+			name:    "got correct number cipher suite",
+			args:    args{definedCipherSuites: []string{"0x2f", "0x35"}},
+			want:    nil,
+			wantErr: true,
+		},
+		{
+			name:    "got insecure number cipher suite",
+			args:    args{definedCipherSuites: []string{"0x0005", "0x000a"}},
+			want:    nil,
+			wantErr: true,
+		},
+		{
+			name:    "got insecure string cipher suite",
+			args:    args{definedCipherSuites: []string{"TLS_ECDHE_ECDSA_WITH_RC4_128_SHA", "TLS_ECDHE_RSA_WITH_RC4_128_SHA"}},
+			want:    nil,
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := collectCipherSuites(tt.args.definedCipherSuites)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("collectCipherSuites() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("validateCipherSuites() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}