2 files changed, 104 insertions, 0 deletions
diff --git a/go/internal/keyline/key_line.go b/go/internal/keyline/key_line.go
new file mode 100644
index 0000000..7b19c87
--- /dev/null
+++ b/go/internal/keyline/key_line.go
@@ -0,0 +1,53 @@
+package keyline
+
+import (
+	"errors"
+	"fmt"
+	"path"
+	"regexp"
+	"strings"
+
+	"gitlab.com/gitlab-org/gitlab-shell/go/internal/executable"
+)
+
+var (
+	keyRegex = regexp.MustCompile(`\A[a-z0-9-]+\z`)
+)
+
+const (
+	PublicKeyPrefix = "key"
+	SshOptions      = "no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty"
+)
+
+type KeyLine struct {
+	Id      string // This can be either an ID of a Key or username
+	Value   string // This can be either a public key or a principal name
+	Prefix  string
+	RootDir string
+}
+
+func NewPublicKeyLine(id string, publicKey string, rootDir string) (*KeyLine, error) {
+	if err := validate(id, publicKey); err != nil {
+		return nil, err
+	}
+
+	return &KeyLine{Id: id, Value: publicKey, Prefix: PublicKeyPrefix, RootDir: rootDir}, nil
+}
+
+func (k *KeyLine) ToString() string {
+	command := fmt.Sprintf("%s %s-%s", path.Join(k.RootDir, executable.BinDir, executable.GitlabShell), k.Prefix, k.Id)
+
+	return fmt.Sprintf(`command="%s",%s %s`, command, SshOptions, k.Value)
+}
+
+func validate(id string, value string) error {
+	if !keyRegex.MatchString(id) {
+		return errors.New(fmt.Sprintf("Invalid key_id: %s", id))
+	}
+
+	if strings.Contains(value, "\n") {
+		return errors.New(fmt.Sprintf("Invalid value: %s", value))
+	}
+
+	return nil
+}
diff --git a/go/internal/keyline/key_line_test.go b/go/internal/keyline/key_line_test.go
new file mode 100644
index 0000000..fc2bdf3
--- /dev/null
+++ b/go/internal/keyline/key_line_test.go
@@ -0,0 +1,51 @@
+package keyline
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFailingNewPublicKeyLine(t *testing.T) {
+	testCases := []struct {
+		desc          string
+		id            string
+		publicKey     string
+		expectedError string
+	}{
+		{
+			desc:          "When Id has non-alphanumeric and non-dash characters in it",
+			id:            "key\n1",
+			publicKey:     "public-key",
+			expectedError: "Invalid key_id: key\n1",
+		},
+		{
+			desc:          "When public key has newline in it",
+			id:            "key",
+			publicKey:     "public\nkey",
+			expectedError: "Invalid value: public\nkey",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			result, err := NewPublicKeyLine(tc.id, tc.publicKey, "root-dir")
+
+			require.Empty(t, result)
+			require.EqualError(t, err, tc.expectedError)
+		})
+	}
+}
+
+func TestToString(t *testing.T) {
+	keyLine := &KeyLine{
+		Id:      "1",
+		Value:   "public-key",
+		Prefix:  "key",
+		RootDir: "/tmp",
+	}
+
+	result := keyLine.ToString()
+
+	require.Equal(t, `command="/tmp/bin/gitlab-shell key-1",no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty public-key`, result)
+}