test(signer): add unit tests for signserver package

Signed-off-by: Matías Insaurralde <matias@chainloop.dev>

Author: matiasinsaurralde

pkg/attestation/signer/signserver/signserver_test.go

@@ -0,0 +1,336 @@
+//
+// Copyright 2026 The Chainloop Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package signserver
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"io"
+	"math/big"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// --- helpers -----------------------------------------------------------------
+
+func generateSelfSignedCertPEM(t *testing.T) []byte {
+	t.Helper()
+	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	require.NoError(t, err)
+	template := &x509.Certificate{
+		SerialNumber: big.NewInt(1),
+		Subject:      pkix.Name{CommonName: "test"},
+		NotBefore:    time.Now().Add(-time.Minute),
+		NotAfter:     time.Now().Add(time.Hour),
+		IsCA:         true,
+	}
+	der, err := x509.CreateCertificate(rand.Reader, template, template, &key.PublicKey, key)
+	require.NoError(t, err)
+	return pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: der})
+}
+
+func generatePrivateKeyPEM(t *testing.T) []byte {
+	t.Helper()
+	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	require.NoError(t, err)
+	der, err := x509.MarshalPKCS8PrivateKey(key)
+	require.NoError(t, err)
+	return pem.EncodeToMemory(&pem.Block{Type: "PRIVATE KEY", Bytes: der})
+}
+
+// generateEncryptedPrivateKeyPEM creates a PEM-encrypted private key (RFC1423/legacy format).
+//
+//nolint:staticcheck
+func generateEncryptedPrivateKeyPEM(t *testing.T, password string) []byte {
+	t.Helper()
+	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	require.NoError(t, err)
+	der, err := x509.MarshalPKCS8PrivateKey(key)
+	require.NoError(t, err)
+	// x509.EncryptPEMBlock is deprecated but remains the standard way to test
+	// the RFC1423 decryption path exercised by privateKeyFromPem.
+	block, err := x509.EncryptPEMBlock(rand.Reader, "PRIVATE KEY", der, []byte(password), x509.PEMCipherAES128) //nolint:staticcheck
+	require.NoError(t, err)
+	return pem.EncodeToMemory(block)
+}
+
+// writePEMToTempFile writes a raw PEM block to a temp file and returns its path.
+func writePEMToTempFile(t *testing.T, blockType string, der []byte) string {
+	t.Helper()
+	f, err := os.CreateTemp(t.TempDir(), "*.pem")
+	require.NoError(t, err)
+	defer f.Close()
+	err = pem.Encode(f, &pem.Block{Type: blockType, Bytes: der})
+	require.NoError(t, err)
+	return f.Name()
+}
+
+// tlsServerCAFile starts a TLS httptest server and returns it together with a
+// temp-file path containing its CA certificate. Caller is responsible for
+// calling srv.Close().
+func tlsServerWithCA(t *testing.T, handler http.Handler) (*httptest.Server, string) {
+	t.Helper()
+	srv := httptest.NewTLSServer(handler)
+	caPath := writePEMToTempFile(t, "CERTIFICATE", srv.TLS.Certificates[0].Certificate[0])
+	return srv, caPath
+}
+
+// --- TestParseKeyReference ---------------------------------------------------
+
+func TestParseKeyReference(t *testing.T) {
+	tests := []struct {
+		name       string
+		input      string
+		wantHost   string
+		wantWorker string
+		wantErr    bool
+	}{
+		{
+			name:       "valid reference",
+			input:      "signserver://myhost.com/CMSSigner",
+			wantHost:   "myhost.com",
+			wantWorker: "CMSSigner",
+		},
+		{
+			name:       "valid reference with port",
+			input:      "signserver://myhost.com:8443/PlainSigner",
+			wantHost:   "myhost.com:8443",
+			wantWorker: "PlainSigner",
+		},
+		{
+			name:    "missing worker segment",
+			input:   "signserver://myhost.com",
+			wantErr: true,
+		},
+		{
+			name:    "too many path segments",
+			input:   "signserver://myhost.com/worker/extra",
+			wantErr: true,
+		},
+		{
+			name:    "no scheme separator",
+			input:   "noscheme",
+			wantErr: true,
+		},
+		{
+			// ParseKeyReference only validates structure, not the scheme prefix.
+			// Scheme enforcement (signserver://) is the caller's responsibility (GetSigner).
+			name:       "non-signserver scheme parses successfully",
+			input:      "https://myhost.com/worker",
+			wantHost:   "myhost.com",
+			wantWorker: "worker",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			host, worker, err := ParseKeyReference(tc.input)
+			if tc.wantErr {
+				require.Error(t, err)
+				return
+			}
+			require.NoError(t, err)
+			assert.Equal(t, tc.wantHost, host)
+			assert.Equal(t, tc.wantWorker, worker)
+		})
+	}
+}
+
+// --- TestNewSigner_WithOptions ------------------------------------------------
+
+func TestNewSigner_WithOptions(t *testing.T) {
+	s := NewSigner("myhost.com", "CMSSigner",
+		WithCAPath("/ca.pem"),
+		WithClientCertPath("/cert.pem"),
+		WithClientCertPass("secret"),
+	)
+	assert.Equal(t, "myhost.com", s.host)
+	assert.Equal(t, "CMSSigner", s.worker)
+	assert.Equal(t, "/ca.pem", s.caPath)
+	assert.Equal(t, "/cert.pem", s.clientCertPath)
+	assert.Equal(t, "secret", s.clientCertPass)
+}
+
+func TestNewSigner_Defaults(t *testing.T) {
+	s := NewSigner("host", "worker")
+	assert.Empty(t, s.caPath)
+	assert.Empty(t, s.clientCertPath)
+	assert.Empty(t, s.clientCertPass)
+}
+
+// --- TestPublicKey -----------------------------------------------------------
+
+func TestPublicKey_NotSupported(t *testing.T) {
+	s := NewSigner("host", "worker")
+	key, err := s.PublicKey()
+	assert.Error(t, err)
+	assert.Nil(t, key)
+}
+
+// --- TestSignMessage ---------------------------------------------------------
+
+func TestSignMessage_Success(t *testing.T) {
+	var gotWorker string
+	var gotFileName string
+	var gotFileContent []byte
+
+	srv, caPath := tlsServerWithCA(t, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		require.NoError(t, r.ParseMultipartForm(1<<20))
+		gotWorker = r.FormValue("workerName")
+		f, fh, err := r.FormFile("file")
+		require.NoError(t, err)
+		gotFileName = fh.Filename
+		gotFileContent, _ = io.ReadAll(f)
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("fakesignature"))
+	}))
+	defer srv.Close()
+
+	host := strings.TrimPrefix(srv.URL, "https://")
+	s := NewSigner(host, "CMSSigner", WithCAPath(caPath))
+
+	sig, err := s.SignMessage(strings.NewReader("hello attestation"))
+	require.NoError(t, err)
+	assert.Equal(t, []byte("fakesignature"), sig)
+	assert.Equal(t, "CMSSigner", gotWorker)
+	assert.Equal(t, "attestation.json", gotFileName)
+	assert.Equal(t, []byte("hello attestation"), gotFileContent)
+}
+
+func TestSignMessage_Non200Status(t *testing.T) {
+	srv, caPath := tlsServerWithCA(t, http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+	}))
+	defer srv.Close()
+
+	host := strings.TrimPrefix(srv.URL, "https://")
+	s := NewSigner(host, "CMSSigner", WithCAPath(caPath))
+
+	_, err := s.SignMessage(strings.NewReader("data"))
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "500")
+}
+
+func TestSignMessage_NetworkError(t *testing.T) {
+	srv, caPath := tlsServerWithCA(t, http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {}))
+	host := strings.TrimPrefix(srv.URL, "https://")
+	srv.Close() // closed before the call
+
+	s := NewSigner(host, "CMSSigner", WithCAPath(caPath))
+	_, err := s.SignMessage(strings.NewReader("data"))
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "failed to send request")
+}
+
+func TestSignMessage_InvalidCAPath(t *testing.T) {
+	s := NewSigner("host", "worker", WithCAPath("/nonexistent/ca.pem"))
+	_, err := s.SignMessage(strings.NewReader("data"))
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "failed to read ca cert")
+}
+
+// --- TestCertFromPem ---------------------------------------------------------
+
+func TestCertFromPem(t *testing.T) {
+	cert1 := generateSelfSignedCertPEM(t)
+	cert2 := generateSelfSignedCertPEM(t)
+	keyOnly := generatePrivateKeyPEM(t)
+
+	tests := []struct {
+		name      string
+		input     []byte
+		wantCerts int
+	}{
+		{"single certificate", cert1, 1},
+		{"two certificates", append(cert1, cert2...), 2},
+		{"empty input", []byte{}, 0},
+		{"key block only — no certs extracted", keyOnly, 0},
+		{"cert followed by key", append(cert1, keyOnly...), 1},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			result, err := certFromPem(tc.input)
+			require.NoError(t, err)
+			assert.Len(t, result.Certificate, tc.wantCerts)
+		})
+	}
+}
+
+// --- TestPrivateKeyFromPem ---------------------------------------------------
+
+func TestPrivateKeyFromPem(t *testing.T) {
+	tests := []struct {
+		name     string
+		pemBytes func(t *testing.T) []byte
+		password string
+		wantErr  bool
+	}{
+		{
+			name:     "unencrypted PKCS8 key with empty password",
+			pemBytes: func(t *testing.T) []byte { return generatePrivateKeyPEM(t) },
+			password: "",
+		},
+		{
+			name:     "RFC1423 encrypted key with correct password",
+			pemBytes: func(t *testing.T) []byte { return generateEncryptedPrivateKeyPEM(t, "correct") },
+			password: "correct",
+		},
+		{
+			name:     "RFC1423 encrypted key with wrong password",
+			pemBytes: func(t *testing.T) []byte { return generateEncryptedPrivateKeyPEM(t, "correct") },
+			password: "wrong",
+			wantErr:  true,
+		},
+		{
+			name:     "no PEM data at all",
+			pemBytes: func(_ *testing.T) []byte { return []byte("not-pem-data") },
+			password: "",
+			wantErr:  true,
+		},
+		{
+			name:     "certificate block only — no key",
+			pemBytes: func(t *testing.T) []byte { return generateSelfSignedCertPEM(t) },
+			password: "",
+			wantErr:  true,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			key, err := privateKeyFromPem(tc.pemBytes(t), tc.password)
+			if tc.wantErr {
+				require.Error(t, err)
+				return
+			}
+			require.NoError(t, err)
+			assert.NotNil(t, key)
+			_, ok := key.(*ecdsa.PrivateKey)
+			assert.True(t, ok, "expected *ecdsa.PrivateKey")
+		})
+	}
+}