Continue certificate signing implementation

- parse PEM CSRs to DER before sending them to the signer
- handle SignCertificate and SignOpenPGP response messages
- add file system prefix constants for writing certificate files
- define supported hash algorithms
- fix handling of signing requests without organization, organizational unit,
  or location information
- use a different SMTP port for debugging with mailpit

internal/handler/handler.go

@@ -1,5 +1,5 @@
 /*
-Copyright 2022-2023 CAcert Inc.
+Copyright CAcert Inc.
 SPDX-License-Identifier: Apache-2.0
 
 Licensed under the Apache License, Version 2.0 (the "License");
@@ -132,6 +132,20 @@ func (s *SignerClientHandler) ResponseData(ctx context.Context, in <-chan []byte
 				return fmt.Errorf("could not unmarshal fetch CRL response data: %w", err)
 			}
 
+			response.Response = &resp
+		case messages.RespSignCertificate:
+			var resp messages.SignCertificateResponse
+			if err := msgpack.Unmarshal(frame, &resp); err != nil {
+				return fmt.Errorf("could not unmarshal sign certificate response data: %w", err)
+			}
+
+			response.Response = &resp
+		case messages.RespSignOpenPGP:
+			var resp messages.SignOpenPGPResponse
+			if err := msgpack.Unmarshal(frame, &resp); err != nil {
+				return fmt.Errorf("could not unmarshal sign OpenPGP response data: %w", err)
+			}
+
 			response.Response = &resp
 		case messages.RespError:
 			var resp messages.ErrorResponse

internal/legacydb/legacydb.go

@@ -15,7 +15,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-// Package legacydb is emulates the behavior of the old signer client by polling from a MySQL database using the old
+// Package legacydb emulates the behavior of the old signer client by polling from a MySQL database using the old
 // schema, reading CSR files from the filesystem and storing certificates in the file system.
 package legacydb
 
@@ -26,6 +26,7 @@ import (
 	"crypto/rand"
 	"crypto/x509"
 	"database/sql"
+	"encoding/pem"
 	"errors"
 	"fmt"
 	"math/big"
@@ -172,6 +173,14 @@ SET warning = warning + 1
 WHERE id = ?`
 )
 
+const (
+	prefixOpenPGP              = "gpg"
+	prefixPersonalClient       = "client"
+	prefixPersonalServer       = "server"
+	prefixOrganizationalClient = "orgclient"
+	prefixOrganizationalServer = "orgserver"
+)
+
 type pendingResponse struct {
 	responseType responseType
 	rowID        int
@@ -315,6 +324,12 @@ func New(logger *logrus.Logger, config *config.Database, commands chan *protocol
 		respOrganizationalServerCertificate:      "org_server",
 	}
 
+	supportedHashAlgorithms := map[string]crypto.Hash{
+		"sha256": crypto.SHA256,
+		"sha384": crypto.SHA384,
+		"sha512": crypto.SHA512,
+	}
+
 	failureQuery := map[responseType]string{
 		respGPG:                                  sqlRecordFailedOpenPGP,
 		respPersonalClientCertificate:            sqlRecordFailedPersonalClientCertificate,
@@ -332,6 +347,7 @@ func New(logger *logrus.Logger, config *config.Database, commands chan *protocol
 		logger:       logger,
 		commands:     commands,
 		emails:       emails,
+		algorithms:   supportedHashAlgorithms,
 		issuerIDs:    issuerIDs,
 		profiles:     profiles,
 		pending:      pending,
@@ -540,7 +556,7 @@ func (d *LegacyDB) requestCerts(ctx context.Context, query string, rt responseTy
 		var (
 			csrID       int
 			csrFileName string
-			certType    int
+			certType    sql.NullInt16
 			md          string
 			subject     string
 		)
@@ -549,7 +565,7 @@ func (d *LegacyDB) requestCerts(ctx context.Context, query string, rt responseTy
 			return fmt.Errorf("could not scan row: %w", err)
 		}
 
-		csrBytes, err := os.ReadFile(csrFileName)
+		pemBytes, err := os.ReadFile(csrFileName)
 		if err != nil {
 			d.logger.WithFields(logrus.Fields{
 				"id":        csrID,
@@ -561,6 +577,23 @@ func (d *LegacyDB) requestCerts(ctx context.Context, query string, rt responseTy
 			continue
 		}
 
+		csrBlock, remaining := pem.Decode(pemBytes)
+		if len(remaining) > 0 {
+			d.logger.WithFields(logrus.Fields{"id": csrID, "file_name": csrFileName}).Warn("unhandled CSR bytes")
+
+			idsWithIssues = append(idsWithIssues, csrID)
+
+			continue
+		}
+
+		if csrBlock.Type != "CERTIFICATE REQUEST" {
+			d.logger.WithFields(logrus.Fields{"id": csrID, "file_name": csrFileName, "pem_block_type": csrBlock.Type}).Warn("unhandled PEM block type")
+
+			idsWithIssues = append(idsWithIssues, csrID)
+
+			continue
+		}
+
 		hashAlg, ok := d.algorithms[md]
 		if !ok {
 			d.logger.WithFields(logrus.Fields{}).Warn("unsupported hash algorithm")
@@ -582,22 +615,11 @@ func (d *LegacyDB) requestCerts(ctx context.Context, query string, rt responseTy
 			continue
 		}
 
+		signCertCommand := buildSignCertificateCommand(issuerID, profileID, csrBlock.Bytes, subjParts, hashAlg)
+
 		command := &protocol.Command{
 			Announce: messages.BuildCommandAnnounce(messages.CmdSignCertificate),
-			Command: messages.SignCertificateCommand{
-				IssuerID:           issuerID,
-				ProfileName:        profileID,
-				CSRData:            csrBytes,
-				CommonName:         subjParts.Subject.CommonName,
-				Organization:       subjParts.Subject.Organization[0],
-				OrganizationalUnit: subjParts.Subject.OrganizationalUnit[0],
-				Locality:           subjParts.Subject.Locality[0],
-				Province:           subjParts.Subject.Province[0],
-				Country:            subjParts.Subject.Country[0],
-				Hostnames:          subjParts.DNSNames,
-				EmailAddresses:     subjParts.EmailAddresses,
-				PreferredHash:      hashAlg,
-			},
+			Command:  signCertCommand,
 		}
 
 		d.Lock()
@@ -617,6 +639,45 @@ func (d *LegacyDB) requestCerts(ctx context.Context, query string, rt responseTy
 	return nil
 }
 
+func buildSignCertificateCommand(
+	issuerID string,
+	profileID string,
+	csrBytes []byte,
+	subjParts *x509.Certificate,
+	hashAlg crypto.Hash,
+) messages.SignCertificateCommand {
+	signCertCommand := messages.SignCertificateCommand{
+		IssuerID:       issuerID,
+		ProfileName:    profileID,
+		CSRData:        csrBytes,
+		CommonName:     subjParts.Subject.CommonName,
+		Hostnames:      subjParts.DNSNames,
+		EmailAddresses: subjParts.EmailAddresses,
+		PreferredHash:  hashAlg,
+	}
+
+	if len(subjParts.Subject.Organization) > 0 {
+		signCertCommand.Organization = subjParts.Subject.Organization[0]
+	}
+
+	if len(subjParts.Subject.OrganizationalUnit) > 0 {
+		signCertCommand.OrganizationalUnit = subjParts.Subject.OrganizationalUnit[0]
+	}
+
+	if len(subjParts.Subject.Locality) > 0 {
+		signCertCommand.Locality = subjParts.Subject.Locality[0]
+	}
+
+	if len(subjParts.Subject.Province) > 0 {
+		signCertCommand.Province = subjParts.Subject.Province[0]
+	}
+
+	if len(subjParts.Subject.Country) > 0 {
+		signCertCommand.Country = subjParts.Subject.Country[0]
+	}
+	return signCertCommand
+}
+
 var (
 	errInvalidSANPart         = errors.New("invalid SAN part, missing colon")
 	errUnsupportedSubjectPart = errors.New("unsupported subject part")
@@ -702,19 +763,23 @@ func parseSubjectStringComponent(identifier, value string, res *x509.Certificate
 }
 
 func (d *LegacyDB) revokePersonalClientCerts(_ context.Context) error {
-	panic("not implemented")
+	logrus.Debug("not implemented")
+	return nil
 }
 
 func (d *LegacyDB) revokePersonalServerCerts(_ context.Context) error {
-	panic("not implemented")
+	logrus.Debug("not implemented")
+	return nil
 }
 
 func (d *LegacyDB) revokeOrganizationClientCerts(_ context.Context) error {
-	panic("not implemented")
+	logrus.Debug("not implemented")
+	return nil
 }
 
 func (d *LegacyDB) revokeOrganizationServerCerts(_ context.Context) error {
-	panic("not implemented")
+	logrus.Debug("not implemented")
+	return nil
 }
 
 func (d *LegacyDB) writeCertificate(prefix string, rowID int, signatureData []byte) (string, error) {
@@ -728,10 +793,10 @@ func (d *LegacyDB) writeCertificate(prefix string, rowID int, signatureData []by
 	return crtFileName, nil
 }
 
-func (d *LegacyDB) recordCertificate(_ context.Context, query string, rowID int, certBytes []byte) error {
+func (d *LegacyDB) recordCertificate(_ context.Context, prefix, query string, rowID int, certBytes []byte) error {
 	panic(fmt.Sprintf(
-		"not implemented: record certificate with query %s for rowID %d (%d bytes)",
-		query, rowID, len(certBytes),
+		"not implemented: record certificate to prefix %s with query %s for rowID %d (%d bytes)",
+		prefix, query, rowID, len(certBytes),
 	))
 }
 
@@ -778,7 +843,7 @@ func (d *LegacyDB) recordSignedOpenPGPKey(ctx context.Context, rowID int, signat
 
 	gpgExpiry := entity.Subkeys[0].Sig.CreationTime.Add(time.Second * time.Duration(*lifeTimeSecs))
 
-	crtFileName, err := d.writeCertificate("gpg", rowID, signatureData)
+	crtFileName, err := d.writeCertificate(prefixOpenPGP, rowID, signatureData)
 	if err != nil {
 		return fmt.Errorf("could not write OpenPGP result: %w", err)
 	}
@@ -847,13 +912,13 @@ func (d *LegacyDB) handleSignedCertificate(
 
 	switch pending.responseType {
 	case respPersonalClientCertificate, respPersonalCodeSigningCertificate:
-		err = d.recordCertificate(ctx, sqlRecordPersonalClientCert, pending.rowID, r.CertificateData)
+		err = d.recordCertificate(ctx, prefixPersonalClient, sqlRecordPersonalClientCert, pending.rowID, r.CertificateData)
 	case respPersonalServerCertificate:
-		err = d.recordCertificate(ctx, sqlRecordPersonalServerCert, pending.rowID, r.CertificateData)
+		err = d.recordCertificate(ctx, prefixPersonalServer, sqlRecordPersonalServerCert, pending.rowID, r.CertificateData)
 	case respOrganizationalClientCertificate, respOrganizationalCodeSigningCertificate:
-		err = d.recordCertificate(ctx, sqlRecordOrganizationalClientCert, pending.rowID, r.CertificateData)
+		err = d.recordCertificate(ctx, prefixOrganizationalClient, sqlRecordOrganizationalClientCert, pending.rowID, r.CertificateData)
 	case respOrganizationalServerCertificate:
-		err = d.recordCertificate(ctx, sqlRecordOrganizationalServerCert, pending.rowID, r.CertificateData)
+		err = d.recordCertificate(ctx, prefixOrganizationalServer, sqlRecordOrganizationalServerCert, pending.rowID, r.CertificateData)
 	default:
 		return fmt.Errorf("unexpected response type for pending request %s", announce.ID)
 	}
@@ -936,7 +1001,8 @@ func (d *LegacyDB) sendNotificationEmail(ctx context.Context, e emailData) error
 		return fmt.Errorf("could not set text template for email body: %w", err)
 	}
 
-	c, err := mail.NewClient("localhost")
+	const smtpPort = 1025
+	c, err := mail.NewClient("localhost", mail.WithPort(smtpPort))
 	if err != nil {
 		return fmt.Errorf("could not create mail client: %w", err)
 	}