Allow ocsp-responder to filter requests by serial prefix (#3815)

cmd/ocsp-responder/main.go

@@ -43,9 +43,10 @@ serialNumber field, since we will always query on it.
 
 */
 type DBSource struct {
-	dbMap     dbSelector
-	caKeyHash []byte
-	log       blog.Logger
+	dbMap             dbSelector
+	caKeyHash         []byte
+	reqSerialPrefixes []string
+	log               blog.Logger
 }
 
 // Since the only thing we use from gorp is the SelectOne method on the
@@ -58,8 +59,8 @@ type dbSelector interface {
 
 // NewSourceFromDatabase produces a DBSource representing the binding of a
 // given DB schema to a CA key.
-func NewSourceFromDatabase(dbMap dbSelector, caKeyHash []byte, log blog.Logger) (src *DBSource, err error) {
-	src = &DBSource{dbMap: dbMap, caKeyHash: caKeyHash, log: log}
+func NewSourceFromDatabase(dbMap dbSelector, caKeyHash []byte, reqSerialPrefixes []string, log blog.Logger) (src *DBSource, err error) {
+	src = &DBSource{dbMap: dbMap, caKeyHash: caKeyHash, reqSerialPrefixes: reqSerialPrefixes, log: log}
 	return
 }
 
@@ -77,6 +78,16 @@ func (src *DBSource) Response(req *ocsp.Request) ([]byte, http.Header, error) {
 	}
 
 	serialString := core.SerialToString(req.SerialNumber)
+	if len(src.reqSerialPrefixes) > 0 {
+		match := false
+		for _, prefix := range src.reqSerialPrefixes {
+			match = strings.HasPrefix(serialString, prefix)
+		}
+		if !match {
+			return nil, nil, cfocsp.ErrNotFound
+		}
+	}
+
 	src.log.Debugf("Searching for OCSP issued by us for serial %s", serialString)
 
 	var response dbResponse
@@ -105,7 +116,7 @@ func (src *DBSource) Response(req *ocsp.Request) ([]byte, http.Header, error) {
 	return response.OCSPResponse, nil, nil
 }
 
-func makeDBSource(dbMap dbSelector, issuerCert string, log blog.Logger) (*DBSource, error) {
+func makeDBSource(dbMap dbSelector, issuerCert string, reqSerialPrefixes []string, log blog.Logger) (*DBSource, error) {
 	// Load the CA's key so we can store its SubjectKey in the DB
 	caCertDER, err := cmd.LoadCert(issuerCert)
 	if err != nil {
@@ -120,7 +131,7 @@ func makeDBSource(dbMap dbSelector, issuerCert string, log blog.Logger) (*DBSour
 	}
 
 	// Construct source from DB
-	return NewSourceFromDatabase(dbMap, caCert.SubjectKeyId, log)
+	return NewSourceFromDatabase(dbMap, caCert.SubjectKeyId, reqSerialPrefixes, log)
 }
 
 type config struct {
@@ -142,6 +153,8 @@ type config struct {
 
 		ShutdownStopTimeout cmd.ConfigDuration
 
+		RequiredSerialPrefixes []string
+
 		Features map[string]bool
 	}
 
@@ -201,7 +214,7 @@ as generated by Boulder's single-ocsp command.
 		cmd.FailOnError(err, "Could not connect to database")
 		sa.SetSQLDebug(dbMap, logger)
 		go sa.ReportDbConnCount(dbMap, scope)
-		source, err = makeDBSource(dbMap, c.Common.IssuerCert, logger)
+		source, err = makeDBSource(dbMap, c.Common.IssuerCert, c.OCSPResponder.RequiredSerialPrefixes, logger)
 		cmd.FailOnError(err, "Couldn't load OCSP DB")
 		// Export the MaxDBConns
 		dbConnStat := prometheus.NewGauge(prometheus.GaugeOpts{

cmd/ocsp-responder/main_test.go

@@ -14,6 +14,7 @@ import (
 	"golang.org/x/crypto/ocsp"
 
 	cfocsp "github.com/cloudflare/cfssl/ocsp"
+	"github.com/letsencrypt/boulder/core"
 	blog "github.com/letsencrypt/boulder/log"
 	"github.com/letsencrypt/boulder/metrics"
 	"github.com/letsencrypt/boulder/test"
@@ -71,7 +72,7 @@ func TestMux(t *testing.T) {
 }
 
 func TestDBHandler(t *testing.T) {
-	src, err := makeDBSource(mockSelector{}, "./testdata/test-ca.der.pem", blog.NewMock())
+	src, err := makeDBSource(mockSelector{}, "./testdata/test-ca.der.pem", nil, blog.NewMock())
 	if err != nil {
 		t.Fatalf("makeDBSource: %s", err)
 	}
@@ -127,7 +128,7 @@ func (bs brokenSelector) SelectOne(_ interface{}, _ string, _ ...interface{}) er
 
 func TestErrorLog(t *testing.T) {
 	mockLog := blog.NewMock()
-	src, err := makeDBSource(brokenSelector{}, "./testdata/test-ca.der.pem", mockLog)
+	src, err := makeDBSource(brokenSelector{}, "./testdata/test-ca.der.pem", nil, mockLog)
 	test.AssertNotError(t, err, "Failed to create broken dbMap")
 
 	ocspReq, err := ocsp.ParseRequest(req)
@@ -150,3 +151,22 @@ func mustRead(path string) []byte {
 	}
 	return b
 }
+
+func TestRequiredSerialPrefix(t *testing.T) {
+	mockLog := blog.NewMock()
+	src, err := makeDBSource(mockSelector{}, "./testdata/test-ca.der.pem", []string{"nope"}, mockLog)
+	test.AssertNotError(t, err, "failed to create DBSource")
+
+	ocspReq, err := ocsp.ParseRequest(req)
+	test.AssertNotError(t, err, "Failed to parse OCSP request")
+
+	_, _, err = src.Response(ocspReq)
+	test.AssertEquals(t, err, cfocsp.ErrNotFound)
+
+	fmt.Println(core.SerialToString(ocspReq.SerialNumber))
+
+	src, err = makeDBSource(mockSelector{}, "./testdata/test-ca.der.pem", []string{"00"}, mockLog)
+	test.AssertNotError(t, err, "failed to create DBSource")
+	_, _, err = src.Response(ocspReq)
+	test.AssertNotError(t, err, "src.Response failed with acceptable prefix")
+}

test/config-next/ocsp-responder.json

@@ -6,7 +6,8 @@
     "listenAddress": "0.0.0.0:4002",
     "maxAge": "10s",
     "shutdownStopTimeout": "10s",
-    "debugAddr": ":8005"
+    "debugAddr": ":8005",
+    "requiredSerialPrefixes": ["ff"]
   },
 
   "syslog": {