Support retrieving PGP keys from keyservers

pgp/keysource.go

@@ -9,6 +9,7 @@ import (
 	"encoding/hex"
 	"fmt"
 	"io/ioutil"
+	"net/http"
 	"os"
 	"os/user"
 	"path"
@@ -81,16 +82,46 @@ func (key *MasterKey) encryptWithGPGBinary(dataKey []byte) error {
 	return nil
 }
 
-func (key *MasterKey) encryptWithCryptoOpenPGP(dataKey []byte) error {
+func getKeyFromKeyServer(keyserver string, fingerprint string) (openpgp.Entity, error) {
+	url := fmt.Sprintf("https://%s/pks/lookup?op=get&options=mr&search=0x%s", keyserver, fingerprint)
+	resp, err := http.Get(url)
+	if err != nil {
+		return openpgp.Entity{}, fmt.Errorf("error getting key from keyserver: %s", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		return openpgp.Entity{}, fmt.Errorf("keyserver returned non-200 status code %d", resp.Status)
+	}
+	ents, err := openpgp.ReadArmoredKeyRing(resp.Body)
+	if err != nil {
+		return openpgp.Entity{}, fmt.Errorf("could not read entities: %s", err)
+	}
+	return *ents[0], nil
+}
+
+func (key *MasterKey) getPubKey() (openpgp.Entity, error) {
 	ring, err := key.pubRing()
+	if err == nil {
+		fingerprints := key.fingerprintMap(ring)
+		entity, ok := fingerprints[key.Fingerprint]
+		if ok {
+			return entity, nil
+		}
+	}
+	entity, err := getKeyFromKeyServer("gpg.mozilla.org", key.Fingerprint)
+	if err != nil {
+		return openpgp.Entity{},
+			fmt.Errorf("key with fingerprint %s is not available "+
+				"in keyring and could not be retrieved from keyserver", key.Fingerprint)
+	}
+	return entity, nil
+}
+
+func (key *MasterKey) encryptWithCryptoOpenPGP(dataKey []byte) error {
+	entity, err := key.getPubKey()
 	if err != nil {
 		return err
 	}
-	fingerprints := key.fingerprintMap(ring)
-	entity, ok := fingerprints[key.Fingerprint]
-	if !ok {
-		return fmt.Errorf("key with fingerprint %s is not available in keyring", key.Fingerprint)
-	}
 	encbuf := new(bytes.Buffer)
 	armorbuf, err := armor.Encode(encbuf, "PGP MESSAGE", nil)
 	if err != nil {

pgp/keysource_test.go

@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"testing"
 	"testing/quick"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestPGP(t *testing.T) {
@@ -40,3 +42,9 @@ func TestPGPKeySourceFromString(t *testing.T) {
 		t.Error("Fingerprint does not match")
 	}
 }
+
+func TestRetrievePGPKey(t *testing.T) {
+	fingerprint := "1022470DE3F0BC54BC6AB62DE05550BC07FB1A0A"
+	_, err := getKeyFromKeyServer("gpg.mozilla.org", fingerprint)
+	assert.NoError(t, err)
+}