refactor(device): implement verification key once

The verification key has a fixed source, so remove the vfunc.

src/libvalent/device/valent-channel.c

@@ -11,6 +11,7 @@
 #include <json-glib/json-glib.h>
 #include <libvalent-core.h>
 
+#include "valent-certificate.h"
 #include "valent-packet.h"
 
 #include "valent-channel.h"
@@ -40,9 +41,8 @@
  *
  * Implementations should override [[email protected]] and
  * [[email protected]] to support accepting and opening auxiliary
- * connections, respectively. If pairing involves exchanging a key, override
- * [[email protected]_verification_key]. To know when to store persistent
- * data related to the connection, override [[email protected]_data].
+ * connections, respectively. To know when to store persistent data related to
+ * the connection, override [[email protected]_data].
  *
  * Since: 1.0
  */
@@ -54,6 +54,7 @@ typedef struct
   JsonNode         *identity;
   GTlsCertificate  *peer_certificate;
   JsonNode         *peer_identity;
+  char             *verification_key;
 
   /* Packet Buffer */
   GDataInputStream *input_buffer;
@@ -74,12 +75,6 @@ static GParamSpec *properties[PROP_PEER_IDENTITY + 1] = { NULL, };
 
 
 /* LCOV_EXCL_START */
-static const char *
-valent_channel_real_get_verification_key (ValentChannel *channel)
-{
-  return NULL;
-}
-
 static GIOStream *
 valent_channel_real_download (ValentChannel  *channel,
                               JsonNode       *packet,
@@ -336,6 +331,7 @@ valent_channel_finalize (GObject *object)
   g_clear_pointer (&priv->identity, json_node_unref);
   g_clear_object (&priv->peer_certificate);
   g_clear_pointer (&priv->peer_identity, json_node_unref);
+  g_clear_pointer (&priv->verification_key, g_free);
   valent_object_unlock (VALENT_OBJECT (self));
 
   G_OBJECT_CLASS (valent_channel_parent_class)->finalize (object);
@@ -422,7 +418,6 @@ valent_channel_class_init (ValentChannelClass *klass)
   object_class->get_property = valent_channel_get_property;
   object_class->set_property = valent_channel_set_property;
 
-  klass->get_verification_key = valent_channel_real_get_verification_key;
   klass->download = valent_channel_real_download;
   klass->download_async = valent_channel_real_download_async;
   klass->download_finish = valent_channel_real_download_finish;
@@ -646,30 +641,59 @@ valent_channel_get_peer_identity (ValentChannel *channel)
 }
 
 /**
- * valent_channel_get_verification_key: (virtual get_verification_key)
+ * valent_channel_get_verification_key:
  * @channel: a `ValentChannel`
  *
  * Get a verification key for the connection.
  *
- * Implementations that involve exchanging a key should return a string for the
- * user to authenticate the connection, similar to a Bluetooth PIN.
- *
- * Returns: (transfer none): a verification key
+ * Returns: (nullable) (transfer none): a verification key
  *
  * Since: 1.0
  */
 const char *
 valent_channel_get_verification_key (ValentChannel *channel)
 {
-  const char *ret;
-
-  VALENT_ENTRY;
+  ValentChannelPrivate *priv = valent_channel_get_instance_private (channel);
 
   g_return_val_if_fail (VALENT_IS_CHANNEL (channel), NULL);
 
-  ret = VALENT_CHANNEL_GET_CLASS (channel)->get_verification_key (channel);
+  if (priv->verification_key == NULL)
+    {
+      g_autoptr (GChecksum) checksum = NULL;
+      GTlsCertificate *cert = NULL;
+      GTlsCertificate *peer_cert = NULL;
+      GByteArray *pubkey;
+      GByteArray *peer_pubkey;
+      size_t cmplen;
+
+      cert = valent_channel_get_certificate (channel);
+      peer_cert = valent_channel_get_peer_certificate (channel);
+      if (cert == NULL || peer_cert == NULL)
+        return NULL;
+
+      pubkey = valent_certificate_get_public_key (cert);
+      peer_pubkey = valent_certificate_get_public_key (peer_cert);
+      if (pubkey == NULL || peer_pubkey == NULL)
+        return NULL;
+
+      checksum = g_checksum_new (G_CHECKSUM_SHA256);
+      cmplen = MIN (pubkey->len, peer_pubkey->len);
+
+      if (memcmp (pubkey->data, peer_pubkey->data, cmplen) > 0)
+        {
+          g_checksum_update (checksum, pubkey->data, pubkey->len);
+          g_checksum_update (checksum, peer_pubkey->data, peer_pubkey->len);
+        }
+      else
+        {
+          g_checksum_update (checksum, peer_pubkey->data, peer_pubkey->len);
+          g_checksum_update (checksum, pubkey->data, pubkey->len);
+        }
+
+      priv->verification_key = g_strndup (g_checksum_get_string (checksum), 8);
+    }
 
-  VALENT_RETURN (ret);
+  return priv->verification_key;
 }
 
 /**

src/libvalent/device/valent-channel.h

@@ -23,7 +23,6 @@ struct _ValentChannelClass
   ValentObjectClass   parent_class;
 
   /* virtual functions */
-  const char        * (*get_verification_key) (ValentChannel        *channel);
   GIOStream         * (*download)             (ValentChannel        *channel,
                                                JsonNode             *packet,
                                                GCancellable         *cancellable,

src/plugins/lan/valent-lan-channel.c

@@ -16,11 +16,10 @@
 
 struct _ValentLanChannel
 {
-  ValentChannel    parent_instance;
+  ValentChannel  parent_instance;
 
-  char            *verification_key;
-  char            *host;
-  uint16_t         port;
+  char          *host;
+  uint16_t       port;
 };
 
 G_DEFINE_FINAL_TYPE (ValentLanChannel, valent_lan_channel, VALENT_TYPE_CHANNEL)
@@ -36,47 +35,6 @@ static GParamSpec *properties[PROP_PORT + 1] = { NULL, };
 /*
  * ValentChannel
  */
-static const char *
-valent_lan_channel_get_verification_key (ValentChannel *channel)
-{
-  ValentLanChannel *self = VALENT_LAN_CHANNEL (channel);
-  g_autoptr (GChecksum) checksum = NULL;
-  GTlsCertificate *cert = NULL;
-  GTlsCertificate *peer_cert = NULL;
-  GByteArray *pubkey;
-  GByteArray *peer_pubkey;
-  size_t cmplen;
-
-  if (self->verification_key == NULL)
-    {
-      if ((cert = valent_channel_get_certificate (channel)) == NULL ||
-          (peer_cert = valent_channel_get_peer_certificate (channel)) == NULL)
-        g_return_val_if_reached (NULL);
-
-      if ((pubkey = valent_certificate_get_public_key (cert)) == NULL ||
-          (peer_pubkey = valent_certificate_get_public_key (peer_cert)) == NULL)
-        g_return_val_if_reached (NULL);
-
-      checksum = g_checksum_new (G_CHECKSUM_SHA256);
-      cmplen = MIN (pubkey->len, peer_pubkey->len);
-
-      if (memcmp (pubkey->data, peer_pubkey->data, cmplen) > 0)
-        {
-          g_checksum_update (checksum, pubkey->data, pubkey->len);
-          g_checksum_update (checksum, peer_pubkey->data, peer_pubkey->len);
-        }
-      else
-        {
-          g_checksum_update (checksum, peer_pubkey->data, peer_pubkey->len);
-          g_checksum_update (checksum, pubkey->data, pubkey->len);
-        }
-
-      self->verification_key = g_strndup (g_checksum_get_string (checksum), 8);
-    }
-
-  return self->verification_key;
-}
-
 static GIOStream *
 valent_lan_channel_download (ValentChannel  *channel,
                              JsonNode       *packet,
@@ -256,7 +214,6 @@ valent_lan_channel_finalize (GObject *object)
   ValentLanChannel *self = VALENT_LAN_CHANNEL (object);
 
   g_clear_pointer (&self->host, g_free);
-  g_clear_pointer (&self->verification_key, g_free);
 
   G_OBJECT_CLASS (valent_lan_channel_parent_class)->finalize (object);
 }
@@ -321,7 +278,6 @@ valent_lan_channel_class_init (ValentLanChannelClass *klass)
   object_class->get_property = valent_lan_channel_get_property;
   object_class->set_property = valent_lan_channel_set_property;
 
-  channel_class->get_verification_key = valent_lan_channel_get_verification_key;
   channel_class->download = valent_lan_channel_download;
   channel_class->upload = valent_lan_channel_upload;
   channel_class->store_data = valent_lan_channel_store_data;

tests/fixtures/valent-mock-channel.c

@@ -40,14 +40,6 @@ static GParamSpec *properties[N_PROPERTIES] = { NULL, };
 /*
  * ValentChannel
  */
-static const char *
-valent_mock_channel_get_verification_key (ValentChannel *channel)
-{
-  g_assert (VALENT_IS_MOCK_CHANNEL (channel));
-
-  return "Mock Channel";
-}
-
 static GIOStream *
 valent_mock_channel_download (ValentChannel  *channel,
                               JsonNode       *packet,
@@ -217,7 +209,6 @@ valent_mock_channel_class_init (ValentMockChannelClass *klass)
   object_class->get_property = valent_mock_channel_get_property;
   object_class->set_property = valent_mock_channel_set_property;
 
-  channel_class->get_verification_key = valent_mock_channel_get_verification_key;
   channel_class->download = valent_mock_channel_download;
   channel_class->upload = valent_mock_channel_upload;
 

tests/libvalent/device/test-channel-service.c

@@ -341,8 +341,8 @@ test_channel_service_channel (ChannelServiceFixture *fixture,
 
   channel_verification = valent_channel_get_verification_key (fixture->channel);
   endpoint_verification = valent_channel_get_verification_key (fixture->endpoint);
-  g_assert_nonnull (channel_verification);
-  g_assert_nonnull (endpoint_verification);
+  g_assert_null (channel_verification);
+  g_assert_null (endpoint_verification);
   g_assert_cmpstr (channel_verification, ==, endpoint_verification);
 
   /* Packet Exchange */