1 files changed, 39 insertions, 0 deletions
diff --git a/src/or/hs_client.c b/src/or/hs_client.c
index 051490aaaf..37981c8b65 100644
--- a/src/or/hs_client.c
+++ b/src/or/hs_client.c
@@ -46,3 +46,42 @@ hs_client_note_connection_attempt_succeeded(const edge_connection_t *conn)
   }
 }
 
+/* With the given encoded descriptor in desc_str and the service key in
+ * service_identity_pk, decode the descriptor and set the desc pointer with a
+ * newly allocated descriptor object.
+ *
+ * Return 0 on success else a negative value and desc is set to NULL. */
+int
+hs_client_decode_descriptor(const char *desc_str,
+                            const ed25519_public_key_t *service_identity_pk,
+                            hs_descriptor_t **desc)
+{
+  int ret;
+  uint8_t subcredential[DIGEST256_LEN];
+
+  tor_assert(desc_str);
+  tor_assert(service_identity_pk);
+  tor_assert(desc);
+
+  /* Create subcredential for this HS so that we can decrypt */
+  {
+    ed25519_public_key_t blinded_pubkey;
+    uint64_t current_time_period = hs_get_time_period_num(approx_time());
+    hs_build_blinded_pubkey(service_identity_pk, NULL, 0, current_time_period,
+                            &blinded_pubkey);
+    hs_get_subcredential(service_identity_pk, &blinded_pubkey, subcredential);
+  }
+
+  /* Parse descriptor */
+  ret = hs_desc_decode_descriptor(desc_str, subcredential, desc);
+  memwipe(subcredential, 0, sizeof(subcredential));
+  if (ret < 0) {
+    log_warn(LD_GENERAL, "Could not parse received descriptor as client");
+    goto err;
+  }
+
+  return 0;
+ err:
+  return -1;
+}
+