return signed 404 statements for unknown denomination key hashes (#6889)

src/exchange/taler-exchange-httpd_deposit.c

@@ -431,21 +431,16 @@ TEH_handler_deposit (struct MHD_Connection *connection,
   /* check denomination exists and is valid */
   {
     struct TEH_DenominationKey *dk;
-    enum TALER_ErrorCode ec;
-    unsigned int hc;
     struct GNUNET_TIME_Absolute now;
+    MHD_RESULT mret;
 
     dk = TEH_keys_denomination_by_hash (&deposit.coin.denom_pub_hash,
-                                        &ec,
+                                        connection,
-                                        &hc);
+                                        &mret);
     if (NULL == dk)
     {
-      TALER_LOG_DEBUG ("Unknown denomination key in /deposit request\n");
       GNUNET_JSON_parse_free (spec);
-      return TALER_MHD_reply_with_error (connection,
+      return mret;
-                                         hc,
-                                         ec,
-                                         NULL);
     }
     now = GNUNET_TIME_absolute_get ();
     if (now.abs_value_us >= dk->meta.expire_deposit.abs_value_us)

src/exchange/taler-exchange-httpd_keys.c

@@ -1801,30 +1801,32 @@ TEH_keys_get_state (void)
 
 struct TEH_DenominationKey *
 TEH_keys_denomination_by_hash (const struct GNUNET_HashCode *h_denom_pub,
-                               enum TALER_ErrorCode *ec,
+                               struct MHD_Connection *conn,
-                               unsigned int *hc)
+                               MHD_RESULT *mret)
 {
   struct TEH_KeyStateHandle *ksh;
 
   ksh = TEH_keys_get_state ();
   if (NULL == ksh)
   {
-    *hc = MHD_HTTP_INTERNAL_SERVER_ERROR;
+    *mret = TALER_MHD_reply_with_error (conn,
-    *ec = TALER_EC_EXCHANGE_GENERIC_KEYS_MISSING;
+                                        MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                        TALER_EC_EXCHANGE_GENERIC_KEYS_MISSING,
+                                        NULL);
     return NULL;
   }
   return TEH_keys_denomination_by_hash2 (ksh,
                                          h_denom_pub,
-                                         ec,
+                                         conn,
-                                         hc);
+                                         mret);
 }
 
 
 struct TEH_DenominationKey *
 TEH_keys_denomination_by_hash2 (struct TEH_KeyStateHandle *ksh,
                                 const struct GNUNET_HashCode *h_denom_pub,
-                                enum TALER_ErrorCode *ec,
+                                struct MHD_Connection *conn,
-                                unsigned int *hc)
+                                MHD_RESULT *mret)
 {
   struct TEH_DenominationKey *dk;
 
@@ -1832,8 +1834,8 @@ TEH_keys_denomination_by_hash2 (struct TEH_KeyStateHandle *ksh,
                                           h_denom_pub);
   if (NULL == dk)
   {
-    *hc = MHD_HTTP_NOT_FOUND;
+    *mret = TEH_RESPONSE_reply_unknown_denom_pub_hash (conn,
-    *ec = TALER_EC_EXCHANGE_GENERIC_DENOMINATION_KEY_UNKNOWN;
+                                                       h_denom_pub);
     return NULL;
   }
   return dk;

src/exchange/taler-exchange-httpd_keys.h

@@ -129,15 +129,15 @@ TEH_keys_update_states (void);
  * key state is resolved.
  *
  * @param h_denom_pub hash of denomination public key
- * @param[out] ec set to the error code, in case the operation failed
+ * @param[in,out] connection used to return status message if NULL is returned
- * @param[out] hc set to the HTTP status code to use
+ * @param[out] mret set to the MHD status if NULL is returned
  * @return the denomination key issue,
  *         or NULL if @a h_denom_pub could not be found
  */
 struct TEH_DenominationKey *
 TEH_keys_denomination_by_hash (const struct GNUNET_HashCode *h_denom_pub,
-                               enum TALER_ErrorCode *ec,
+                               struct MHD_Connection *conn,
-                               unsigned int *hc);
+                               MHD_RESULT *mret);
 
 
 /**
@@ -148,16 +148,16 @@ TEH_keys_denomination_by_hash (const struct GNUNET_HashCode *h_denom_pub,
  *
  * @param ksh key state state to look in
  * @param h_denom_pub hash of denomination public key
- * @param[out] ec set to the error code, in case the operation failed
+ * @param[in,out] connection used to return status message if NULL is returned
- * @param[out] hc set to the HTTP status code to use
+ * @param[out] mret set to the MHD status if NULL is returned
  * @return the denomination key issue,
  *         or NULL if @a h_denom_pub could not be found
  */
 struct TEH_DenominationKey *
 TEH_keys_denomination_by_hash2 (struct TEH_KeyStateHandle *ksh,
                                 const struct GNUNET_HashCode *h_denom_pub,
-                                enum TALER_ErrorCode *ec,
+                                struct MHD_Connection *conn,
-                                unsigned int *hc);
+                                MHD_RESULT *mret);
 
 /**
  * Request to sign @a msg using the public key corresponding to

src/exchange/taler-exchange-httpd_melt.c

@@ -466,22 +466,15 @@ check_for_denomination_key (struct MHD_Connection *connection,
   /* Baseline: check if deposits/refreshs are generally
      simply still allowed for this denomination */
   struct TEH_DenominationKey *dk;
-  unsigned int hc;
-  enum TALER_ErrorCode ec;
   struct GNUNET_TIME_Absolute now;
+  MHD_RESULT mret;
 
   dk = TEH_keys_denomination_by_hash (
     &rmc->refresh_session.coin.denom_pub_hash,
-    &ec,
+    connection,
-    &hc);
+    &mret);
   if (NULL == dk)
-  {
+    return mret;
-    return TALER_MHD_reply_with_error (
-      connection,
-      MHD_HTTP_NOT_FOUND,
-      TALER_EC_EXCHANGE_GENERIC_DENOMINATION_KEY_UNKNOWN,
-      NULL);
-  }
   now = GNUNET_TIME_absolute_get ();
   if (now.abs_value_us >= dk->meta.expire_legal.abs_value_us)
   {

src/exchange/taler-exchange-httpd_recoup.c

@@ -363,24 +363,15 @@ verify_and_execute_recoup (struct MHD_Connection *connection,
   struct GNUNET_HashCode c_hash;
   void *coin_ev;
   size_t coin_ev_size;
-  enum TALER_ErrorCode ec;
+  MHD_RESULT mret;
-  unsigned int hc;
   struct GNUNET_TIME_Absolute now;
 
   /* check denomination exists and is in recoup mode */
   dk = TEH_keys_denomination_by_hash (&coin->denom_pub_hash,
-                                      &ec,
+                                      connection,
-                                      &hc);
+                                      &mret);
   if (NULL == dk)
-  {
+    return mret;
-    TALER_LOG_WARNING (
-      "Denomination key in recoup request not in recoup mode\n");
-    return TALER_MHD_reply_with_error (connection,
-                                       hc,
-                                       ec,
-                                       NULL);
-  }
-
   now = GNUNET_TIME_absolute_get ();
   if (now.abs_value_us >= dk->meta.expire_deposit.abs_value_us)
   {

src/exchange/taler-exchange-httpd_refreshes_reveal.c

@@ -565,8 +565,7 @@ resolve_refreshes_reveal_denominations (struct MHD_Connection *connection,
                                    &dk_h[i]),
       GNUNET_JSON_spec_end ()
     };
-    unsigned int hc;
+    MHD_RESULT mret;
-    enum TALER_ErrorCode ec;
 
     res = TALER_MHD_parse_json_array (connection,
                                       new_denoms_h_json,
@@ -579,15 +578,10 @@ resolve_refreshes_reveal_denominations (struct MHD_Connection *connection,
     }
     dks[i] = TEH_keys_denomination_by_hash2 (ksh,
                                              &dk_h[i],
-                                             &ec,
+                                             connection,
-                                             &hc);
+                                             &mret);
     if (NULL == dks[i])
-    {
+      return mret;
-      return TALER_MHD_reply_with_error (connection,
-                                         hc,
-                                         ec,
-                                         NULL);
-    }
 
     if (now.abs_value_us >= dks[i]->meta.expire_withdraw.abs_value_us)
     {

src/exchange/taler-exchange-httpd_refund.c

@@ -449,21 +449,17 @@ verify_and_execute_refund (struct MHD_Connection *connection,
   {
     /* Obtain information about the coin's denomination! */
     struct TEH_DenominationKey *dk;
-    unsigned int hc;
+    MHD_RESULT mret;
-    enum TALER_ErrorCode ec;
 
     dk = TEH_keys_denomination_by_hash (&denom_hash,
-                                        &ec,
+                                        connection,
-                                        &hc);
+                                        &mret);
     if (NULL == dk)
     {
       /* DKI not found, but we do have a coin with this DK in our database;
          not good... */
       GNUNET_break (0);
-      return TALER_MHD_reply_with_error (connection,
+      return mret;
-                                         hc,
-                                         ec,
-                                         NULL);
     }
 
     if (GNUNET_TIME_absolute_get ().abs_value_us >=

src/exchange/taler-exchange-httpd_responses.c

@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2014-2017 Taler Systems SA
+  Copyright (C) 2014-2021 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify it under the
   terms of the GNU Affero General Public License as published by the Free Software
@@ -417,6 +417,55 @@ TEH_RESPONSE_compile_transaction_history (
 }
 
 
+MHD_RESULT
+TEH_RESPONSE_reply_unknown_denom_pub_hash (
+  struct MHD_Connection *connection,
+  const struct GNUNET_HashCode *dph)
+{
+  struct TALER_ExchangePublicKeyP epub;
+  struct TALER_ExchangeSignatureP esig;
+  struct GNUNET_TIME_Absolute now;
+  enum TALER_ErrorCode ec;
+
+  now = GNUNET_TIME_absolute_get ();
+  GNUNET_TIME_round_abs (&now);
+  {
+    struct TALER_DenominationUnknownAffirmationPS dua = {
+      .purpose.size = htonl (sizeof (dua)),
+      .purpose.purpose = htonl (TALER_SIGNATURE_EXCHANGE_AFFIRM_DENOM_UNKNOWN),
+      .timestamp = GNUNET_TIME_absolute_hton (now),
+      .h_denom_pub = *dph,
+    };
+
+    ec = TEH_keys_exchange_sign (&dua,
+                                 &epub,
+                                 &esig);
+  }
+  if (TALER_EC_NONE != ec)
+  {
+    GNUNET_break (0);
+    return TALER_MHD_reply_with_error (connection,
+                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                       ec,
+                                       NULL);
+  }
+  return TALER_MHD_reply_json_pack (
+    connection,
+    MHD_HTTP_NOT_FOUND,
+    "{s:I,s:o,s:o,s:o,s:o}",
+    "code",
+    TALER_EC_EXCHANGE_GENERIC_DENOMINATION_KEY_UNKNOWN,
+    "timestamp",
+    GNUNET_JSON_from_time_abs (now),
+    "exchange_pub",
+    GNUNET_JSON_from_data_auto (&epub),
+    "exchange_sig",
+    GNUNET_JSON_from_data_auto (&esig),
+    "h_denom_pub",
+    GNUNET_JSON_from_data_auto (dph));
+}
+
+
 /**
  * Send proof that a request is invalid to client because of
  * insufficient funds.  This function will create a message with all

src/exchange/taler-exchange-httpd_responses.h

@@ -48,6 +48,20 @@ TEH_RESPONSE_compile_reserve_history (
   struct TALER_Amount *balance);
 
 
+/**
+ * Send assertion that the given denomination key hash
+ * is unknown to us at this time.
+ *
+ * @param connection connection to the client
+ * @param dph denomination public key hash
+ * @return MHD result code
+ */
+MHD_RESULT
+TEH_RESPONSE_reply_unknown_denom_pub_hash (
+  struct MHD_Connection *connection,
+  const struct GNUNET_HashCode *dph);
+
+
 /**
  * Send proof that a request is invalid to client because of
  * insufficient funds.  This function will create a message with all

src/exchange/taler-exchange-httpd_withdraw.c

@@ -379,20 +379,16 @@ TEH_handler_withdraw (const struct TEH_RequestHandler *rh,
       return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
   }
   {
-    unsigned int hc;
+    MHD_RESULT mret;
-    enum TALER_ErrorCode ec;
     struct GNUNET_TIME_Absolute now;
 
     dk = TEH_keys_denomination_by_hash (&wc.denom_pub_hash,
-                                        &ec,
+                                        connection,
-                                        &hc);
+                                        &mret);
     if (NULL == dk)
     {
       GNUNET_JSON_parse_free (spec);
-      return TALER_MHD_reply_with_error (connection,
+      return mret;
-                                         hc,
-                                         ec,
-                                         NULL);
     }
     now = GNUNET_TIME_absolute_get ();
     if (now.abs_value_us >= dk->meta.expire_withdraw.abs_value_us)

src/include/taler_signatures.h

@@ -155,6 +155,11 @@
  */
 #define TALER_SIGNATURE_EXCHANGE_CONFIRM_RECOUP_REFRESH 1041
 
+/**
+ * Signature where the Exchange confirms that it does not know a denomination (hash).
+ */
+#define TALER_SIGNATURE_EXCHANGE_AFFIRM_DENOM_UNKNOWN 1042
+
 
 /**********************/
 /* Auditor signatures */
@@ -1514,6 +1519,30 @@ struct TALER_RecoupRefreshConfirmationPS
 };
 
 
+/**
+ * Response by which the exchange affirms that it does not
+ * currently know a denomination by the given hash.
+ */
+struct TALER_DenominationUnknownAffirmationPS
+{
+
+  /**
+   * Purpose is #TALER_SIGNATURE_EXCHANGE_AFFIRM_DENOM_UNKNOWN
+   */
+  struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
+
+  /**
+   * When did the exchange sign this message.
+   */
+  struct GNUNET_TIME_AbsoluteNBO timestamp;
+
+  /**
+   * Hash of the public denomination key we do not know.
+   */
+  struct GNUNET_HashCode h_denom_pub;
+};
+
+
 /**
  * Response by which the exchange affirms that it has
  * closed a reserve and send back the funds.