[taler-anastasis] 02/02: fix rate limiting

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grothoff pushed a commit to branch master
in repository anastasis.

commit 35637de34924ab92ceee8cde9cc5ae771d8faa21
Author: Christian Grothoff <christian@grothoff.org>
AuthorDate: Mon Mar 29 10:25:42 2021 +0200

    fix rate limiting
---
 src/backend/anastasis-httpd_truth.c    | 10 ++++++++--
 src/stasis/plugin_anastasis_postgres.c | 13 +++++++++++--
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/backend/anastasis-httpd_truth.c 
b/src/backend/anastasis-httpd_truth.c
index 0e3987d..7a348e4 100644
--- a/src/backend/anastasis-httpd_truth.c
+++ b/src/backend/anastasis-httpd_truth.c
@@ -973,7 +973,7 @@ AH_handler_truth_get (
                                            TALER_EC_GENERIC_DB_FETCH_FAILED,
                                            "create_challenge_code (for rate 
limiting)");
       }
-      if (0 != rt.abs_value_us)
+      if (0 == qs)
       {
         GNUNET_free (decrypted_truth);
         GNUNET_free (truth_mime);
@@ -1090,13 +1090,19 @@ AH_handler_truth_get (
     {
     case GNUNET_DB_STATUS_HARD_ERROR:
     case GNUNET_DB_STATUS_SOFT_ERROR:
-    case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
       GNUNET_break (0);
       GNUNET_free (decrypted_truth);
       return TALER_MHD_reply_with_error (gc->connection,
                                          MHD_HTTP_INTERNAL_SERVER_ERROR,
                                          TALER_EC_GENERIC_DB_FETCH_FAILED,
                                          "store_challenge_code");
+    case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
+      /* 0 == retry_counter of existing challenge => rate limit exceeded */
+      GNUNET_free (decrypted_truth);
+      return TALER_MHD_reply_with_error (connection,
+                                         MHD_HTTP_TOO_MANY_REQUESTS,
+                                         TALER_EC_ANASTASIS_TRUTH_RATE_LIMITED,
+                                         NULL);
     case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
       /* challenge code was stored successfully*/
       break;
diff --git a/src/stasis/plugin_anastasis_postgres.c 
b/src/stasis/plugin_anastasis_postgres.c
index bd4b2b8..4a759ce 100644
--- a/src/stasis/plugin_anastasis_postgres.c
+++ b/src/stasis/plugin_anastasis_postgres.c
@@ -1598,6 +1598,7 @@ postgres_create_challenge_code (
     }
 
     {
+      uint32_t retry_counter;
       struct GNUNET_PQ_QueryParam params[] = {
         GNUNET_PQ_query_param_auto_from_type (truth_uuid),
         TALER_PQ_query_param_absolute_time (&now),
@@ -1607,6 +1608,8 @@ postgres_create_challenge_code (
       struct GNUNET_PQ_ResultSpec rs[] = {
         GNUNET_PQ_result_spec_uint64 ("code",
                                       code),
+        GNUNET_PQ_result_spec_uint32 ("retry_counter",
+                                      &retry_counter),
         GNUNET_PQ_result_spec_absolute_time ("retransmission_date",
                                              retransmission_date),
         GNUNET_PQ_result_spec_end
@@ -1626,8 +1629,14 @@ postgres_create_challenge_code (
       case GNUNET_DB_STATUS_SOFT_ERROR:
         goto retry;
       case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
+        /* no active challenge, create fresh one (below) */
         break;
       case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
+        if (0 == retry_counter)
+        {
+          rollback (pg);
+          return GNUNET_DB_STATUS_SUCCESS_NO_RESULTS;
+        }
         rollback (pg);
         return qs;
       }
@@ -1990,7 +1999,7 @@ libanastasis_plugin_db_postgres_init (void *cls)
                             5),
     GNUNET_PQ_make_prepare ("challengecode_select",
                             "SELECT "
-                            " code "
+                            " code"
                             " FROM anastasis_challengecode"
                             " WHERE truth_uuid=$1"
                             "   AND expiration_date > $2"
@@ -1999,12 +2008,12 @@ libanastasis_plugin_db_postgres_init (void *cls)
     GNUNET_PQ_make_prepare ("challengecode_select_meta",
                             "SELECT "
                             " code"
+                            ",retry_counter"
                             ",retransmission_date"
                             " FROM anastasis_challengecode"
                             " WHERE truth_uuid=$1"
                             "   AND expiration_date > $2"
                             "   AND creation_date > $3"
-                            "   AND retry_counter > 0"
                             " ORDER BY creation_date DESC"
                             " LIMIT 1;",
                             2),

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