test and hopefully fix JSON canonicalization

3 files changed, 89 insertions, 3 deletions

diff --git a/src/include/taler_json_lib.h b/src/include/taler_json_lib.h
index 2a101d26..51ebe6d9 100644
--- a/src/include/taler_json_lib.h
+++ b/src/include/taler_json_lib.h
@@ -563,6 +563,12 @@ enum GNUNET_GenericReturnValue
 TALER_JSON_parse_agemask (const json_t *root,
                           struct TALER_AgeMask *mask);
 
+/**
+ * Canonicalize a JSON input to a string according to RFC 8785.
+ */
+char *
+TALER_JSON_canonicalize (const json_t *input);
+
 #endif /* TALER_JSON_LIB_H_ */
 
 /* End of taler_json_lib.h */
diff --git a/src/json/json.c b/src/json/json.c
index bf3b2a0e..da447252 100644
--- a/src/json/json.c
+++ b/src/json/json.c
@@ -144,6 +144,9 @@ rfc8785encode (char **inp)
     if ( (1 == mbl) &&
          (val <= 0x1F) )
     {
+      /* Should not happen, as input is produced by
+       * JSON stringification */
+      GNUNET_break (0);
       lowdump (&buf,
                val);
     }
@@ -193,6 +196,12 @@ rfc8785encode (char **inp)
           }
         }
         break;
+      default:
+        mbl = 2;
+        GNUNET_buffer_write (&buf,
+                             pos,
+                             mbl);
+        break;
       }
     }
     else
@@ -1009,6 +1018,24 @@ TALER_deposit_extension_hash (const json_t *extensions,
 }
 
 
+char *
+TALER_JSON_canonicalize (const json_t *input)
+{
+  char *wire_enc;
+
+  if (NULL == (wire_enc = json_dumps (input,
+                                      JSON_ENCODE_ANY
+                                      | JSON_COMPACT
+                                      | JSON_SORT_KEYS)))
+  {
+    GNUNET_break (0);
+    return NULL;
+  }
+  rfc8785encode (&wire_enc);
+  return wire_enc;
+}
+
+
 enum GNUNET_GenericReturnValue
 TALER_JSON_extensions_config_hash (const json_t *config,
                                    struct TALER_ExtensionConfigHash *ech)
diff --git a/src/json/test_json.c b/src/json/test_json.c
index a8c1c6d8..5fe51d46 100644
--- a/src/json/test_json.c
+++ b/src/json/test_json.c
@@ -160,7 +160,7 @@ test_contract (void)
   GNUNET_assert (GNUNET_OK ==
                  TALER_JSON_contract_part_forget (c1,
                                                   "k2"));
-  json_dumpf (c1, stderr, JSON_INDENT (2));
+  // json_dumpf (c1, stderr, JSON_INDENT (2));
   GNUNET_assert (GNUNET_OK ==
                  TALER_JSON_contract_hash (c1,
                                            &h2));
@@ -182,7 +182,7 @@ test_contract (void)
   GNUNET_assert (GNUNET_OK ==
                  TALER_JSON_contract_hash (c1,
                                            &h1));
-  json_dumpf (c1, stderr, JSON_INDENT (2));
+  // json_dumpf (c1, stderr, JSON_INDENT (2));
   json_decref (c1);
   {
     char *s;
@@ -331,6 +331,57 @@ test_contract (void)
 
 
 static int
+test_json_canon (void)
+{
+  {
+    json_t *c1;
+    char *canon;
+    c1 = json_pack ("{s:s}",
+                    "k1", "Hello\nWorld");
+
+    canon = TALER_JSON_canonicalize (c1);
+    GNUNET_assert (NULL != canon);
+
+    printf ("canon: '%s'\n", canon);
+
+    GNUNET_assert (0 == strcmp (canon,
+                                "{\"k1\":\"Hello\\nWorld\"}"));
+  }
+  {
+    json_t *c1;
+    char *canon;
+    c1 = json_pack ("{s:s}",
+                    "k1", "Testing “unicode” characters");
+
+    canon = TALER_JSON_canonicalize (c1);
+    GNUNET_assert (NULL != canon);
+
+    printf ("canon: '%s'\n", canon);
+
+    GNUNET_assert (0 == strcmp (canon,
+                                "{\"k1\":\"Testing “unicode” characters\"}"));
+  }
+  {
+    json_t *c1;
+    char *canon;
+    c1 = json_pack ("{s:s}",
+                    "k1", "low range \x05 chars");
+
+    canon = TALER_JSON_canonicalize (c1);
+    GNUNET_assert (NULL != canon);
+
+    printf ("canon: '%s'\n", canon);
+
+    GNUNET_assert (0 == strcmp (canon,
+                                "{\"k1\":\"low range \\u0005 chars\"}"));
+  }
+
+
+  return 0;
+}
+
+
+static int
 test_rfc8785 (void)
 {
   struct TALER_PrivateContractHash h1;
@@ -348,7 +399,7 @@ test_rfc8785 (void)
                                              sizeof (h1));
     if (0 !=
         strcmp (s,
-                "J678K3PW9Y3DG63Z3T7ZYR2P7CEXMVZ2SFPQMABACK9TJRYREPP82542PCJ0P7Y7FAQAMWECDX50XH1RBTWHX6SSJHH6FXRV0JCS6R8"))
+                "531S33T8ZRGW6548G7T67PMDNGS4Z1D8A2GMB87G3PNKYTW6KGF7Q99XVCGXBKVA2HX6PR5ENJ1PQ5ZTYMMXQB6RM7S82VP7ZG2X5G8"))
     {
       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                   "Invalid reference hash: %s\n",
@@ -377,6 +428,8 @@ main (int argc,
     return 1;
   if (0 != test_contract ())
     return 2;
+  if (0 != test_json_canon ())
+    return 2;
   if (0 != test_rfc8785 ())
     return 2;
   return 0;