From ae2ce4aaeed35fd077cac016795f069b35189756 Mon Sep 17 00:00:00 2001
From: Christian Grothoff <christian@grothoff.org>
Date: Sun, 21 Nov 2021 00:53:11 +0100
Subject: trying to fix #7039 insanity for RFC 8785, Dold: please check

---
 src/json/Makefile.am |   1 +
 src/json/json.c      | 158 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 src/json/test_json.c |  36 ++++++++++++
 3 files changed, 194 insertions(+), 1 deletion(-)

(limited to 'src/json')

diff --git a/src/json/Makefile.am b/src/json/Makefile.am
index d3e4339fe..2f5ec3f17 100644
--- a/src/json/Makefile.am
+++ b/src/json/Makefile.am
@@ -22,6 +22,7 @@ libtalerjson_la_LIBADD = \
   $(top_builddir)/src/util/libtalerutil.la \
   -lgnunetjson \
   -lgnunetutil \
+  -lunistring \
   -ljansson \
   -lm \
   $(XLIB)
diff --git a/src/json/json.c b/src/json/json.c
index 479a0ae96..af2b84e27 100644
--- a/src/json/json.c
+++ b/src/json/json.c
@@ -23,6 +23,7 @@
 #include <gnunet/gnunet_util_lib.h>
 #include "taler_util.h"
 #include "taler_json_lib.h"
+#include <unistr.h>
 
 
 /**
@@ -60,6 +61,161 @@ contains_real (const json_t *json)
 }
 
 
+/**
+ * Dump character in the low range into @a buf
+ * following RFC 8785.
+ *
+ * @param[in,out] buf buffer to modify
+ * @param val value to dump
+ */
+static void
+lowdump (struct GNUNET_Buffer *buf,
+         unsigned char val)
+{
+  char scratch[7];
+
+  switch (val)
+  {
+  case 0x8:
+    GNUNET_buffer_write (buf,
+                         "\b",
+                         2);
+    break;
+  case 0x9:
+    GNUNET_buffer_write (buf,
+                         "\t",
+                         2);
+    break;
+  case 0xA:
+    GNUNET_buffer_write (buf,
+                         "\n",
+                         2);
+    break;
+  case 0xC:
+    GNUNET_buffer_write (buf,
+                         "\f",
+                         2);
+    break;
+  case 0xD:
+    GNUNET_buffer_write (buf,
+                         "\r",
+                         2);
+    break;
+  default:
+    GNUNET_snprintf (scratch,
+                     sizeof (scratch),
+                     "\\u%04x",
+                     (unsigned int) val);
+    GNUNET_buffer_write (buf,
+                         scratch,
+                         6);
+    break;
+  }
+}
+
+
+/**
+ * Re-encode string at @a inp to match RFC 8785 (section 3.2.2.2).
+ *
+ * @param[in,out] inp pointer to string to re-encode
+ * @return number of bytes in resulting @a inp
+ */
+static size_t
+rfc8785encode (char **inp)
+{
+  struct GNUNET_Buffer buf = { 0 };
+  size_t left = strlen (*inp) + 1;
+  size_t olen;
+  char *in = *inp;
+  const char *pos = in;
+
+  GNUNET_buffer_prealloc (&buf,
+                          left + 40);
+  buf.warn_grow = 0; /* disable, + 40 is just a wild guess */
+  while (1)
+  {
+    int mbl = u8_mblen ((unsigned char *) pos,
+                        left);
+    unsigned char val;
+
+    if (0 == mbl)
+      break;
+    val = (unsigned char) *pos;
+    if ( (1 == mbl) &&
+         (val <= 0x1F) )
+    {
+      lowdump (&buf,
+               val);
+    }
+    else if ( (1 == mbl) && ('\\' == *pos) )
+    {
+      switch (*(pos + 1))
+      {
+      case '\\':
+        mbl = 2;
+        GNUNET_buffer_write (&buf,
+                             pos,
+                             mbl);
+        break;
+      case 'u':
+        {
+          unsigned int num;
+          uint32_t n32;
+          unsigned char res[8];
+          size_t rlen;
+
+          GNUNET_assert ( (1 ==
+                           sscanf (pos + 2,
+                                   "%4x",
+                                   &num)) ||
+                          (1 ==
+                           sscanf (pos + 2,
+                                   "%4X",
+                                   &num)) );
+          mbl = 6;
+          n32 = (uint32_t) num;
+          rlen = sizeof (res);
+          u32_to_u8 (&n32,
+                     1,
+                     res,
+                     &rlen);
+          if ( (1 == rlen) &&
+               (res[0] <= 0x1F) )
+          {
+            lowdump (&buf,
+                     res[0]);
+          }
+          else
+          {
+            GNUNET_buffer_write (&buf,
+                                 (const char *) res,
+                                 rlen);
+          }
+        }
+        break;
+      }
+    }
+    else
+    {
+      GNUNET_buffer_write (&buf,
+                           pos,
+                           mbl);
+    }
+    left -= mbl;
+    pos += mbl;
+  }
+
+  /* 0-terminate buffer */
+  GNUNET_buffer_write (&buf,
+                       "",
+                       1);
+  GNUNET_free (in);
+  *inp = GNUNET_buffer_reap (&buf,
+                             &olen);
+  return olen;
+}
+
+
 /**
  * Dump the @a json to a string and hash it.
  *
@@ -97,7 +253,7 @@ dump_and_hash (const json_t *json,
     GNUNET_break (0);
     return GNUNET_SYSERR;
   }
-  len = strlen (wire_enc) + 1;
+  len = rfc8785encode (&wire_enc);
   if (NULL == salt)
   {
     GNUNET_CRYPTO_hash (wire_enc,
diff --git a/src/json/test_json.c b/src/json/test_json.c
index ffc5b33c7..a8c1c6d8e 100644
--- a/src/json/test_json.c
+++ b/src/json/test_json.c
@@ -330,6 +330,40 @@ test_contract (void)
 }
 
 
+static int
+test_rfc8785 (void)
+{
+  struct TALER_PrivateContractHash h1;
+  json_t *c1;
+
+  c1 = json_pack ("{s:s}",
+                  "k1", "\x08\x0B\t\1\\\x0d");
+  GNUNET_assert (GNUNET_OK ==
+                 TALER_JSON_contract_hash (c1,
+                                           &h1));
+  {
+    char *s;
+
+    s = GNUNET_STRINGS_data_to_string_alloc (&h1,
+                                             sizeof (h1));
+    if (0 !=
+        strcmp (s,
+                "J678K3PW9Y3DG63Z3T7ZYR2P7CEXMVZ2SFPQMABACK9TJRYREPP82542PCJ0P7Y7FAQAMWECDX50XH1RBTWHX6SSJHH6FXRV0JCS6R8"))
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "Invalid reference hash: %s\n",
+                  s);
+      GNUNET_free (s);
+      json_decref (c1);
+      return 1;
+    }
+    GNUNET_free (s);
+  }
+  json_decref (c1);
+  return 0;
+}
+
+
 int
 main (int argc,
       const char *const argv[])
@@ -343,6 +377,8 @@ main (int argc,
     return 1;
   if (0 != test_contract ())
     return 2;
+  if (0 != test_rfc8785 ())
+    return 2;
   return 0;
 }
 
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