commit 0342d7201ccdb905b8ef6381e3e85e9ef5cadf5c
author Thiago Macieira <thiago.macieira@intel.com> Sun Feb 26 13:12:50 2017 -0800
committer Thiago Macieira <thiago.macieira@intel.com> Mon May 08 20:59:16 2017 -0700
tree 9527d14bce000f42821187c26e1278e23df87dfb
parent addf8043e455cd3df2986419960c9462b9079139

Validation: Implement recognition of known tags

This implements:
 - CborValidateNoUnknownTagsSA
 - CborValidateNoUnknownTagsSR
 - CborValidateNoUnknownTags

This commit adds a Perl script that parses a machine-readable list of
known tags (also added in this commit). That allows us to more easily
update the known tag list when more tags are added by IANA to the
registry (see API documentation for the rationale on what tags we
recognise).

If there's an interest, we can change the file where the tag list is
generated into code so that implementations can choose which tags they
want to recognise at compile time.

Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>

src/cborvalidation.c

diff --git a/src/cborvalidation.c b/src/cborvalidation.c
index 6b19c58..dbc5008 100644
--- a/src/cborvalidation.c
+++ b/src/cborvalidation.c
@@ -116,9 +116,115 @@
  *
  * \par
  * These are the tags known to the current TinyCBOR release:
-[will be added in the next commit]
+<table>
+  <tr>
+    <th>Tag</th>
+    <th>Data Item</th>
+    <th>Semantics</th>
+  </tr>
+  <tr>
+    <td>0</td>
+    <td>UTF-8 text string</td>
+    <td>Standard date/time string</td>
+  </td>
+  <tr>
+    <td>1</td>
+    <td>integer</td>
+    <td>Epoch-based date/time</td>
+  </td>
+  <tr>
+    <td>2</td>
+    <td>byte string</td>
+    <td>Positive bignum</td>
+  </td>
+  <tr>
+    <td>3</td>
+    <td>byte string</td>
+    <td>Negative bignum</td>
+  </td>
+  <tr>
+    <td>4</td>
+    <td>array</td>
+    <td>Decimal fraction</td>
+  </td>
+  <tr>
+    <td>5</td>
+    <td>array</td>
+    <td>Bigfloat</td>
+  </td>
+  <tr>
+    <td>21</td>
+    <td>byte string, array, map</td>
+    <td>Expected conversion to base64url encoding</td>
+  </td>
+  <tr>
+    <td>22</td>
+    <td>byte string, array, map</td>
+    <td>Expected conversion to base64 encoding</td>
+  </td>
+  <tr>
+    <td>23</td>
+    <td>byte string, array, map</td>
+    <td>Expected conversion to base16 encoding</td>
+  </td>
+  <tr>
+    <td>24</td>
+    <td>byte string</td>
+    <td>Encoded CBOR data item</td>
+  </td>
+  <tr>
+    <td>32</td>
+    <td>UTF-8 text string</td>
+    <td>URI</td>
+  </td>
+  <tr>
+    <td>33</td>
+    <td>UTF-8 text string</td>
+    <td>base64url</td>
+  </td>
+  <tr>
+    <td>34</td>
+    <td>UTF-8 text string</td>
+    <td>base64</td>
+  </td>
+  <tr>
+    <td>35</td>
+    <td>UTF-8 text string</td>
+    <td>Regular expression</td>
+  </td>
+  <tr>
+    <td>36</td>
+    <td>UTF-8 text string</td>
+    <td>MIME message</td>
+  </td>
+  <tr>
+    <td>55799</td>
+    <td>any</td>
+    <td>Self-describe CBOR</td>
+  </td>
+</table>
  */
 
+struct KnownTagData { uint32_t tag; };
+static const struct KnownTagData knownTagData[] = {
+    { 0 },
+    { 1 },
+    { 2 },
+    { 3 },
+    { 4 },
+    { 5 },
+    { 21 },
+    { 22 },
+    { 23 },
+    { 24 },
+    { 32 },
+    { 33 },
+    { 34 },
+    { 35 },
+    { 36 },
+    { 55799 }
+};
+
 static CborError validate_value(CborValue *it, int flags, int recursionLeft);
 
 static inline CborError validate_simple_type(uint8_t simple_type, int flags)
@@ -135,20 +241,34 @@
 static inline CborError validate_tag(CborValue *it, CborTag tag, int flags, int recursionLeft)
 {
     CborType type = cbor_value_get_type(it);
+    const size_t knownTagCount = sizeof(knownTagData) / sizeof(knownTagData[0]);
+    const struct KnownTagData *tagData = knownTagData;
+    const struct KnownTagData * const knownTagDataEnd = knownTagData + knownTagCount;
+
     if (!recursionLeft)
         return CborErrorNestingTooDeep;
-
     if (flags & CborValidateNoTags)
         return CborErrorExcludedType;
-    if (flags & CborValidateNoUnknownTags) {
-        if (tag > 255 && (flags & CborValidateNoUnknownTagsSR) == 0)
+
+    /* find the tag data, if any */
+    for ( ; tagData != knownTagDataEnd; ++tagData) {
+        if (tagData->tag < tag)
+            continue;
+        if (tagData->tag > tag)
+            tagData = NULL;
+        break;
+    }
+    if (tagData == knownTagDataEnd)
+        tagData = NULL;
+
+    if (flags & CborValidateNoUnknownTags && !tagData) {
+        /* tag not found */
+        if (flags & CborValidateNoUnknownTagsSA && tag < 24)
             return CborErrorUnknownTag;
-        if (flags & CborValidateNoUnknownTagsSR) {
-            if (tag > 23 && (flags & CborValidateNoUnknownTagsSA) == 0)
-                return CborErrorUnknownTag;
-            if (flags & CborValidateNoUnknownTagsSA)
-                return CborErrorUnknownTag;
-        }
+        if ((flags & CborValidateNoUnknownTagsSR) == CborValidateNoUnknownTagsSR && tag < 256)
+            return CborErrorUnknownTag;
+        if ((flags & CborValidateNoUnknownTags) == CborValidateNoUnknownTags)
+            return CborErrorUnknownTag;
     }
 
     return validate_value(it, flags, recursionLeft);