Fix encoding of extension values (Issue #80)

OpenPrinting · Mar 25, 2024 · bf38abb · bf38abb
1 parent c370400
commit bf38abb
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Showing 3 changed files with 15 additions and 35 deletions.
diff --git a/CHANGES.md b/CHANGES.md
@@ -25,6 +25,7 @@ libcups v3.0rc1 (TBD)
 - Fixed JSON output from `ipptool`.
 - Fixed hang/crash in `cupsEnumDests`/`cupsGetDests` (Issue #74)
 - Fixed encoding of IPv6 addresses in HTTP requests (Issue #78)
+- Fixed encoding of `IPP_TAG_EXTENSION` values in IPP messages (Issue #80)
 
 
 libcups v3.0b2 (October 5, 2023)

diff --git a/cups/ipp.c b/cups/ipp.c
@@ -2085,7 +2085,7 @@ ippGetOctetString(
     size_t          *datalen)		// O - Length of octetString data
 {
   // Range check input...
-  if (!attr || attr->value_tag != IPP_TAG_STRING || element >= attr->num_values)
+  if (!attr || (attr->value_tag != IPP_TAG_STRING && attr->value_tag != IPP_TAG_EXTENSION) || element >= attr->num_values)
   {
     if (datalen)
       *datalen = 0;
@@ -2563,25 +2563,6 @@ ippReadIO(void        *src,		// I - Data source
 
 	  // Read this attribute...
           tag = (ipp_tag_t)buffer[0];
-          if (tag == IPP_TAG_EXTENSION)
-          {
-            // Read 32-bit "extension" tag...
-	    if ((*cb)(src, buffer, 4) < 4)
-	    {
-	      DEBUG_puts("1ippReadIO: Callback returned EOF/error");
-	      goto rollback;
-	    }
-
-	    tag = (ipp_tag_t)((buffer[0] << 24) | (buffer[1] << 16) | (buffer[2] << 8) | buffer[3]);
-
-            if (tag & IPP_TAG_CUPS_CONST)
-            {
-              // Fail if the high bit is set in the tag...
-	      _cupsSetError(IPP_STATUS_ERROR_INTERNAL, _("IPP extension tag larger than 0x7FFFFFFF."), 1);
-	      DEBUG_printf("1ippReadIO: bad tag 0x%x.", tag);
-	      goto rollback;
-            }
-          }
 
 	  if (tag == IPP_TAG_END)
 	  {
@@ -3387,7 +3368,7 @@ ippSetOctetString(
 
 
   // Range check input...
-  if (!ipp || !attr || !*attr || ((*attr)->value_tag != IPP_TAG_STRING && (*attr)->value_tag != IPP_TAG_NOVALUE && (*attr)->value_tag != IPP_TAG_UNKNOWN) || element > (*attr)->num_values || datalen > IPP_MAX_LENGTH)
+  if (!ipp || !attr || !*attr || ((*attr)->value_tag != IPP_TAG_STRING && (*attr)->value_tag != IPP_TAG_NOVALUE && (*attr)->value_tag != IPP_TAG_UNKNOWN && (*attr)->value_tag != IPP_TAG_EXTENSION) || element > (*attr)->num_values || datalen > IPP_MAX_LENGTH)
     return (false);
 
   // Set the value and return...
@@ -3948,6 +3929,16 @@ ippSetValueTag(
         if (temp_tag == IPP_TAG_NAME || temp_tag == IPP_TAG_NAMELANG)
           break;			// Silently "allow" name -> keyword
 
+        return (false);
+
+    case IPP_TAG_EXTENSION :
+        if (temp_tag == IPP_TAG_STRING && value_tag == IPP_TAG_EXTENSION)
+        {
+          // Allow octetString -> extension
+          (*attr)->value_tag = value_tag;
+          break;
+        }
+
     default :
         return (false);
   }
@@ -4717,19 +4708,7 @@ ippWriteIO(void        *dst,		// I - Destination
 	    DEBUG_printf("2ippWriteIO: writing value tag=%x(%s)", attr->value_tag, ippTagString(attr->value_tag));
             DEBUG_printf("2ippWriteIO: writing name=%d,\"%s\"", n, attr->name);
 
-            if (attr->value_tag > 0xff)
-            {
-              *bufptr++ = IPP_TAG_EXTENSION;
-	      *bufptr++ = (ipp_uchar_t)(attr->value_tag >> 24);
-	      *bufptr++ = (ipp_uchar_t)(attr->value_tag >> 16);
-	      *bufptr++ = (ipp_uchar_t)(attr->value_tag >> 8);
-	      *bufptr++ = (ipp_uchar_t)attr->value_tag;
-            }
-            else
-            {
-	      *bufptr++ = (ipp_uchar_t)attr->value_tag;
-	    }
-
+	    *bufptr++ = (ipp_uchar_t)attr->value_tag;
 	    *bufptr++ = (ipp_uchar_t)(n >> 8);
 	    *bufptr++ = (ipp_uchar_t)n;
 	    memcpy(bufptr, attr->name, (size_t)n);

diff --git a/cups/ipp.h b/cups/ipp.h
@@ -484,7 +484,7 @@ typedef enum ipp_tag_e			// Value and group tag values for attributes
   IPP_TAG_LANGUAGE,			// Language value
   IPP_TAG_MIMETYPE,			// MIME media type value
   IPP_TAG_MEMBERNAME,			// Collection member name value
-  IPP_TAG_EXTENSION = 0x7f,		// Extension point for 32-bit tags
+  IPP_TAG_EXTENSION = 0x7f,		// Extension point for 32-bit tags (part of value)
   IPP_TAG_CUPS_MASK = 0x7fffffff,	// Mask for copied attribute values
   // The following expression is used to avoid compiler warnings with +/-0x80000000
   IPP_TAG_CUPS_CONST = -0x7fffffff-1	// Bitflag for copied/const attribute values