disallow non-shortest-form encodings in utf-8 checking; when converting utf-8 to...

diff --git a/src/plugin_common/tags.c b/src/plugin_common/tags.c
index 8c3008b..f580f44 100644 (file)
--- a/src/plugin_common/tags.c
+++ b/src/plugin_common/tags.c
@@ -33,19 +33,54 @@ static __inline unsigned local__wide_strlen(const FLAC__uint16 *s)
        return n;
 }
 
+/*
+ * also disallows non-shortest-form encodings, c.f.
+ *   http://www.unicode.org/versions/corrigendum1.html
+ * and a more clear explanation at the end of this section:
+ *   http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
+ */
 static __inline unsigned local__utf8len(const FLAC__byte *utf8)
 {
        FLAC__ASSERT(0 != utf8);
-       if ((utf8[0] & 0x80) == 0)
+       if ((utf8[0] & 0x80) == 0) {
                return 1;
-       else if ((utf8[0] & 0xE0) == 0xC0 && (utf8[1] & 0xC0) == 0x80)
+       }
+       else if ((utf8[0] & 0xE0) == 0xC0 && (utf8[1] & 0xC0) == 0x80) {
+               if ((utf8[0] & 0x01) == 0xC0) /* overlong sequence check */
+                       return 0;
                return 2;
-       else if ((utf8[0] & 0xF0) == 0xE0 && (utf8[1] & 0xC0) == 0x80 && (utf8[2] & 0xC0) == 0x80)
+       }
+       else if ((utf8[0] & 0xF0) == 0xE0 && (utf8[1] & 0xC0) == 0x80 && (utf8[2] & 0xC0) == 0x80) {
+               if (utf8[0] == 0xE0 && (utf8[1] & 0xE0) == 0x80) /* overlong sequence check */
+                       return 0;
+               /* illegal surrogates check (U+D800...U+DFFF and U+FFFE...U+FFFF) */
+               if (utf8[0] == 0xED && (utf8[1] & 0xE0) == 0xA0) /* D800-DFFF */
+                       return 0;
+               if (utf8[0] == 0xEF && utf8[1] == 0xBF && (utf8[2] & 0xFE) == 0xBE) /* FFFE-FFFF */
+                       return 0;
                return 3;
-       else
+       }
+       else if ((utf8[0] & 0xF8) == 0xF0 && (utf8[1] & 0xC0) == 0x80 && (utf8[2] & 0xC0) == 0x80 && (utf8[3] & 0xC0) == 0x80) {
+               if (utf8[0] == 0xF0 && (utf8[1] & 0xF0) == 0x80) /* overlong sequence check */
+                       return 0;
+               return 4;
+       }
+       else if ((utf8[0] & 0xFC) == 0xF8 && (utf8[1] & 0xC0) == 0x80 && (utf8[2] & 0xC0) == 0x80 && (utf8[3] & 0xC0) == 0x80 && (utf8[4] & 0xC0) == 0x80) {
+               if (utf8[0] == 0xF8 && (utf8[1] & 0xF8) == 0x80) /* overlong sequence check */
+                       return 0;
+               return 5;
+       }
+       else if ((utf8[0] & 0xFE) == 0xFC && (utf8[1] & 0xC0) == 0x80 && (utf8[2] & 0xC0) == 0x80 && (utf8[3] & 0xC0) == 0x80 && (utf8[4] & 0xC0) == 0x80 && (utf8[5] & 0xC0) == 0x80) {
+               if (utf8[0] == 0xFC && (utf8[1] & 0xFC) == 0x80) /* overlong sequence check */
+                       return 0;
+               return 6;
+       }
+       else {
                return 0;
+       }
 }
 
+
 static __inline unsigned local__utf8_to_ucs2(const FLAC__byte *utf8, FLAC__uint16 *ucs2)
 {
        const unsigned len = local__utf8len(utf8);
@@ -58,6 +93,8 @@ static __inline unsigned local__utf8_to_ucs2(const FLAC__byte *utf8, FLAC__uint1
                *ucs2 = (*utf8 & 0x3F)<<6 | (*(utf8+1) & 0x3F);
        else if (len == 3)
                *ucs2 = (*utf8 & 0x1F)<<12 | (*(utf8+1) & 0x3F)<<6 | (*(utf8+2) & 0x3F);
+       else
+               *ucs2 = '?';
 
        return len;
 }
@@ -71,8 +108,8 @@ static FLAC__uint16 *local__convert_utf8_to_ucs2(const char *src, unsigned lengt
 
        /* calculate length */
        {
-               const char *s, *end;
-               for (s=src, end=src+length; s<end; chars++) {
+               const unsigned char *s, *end;
+               for (s=(const unsigned char *)src, end=s+length; s<end; chars++) {
                        const unsigned n = local__utf8len(s);
                        if (n == 0)
                                return 0;
@@ -90,9 +127,10 @@ static FLAC__uint16 *local__convert_utf8_to_ucs2(const char *src, unsigned lengt
 
        /* convert */
        {
+               const unsigned char *s = (const unsigned char *)src;
                FLAC__uint16 *u = out;
                for ( ; chars; chars--)
-                       src += local__utf8_to_ucs2(src, u++);
+                       s += local__utf8_to_ucs2(s, u++);
        }
 
        return out;
@@ -148,7 +186,7 @@ static char *local__convert_ucs2_to_utf8(const FLAC__uint16 *src, unsigned lengt
 
        /* convert */
        {
-               char *u = out;
+               unsigned char *u = (unsigned char *)out;
                for ( ; *src; src++)
                        u += local__ucs2_to_utf8(*src, u);
                local__ucs2_to_utf8(*src, u);
@@ -226,7 +264,7 @@ void FLAC_plugin__tags_destroy(FLAC__StreamMetadata **tags)
 const char *FLAC_plugin__tags_get_tag_utf8(const FLAC__StreamMetadata *tags, const char *name)
 {
        const int i = FLAC__metadata_object_vorbiscomment_find_entry_from(tags, /*offset=*/0, name);
-       return (i < 0? 0 : strchr(tags->data.vorbis_comment.comments[i].entry, '=')+1);
+       return (i < 0? 0 : strchr((const char *)tags->data.vorbis_comment.comments[i].entry, '=')+1);
 }
 
 FLAC__uint16 *FLAC_plugin__tags_get_tag_ucs2(const FLAC__StreamMetadata *tags, const char *name)