If two pattern classes start with the same digit and have the same number of characters, they will compare equal.

The example given in the issue report is that of [234] and [246], which have
these characteristics, yet they are clearly not equivalent.  The code still
uses these two characteristics, yet when the two scores compare equal, an
additional check will be done to compare all characters within the class to
verify equality.
(closes issue #15421)
 Reported by: jsmith
 Patches: 
       20091109__issue15421__2.diff.txt uploaded by tilghman (license 14)
 Tested by: jsmith, thedavidfactor


git-svn-id: http://svn.digium.com/svn/asterisk/branches/1.4@229360 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 36 insertions, 18 deletions

diff --git a/main/pbx.c b/main/pbx.c
index 6fe2c3c73..529899793 100644
--- a/main/pbx.c
+++ b/main/pbx.c
@@ -647,9 +647,8 @@ static void pbx_destroy(struct ast_pbx *p)
  *	   we could encode the special cases as 0xffXX where XX
  *	   is 1, 2, 3, 4 as used above.
  */
-static int ext_cmp1(const char **p)
+static int ext_cmp1(const char **p, unsigned char *bitwise)
 {
-	uint32_t chars[8];
 	int c, cmin = 0xff, count = 0;
 	const char *end;
 
@@ -658,6 +657,7 @@ static int ext_cmp1(const char **p)
 	 */
 	while ( (c = *(*p)++) && (c == ' ' || c == '-') )
 		;	/* ignore some characters */
+	memset(bitwise, 0xff, 32);
 
 	/* always return unless we have a set of chars */
 	switch (c) {
@@ -665,12 +665,19 @@ static int ext_cmp1(const char **p)
 		return 0x0000 | (c & 0xff);
 
 	case 'N':	/* 2..9 */
-		return 0x0800 | '2' ;
+		bitwise[6] = 0x01;
+		bitwise[7] = 0xfe;
+		return 0x0800 | '2';
 
 	case 'X':	/* 0..9 */
+		bitwise[5] = 0x7f;
+		bitwise[6] = 0x00;
+		bitwise[7] = 0xfe;
 		return 0x0A00 | '0';
 
 	case 'Z':	/* 1..9 */
+		bitwise[6] = 0x00;
+		bitwise[7] = 0xfe;
 		return 0x0900 | '1';
 
 	case '.':	/* wildcard */
@@ -694,22 +701,28 @@ static int ext_cmp1(const char **p)
 		return 0x40000;	/* XXX make this entry go last... */
 	}
 
-	bzero(chars, sizeof(chars));	/* clear all chars in the set */
 	for (; *p < end  ; (*p)++) {
 		unsigned char c1, c2;	/* first-last char in range */
 		c1 = (unsigned char)((*p)[0]);
 		if (*p + 2 < end && (*p)[1] == '-') { /* this is a range */
 			c2 = (unsigned char)((*p)[2]);
-			*p += 2;	/* skip a total of 3 chars */
-		} else			/* individual character */
+			*p += 2;    /* skip a total of 3 chars */
+		} else {        /* individual character */
 			c2 = c1;
-		if (c1 < cmin)
+		}
+		if (c1 < cmin) {
 			cmin = c1;
+		}
 		for (; c1 <= c2; c1++) {
-			uint32_t mask = 1 << (c1 % 32);
-			if ( (chars[ c1 / 32 ] & mask) == 0)
+			unsigned char mask = 1 << (c1 % 8);
+			/* Count the number of characters in the class, discarding duplicates. */
+			if ( (bitwise[ c1 / 8 ] & mask) == 1) {
 				count += 0x100;
-			chars[ c1 / 32 ] |= mask;
+			}
+			/*!\note If two patterns score the same, but one includes '0' (as
+			 * the lowest ASCII value in the given class) and the other does
+			 * not, then the one including '0' will compare as coming first. */
+			bitwise[ c1 / 8 ] &= ~mask;
 		}
 	}
 	(*p)++;
@@ -723,8 +736,9 @@ static int ext_cmp(const char *a, const char *b)
 {
 	/* make sure non-patterns come first.
 	 * If a is not a pattern, it either comes first or
-	 * we use strcmp to compare the strings.
+	 * we do a more complex pattern comparison.
 	 */
+	unsigned char bitwise[2][32];
 	int ret = 0;
 
 	if (a[0] != '_')
@@ -733,16 +747,20 @@ static int ext_cmp(const char *a, const char *b)
 	/* Now we know a is a pattern; if b is not, a comes first */
 	if (b[0] != '_')
 		return 1;
-#if 0	/* old mode for ext matching */
-	return strcmp(a, b);
-#endif
+
 	/* ok we need full pattern sorting routine */
-	while (!ret && a && b)
-		ret = ext_cmp1(&a) - ext_cmp1(&b);
-	if (ret == 0)
+	while (!ret && a && b) {
+		ret = ext_cmp1(&a, bitwise[0]) - ext_cmp1(&b, bitwise[1]);
+		if (ret == 0) {
+			/* Are the classes different, even though they score the same? */
+			ret = memcmp(bitwise[0], bitwise[1], 32);
+		}
+	}
+	if (ret == 0) {
 		return 0;
-	else
+	} else {
 		return (ret > 0) ? 1 : -1;
+	}
 }
 
 /*!