implement the new sorting algorithm for extensions,

see the documentation near functions ext_cmp1() and ext_cmp().

All sorting decisions are now in one place so it is easy
to revise them.

NOTE
the major change is that now most specific patterns come first,
so there might be differences in how diaplans behave.
If you really really really need to revert to the old sorting order
while you adapt your dialplan, you can uncomment the '#if 0' line
in ext_cmp().



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@26216 65c4cc65-6c06-0410-ace0-fbb531ad65f3

pbx.c

@@ -560,6 +560,127 @@ static void pbx_destroy(struct ast_pbx *p)
 	free(p);
 }
 
+/*!
+ * \brief helper functions to sort extensions and patterns in the desired way,
+ * so that more specific patterns appear first.
+ *
+ * ext_cmp1 compares individual characters (or sets of), returning
+ * an int where bits 0-7 are the ASCII code of the first char in the set,
+ * while bit 8-15 are the cardinality of the set minus 1.
+ * This way more specific patterns (smaller cardinality) appear first.
+ * Wildcards have a special value, so that we can directly compare them to
+ * sets by subtracting the two values. In particular:
+ * 	0x000xx		one character, xx
+ * 	0x0yyxx		yy character set starting with xx
+ * 	0x10000		'.' (one or more of anything)
+ * 	0x20000		'!' (zero or more of anything)
+ * 	0x30000		NUL (end of string)
+ * 	0x40000		error in set.
+ * The pointer to the string is advanced according to needs.
+ * NOTES:
+ *	1. the empty set is equivalent to NUL.
+ *	2. given that a full set has always 0 as the first element,
+ *	   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)
+{
+	uint32_t chars[8];
+	int c, cmin = 0xff, count = 0;
+	const char *end;
+
+	/* load, sign extend and advance pointer until we find
+	 * a valid character.
+	 */
+	while ( (c = *(*p)++) && (c == ' ' || c == '-') )
+		;	/* ignore some characters */
+
+	/* always return unless we have a set of chars */
+	switch (c) {
+	default:	/* ordinary character */
+		return 0x0000 | (c & 0xff);
+
+	case 'N':	/* 2..9 */
+		return 0x0700 | '2' ;
+
+	case 'X':	/* 0..9 */
+		return 0x0900 | '0';
+
+	case 'Z':	/* 1..9 */
+		return 0x0800 | '1';
+
+	case '.':	/* wildcard */
+		return 0x10000;
+
+	case '!':	/* earlymatch */
+		return 0x20000;	/* less specific than NULL */
+
+	case '\0':	/* empty string */
+		*p = NULL;
+		return 0x30000;
+
+	case '[':	/* pattern */
+		break;
+	}
+	/* locate end of set */
+	end = strchr(*p, ']');	
+
+	if (end == NULL) {
+		ast_log(LOG_WARNING, "Wrong usage of [] in the extension\n");
+		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 */
+			c2 = c1;
+		if (c1 < cmin)
+			cmin = c1;
+		for (; c1 <= c2; c1++) {
+			uint32_t mask = 1 << (c1 % 32);
+			if ( (chars[ c1 / 32 ] & mask) == 0)
+				count += 0x100;
+			chars[ c1 / 32 ] |= mask;
+		}
+	}
+	(*p)++;
+	return count == 0 ? 0x30000 : (count | cmin);
+}
+
+/*!
+ * \brief the full routine to compare extensions in rules.
+ */
+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.
+	 */
+	int ret = 0;
+
+	if (a[0] != '_')
+		return (b[0] == '_') ? -1 : strcmp(a, 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)
+		return 0;
+	else
+		return (ret > 0) ? 1 : -1;
+}
+
 /*!
  * When looking up extensions, we can have different requests
  * identified by the 'action' argument, as follows.
@@ -4162,10 +4283,10 @@ int ast_add_extension2(struct ast_context *con,
 	} } while(0)
 
 	/*
-	 * This is a fairly complex routine.  Different extensions are kept
-	 * in order by the extension number.  Then, extensions of different
-	 * priorities (same extension) are kept in a list, according to the
-	 * peer pointer.
+	 * Sort extensions (or patterns) according to the rules indicated above.
+	 * These are implemented by the function ext_cmp()).
+	 * All priorities for the same ext/pattern/cid are kept in a list,
+	 * using the 'peer' field  as a link field..
 	 */
 	struct ast_exten *tmp, *e, *el = NULL;
 	int res;
@@ -4226,14 +4347,7 @@ int ast_add_extension2(struct ast_context *con,
 
 	ast_mutex_lock(&con->lock);
 	for (e = con->root; e; el = e, e = e->next) {   /* scan the extension list */
-		/* XXX should use ext_cmp() to sort patterns correctly */
-		/* almost strcmp, but make sure patterns are always last! */
-		if (e->exten[0] != '_' && extension[0] == '_')
-			res = -1;
-		else if (e->exten[0] == '_' && extension[0] != '_')
-			res = 1;
-		else
-			res= strcmp(e->exten, extension);
+		res = ext_cmp(e->exten, extension);
 		if (res == 0) { /* extension match, now look at cidmatch */
 			if (!e->matchcid && !tmp->matchcid)
 				res = 0;
@@ -4257,7 +4371,10 @@ int ast_add_extension2(struct ast_context *con,
 			}
 			return ret;
 	}
-	/* ok found the insertion place, right before 'e' (if any) */
+	/*
+	 * not an exact match, this is the first entry with this pattern,
+	 * so insert in the main list right before 'e' (if any)
+	 */
 	tmp->next = e;
 	if (el)
 		el->next = tmp;