A string is rewritten according to a set of rules, called a `rewrite
context'.
The rules are based on Regular Expressions (POSIX regex) with
-substring matching; extensions are planned to allow basic variable
-substitution and map resolution of substrings.
+substring matching; basic variable substitution and map resolution
+of substrings is allowed by specific mechanisms detailed in the following.
The behavior of pattern matching/substitution can be altered by a set
of flags.
.LP
for the slapd server (initially dedicated to the LDAP backend).
.SH Passes
An incoming string is matched agains a set of rules.
-Rules are made of a match pattern, a substitution pattern and a set of
-actions.
+Rules are made of a regex match pattern, a substitution pattern
+and a set of actions, described by a set of flags.
In case of match a string rewriting is performed according to the
substitution pattern that allows to refer to substrings matched in the
incoming string.
The actions, if any, are finally performed.
The substitution pattern allows map resolution of substrings.
A map is a generic object that maps a substitution pattern to a value.
+The flags are divided in "Pattern matching Flags" and "Action Flags";
+the former alter the regex match pattern behaviorm while the latter
+alter the action that is taken after substitution.
.SH "Pattern Matching Flags"
.TP
.B `C'
.TP
.B `R'
use POSIX Basic Regular Expressions (default is Extended)
+.TP
+.B `M{n}'
+allow no more than
+.B n
+recursive passes for a specific rule; does not alter the max total count
+of passes, so it can only enforce a stricter limit for a specific rule.
.SH "Action Flags"
.TP
.B `:'
By convention, the freely available codes are above 16 included;
the others are reserved.
.LP
-The ordering of the flags is significant.
+The ordering of the flags can be significant.
For instance: `IG{2}' means ignore errors and jump two lines ahead
both in case of match and in case of error, while `G{2}I' means ignore
errors, but jump two lines ahead only in case of match.
it will result in accessing the aliased one.
.TP
.B rewriteRule "<regex match pattern>" "<substitution pattern>" "[ <flags> ]"
-Determines how a tring can be rewritten if a pattern is matched.
+Determines how a string can be rewritten if a pattern is matched.
Examples are reported below.
.SH "Additional configuration syntax:"
.TP
Sets a value with global scope, that can be dereferenced by the
command `%{$paramName}'.
.TP
-.B rewriteMaxPasses <number of passes>
+.B rewriteMaxPasses <number of passes> [<number of passes per rule>]
Sets the maximum number of total rewriting passes that can be
performed in a single rewrite operation (to avoid loops).
+A safe default is set to 100; note that reaching this limit is still
+treated as a success; recursive invocation of rules is simply
+interrupted.
+The count applies to the rewriting operation as a whole, not
+to any single rule; an optional per-rule limit can be set.
+This limit is overridden by setting specific per-rule limits
+with the `M{n}' flag.
.SH "Configuration examples:"
.nf
# set to `off' to disable rewriting
* lines handled are of the form:
*
* rewriteEngine {on|off}
- * rewriteMaxPasses numPasses
+ * rewriteMaxPasses numPasses [numPassesPerRule]
* rewriteContext contextName [alias aliasedContextName]
* rewriteRule pattern substPattern [ruleFlags]
* rewriteMap mapType mapName [mapArgs]
fname, lineno, "" );
return -1;
}
+
info->li_max_passes = atoi( argv[ 1 ] );
+ if ( info->li_max_passes <= 0 ) {
+ Debug( LDAP_DEBUG_ANY,
+ "[%s:%d] negative or null rewriteMaxPasses'\n",
+ fname, lineno, 0 );
+ }
+
+ if ( argc > 2 ) {
+ info->li_max_passes_per_rule = atoi( argv[ 2 ] );
+ if ( info->li_max_passes_per_rule <= 0 ) {
+ Debug( LDAP_DEBUG_ANY,
+ "[%s:%d] negative or null rewriteMaxPassesPerRule'\n",
+ fname, lineno, 0 );
+ }
+
+ } else {
+ info->li_max_passes_per_rule = info->li_max_passes;
+ }
rc = REWRITE_SUCCESS;
/*
info->li_state = REWRITE_DEFAULT;
info->li_max_passes = REWRITE_MAX_PASSES;
+ info->li_max_passes_per_rule = REWRITE_MAX_PASSES;
info->li_rewrite_mode = mode;
/*
#define REWRITE_FLAG_UNWILLING '#'
#define REWRITE_FLAG_GOTO 'G' /* requires an arg */
#define REWRITE_FLAG_USER 'U' /* requires an arg */
+#define REWRITE_FLAG_MAX_PASSES 'M' /* requires an arg */
#define REWRITE_FLAG_IGNORE_ERR 'I'
/*
#define REWRITE_RECURSE 0x0001
#define REWRITE_EXEC_ONCE 0x0002
int lr_mode;
+ int lr_max_passes;
struct rewrite_action *lr_action;
};
*/
#define REWRITE_MAXPASSES 100
int li_max_passes;
+ int li_max_passes_per_rule;
/*
* Behavior in case a NULL or non-existent context is required
{
int flags = REWRITE_REGEX_EXTENDED | REWRITE_REGEX_ICASE;
int mode = REWRITE_RECURSE;
+ int max_passes = info->li_max_passes_per_rule;
struct rewrite_rule *rule = NULL;
struct rewrite_subst *subst = NULL;
break;
}
+ case REWRITE_FLAG_MAX_PASSES: { /* 'U' */
+ /*
+ * Set the number of max passes per rule
+ */
+ char *next = NULL;
+
+ if ( p[ 1 ] != '{' ) {
+ /* XXX Need to free stuff */
+ return REWRITE_ERR;
+ }
+
+ max_passes = strtol( &p[ 2 ], &next, 0 );
+ if ( next == NULL || next == &p[ 2 ] || next[0] != '}' ) {
+ /* XXX Need to free stuff */
+ return REWRITE_ERR;
+ }
+
+ if ( max_passes < 1 ) {
+ /* FIXME: nonsense ... */
+ max_passes = 1;
+ }
+
+ p = next; /* p is incremented by the for ... */
+
+ break;
+ }
+
case REWRITE_FLAG_IGNORE_ERR: /* 'I' */
/*
* Ignore errors!
*/
rule->lr_flags = flags; /* don't really need any longer ... */
rule->lr_mode = mode;
+ rule->lr_max_passes = max_passes;
rule->lr_action = first_action;
/*
recurse:;
Debug( LDAP_DEBUG_TRACE, "==> rewrite_rule_apply"
- " rule='%s' string='%s'\n",
- rule->lr_pattern, string, 0 );
+ " rule='%s' string='%s' [%s pass(es)]\n",
+ rule->lr_pattern, string, strcnt + 1 );
op->lo_num_passes++;
if ( regexec( &rule->lr_regex, string, nmatch, match, 0 ) != 0 ) {
}
if ( ( rule->lr_mode & REWRITE_RECURSE ) == REWRITE_RECURSE
- && op->lo_num_passes <= info->li_max_passes ) {
+ && op->lo_num_passes < info->li_max_passes
+ && ++strcnt < rule->lr_max_passes ) {
string = *result;
- strcnt++;
goto recurse;
}
projects / openldap / commitdiff