ossp-pkg/l2/l2_ch_filter.c
1.10
/*
** L2 - OSSP Logging Library
** Copyright (c) 2001 The OSSP Project (http://www.ossp.org/)
** Copyright (c) 2001 Cable & Wireless Deutschland (http://www.cw.com/de/)
**
** This file is part of OSSP L2, a flexible logging library which
** can be found at http://www.ossp.org/pkg/l2/.
**
** Permission to use, copy, modify, and distribute this software for
** any purpose with or without fee is hereby granted, provided that
** the above copyright notice and this permission notice appear in all
** copies.
**
** THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
** WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL THE AUTHORS AND COPYRIGHT HOLDERS AND THEIR
** CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
** USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
** OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
** OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
** SUCH DAMAGE.
**
** l2_ch_filter.c: filtering channel implementation
*/
#include "l2.h"
#include "l2_ut_pcre.h"
/* declare private channel configuration */
typedef struct {
char *szRegex;
int bNegate;
pcre *pcreRegex;
pcre_extra *pcreExtra;
} l2_ch_filter_t;
/* create channel */
static l2_result_t hook_create(l2_context_t *ctx, l2_channel_t *ch)
{
l2_ch_filter_t *cfg;
/* allocate private channel configuration */
if ((cfg = (l2_ch_filter_t *)malloc(sizeof(l2_ch_filter_t))) == NULL)
return L2_ERR_MEM;
/* initialize configuration with reasonable defaults */
cfg->szRegex = NULL;
cfg->bNegate = 0;
cfg->pcreRegex = NULL;
cfg->pcreExtra = NULL;
/* link private channel configuration into channel context */
ctx->vp = cfg;
return L2_OK;
}
/* configure channel */
static l2_result_t hook_configure(l2_context_t *ctx, l2_channel_t *ch, const char *fmt, va_list ap)
{
l2_ch_filter_t *cfg = (l2_ch_filter_t *)ctx->vp;
l2_param_t pa[3];
l2_result_t rv;
const char *szError;
int nErrorOffset;
/* feed and call generic parameter parsing engine */
L2_PARAM_SET(pa[0], regex, STRING, &cfg->szRegex);
L2_PARAM_SET(pa[1], negate, INT, &cfg->bNegate);
L2_PARAM_END(pa[2]);
if ((rv = l2_util_setparams(pa, fmt, ap)) != L2_OK)
return rv;
/* translate regular expression into finite state machine */
if (cfg->szRegex != NULL) {
/* compile regular expression into FSM */
if ((cfg->pcreRegex = pcre_compile(cfg->szRegex, 0, &szError, &nErrorOffset, NULL)) == NULL) {
l2_channel_errorinfo(ch, L2_ERR_ARG, "%s ('%c')", szError, cfg->szRegex[nErrorOffset]);
return L2_ERR_ARG;
}
/* study FSM for more performance */
cfg->pcreExtra = pcre_study(cfg->pcreRegex, 0, &szError);
if (szError != NULL) {
free(cfg->pcreRegex);
cfg->pcreRegex = NULL;
l2_channel_errorinfo(ch, L2_ERR_ARG, "%s", szError);
return L2_ERR_ARG;
}
}
return L2_OK;
}
/* write to channel */
static l2_result_t hook_write(l2_context_t *ctx, l2_channel_t *ch,
l2_level_t level, const char *buf, size_t buf_size)
{
l2_ch_filter_t *cfg = (l2_ch_filter_t *)ctx->vp;
l2_channel_t *downstream = l2_channel_downstream(ch);
l2_result_t rv;
int bPass, iCheck;
bPass = TRUE;
/* apply filter */
if (cfg->pcreRegex != NULL) {
iCheck = pcre_exec(cfg->pcreRegex, cfg->pcreExtra, buf, buf_size, 0, 0, NULL, 0);
if (iCheck >= 0)
bPass = TRUE;
else
bPass = FALSE;
if (cfg->bNegate)
bPass = !bPass;
}
/* write to downstream channel */
if (bPass)
if ((rv = l2_channel_write(downstream, level, buf, buf_size)) != L2_OK)
return rv;
return L2_OK;
}
static l2_result_t hook_destroy(l2_context_t *ctx, l2_channel_t *ch)
{
l2_ch_filter_t *cfg = (l2_ch_filter_t *)ctx->vp;
l2_channel_t *downstream = l2_channel_downstream(ch);
l2_result_t rv;
/* destroy downstream channel */
if ((rv = l2_channel_destroy(downstream)) != L2_OK)
return rv;
/* destroy channel configuration */
if (cfg->szRegex != NULL)
free(cfg->szRegex);
if (cfg->pcreRegex != NULL)
free(cfg->pcreRegex);
if (cfg->pcreExtra != NULL)
free(cfg->pcreExtra);
return L2_OK;
}
l2_handler_t l2_handler_filter = {
L2_CHANNEL_FILTER,
hook_create,
hook_configure,
NULL,
hook_write,
NULL,
NULL,
hook_destroy
};