OSSP CVS Repository

ossp-pkg/l2/l2_ch_filter.c 1.9

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/*
**  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 */
        if ((cfg->pcreExtra = pcre_study(cfg->pcreRegex, 0, &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;

    bPass = TRUE;

    /* apply filter */
    if (cfg->pcreRegex != NULL && cfg->pcreExtra != NULL) {
       if (pcre_exec(cfg->pcreRegex, cfg->pcreExtra, buf, buf_size, 0, 0, NULL, 0) > 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
};

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