/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000-2004 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * 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 APACHE SOFTWARE FOUNDATION OR
 * ITS 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * Portions of this software are based upon public domain software
 * originally written at the National Center for Supercomputing Applications,
 * University of Illinois, Urbana-Champaign.
 */

#include "httpd.h"
#include "http_config.h"
#include "http_log.h"

static char *log_fname;
static char *local_addr;
static char *remote_addr;
static char *request_plus_headers;
static char buffer[2048];

static void exception_hook(ap_exception_info_t *ei)
{
    int msg_len;
    int logfd;
    char msg_prefix[40];
    time_t now;
    char *newline;
    const char *separator = "\n-----\n";

    time(&now);
    ap_snprintf(msg_prefix, sizeof msg_prefix,
                "[%s pid %ld",
                asctime(localtime(&now)),
                (long)getpid());
    newline = strchr(msg_prefix, '\n'); /* dang asctime() */
    if (newline) {                      /* silly we are */
        *newline = ']';
    }

    if (log_fname) {
        logfd = open(log_fname, O_WRONLY|O_APPEND|O_CREAT, 0644);
        if (logfd == -1) {
            logfd = 2; /* unix, so fd 2 is the web server error log */
            ap_snprintf(buffer, sizeof buffer,
                        "%s error %d opening %s\n",
                        msg_prefix, errno, log_fname);
            write(logfd, buffer, strlen(buffer));
        }
    }
    else {
        logfd = 2;
    }

    msg_len = ap_snprintf(buffer, sizeof buffer,
                          "%s sig %d crash\n",
                          msg_prefix, ei->sig);
    write(logfd, buffer, msg_len);

    if (local_addr) {
        msg_len = ap_snprintf(buffer, sizeof buffer,
                              "%s active connection: %s->%s\n",
                              msg_prefix, remote_addr, local_addr);
    }
    else {
        msg_len = ap_snprintf(buffer, sizeof buffer,
                              "%s no active connection at crash\n",
                              msg_prefix);
    }

    write(logfd, buffer, msg_len);

    if (request_plus_headers) {
        msg_len = ap_snprintf(buffer, sizeof buffer,
                              "%s active request:\n",
                              msg_prefix);
        write(logfd, buffer, msg_len);
        write(logfd, request_plus_headers, strlen(request_plus_headers));
        write(logfd, separator, strlen(separator));
    }
    else {
        msg_len = ap_snprintf(buffer, sizeof buffer,
                              "%s no request active at crash\n",
                              msg_prefix);
        write(logfd, buffer, msg_len);
        write(logfd, separator, strlen(separator));
    }
}

static void init(server_rec *s, pool *p)
{
    int rc = ap_add_fatal_exception_hook(exception_hook);

    if (rc) {
        ap_log_error(APLOG_MARK, APLOG_ALERT|APLOG_NOERRNO, s,
                     "fatal exception hooks are not enabled; please "
                     "enable them with EnableExceptionHook directive "
                     "or disable mod_whatkilledus_13");
    }
}

static void clear_conn_info(void *ignored)
{
    local_addr = remote_addr = NULL;
}

static void save_conn_info(request_rec *r)
{
    conn_rec *c = r->connection;
    local_addr =  ap_psprintf(c->pool, "%pI", &c->local_addr);
    remote_addr = ap_psprintf(c->pool, "%pI", &c->remote_addr);

    ap_register_cleanup(c->pool, NULL, clear_conn_info, ap_null_cleanup);
}

static void clear_req_info(void *ignored)
{
    request_plus_headers = NULL;
}

#define FIELD_SEPARATOR   "|"
#define KEYVAL_SEPARATOR  ":"

static int count_headers(void *in_len, const char *key, const char *value)
{
    int *len = in_len;

    *len += strlen(FIELD_SEPARATOR);
    *len += strlen(key);
    *len += strlen(KEYVAL_SEPARATOR);
    *len += strlen(value);

    return 1;
}

static int copy_headers(void *in_ch, const char *key, const char *value)
{
    char **ch = in_ch;

    strcpy(*ch, FIELD_SEPARATOR);
    *ch += strlen(FIELD_SEPARATOR);

    strcpy(*ch, key);
    *ch += strlen(key);

    strcpy(*ch, KEYVAL_SEPARATOR);
    *ch += strlen(KEYVAL_SEPARATOR);

    strcpy(*ch, value);
    *ch += strlen(value);

    return 1;
}

static void save_req_info(request_rec *r)
{
    /* to save for the request:
     * r->the_request + 
     * foreach header:
     *   '|' + header field
     */
    int len = strlen(r->the_request);
    char *ch;
    ap_table_do(count_headers, &len, r->headers_in, NULL);

    request_plus_headers = ap_palloc(r->pool, len + 1);
    ch = request_plus_headers;
    strcpy(ch, r->the_request);
    ch += strlen(ch);

    ap_table_do(copy_headers, &ch, r->headers_in, NULL);

    ap_assert(ch == request_plus_headers + len);

    ap_register_cleanup(r->pool, NULL, clear_req_info, ap_null_cleanup);
}

static int post_read(request_rec *r)
{
    /* save whatever info, like client, which vhost, which port
     * (to know SSL or not), etc.
     */
    if (!local_addr) { /* first request on this connection */
        save_conn_info(r);
    }

    save_req_info(r);

    return DECLINED;
}

static const char *cmd_file(cmd_parms *cmd, void *dconf, char *fname)
{
    log_fname = ap_pstrdup(cmd->pool, fname);
    return NULL;
}

static const command_rec command_table[] = {
    {
        "WKUFile", cmd_file, NULL, RSRC_CONF, TAKE1, "the filename of the mod_whatkilledus_13 logfile"
    }
    ,
    {
        NULL
    }
};

module MODULE_VAR_EXPORT whatkilledus_13_module = {
    STANDARD_MODULE_STUFF,
    init,                       /* initializer */
    NULL,                       /* create per-dir config */
    NULL,                       /* merge per-dir config */
    NULL,                       /* server config */
    NULL,                       /* merge server config */
    command_table,              /* command table */
    NULL,                       /* handlers */
    NULL,                       /* filename translation */
    NULL,                       /* check_user_id */
    NULL,                       /* check auth */
    NULL,                       /* check access */
    NULL,                       /* type_checker */
    NULL,                       /* fixups */
    NULL,                       /* logger */
    NULL,                       /* header parser */
    NULL,                       /* child_init */
    NULL,                       /* child_exit */
    post_read                   /* post read-request */
};