modules/debugging/mod_dumpio.c

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * Originally written @ Covalent by Jim Jagielski
 */

/*
 * mod_dumpio.c:
 *  Think of this as a filter sniffer for Apache 2.x. It logs
 *  all filter data right before and after it goes out on the
 *  wire (BUT right before SSL encoded or after SSL decoded).
 *  It can produce a *huge* amount of data.
 */


#include "httpd.h"
#include "http_connection.h"
#include "http_config.h"
#include "http_core.h"
#include "http_log.h"
#include "apr_strings.h"

module AP_MODULE_DECLARE_DATA dumpio_module ;

typedef struct dumpio_conf_t {
    int enable_input;
    int enable_output;
} dumpio_conf_t;

/* consider up to 80 additional characters, and factor the longest
 * line length of all \xNN sequences; log_error cannot record more
 * than MAX_STRING_LEN characters.
 */
#define dumpio_MAX_STRING_LEN (MAX_STRING_LEN / 4 - 80)

/*
 * Workhorse function: simply log to the current error_log
 * info about the data in the bucket as well as the data itself
 */
static void dumpit(ap_filter_t *f, apr_bucket *b, dumpio_conf_t *ptr)
{
    conn_rec *c = f->c;

    ap_log_cerror(APLOG_MARK, APLOG_TRACE7, 0, c,
                  "mod_dumpio:  %s (%s-%s): %" APR_SIZE_T_FMT " bytes",
                  f->frec->name,
                  (APR_BUCKET_IS_METADATA(b)) ? "metadata" : "data",
                  b->type->name,
                  b->length) ;

    if (!(APR_BUCKET_IS_METADATA(b)))
    {
#if APR_CHARSET_EBCDIC
        char xlatebuf[dumpio_MAX_STRING_LEN + 1];
#endif
        const char *buf;
        apr_size_t nbytes;
        apr_status_t rv = apr_bucket_read(b, &buf, &nbytes, APR_BLOCK_READ);

        if (rv == APR_SUCCESS)
        {
            while (nbytes)
            {
                apr_size_t logbytes = nbytes;
                if (logbytes > dumpio_MAX_STRING_LEN)
                    logbytes = dumpio_MAX_STRING_LEN;
                nbytes -= logbytes;

#if APR_CHARSET_EBCDIC
                memcpy(xlatebuf, buf, logbytes);
                ap_xlate_proto_from_ascii(xlatebuf, logbytes);
                xlatebuf[logbytes] = '\0';
                ap_log_cerror(APLOG_MARK, APLOG_TRACE7, 0, c,
                              "mod_dumpio:  %s (%s-%s): %s", f->frec->name,
                              (APR_BUCKET_IS_METADATA(b)) ? "metadata" : "data",
                              b->type->name, xlatebuf);
#else
                /* XXX: Seriously flawed; we do not pay attention to embedded
                 * \0's in the request body, these should be escaped; however,
                 * the logging function already performs a significant amount
                 * of escaping, and so any escaping would be double-escaped.
                 * The coding solution is to throw away the current logic
                 * within ap_log_error, and introduce new vformatter %-escapes
                 * for escaping text, and for binary text (fixed len strings).
                 */
                ap_log_cerror(APLOG_MARK, APLOG_TRACE7, 0, c,
                              "mod_dumpio:  %s (%s-%s): %.*s", f->frec->name,
                              (APR_BUCKET_IS_METADATA(b)) ? "metadata" : "data",
                              b->type->name, (int)logbytes, buf);
#endif
                buf += logbytes;
            }
        }
        else {
            ap_log_cerror(APLOG_MARK, APLOG_TRACE7, rv, c,
                          "mod_dumpio:  %s (%s-%s): %s", f->frec->name,
                          (APR_BUCKET_IS_METADATA(b)) ? "metadata" : "data",
                          b->type->name, "error reading data");
        }
    }
}

#define whichmode( mode ) \
 ( (( mode ) == AP_MODE_READBYTES) ? "readbytes" : \
   (( mode ) == AP_MODE_GETLINE) ? "getline" : \
   (( mode ) == AP_MODE_EATCRLF) ? "eatcrlf" : \
   (( mode ) == AP_MODE_SPECULATIVE) ? "speculative" : \
   (( mode ) == AP_MODE_EXHAUSTIVE) ? "exhaustive" : \
   (( mode ) == AP_MODE_INIT) ? "init" : "unknown" \
 )

static int dumpio_input_filter (ap_filter_t *f, apr_bucket_brigade *bb,
    ap_input_mode_t mode, apr_read_type_e block, apr_off_t readbytes)
{

    apr_bucket *b;
    apr_status_t ret;
    conn_rec *c = f->c;
    dumpio_conf_t *ptr = f->ctx;

    ap_log_cerror(APLOG_MARK, APLOG_TRACE7, 0, c,
                  "mod_dumpio: %s [%s-%s] %" APR_OFF_T_FMT " readbytes",
                  f->frec->name,
                  whichmode(mode),
                  ((block) == APR_BLOCK_READ) ? "blocking" : "nonblocking",
                  readbytes);

    ret = ap_get_brigade(f->next, bb, mode, block, readbytes);

    if (ret == APR_SUCCESS) {
        for (b = APR_BRIGADE_FIRST(bb); b != APR_BRIGADE_SENTINEL(bb); b = APR_BUCKET_NEXT(b)) {
          dumpit(f, b, ptr);
        }
    }
    else {
        ap_log_cerror(APLOG_MARK, APLOG_TRACE7, 0, c,
                      "mod_dumpio: %s - %d", f->frec->name, ret) ;
        return ret;
    }

    return APR_SUCCESS ;
}

static int dumpio_output_filter (ap_filter_t *f, apr_bucket_brigade *bb)
{
    apr_bucket *b;
    conn_rec *c = f->c;
    dumpio_conf_t *ptr = f->ctx;

    ap_log_cerror(APLOG_MARK, APLOG_TRACE7, 0, c, "mod_dumpio: %s", f->frec->name);

    for (b = APR_BRIGADE_FIRST(bb); b != APR_BRIGADE_SENTINEL(bb); b = APR_BUCKET_NEXT(b)) {
        /*
         * If we ever see an EOS, make sure to FLUSH.
         */
        if (APR_BUCKET_IS_EOS(b)) {
            apr_bucket *flush = apr_bucket_flush_create(f->c->bucket_alloc);
            APR_BUCKET_INSERT_BEFORE(b, flush);
        }
        dumpit(f, b, ptr);
    }

    return ap_pass_brigade(f->next, bb) ;
}

static int dumpio_pre_conn(conn_rec *c, void *csd)
{
    dumpio_conf_t *ptr;

    if (!APLOGctrace7(c)) {
        /* Nothing to do below TRACE7 */
        return DECLINED;
    }

    ptr = (dumpio_conf_t *) ap_get_module_config(c->base_server->module_config,
                                                 &dumpio_module);

    if (ptr->enable_input)
        ap_add_input_filter("DUMPIO_IN", ptr, NULL, c);
    if (ptr->enable_output)
        ap_add_output_filter("DUMPIO_OUT", ptr, NULL, c);
    return OK;
}

static void dumpio_register_hooks(apr_pool_t *p)
{
/*
 * We know that SSL is CONNECTION + 5
 */
  ap_register_output_filter("DUMPIO_OUT", dumpio_output_filter,
        NULL, AP_FTYPE_CONNECTION + 3) ;

  ap_register_input_filter("DUMPIO_IN", dumpio_input_filter,
        NULL, AP_FTYPE_CONNECTION + 3) ;

  ap_hook_pre_connection(dumpio_pre_conn, NULL, NULL, APR_HOOK_MIDDLE);
}

static void *dumpio_create_sconfig(apr_pool_t *p, server_rec *s)
{
    dumpio_conf_t *ptr = apr_pcalloc(p, sizeof *ptr);
    ptr->enable_input = 0;
    ptr->enable_output = 0;
    return ptr;
}

static const char *dumpio_enable_input(cmd_parms *cmd, void *dummy, int arg)
{
    dumpio_conf_t *ptr = ap_get_module_config(cmd->server->module_config,
                                              &dumpio_module);

    ptr->enable_input = arg;
    return NULL;
}

static const char *dumpio_enable_output(cmd_parms *cmd, void *dummy, int arg)
{
    dumpio_conf_t *ptr = ap_get_module_config(cmd->server->module_config,
                                              &dumpio_module);

    ptr->enable_output = arg;
    return NULL;
}

static const command_rec dumpio_cmds[] = {
    AP_INIT_FLAG("DumpIOInput", dumpio_enable_input, NULL,
                 RSRC_CONF, "Enable I/O Dump on Input Data"),
    AP_INIT_FLAG("DumpIOOutput", dumpio_enable_output, NULL,
                 RSRC_CONF, "Enable I/O Dump on Output Data"),
    { NULL }
};

AP_DECLARE_MODULE(dumpio) = {
        STANDARD20_MODULE_STUFF,
        NULL,                   /* create per-dir    config structures */
        NULL,                   /* merge  per-dir    config structures */
        dumpio_create_sconfig,  /* create per-server config structures */
        NULL,                   /* merge  per-server config structures */
        dumpio_cmds,            /* table of config file commands       */
        dumpio_register_hooks   /* register hooks                      */
};