libhtp/htp/htp_transcoder.c

/***************************************************************************
 * Copyright (c) 2009-2010 Open Information Security Foundation
 * Copyright (c) 2010-2013 Qualys, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.

 * - 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.

 * - Neither the name of the Qualys, Inc. nor the names of its
 *   contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 ***************************************************************************/

/**
 * @file
 * @author Ivan Ristic <ivanr@webkreator.com>
 */

#include "htp_config_auto.h"

#include "htp_private.h"

/**
 * Transcode all parameters supplied in the table.
 *
 * @param[in] connp
 * @param[in] params
 * @param[in] destroy_old
 */
int htp_transcode_params(htp_connp_t *connp, htp_table_t **params, int destroy_old) {
    htp_table_t *input_params = *params;

    // No transcoding unless necessary
    if ((connp->cfg->internal_encoding == NULL)||(connp->cfg->request_encoding == NULL)) return HTP_OK;

    // Create a new table that will hold transcoded parameters
    htp_table_t *output_params = htp_table_create(htp_table_size(input_params));
    if (output_params == NULL) return HTP_ERROR;

    // Initialize iconv
    iconv_t cd = iconv_open(connp->cfg->internal_encoding, connp->cfg->request_encoding);
    if (cd == (iconv_t) -1) {
        htp_table_destroy(output_params);
        return HTP_ERROR;
    }

    #if (_LIBICONV_VERSION >= 0x0108 && HAVE_ICONVCTL)
    int iconv_param = 0;
    iconvctl(cd, ICONV_SET_TRANSLITERATE, &iconv_param);
    iconv_param = 1;
    iconvctl(cd, ICONV_SET_DISCARD_ILSEQ, &iconv_param);
    #endif

    // Convert the parameters, one by one
    bstr *name = NULL;
    bstr *value = NULL;
    for (int i = 0, n = htp_table_size(input_params); i < n; i++) {
        value = htp_table_get_index(input_params, i, &name);

        bstr *new_name = NULL, *new_value = NULL;

        // Convert name
        htp_transcode_bstr(cd, name, &new_name);
        if (new_name == NULL) {
            iconv_close(cd);

            bstr *b = NULL;
            for (int j = 0, k = htp_table_size(output_params); j < k; j++) {
                b = htp_table_get_index(output_params, j, NULL);
                bstr_free(b);
            }

            htp_table_destroy(output_params);
            return HTP_ERROR;
        }

        // Convert value
        htp_transcode_bstr(cd, value, &new_value);
        if (new_value == NULL) {
            bstr_free(new_name);
            iconv_close(cd);

            bstr *b = NULL;
            for (int j = 0, k = htp_table_size(output_params); j < k; j++) {
                b = htp_table_get_index(output_params, j, NULL);
                bstr_free(b);
            }

            htp_table_destroy(output_params);
            return HTP_ERROR;
        }

        // Add to new table
        htp_table_addn(output_params, new_name, new_value);
    }

    // Replace the old parameter table
    *params = output_params;

    // Destroy the old parameter table if necessary
    if (destroy_old) {
        bstr *b = NULL;
        for (int i = 0, n = htp_table_size(input_params); i < n; i++) {
            b = htp_table_get_index(input_params, i, NULL);
            bstr_free(b);
        }

        htp_table_destroy(input_params);
    }

    iconv_close(cd);

    return HTP_OK;
}

/**
 * Transcode one bstr.
 *
 * @param[in] cd
 * @param[in] input
 * @param[in] output
 */
int htp_transcode_bstr(iconv_t cd, bstr *input, bstr **output) {
    // Reset conversion state for every new string
    iconv(cd, NULL, 0, NULL, 0);

    bstr_builder_t *bb = NULL;

    const size_t buflen = 10;
    unsigned char *buf = malloc(buflen);
    if (buf == NULL) {
        return HTP_ERROR;
    }

    const char *inbuf = (const char *)bstr_ptr(input);
    size_t inleft = bstr_len(input);
    char *outbuf = (char *)buf;
    size_t outleft = buflen;

    int loop = 1;
    while (loop) {
        loop = 0;

        if (iconv(cd, (ICONV_CONST char **)&inbuf, &inleft, (char **)&outbuf, &outleft) == (size_t) - 1) {
            if (errno == E2BIG) {
                // Create bstr builder on-demand
                if (bb == NULL) {
                    bb = bstr_builder_create();
                    if (bb == NULL) {
                        free(buf);
                        return HTP_ERROR;
                    }
                }

                // The output buffer is full
                bstr_builder_append_mem(bb, buf, buflen - outleft);

                outbuf = (char *)buf;
                outleft = buflen;

                // Continue in the loop, as there's more work to do
                loop = 1;
            } else {
                // Error
                if (bb != NULL) bstr_builder_destroy(bb);
                free(buf);
                return HTP_ERROR;
            }
        }
    }

    if (bb != NULL) {
        bstr_builder_append_mem(bb, buf, buflen - outleft);
        *output = bstr_builder_to_str(bb);
        bstr_builder_destroy(bb);
        if (*output == NULL) {
            free(buf);
            return HTP_ERROR;
        }
    } else {
        *output = bstr_dup_mem(buf, buflen - outleft);
        if (*output == NULL) {
            free(buf);
            return HTP_ERROR;
        }
    }

    free(buf);

    return HTP_OK;
}