func_base64.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2005 - 2006, Digium, Inc.
 * Copyright (C) 2005, Claude Patry
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */
 
/*! \file
 *
 * \brief Use the base64 as functions
 *
 * \ingroup functions
 */
 
/*** MODULEINFO
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#include "asterisk/module.h"
#include "asterisk/pbx.h"   /* function register/unregister */
#include "asterisk/utils.h"
#include "asterisk/strings.h"
 
/*** DOCUMENTATION
    <function name="BASE64_ENCODE" language="en_US">
        <synopsis>
            Encode a string in base64.
        </synopsis>
        <syntax>
            <parameter name="string" required="true">
                <para>Input string</para>
            </parameter>
        </syntax>
        <description>
            <para>Returns the base64 string.</para>
        </description>
        <see-also>
            <ref type="function">BASE64_DECODE</ref>
            <ref type="function">AES_DECRYPT</ref>
            <ref type="function">AES_ENCRYPT</ref>
        </see-also>
    </function>
    <function name="BASE64_DECODE" language="en_US">
        <synopsis>
            Decode a base64 string.
        </synopsis>
        <syntax>
            <parameter name="string" required="true">
                <para>Input string.</para>
            </parameter>
        </syntax>
        <description>
            <para>Returns the plain text string.</para>
        </description>
        <see-also>
            <ref type="function">BASE64_ENCODE</ref>
            <ref type="function">AES_DECRYPT</ref>
            <ref type="function">AES_ENCRYPT</ref>
        </see-also>
    </function>
 ***/
 
static int base64_helper(struct ast_channel *chan, const char *cmd, char *data,
             char *buf, struct ast_str **str, ssize_t len)
{
    if (ast_strlen_zero(data)) {
        ast_log(LOG_WARNING, "Syntax: %s(<data>) - missing argument!\n", cmd);
        return -1;
    }
 
    if (cmd[7] == 'E') {
        if (buf) {
            ast_base64encode(buf, (unsigned char *) data, strlen(data), len);
        } else {
            if (len >= 0) {
                /* This calculation accounts for padding and the trailing 0 byte. Borrowed
                   from utils.c */
                size_t bytes_needed_to_encode_data = ((strlen(data) * 4 / 3 + 3) & ~3) + 1;
                ast_str_make_space(str, len ? len : ast_str_strlen(*str) + bytes_needed_to_encode_data);
            }
            ast_base64encode(ast_str_buffer(*str) + ast_str_strlen(*str), (unsigned char *) data, strlen(data), ast_str_size(*str) - ast_str_strlen(*str));
            ast_str_update(*str);
        }
    } else {
        int decoded_len;
        if (buf) {
            decoded_len = ast_base64decode((unsigned char *) buf, data, len);
            /* add a terminating null at the end of buf, or at the
             * end of our decoded string, which ever is less */
            buf[decoded_len <= (len - 1) ? decoded_len : len - 1] = '\0';
        } else {
            if (len >= 0) {
                ast_str_make_space(str, len ? len : ast_str_strlen(*str) + strlen(data) * 3 / 4 + 2);
            }
            decoded_len = ast_base64decode((unsigned char *) ast_str_buffer(*str) + ast_str_strlen(*str), data, ast_str_size(*str) - ast_str_strlen(*str));
            if (len)
                /* add a terminating null at the end of our
                 * buffer, or at the end of our decoded string,
                 * which ever is less */
                ast_str_buffer(*str)[decoded_len <= (len - 1) ? decoded_len : len - 1] = '\0';
            else
                /* space for the null is allocated above */
                ast_str_buffer(*str)[decoded_len] = '\0';
 
            ast_str_update(*str);
        }
    }
 
    return 0;
}
 
static int base64_buf_helper(struct ast_channel *chan, const char *cmd, char *data,
             char *buf, size_t len)
{
    return base64_helper(chan, cmd, data, buf, NULL, len);
}
 
static int base64_str_helper(struct ast_channel *chan, const char *cmd, char *data,
             struct ast_str **buf, ssize_t len)
{
    return base64_helper(chan, cmd, data, NULL, buf, len);
}
 
static struct ast_custom_function base64_encode_function = {
    .name = "BASE64_ENCODE",
    .read = base64_buf_helper,
    .read2 = base64_str_helper,
};
 
static struct ast_custom_function base64_decode_function = {
    .name = "BASE64_DECODE",
    .read = base64_buf_helper,
    .read2 = base64_str_helper,
};
 
static int unload_module(void)
{
    return ast_custom_function_unregister(&base64_encode_function) |
        ast_custom_function_unregister(&base64_decode_function);
}
 
static int load_module(void)
{
    return ast_custom_function_register(&base64_encode_function) |
        ast_custom_function_register(&base64_decode_function);
}
 
AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "base64 encode/decode dialplan functions");