ubase64.c

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// SPDX-FileCopyrightText: 2017-2021 pancake <pancake@nopcode.org>
// SPDX-License-Identifier: LGPL-3.0-only
 
/* Original code from:
 * dmc - dynamic mail client -- author: pancake
 * See LICENSE file for copyright and license details.
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <rz_util.h>
 
#define SZ 1024
static const char cb64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static const char cd64[] = "|$$$}rstuvwxyz{$$$$$$$>?@ABCDEFGHIJKLMNOPQRSTUVW$$$$$$XYZ[\\]^_`abcdefghijklmnopq";
 
static void local_b64_encode(const ut8 in[3], char out[4], int len) {
    if (len < 1) {
        return;
    }
    out[0] = cb64[in[0] >> 2];
    out[1] = cb64[((in[0] & 0x03) << 4) | ((len > 1) ? ((in[1] & 0xf0) >> 4) : 0)];
    out[2] = (len > 1 ? cb64[((in[1] & 0x0f) << 2) | (len > 2 ? ((in[2] & 0xc0) >> 6) : 0)] : '=');
    out[3] = (len > 2 ? cb64[in[2] & 0x3f] : '=');
}
 
static int local_b64_decode(const char in[4], ut8 out[3]) {
    int len = 3;
    ut8 i, v[4] = { 0 };
    for (i = 0; i < 4; i++) {
        if (in[i] < 43 || in[i] > 122) {
            return -1;
        }
        v[i] = cd64[in[i] - 43];
        if (v[i] == '$') {
            len = i ? i - 1 : -1;
            break;
        }
        v[i] -= 62;
    }
    out[0] = v[0] << 2 | v[1] >> 4;
    out[1] = v[1] << 4 | v[2] >> 2;
    out[2] = ((v[2] << 6) & 0xc0) | v[3];
    return len;
}
 
RZ_API int rz_base64_decode(ut8 *bout, const char *bin, int len) {
    int in, out;
    if (len < 0) {
        len = strlen(bin);
    }
    for (in = out = 0; in + 3 < len; in += 4) {
        int ret = local_b64_decode(bin + in, bout + out);
        if (ret < 1) {
            return -1;
        }
        out += ret;
    }
    bout[out] = 0;
    /* XXX this makes no sense, just return out? */
    return (in != out) ? out : -1;
}
 
RZ_API ut8 *rz_base64_decode_dyn(const char *in, int len) {
    ut8 *bout;
    if (!in) {
        return NULL;
    }
    if (len < 0) {
        len = strlen(in) + 1;
    }
    bout = calloc(4, len + 1);
    if (rz_base64_decode(bout, in, len) == -1) {
        free(bout);
        return NULL;
    }
    return bout;
}
 
RZ_API size_t rz_base64_encode(char *bout, const ut8 *bin, size_t sz) {
    rz_return_val_if_fail(bin, 0);
    size_t in, out;
    for (in = out = 0; in < sz; in += 3, out += 4) {
        local_b64_encode(bin + in, (char *)bout + out,
            (sz - in) > 3 ? 3 : sz - in);
    }
    bout[out] = 0;
    return out;
}
 
RZ_API char *rz_base64_encode_dyn(const ut8 *bin, size_t sz) {
    rz_return_val_if_fail(bin, NULL);
    if (sz > (SIZE_MAX - 2) / 4) {
        return NULL;
    }
    const size_t osz = (sz * 4) + 2;
    char *bout = malloc(osz);
    if (!bout) {
        return NULL;
    }
    rz_base64_encode(bout, bin, sz);
    return bout;
}