base64 encode openssl

base64_ossl

int Base64Encode(const unsigned char *buffer, size_t length, char **output) 
{
    BIO *bio, *b64;
    BUF_MEM *ptr;

    b64 = BIO_new(BIO_f_base64());
    bio = BIO_new(BIO_s_mem());
    bio = BIO_push(b64, bio);

    BIO_set_flags(bio, BIO_FLAGS_BASE64_NO_NL);
    BIO_write(bio, buffer, length);
    BIO_flush(bio);
    BIO_get_mem_ptr(bio, &ptr);
    BIO_set_close(bio, BIO_NOCLOSE);
    BIO_free_all(bio);

    *output = (char *)zalloc(ptr->length + 1);
    memcpy(*output, ptr->data, ptr->length);
    int len = ptr->length;

    BUF_MEM_free(ptr);
    return len;
}