int BIO_dump_indent_cb(int (*cb) (const void *data, size_t len, void *u),
                       void *u, const char *s, int len, int indent)
{
    int ret = 0;
    char buf[288 + 1], tmp[20], str[128 + 1];
    int i, j, rows, trc;
    unsigned char ch;
    int dump_width;

    trc = 0;

#ifdef TRUNCATE
    for (; (len > 0) && ((s[len - 1] == ' ') || (s[len - 1] == '\0')); len--)
        trc++;
#endif

    if (indent < 0)
        indent = 0;
    if (indent) {
        if (indent > 128)
            indent = 128;
        memset(str, ' ', indent);
    }
    str[indent] = '\0';

    dump_width = DUMP_WIDTH_LESS_INDENT(indent);
    rows = (len / dump_width);
    if ((rows * dump_width) < len)
        rows++;
    for (i = 0; i < rows; i++) {
        OPENSSL_strlcpy(buf, str, sizeof buf);
        BIO_snprintf(tmp, sizeof tmp, "%04x - ", i * dump_width);
        OPENSSL_strlcat(buf, tmp, sizeof buf);
        for (j = 0; j < dump_width; j++) {
            if (((i * dump_width) + j) >= len) {
                OPENSSL_strlcat(buf, "   ", sizeof buf);
            } else {
                ch = ((unsigned char)*(s + i * dump_width + j)) & 0xff;
                BIO_snprintf(tmp, sizeof tmp, "%02x%c", ch,
                             j == 7 ? '-' : ' ');
                OPENSSL_strlcat(buf, tmp, sizeof buf);
            }
        }
        OPENSSL_strlcat(buf, "  ", sizeof buf);
        for (j = 0; j < dump_width; j++) {
            if (((i * dump_width) + j) >= len)
                break;
            ch = ((unsigned char)*(s + i * dump_width + j)) & 0xff;
#ifndef CHARSET_EBCDIC
            BIO_snprintf(tmp, sizeof tmp, "%c",
                         ((ch >= ' ') && (ch <= '~')) ? ch : '.');
#else
            BIO_snprintf(tmp, sizeof tmp, "%c",
                         ((ch >= os_toascii[' ']) && (ch <= os_toascii['~']))
                         ? os_toebcdic[ch]
                         : '.');
#endif
            OPENSSL_strlcat(buf, tmp, sizeof buf);
        }
        OPENSSL_strlcat(buf, "\n", sizeof buf);
        /*
         * if this is the last call then update the ddt_dump thing so that we
         * will move the selection point in the debug window
         */
        ret += cb((void *)buf, strlen(buf), u);
    }
#ifdef TRUNCATE
    if (trc > 0) {
        BIO_snprintf(buf, sizeof buf, "%s%04x - <SPACES/NULS>\n", str,
                     len + trc);
        ret += cb((void *)buf, strlen(buf), u);
    }
#endif
    return (ret);
}