stl_string calc_mac (DnsRR &tsig_rr, message_buff msg, stl_string sign_key, message_buff *extra) {
struct hmac_md5_ctx md5;
unsigned char md5res [MD5_DIGEST_SIZE];
memset (&md5, 0, sizeof (hmac_md5_ctx));
unsigned char *digestpos = rr_getdata (tsig_rr.RDATA, DNS_TYPE_TSIG, 3);
uint16_t digestlen = uint16_value (digestpos);
// print_buff (sign_key.size(), (unsigned char*)sign_key.c_str());
hmac_md5_set_key(&md5, sign_key.size(), (uint8_t *)sign_key.c_str());
// printf ("Begin MAC calculation\n");
/* original MAC */
if (extra && extra->len) hmac_md5_update(&md5, extra->len, extra->msg);
/* message */
hmac_md5_update(&md5, 10, msg.msg);
hmac_md5_update(&md5, 2, uint16_buff (uint16_value (msg.msg + 10) - 1));
hmac_md5_update(&md5, msg.len - 12, msg.msg + 12);
/* tsig rr */
stl_string canname = tsig_rr.NAME.canonical();
hmac_md5_update(&md5, canname.size(), (const uint8_t *)canname.c_str());
hmac_md5_update(&md5, 2, uint16_buff (QCLASS_ANY));
hmac_md5_update(&md5, 4, uint32_buff (0));
/* start of TSIG rrdata */
domainname dom = domainname (true, tsig_rr.RDATA);
canname = dom.canonical();
hmac_md5_update (&md5, canname.size(), (const uint8_t*)canname.c_str());
hmac_md5_update(&md5, 8, digestpos - 8);
/* rest, excluding original ID */
hmac_md5_update(&md5, tsig_rr.RDLENGTH - (digestpos - tsig_rr.RDATA) - digestlen - 4,
digestpos + digestlen + 4);
hmac_md5_digest(&md5, MD5_DIGEST_SIZE, md5res);
// printf ("End MAC calculation\n");
// print_buff (MD5_DIGEST_SIZE, md5res);
stl_string ret;
ret.append ((char*)md5res, MD5_DIGEST_SIZE);
return ret;
}
term_t cbif_md5_mac_n3(proc_t *proc, term_t *regs)
{
term_t Key = regs[0];
term_t Data = regs[1];
term_t Size = regs[2];
if (!is_list(Key) && !is_boxed_binary(Key))
badarg(Key);
if (!is_list(Data) && !is_boxed_binary(Data))
badarg(Data);
if (!is_int(Size))
badarg(Size);
int trunc_size = int_value(Size);
if (trunc_size < 1 || trunc_size > MD5_DIGEST_SIZE)
badarg(Size);
int key_size = iolist_size(Key);
if (key_size < 0)
badarg(Key);
assert(key_size <= 65536); // TODO: use heap_tmp_buf for a longer Key
uint8_t key_buf[key_size];
iolist_flatten(Key, key_buf);
int data_size = iolist_size(Data);
if (data_size < 0)
badarg(Data);
assert(data_size <= 65536); // TODO: use heap_tmp_buf for larger Data
uint8_t data_buf[data_size];
iolist_flatten(Data, data_buf);
struct hmac_md5_ctx ctx;
hmac_md5_set_key(&ctx, key_size, key_buf);
hmac_md5_update(&ctx, data_size, data_buf);
uint8_t *ptr;
term_t mac = heap_make_bin(&proc->hp, trunc_size, &ptr);
hmac_md5_digest(&ctx, trunc_size, ptr);
return mac;
}
