static int uhash()

in umac.c [1124:1167]

• 33 lines of code
• 5 McCabe index (conditional complexity)

static int uhash(uhash_ctx_t ahc, u_char *msg, long len, u_char *res)
/* assumes that msg is in a writable buffer of length divisible by */
/* L1_PAD_BOUNDARY. Bytes beyond msg[len] may be zeroed.           */
{
    UINT8 nh_result[STREAMS*sizeof(UINT64)];
    UINT32 nh_len;
    int extra_zeroes_needed;

    /* If the message to be hashed is no longer than L1_HASH_LEN, we skip
     * the polyhash.
     */
    if (len <= L1_KEY_LEN) {
	if (len == 0)                  /* If zero length messages will not */
		nh_len = L1_PAD_BOUNDARY;  /* be seen, comment out this case   */
	else
		nh_len = ((len + (L1_PAD_BOUNDARY - 1)) & ~(L1_PAD_BOUNDARY - 1));
        extra_zeroes_needed = nh_len - len;
        zero_pad((UINT8 *)msg + len, extra_zeroes_needed);
        nh(&ahc->hash, (UINT8 *)msg, nh_len, len, nh_result);
        ip_short(ahc,nh_result, res);
    } else {
        /* Otherwise, we hash each L1_KEY_LEN chunk with NH, passing the NH
         * output to poly_hash().
         */
        do {
            nh(&ahc->hash, (UINT8 *)msg, L1_KEY_LEN, L1_KEY_LEN, nh_result);
            poly_hash(ahc,(UINT32 *)nh_result);
            len -= L1_KEY_LEN;
            msg += L1_KEY_LEN;
        } while (len >= L1_KEY_LEN);
        if (len) {
            nh_len = ((len + (L1_PAD_BOUNDARY - 1)) & ~(L1_PAD_BOUNDARY - 1));
            extra_zeroes_needed = nh_len - len;
            zero_pad((UINT8 *)msg + len, extra_zeroes_needed);
            nh(&ahc->hash, (UINT8 *)msg, nh_len, len, nh_result);
            poly_hash(ahc,(UINT32 *)nh_result);
        }

        ip_long(ahc, res);
    }

    uhash_reset(ahc);
    return 1;
}