static int uhash_update()

in umac.c [1045:1097]

• 38 lines of code
• 7 McCabe index (conditional complexity)

static int uhash_update(uhash_ctx_t ctx, const u_char *input, long len)
/* Given len bytes of data, we parse it into L1_KEY_LEN chunks and
 * hash each one with NH, calling the polyhash on each NH output.
 */
{
    UWORD bytes_hashed, bytes_remaining;
    UINT64 result_buf[STREAMS];
    UINT8 *nh_result = (UINT8 *)&result_buf;

    if (ctx->msg_len + len <= L1_KEY_LEN) {
        nh_update(&ctx->hash, (const UINT8 *)input, len);
        ctx->msg_len += len;
    } else {

         bytes_hashed = ctx->msg_len % L1_KEY_LEN;
         if (ctx->msg_len == L1_KEY_LEN)
             bytes_hashed = L1_KEY_LEN;

         if (bytes_hashed + len >= L1_KEY_LEN) {

             /* If some bytes have been passed to the hash function      */
             /* then we want to pass at most (L1_KEY_LEN - bytes_hashed) */
             /* bytes to complete the current nh_block.                  */
             if (bytes_hashed) {
                 bytes_remaining = (L1_KEY_LEN - bytes_hashed);
                 nh_update(&ctx->hash, (const UINT8 *)input, bytes_remaining);
                 nh_final(&ctx->hash, nh_result);
                 ctx->msg_len += bytes_remaining;
                 poly_hash(ctx,(UINT32 *)nh_result);
                 len -= bytes_remaining;
                 input += bytes_remaining;
             }

             /* Hash directly from input stream if enough bytes */
             while (len >= L1_KEY_LEN) {
                 nh(&ctx->hash, (const UINT8 *)input, L1_KEY_LEN,
                                   L1_KEY_LEN, nh_result);
                 ctx->msg_len += L1_KEY_LEN;
                 len -= L1_KEY_LEN;
                 input += L1_KEY_LEN;
                 poly_hash(ctx,(UINT32 *)nh_result);
             }
         }

         /* pass remaining < L1_KEY_LEN bytes of input data to NH */
         if (len) {
             nh_update(&ctx->hash, (const UINT8 *)input, len);
             ctx->msg_len += len;
         }
     }

    return (1);
}