From: Omar Polo <op@omarpolo.com>
Subject: Re: fix spurious flush packet error from gotsh
To: Stefan Sperling <stsp@stsp.name>
Cc: gameoftrees@openbsd.org
Date: Wed, 18 Jan 2023 18:42:25 +0100

On 2023/01/18 18:19:47 +0100, Stefan Sperling <stsp@stsp.name> wrote:
> This fixes the spurious "gotsh: unexpected flush packet" error
> which sometimes shows up when a client trying to fetch changes
> is already up-to-date.
> 
> Still explicitly check for a zero-length packet with a payload
> to keep test_request_bad_length_zero passing.
> 
> ok?

reads fine, ok for me

> diff 05594ba5c50d7a7b10882b9504d75bdd5df348a3 dd990646894efbf02dc48384fade1054276c5521
> commit - 05594ba5c50d7a7b10882b9504d75bdd5df348a3
> commit + dd990646894efbf02dc48384fade1054276c5521
> blob - 02c4cb511fe756c9101538c93243233f34941dd2
> blob + ff9cd1e8a402bfed028e0aa1db7d6cf94c159eb4
> --- lib/serve.c
> +++ lib/serve.c
> @@ -898,13 +898,36 @@ serve_read(int infd, int outfd, int gotd_sock, const c
>  		if (err)
>  			break;
>  		if (n == 0) {
> -			if (curstate != STATE_EXPECT_MORE_WANT &&
> +			if (curstate != STATE_EXPECT_WANT &&
> +			    curstate != STATE_EXPECT_MORE_WANT &&
>  			    curstate != STATE_EXPECT_HAVE &&
>  			    curstate != STATE_EXPECT_DONE) {
>  				err = got_error_msg(GOT_ERR_BAD_PACKET,
>  				    "unexpected flush packet received");
>  				goto done;
>  			}
> +
> +			if (curstate == STATE_EXPECT_WANT) {
> +				ssize_t r;
> +				/*
> +				 * If the client does not want to fetch
> +				 * anything we should receive a flush
> +				 * packet followed by EOF.
> +				 */
> +				r = read(infd, buf, sizeof(buf));
> +				if (r == -1) {
> +					err = got_error_from_errno("read");
> +					goto done;
> +				}
> +				if (r == 0) /* EOF */
> +					goto done;
> +
> +				/* Zero-length field followed by payload. */
> +				err = got_error_msg(GOT_ERR_BAD_PACKET,
> +				    "unexpected flush packet received");
> +				goto done;
> +			}
> +
>  			err = forward_flushpkt(&ibuf);
>  			if (err)
>  				goto done;