Re: [PATCH v4 4/9] make conf_ports() exit immediately after logging error

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Feb 15, 2023 at 03:24:32AM -0500, Laine Stump wrote:
> Rather than having conf_ports() (possibly) log an error, and then
> letting the caller log the entire usage() message and exit, just log
> the errors and exit immediately (using die()).
> 
> For some errors, conf_ports would previously not log any specific
> message, leaving it up to the user to determine the problem by
> guessing. We replace all of those silent returns with die()
> (logging a specific error), thus permitting us to make conf_ports()
> return void, which simplifies the caller.
> 
> While modifying the two callers to conf_ports() to not check for a
> return value, we can further simplify the code by removing the check
> for a non-null optarg, as that is guaranteed to never happen (due to
> prior calls to getopt_long() with "argument required" for all relevant
> options - getopt_long() would have already caught this error).
> 
> Signed-off-by: Laine Stump <laine@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  conf.c | 52 ++++++++++++++++++++++++++++------------------------
>  1 file changed, 28 insertions(+), 24 deletions(-)
> 
> diff --git a/conf.c b/conf.c
> index ad8c249..0d4ff79 100644
> --- a/conf.c
> +++ b/conf.c
> @@ -173,11 +173,9 @@ static int parse_port_range(const char *s, char **endptr,
>   * @optname:	Short option name, t, T, u, or U
>   * @optarg:	Option argument (port specification)
>   * @fwd:	Pointer to @port_fwd to be updated
> - *
> - * Return: -EINVAL on parsing error, 0 otherwise
>   */
> -static int conf_ports(const struct ctx *c, char optname, const char *optarg,
> -		      struct port_fwd *fwd)
> +static void conf_ports(const struct ctx *c, char optname, const char *optarg,
> +		       struct port_fwd *fwd)
>  {
>  	char addr_buf[sizeof(struct in6_addr)] = { 0 }, *addr = addr_buf;
>  	char buf[BUFSIZ], *spec, *ifname = NULL, *p;
> @@ -187,23 +185,32 @@ static int conf_ports(const struct ctx *c, char optname, const char *optarg,
>  
>  	if (!strcmp(optarg, "none")) {
>  		if (fwd->mode)
> -			return -EINVAL;
> +			goto mode_conflict;
> +
>  		fwd->mode = FWD_NONE;
> -		return 0;
> +		return;
>  	}
>  
>  	if (!strcmp(optarg, "auto")) {
> -		if (fwd->mode || c->mode != MODE_PASTA)
> -			return -EINVAL;
> +		if (fwd->mode)
> +			goto mode_conflict;
> +
> +		if (c->mode != MODE_PASTA)
> +			die("'auto' port forwarding is only allowed for pasta");
> +
>  		fwd->mode = FWD_AUTO;
> -		return 0;
> +		return;
>  	}
>  
>  	if (!strcmp(optarg, "all")) {
>  		unsigned i;
>  
> -		if (fwd->mode || c->mode != MODE_PASST)
> -			return -EINVAL;
> +		if (fwd->mode)
> +			goto mode_conflict;
> +
> +		if (c->mode != MODE_PASST)
> +			die("'all' port forwarding is only allowed for passt");
> +
>  		fwd->mode = FWD_ALL;
>  		memset(fwd->map, 0xff, PORT_EPHEMERAL_MIN / 8);
>  
> @@ -214,11 +221,11 @@ static int conf_ports(const struct ctx *c, char optname, const char *optarg,
>  				udp_sock_init(c, 0, AF_UNSPEC, NULL, NULL, i);
>  		}
>  
> -		return 0;
> +		return;
>  	}
>  
>  	if (fwd->mode > FWD_SPEC)
> -		return -EINVAL;
> +		die("Specific ports cannot be specified together with all/none/auto");
>  
>  	fwd->mode = FWD_SPEC;
>  
> @@ -292,7 +299,7 @@ static int conf_ports(const struct ctx *c, char optname, const char *optarg,
>  				udp_sock_init(c, 0, af, addr, ifname, i);
>  		}
>  
> -		return 0;
> +		return;
>  	}
>  
>  	/* Now process base ranges, skipping exclusions */
> @@ -339,14 +346,13 @@ static int conf_ports(const struct ctx *c, char optname, const char *optarg,
>  		}
>  	} while ((p = next_chunk(p, ',')));
>  
> -	return 0;
> +	return;
>  bad:
> -	err("Invalid port specifier %s", optarg);
> -	return -EINVAL;
> -
> +	die("Invalid port specifier %s", optarg);
>  overlap:
> -	err("Overlapping port specifier %s", optarg);
> -	return -EINVAL;
> +	die("Overlapping port specifier %s", optarg);
> +mode_conflict:
> +	die("Port forwarding mode '%s' conflicts with previous mode", optarg);
>  }
>  
>  /**
> @@ -1550,8 +1556,7 @@ void conf(struct ctx *c, int argc, char **argv)
>  
>  		if ((name == 't' && (fwd = &c->tcp.fwd_in)) ||
>  		    (name == 'u' && (fwd = &c->udp.fwd_in.f))) {
> -			if (!optarg || conf_ports(c, name, optarg, fwd))
> -				usage(argv[0]);
> +			conf_ports(c, name, optarg, fwd);
>  		}
>  	} while (name != -1);
>  
> @@ -1589,8 +1594,7 @@ void conf(struct ctx *c, int argc, char **argv)
>  
>  		if ((name == 'T' && (fwd = &c->tcp.fwd_out)) ||
>  		    (name == 'U' && (fwd = &c->udp.fwd_out.f))) {
> -			if (!optarg || conf_ports(c, name, optarg, fwd))
> -				usage(argv[0]);
> +			conf_ports(c, name, optarg, fwd);
>  		}
>  	} while (name != -1);
>  

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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