Re: [PATCH v2 4/9] make conf_ports() exit immediately after logging error

[Stefano Brivio <sbrivio@redhat.com>]

On Wed,  8 Feb 2023 12:48:33 -0500
Laine Stump <laine@redhat.com> wrote:

> Rather than having conf_ports() (possibly) log an error, and then let
> the caller log the entire usage() message and exit, just log the error
> and exit immediately.
> 
> 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 errexit()
> (logging a specific error), thus permitting us to make conf_ports()
> return void, which simplifies the caller.
> 
> We can further simplify the two callers to conf_ports by moving the
> check for a missing argument to the port options into conf_ports
> itself, and make it more useful by again logging an informative error
> for missing option instead of the generic usage() message.
> 
> Signed-off-by: Laine Stump <laine@redhat.com>
> ---
>  conf.c | 55 +++++++++++++++++++++++++++++++------------------------
>  1 file changed, 31 insertions(+), 24 deletions(-)
> 
> diff --git a/conf.c b/conf.c
> index e5035f7..799b9ff 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;
> @@ -185,25 +183,37 @@ static int conf_ports(const struct ctx *c, char optname, const char *optarg,
>  	sa_family_t af = AF_UNSPEC;
>  	bool exclude_only = true;
>  
> +	if (!optarg)
> +		errexit("missing argument to -%s option", optname);

This can't happen, as all the options relevant to this function are
passed to getopt_long() with 'required_argument'. I see there's a
check on !optarg in the caller, but I think you can skip it.

> +
>  	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)
> +			errexit("'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)
> +			errexit("'all' port forwarding is only allowed for passt");
> +
>  		fwd->mode = FWD_ALL;
>  		memset(fwd->map, 0xff, PORT_EPHEMERAL_MIN / 8);
>  
> @@ -214,11 +224,11 @@ 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;
> +		errexit("specific ports cannot be specified together with all/none/auto");

s/specific/Specific/, for consistency.

>  
>  	fwd->mode = FWD_SPEC;
>  
> @@ -292,7 +302,7 @@ 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 +349,13 @@ 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;
> -
> +	errexit("Invalid port specifier %s", optarg);
>  overlap:
> -	err("Overlapping port specifier %s", optarg);
> -	return -EINVAL;
> +	errexit("Overlapping port specifier %s", optarg);
> +mode_conflict:
> +	errexit("Port forwarding mode '%s' conflicts with previous mode", optarg);

Split before 'optarg'.

>  }
>  
>  /**
> @@ -1549,8 +1558,7 @@ 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);
>  
> @@ -1588,8 +1596,7 @@ 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);
>  

-- 
Stefano