Re: [PATCH 2/3] conf: Split add_dns{4,6}() out of get_dns()

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

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On Thu, Feb 23, 2023 at 06:07:59PM +0100, Stefano Brivio wrote:
> The logic handling which resolvers we add, and whether to add them,
> is getting rather cramped in get_dns(): split it into separate
> functions.
> 
> No functional changes intended.
> 
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

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

> ---
>  conf.c | 86 ++++++++++++++++++++++++++++++++++------------------------
>  1 file changed, 51 insertions(+), 35 deletions(-)
> 
> diff --git a/conf.c b/conf.c
> index 4dc0660..ed25e35 100644
> --- a/conf.c
> +++ b/conf.c
> @@ -382,6 +382,53 @@ bind_fail:
>  	die("Failed to bind any port for '-%c %s', exiting", optname, optarg);
>  }
>  
> +/**
> + * add_dns4() - Possibly add the IPv4 address of a DNS resolver to configuration
> + * @c:		Execution context
> + * @addr:	Address found in /etc/resolv.conf
> + * @conf:	Pointer to reference of current entry in array of IPv4 resolvers
> + */
> +static void add_dns4(struct ctx *c, struct in_addr *addr, struct in_addr **conf)
> +{
> +	/* Guest or container can only access local addresses via redirect */
> +	if (IN4_IS_ADDR_LOOPBACK(addr)) {
> +		if (!c->no_map_gw) {
> +			**conf = c->ip4.gw;
> +			(*conf)++;
> +		}
> +	} else {
> +		**conf = *addr;
> +		(*conf)++;
> +	}
> +
> +	if (IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_host))
> +		c->ip4.dns_host = *addr;
> +}
> +
> +/**
> + * add_dns6() - Possibly add the IPv6 address of a DNS resolver to configuration
> + * @c:		Execution context
> + * @addr:	Address found in /etc/resolv.conf
> + * @conf:	Pointer to reference of current entry in array of IPv6 resolvers
> + */
> +static void add_dns6(struct ctx *c,
> +		     struct in6_addr *addr, struct in6_addr **conf)
> +{
> +	/* Guest or container can only access local addresses via redirect */
> +	if (IN6_IS_ADDR_LOOPBACK(addr)) {
> +		if (!c->no_map_gw) {
> +			memcpy(*conf, &c->ip6.gw, sizeof(**conf));
> +			(*conf)++;
> +		}
> +	} else {
> +		memcpy(*conf, addr, sizeof(**conf));
> +		(*conf)++;
> +	}
> +
> +	if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_host))
> +		c->ip6.dns_host = *addr;
> +}
> +
>  /**
>   * get_dns() - Get nameserver addresses from local /etc/resolv.conf
>   * @c:		Execution context
> @@ -420,44 +467,13 @@ static void get_dns(struct ctx *c)
>  
>  			if (!dns4_set &&
>  			    dns4 - &c->ip4.dns[0] < ARRAY_SIZE(c->ip4.dns) - 1
> -			    && inet_pton(AF_INET, p + 1, &dns4_tmp)) {
> -				/* Guest or container can only access local
> -				 * addresses via local redirect
> -				 */
> -				if (IN4_IS_ADDR_LOOPBACK(&dns4_tmp)) {
> -					if (!c->no_map_gw) {
> -						*dns4 = c->ip4.gw;
> -						dns4++;
> -					}
> -				} else {
> -					*dns4 = dns4_tmp;
> -					dns4++;
> -				}
> -
> -				if (IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_host))
> -					c->ip4.dns_host = dns4_tmp;
> -			}
> +			    && inet_pton(AF_INET, p + 1, &dns4_tmp))
> +				add_dns4(c, &dns4_tmp, &dns4);
>  
>  			if (!dns6_set &&
>  			    dns6 - &c->ip6.dns[0] < ARRAY_SIZE(c->ip6.dns) - 1
> -			    && inet_pton(AF_INET6, p + 1, &dns6_tmp)) {
> -				/* Guest or container can only access local
> -				 * addresses via local redirect
> -				 */
> -				if (IN6_IS_ADDR_LOOPBACK(&dns6_tmp)) {
> -					if (!c->no_map_gw) {
> -						memcpy(dns6, &c->ip6.gw,
> -						       sizeof(*dns6));
> -						dns6++;
> -					}
> -				} else {
> -					memcpy(dns6, &dns6_tmp, sizeof(*dns6));
> -					dns6++;
> -				}
> -
> -				if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_host))
> -					c->ip6.dns_host = dns6_tmp;
> -			}
> +			    && inet_pton(AF_INET6, p + 1, &dns6_tmp))
> +				add_dns6(c, &dns6_tmp, &dns6);
>  		} else if (!dnss_set && strstr(line, "search ") == line &&
>  			   s == c->dns_search) {
>  			end = strpbrk(line, "\n");

-- 
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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