From: David Gibson <david@gibson.dropbear.id.au>
To: Stefano Brivio <sbrivio@redhat.com>
Cc: passt-dev@passt.top
Subject: Re: [PATCH] conf, udp: Drop mostly duplicated dns_send arrays, rename related fields
Date: Tue, 15 Nov 2022 13:36:23 +1100 [thread overview]
Message-ID: <Y3L7J74JKV0MAR5l@yekko> (raw)
In-Reply-To: <20221110193508.968090-1-sbrivio@redhat.com>
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On Thu, Nov 10, 2022 at 08:35:08PM +0100, Stefano Brivio wrote:
> Given that we use just the first valid DNS resolver address
> configured, or read from resolv.conf(5) on the host, to forward DNS
> queries to, in case --dns-forward is used, we don't need to duplicate
> dns[] to dns_send[]:
>
> - rename dns_send[] back to dns[]: those are the resolvers we
> advertise to the guest/container
>
> - for forwarding purposes, instead of dns[], use a single field (for
> each protocol version): dns_host
>
> - and rename dns_fwd to dns_match, so that it's clear this is the
> address we are matching DNS queries against, to decide if they need
> to be forwarded
>
> Suggested-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> ---
> conf.c | 76 ++++++++++++++++++++++++--------------------------------
> dhcp.c | 5 ++--
> dhcpv6.c | 5 ++--
> ndp.c | 6 ++---
> passt.h | 20 +++++++--------
> udp.c | 21 +++++++++-------
> 6 files changed, 62 insertions(+), 71 deletions(-)
>
> diff --git a/conf.c b/conf.c
> index 1adcf83..a995eb7 100644
> --- a/conf.c
> +++ b/conf.c
> @@ -355,11 +355,9 @@ overlap:
> */
> static void get_dns(struct ctx *c)
> {
> - struct in6_addr *dns6_send = &c->ip6.dns_send[0];
> - struct in_addr *dns4_send = &c->ip4.dns_send[0];
> + struct in6_addr *dns6 = &c->ip6.dns[0], dns6_tmp;
> + struct in_addr *dns4 = &c->ip4.dns[0], dns4_tmp;
> int dns4_set, dns6_set, dnss_set, dns_set, fd;
> - struct in6_addr *dns6 = &c->ip6.dns[0];
> - struct in_addr *dns4 = &c->ip4.dns[0];
> struct fqdn *s = c->dns_search;
> struct lineread resolvconf;
> int line_len;
> @@ -388,49 +386,44 @@ static void get_dns(struct ctx *c)
> *end = 0;
>
> if (!dns4_set &&
> - dns4 - &c->ip4.dns[0] < ARRAY_SIZE(c->ip4.dns) - 1 &&
> - inet_pton(AF_INET, p + 1, dns4)) {
> + 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)) {
> + if (IN4_IS_ADDR_LOOPBACK(&dns4_tmp)) {
> if (!c->no_map_gw) {
> - *dns4_send = c->ip4.gw;
> - dns4_send++;
> + *dns4 = c->ip4.gw;
> + dns4++;
> }
> } else {
> - *dns4_send = *dns4;
> - dns4_send++;
> + *dns4 = dns4_tmp;
> + dns4++;
> }
>
> - dns4++;
> -
> - dns4->s_addr = htonl(INADDR_ANY);
> - dns4_send->s_addr = htonl(INADDR_ANY);
> + if (IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_host))
> + c->ip4.dns_host = dns4_tmp;
> }
>
> if (!dns6_set &&
> - dns6 - &c->ip6.dns[0] < ARRAY_SIZE(c->ip6.dns) - 1 &&
> - inet_pton(AF_INET6, p + 1, dns6)) {
> + 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)) {
> + if (IN6_IS_ADDR_LOOPBACK(&dns6_tmp)) {
> if (!c->no_map_gw) {
> - memcpy(dns6_send, &c->ip6.gw,
> - sizeof(*dns6_send));
> - dns6_send++;
> + memcpy(dns6, &c->ip6.gw,
> + sizeof(*dns6));
> + dns6++;
> }
> } else {
> - memcpy(dns6_send, dns6,
> - sizeof(*dns6_send));
> - dns6_send++;
> + memcpy(dns6, &dns6_tmp, sizeof(*dns6));
> + dns6++;
> }
>
> - dns6++;
> -
> - memset(dns6, 0, sizeof(*dns6));
> - memset(dns6_send, 0, sizeof(*dns6_send));
> + if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_host))
> + c->ip6.dns_host = dns6_tmp;
> }
> } else if (!dnss_set && strstr(line, "search ") == line &&
> s == c->dns_search) {
> @@ -897,12 +890,10 @@ static void conf_print(const struct ctx *c)
> inet_ntop(AF_INET, &c->ip4.gw, buf4, sizeof(buf4)));
> }
>
> - for (i = 0; !IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_send[i]);
> - i++) {
> + for (i = 0; !IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns[i]); i++) {
> if (!i)
> info("DNS:");
> - inet_ntop(AF_INET, &c->ip4.dns_send[i], buf4,
> - sizeof(buf4));
> + inet_ntop(AF_INET, &c->ip4.dns[i], buf4, sizeof(buf4));
> info(" %s", buf4);
> }
>
> @@ -933,8 +924,7 @@ static void conf_print(const struct ctx *c)
> inet_ntop(AF_INET6, &c->ip6.addr_ll, buf6, sizeof(buf6)));
>
> dns6:
> - for (i = 0; !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_send[i]);
> - i++) {
> + for (i = 0; !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns[i]); i++) {
> if (!i)
> info("DNS:");
> inet_ntop(AF_INET6, &c->ip6.dns[i], buf6, sizeof(buf6));
> @@ -1230,17 +1220,17 @@ void conf(struct ctx *c, int argc, char **argv)
> c->no_dhcp_dns_search = 1;
> break;
> case 9:
> - if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_fwd) &&
> - inet_pton(AF_INET6, optarg, &c->ip6.dns_fwd) &&
> - !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_fwd) &&
> - !IN6_IS_ADDR_LOOPBACK(&c->ip6.dns_fwd))
> + if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_match) &&
> + inet_pton(AF_INET6, optarg, &c->ip6.dns_match) &&
> + !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_match) &&
> + !IN6_IS_ADDR_LOOPBACK(&c->ip6.dns_match))
> break;
>
> - if (IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_fwd) &&
> - inet_pton(AF_INET, optarg, &c->ip4.dns_fwd) &&
> - !IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_fwd) &&
> - !IN4_IS_ADDR_BROADCAST(&c->ip4.dns_fwd) &&
> - !IN4_IS_ADDR_LOOPBACK(&c->ip4.dns_fwd))
> + if (IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_match) &&
> + inet_pton(AF_INET, optarg, &c->ip4.dns_match) &&
> + !IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_match) &&
> + !IN4_IS_ADDR_BROADCAST(&c->ip4.dns_match) &&
> + !IN4_IS_ADDR_LOOPBACK(&c->ip4.dns_match))
> break;
>
> err("Invalid DNS forwarding address: %s", optarg);
> diff --git a/dhcp.c b/dhcp.c
> index 12da47a..6088886 100644
> --- a/dhcp.c
> +++ b/dhcp.c
> @@ -359,9 +359,8 @@ int dhcp(const struct ctx *c, const struct pool *p)
> }
>
> for (i = 0, opts[6].slen = 0;
> - !c->no_dhcp_dns && !IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_send[i]);
> - i++) {
> - ((struct in_addr *)opts[6].s)[i] = c->ip4.dns_send[i];
> + !c->no_dhcp_dns && !IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns[i]); i++) {
> + ((struct in_addr *)opts[6].s)[i] = c->ip4.dns[i];
> opts[6].slen += sizeof(uint32_t);
> }
>
> diff --git a/dhcpv6.c b/dhcpv6.c
> index 67262e6..e763aed 100644
> --- a/dhcpv6.c
> +++ b/dhcpv6.c
> @@ -379,7 +379,7 @@ static size_t dhcpv6_dns_fill(const struct ctx *c, char *buf, int offset)
> if (c->no_dhcp_dns)
> goto search;
>
> - for (i = 0; !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_send[i]); i++) {
> + for (i = 0; !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns[i]); i++) {
> if (!i) {
> srv = (struct opt_dns_servers *)(buf + offset);
> offset += sizeof(struct opt_hdr);
> @@ -387,8 +387,7 @@ static size_t dhcpv6_dns_fill(const struct ctx *c, char *buf, int offset)
> srv->hdr.l = 0;
> }
>
> - memcpy(&srv->addr[i], &c->ip6.dns_send[i],
> - sizeof(srv->addr[i]));
> + memcpy(&srv->addr[i], &c->ip6.dns[i], sizeof(srv->addr[i]));
> srv->hdr.l += sizeof(srv->addr[i]);
> offset += sizeof(srv->addr[i]);
> }
> diff --git a/ndp.c b/ndp.c
> index 6d79477..80e1f19 100644
> --- a/ndp.c
> +++ b/ndp.c
> @@ -121,7 +121,7 @@ int ndp(struct ctx *c, const struct icmp6hdr *ih, const struct in6_addr *saddr)
> if (c->no_dhcp_dns)
> goto dns_done;
>
> - for (n = 0; !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_send[n]); n++);
> + for (n = 0; !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns[n]); n++);
> if (n) {
> *p++ = 25; /* RDNSS */
> *p++ = 1 + 2 * n; /* length */
> @@ -130,8 +130,8 @@ int ndp(struct ctx *c, const struct icmp6hdr *ih, const struct in6_addr *saddr)
> p += 4;
>
> for (i = 0; i < n; i++) {
> - memcpy(p, &c->ip6.dns_send[i], 16);
> - p += 16; /* address */
> + memcpy(p, &c->ip6.dns[i], 16); /* address */
> + p += 16;
> }
>
> for (n = 0; *c->dns_search[n].n; n++)
> diff --git a/passt.h b/passt.h
> index e93eea8..6649c0a 100644
> --- a/passt.h
> +++ b/passt.h
> @@ -101,9 +101,9 @@ enum passt_modes {
> * @addr_seen: Latest IPv4 address seen as source from tap
> * @prefixlen: IPv4 prefix length (netmask)
> * @gw: Default IPv4 gateway, network order
> - * @dns: Host IPv4 DNS addresses, zero-terminated, network order
> - * @dns_send: Offered IPv4 DNS, zero-terminated, network order
> - * @dns_fwd: Address forwarded (UDP) to first IPv4 DNS, network order
> + * @dns: DNS addresses for DHCP, zero-terminated, network order
> + * @dns_match: Forward DNS query if sent to this address, network order
> + * @dns_host: Use this DNS on the host for forwarding, network order
> */
> struct ip4_ctx {
> struct in_addr addr;
> @@ -111,8 +111,8 @@ struct ip4_ctx {
> int prefix_len;
> struct in_addr gw;
> struct in_addr dns[MAXNS + 1];
> - struct in_addr dns_send[MAXNS + 1];
> - struct in_addr dns_fwd;
> + struct in_addr dns_match;
> + struct in_addr dns_host;
> };
>
> /**
> @@ -122,9 +122,9 @@ struct ip4_ctx {
> * @addr_seen: Latest IPv6 global/site address seen as source from tap
> * @addr_ll_seen: Latest IPv6 link-local address seen as source from tap
> * @gw: Default IPv6 gateway
> - * @dns: Host IPv6 DNS addresses, zero-terminated
> - * @dns_send: Offered IPv6 DNS addresses, zero-terminated
> - * @dns_fwd: Address forwarded (UDP) to first IPv6 DNS, network order
> + * @dns: DNS addresses for DHCPv6 and NDP, zero-terminated
> + * @dns_match: Forward DNS query if sent to this address
> + * @dns_host: Use this DNS on the host for forwarding
> */
> struct ip6_ctx {
> struct in6_addr addr;
> @@ -133,8 +133,8 @@ struct ip6_ctx {
> struct in6_addr addr_ll_seen;
> struct in6_addr gw;
> struct in6_addr dns[MAXNS + 1];
> - struct in6_addr dns_send[MAXNS + 1];
> - struct in6_addr dns_fwd;
> + struct in6_addr dns_match;
> + struct in6_addr dns_host;
> };
>
> #include <netinet/if_ether.h>
> diff --git a/udp.c b/udp.c
> index ff7f993..0aa6308 100644
> --- a/udp.c
> +++ b/udp.c
> @@ -678,10 +678,10 @@ static void udp_sock_fill_data_v4(const struct ctx *c, int n,
>
> src_port = ntohs(b->s_in.sin_port);
>
> - if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_fwd) &&
> - IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.dns[0]) &&
> + if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_match) &&
> + IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.dns_host) &&
> src_port == 53) {
> - b->iph.saddr = c->ip4.dns_fwd.s_addr;
> + b->iph.saddr = c->ip4.dns_match.s_addr;
> } else if (IN4_IS_ADDR_LOOPBACK(&b->s_in.sin_addr) ||
> IN4_IS_ADDR_UNSPECIFIED(&b->s_in.sin_addr)||
> IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.addr_seen)) {
> @@ -770,10 +770,11 @@ static void udp_sock_fill_data_v6(const struct ctx *c, int n,
> if (IN6_IS_ADDR_LINKLOCAL(src)) {
> b->ip6h.daddr = c->ip6.addr_ll_seen;
> b->ip6h.saddr = b->s_in6.sin6_addr;
> - } else if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_fwd) &&
> - IN6_ARE_ADDR_EQUAL(src, &c->ip6.dns[0]) && src_port == 53) {
> + } else if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_match) &&
> + IN6_ARE_ADDR_EQUAL(src, &c->ip6.dns_host) &&
> + src_port == 53) {
> b->ip6h.daddr = c->ip6.addr_seen;
> - b->ip6h.saddr = c->ip6.dns_fwd;
> + b->ip6h.saddr = c->ip6.dns_match;
> } else if (IN6_IS_ADDR_LOOPBACK(src) ||
> IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr_seen) ||
> IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr)) {
> @@ -1016,13 +1017,15 @@ int udp_tap_handler(struct ctx *c, int af, const void *addr,
>
> udp_tap_map[V4][src].ts = now->tv_sec;
>
> - if (IN4_ARE_ADDR_EQUAL(&s_in.sin_addr, &c->ip4.gw) && !c->no_map_gw) {
> + if (IN4_ARE_ADDR_EQUAL(&s_in.sin_addr, &c->ip4.gw) &&
> + !c->no_map_gw) {
> if (!(udp_tap_map[V4][dst].flags & PORT_LOCAL) ||
> (udp_tap_map[V4][dst].flags & PORT_LOOPBACK))
> s_in.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
> else
> s_in.sin_addr = c->ip4.addr_seen;
> - } else if (IN4_ARE_ADDR_EQUAL(&s_in.sin_addr, &c->ip4.dns_fwd) &&
> + } else if (IN4_ARE_ADDR_EQUAL(&s_in.sin_addr,
> + &c->ip4.dns_match) &&
> ntohs(s_in.sin_port) == 53) {
> s_in.sin_addr = c->ip4.dns[0];
> }
> @@ -1045,7 +1048,7 @@ int udp_tap_handler(struct ctx *c, int af, const void *addr,
> s_in6.sin6_addr = c->ip6.addr;
> else
> s_in6.sin6_addr = c->ip6.addr_seen;
> - } else if (IN6_ARE_ADDR_EQUAL(addr, &c->ip6.dns_fwd) &&
> + } else if (IN6_ARE_ADDR_EQUAL(addr, &c->ip6.dns_match) &&
> ntohs(s_in6.sin6_port) == 53) {
> s_in6.sin6_addr = c->ip6.dns[0];
> } else if (IN6_IS_ADDR_LINKLOCAL(&s_in6.sin6_addr)) {
--
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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prev parent reply other threads:[~2022-11-15 4:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-10 19:35 [PATCH] conf, udp: Drop mostly duplicated dns_send arrays, rename related fields Stefano Brivio
2022-11-15 2:36 ` David Gibson [this message]
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