[PATCH RFC odhcpd] Improve information provided in router advertisments
Uwe Kleine-König
uwe at kleine-koenig.org
Thu Jun 25 16:27:35 EDT 2020
The two main changes are that Prefix Informations are only sent for
prefixes the router is responsible for and that Route Informations are
sent for all prefixes.
This allows to send router advertisements on the wan interface to tell
hosts there about the routes available via the router. And it also improves
routing between two downstream networks.
Unresolved issues:
- valid life time needs to be determined
- some doubts about the right procedures
- only lightly tested
Signed-off-by: Uwe Kleine-König <uwe at kleine-koenig.org>
---
Hello,
this is a first draft to address an old item on my todo list, see
https://forum.openwrt.org/t/sending-ipv6-router-advertisments-to-wan-interface-about-ula-prefix/6577
.
Some feedback about how to determine the missing timestamp would be very
welcome. The old code used the life time of the assigned addresses, is
this the correct thing to do?
Also I wonder if I could better somehow query odhcp6c and the config for
the source prefix information instead of relying on the unreachable
routes?
Best regards
Uwe
src/dhcpv6-ia.c | 2 --
src/odhcpd.h | 3 --
src/router.c | 86 +++++++++++++++++++++++++++++++++----------------
3 files changed, 58 insertions(+), 33 deletions(-)
diff --git a/src/dhcpv6-ia.c b/src/dhcpv6-ia.c
index 38a901bfc534..16f75b90b718 100644
--- a/src/dhcpv6-ia.c
+++ b/src/dhcpv6-ia.c
@@ -525,8 +525,6 @@ static void managed_handle_pd_data(struct ustream *s, _unused int bytes_new)
else
n->valid += now;
- n->dprefix = 0;
-
++c->managed_size;
}
diff --git a/src/odhcpd.h b/src/odhcpd.h
index 09013c4b094b..9139f6fb65b7 100644
--- a/src/odhcpd.h
+++ b/src/odhcpd.h
@@ -109,9 +109,6 @@ struct odhcpd_ipaddr {
uint32_t preferred;
uint32_t valid;
- /* ipv6 only */
- uint8_t dprefix;
-
/* ipv4 only */
struct in_addr broadcast;
};
diff --git a/src/router.c b/src/router.c
index 7198ee97cb35..122cea974a41 100644
--- a/src/router.c
+++ b/src/router.c
@@ -297,13 +297,17 @@ static bool router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size
}
-/* Detect whether a default route exists, also find the source prefixes */
-static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
+/*
+ * Find the source prefixes. The return value signals if there is a default
+ * route.
+ */
+static bool parse_source_prefixes(struct odhcpd_ipaddr **source_prefixes, ssize_t *source_prefixes_cnt)
{
struct odhcpd_ipaddr p = { .addr.in6 = IN6ADDR_ANY_INIT, .prefix = 0,
- .dprefix = 0, .preferred = 0, .valid = 0};
+ .preferred = 3600, .valid = 3600}; /* XXX */
bool found_default = false;
char line[512], ifname[16];
+ struct odhcpd_ipaddr *pfxs = NULL; ssize_t pfxs_cnt = 0;
rewind(fp_route);
@@ -317,20 +321,25 @@ static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
"%*s 00000000000000000000000000000000 %*s %*s %*s %" SCNx32 " lo",
&p.addr.in6.s6_addr32[0], &p.addr.in6.s6_addr32[1], &p.prefix, &rflags) &&
p.prefix > 0 && (rflags & RTF_NONEXTHOP) && (rflags & RTF_REJECT)) {
+ void *tmp;
+
// Find source prefixes by scanning through unreachable-routes
p.addr.in6.s6_addr32[0] = htonl(p.addr.in6.s6_addr32[0]);
p.addr.in6.s6_addr32[1] = htonl(p.addr.in6.s6_addr32[1]);
- for (ssize_t i = 0; i < len; ++i) {
- if (n[i].prefix <= 64 && n[i].prefix >= p.prefix &&
- !odhcpd_bmemcmp(&p.addr.in6, &n[i].addr.in6, p.prefix)) {
- n[i].dprefix = p.prefix;
- break;
- }
+ tmp = realloc(pfxs, sizeof(*pfxs) * (pfxs_cnt + 1));
+ if (!tmp) {
+ syslog(LOG_ERR, "Realloc failed for list of source prefixes");
+ continue;
}
+ pfxs = tmp;
+ pfxs[pfxs_cnt++] = p;
}
}
+ *source_prefixes = pfxs;
+ *source_prefixes_cnt = pfxs_cnt;
+
return found_default;
}
@@ -447,6 +456,8 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
bool default_route = false;
bool valid_prefix = false;
char buf[INET6_ADDRSTRLEN];
+ struct odhcpd_ipaddr *source_prefixes = NULL;
+ ssize_t source_prefixes_cnt = 0;
memset(&adv, 0, sizeof(adv));
adv.h.nd_ra_type = ND_ROUTER_ADVERT;
@@ -500,7 +511,9 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
if (iface->default_router > 1)
valid_prefix = true;
- } else if (parse_routes(addrs, addr_cnt))
+ }
+
+ if (parse_source_prefixes(&source_prefixes, &source_prefixes_cnt))
default_route = true;
}
@@ -510,6 +523,7 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
struct nd_opt_prefix_info *p = NULL;
uint32_t preferred = 0;
uint32_t valid = 0;
+ bool addr_in_source_prefix = false;
if (addr->prefix > 96 || addr->valid <= (uint32_t)now) {
syslog(LOG_INFO, "Address %s (prefix %d, valid %u) not suitable as RA prefix on %s",
@@ -527,6 +541,20 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
continue; /* PIO filtered out of this RA */
}
+ /*
+ * Only announce prefix if the address belongs to a delegated
+ * network
+ */
+ for (ssize_t j = 0; j < source_prefixes_cnt; ++j) {
+ if (odhcpd_bmemcmp(&addr->addr, &source_prefixes[j].addr,
+ source_prefixes[j].prefix) == 0) {
+ break;
+ }
+ }
+ if (!addr_in_source_prefix) {
+ continue;
+ }
+
for (size_t i = 0; i < pfxs_cnt; ++i) {
if (addr->prefix == pfxs[i].nd_opt_pi_prefix_len &&
!odhcpd_bmemcmp(&pfxs[i].nd_opt_pi_prefix,
@@ -669,33 +697,33 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
* WAN interface.
*/
- for (ssize_t i = 0; i < addr_cnt; ++i) {
- struct odhcpd_ipaddr *addr = &addrs[i];
+ for (ssize_t i = 0; i < source_prefixes_cnt; ++i) {
+ struct odhcpd_ipaddr *spfx = &source_prefixes[i];
struct nd_opt_route_info *tmp;
uint32_t valid;
- if (addr->dprefix >= 64 || addr->dprefix == 0 || addr->valid <= (uint32_t)now) {
- syslog(LOG_INFO, "Address %s (dprefix %d, valid %u) not suitable as RA route on %s",
- inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
- addr->dprefix, addr->valid, iface->name);
+ if (spfx->prefix >= 64 || spfx->prefix == 0 || spfx->valid <= (uint32_t)now) {
+ syslog(LOG_INFO, "Address %s (prefix %d, valid %u) not suitable as RA route on %s",
+ inet_ntop(AF_INET6, &spfx->addr.in6, buf, sizeof(buf)),
+ spfx->prefix, spfx->valid, iface->name);
continue; /* Address not suitable */
}
- if (odhcpd_bmemcmp(&addr->addr, &iface->pio_filter_addr,
+ if (odhcpd_bmemcmp(&spfx->addr, &iface->pio_filter_addr,
iface->pio_filter_length) != 0 ||
- addr->prefix < iface->pio_filter_length) {
+ spfx->prefix < iface->pio_filter_length) {
syslog(LOG_INFO, "Address %s filtered out as RA route on %s",
- inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf)),
+ inet_ntop(AF_INET6, &spfx->addr.in6, buf, sizeof(buf)),
iface->name);
continue; /* PIO filtered out of this RA */
}
- if (addr->dprefix > 32) {
- addr->addr.in6.s6_addr32[1] &= htonl(~((1U << (64 - addr->dprefix)) - 1));
- } else if (addr->dprefix <= 32) {
- addr->addr.in6.s6_addr32[0] &= htonl(~((1U << (32 - addr->dprefix)) - 1));
- addr->addr.in6.s6_addr32[1] = 0;
+ if (spfx->prefix > 32) {
+ spfx->addr.in6.s6_addr32[1] &= htonl(~((1U << (64 - spfx->prefix)) - 1));
+ } else if (spfx->prefix <= 32) {
+ spfx->addr.in6.s6_addr32[0] &= htonl(~((1U << (32 - spfx->prefix)) - 1));
+ spfx->addr.in6.s6_addr32[1] = 0;
}
tmp = realloc(routes, sizeof(*routes) * (routes_cnt + 1));
@@ -709,23 +737,25 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
memset(&routes[routes_cnt], 0, sizeof(*routes));
routes[routes_cnt].type = ND_OPT_ROUTE_INFO;
routes[routes_cnt].len = sizeof(*routes) / 8;
- routes[routes_cnt].prefix = addr->dprefix;
+ routes[routes_cnt].prefix = spfx->prefix;
routes[routes_cnt].flags = 0;
if (iface->route_preference < 0)
routes[routes_cnt].flags |= ND_RA_PREF_LOW;
else if (iface->route_preference > 0)
routes[routes_cnt].flags |= ND_RA_PREF_HIGH;
- valid = TIME_LEFT(addr->valid, now);
+ valid = TIME_LEFT(spfx->valid, now);
routes[routes_cnt].lifetime = htonl(valid < lifetime ? valid : lifetime);
- routes[routes_cnt].addr[0] = addr->addr.in6.s6_addr32[0];
- routes[routes_cnt].addr[1] = addr->addr.in6.s6_addr32[1];
+ routes[routes_cnt].addr[0] = spfx->addr.in6.s6_addr32[0];
+ routes[routes_cnt].addr[1] = spfx->addr.in6.s6_addr32[1];
routes[routes_cnt].addr[2] = 0;
routes[routes_cnt].addr[3] = 0;
++routes_cnt;
}
+ free(source_prefixes);
+
iov[IOV_RA_ROUTES].iov_base = (char *)routes;
iov[IOV_RA_ROUTES].iov_len = routes_cnt * sizeof(*routes);
base-commit: 5da52992a3926b36e53d0a5d55955a6ccbc35872
--
2.27.0
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