[PATCH] odhcpd: add option for setting preferred lifetime

Hans Dedecker dedeckeh at gmail.com
Sat Jan 2 15:31:07 EST 2021


On Fri, Jan 1, 2021 at 9:15 PM <vincent at systemli.org> wrote:
>
> From: Nick Hainke <vincent at systemli.org>
>
> "valid_lft" and "preferred_lft" are different. If the "preferred_lft"
> is expired the prefix should be avoided in source prefix selection.
> However, the interface is allowed to still receive downstream traffic.
>
> ra_use_preferred_lft:
>   Value for the preferred lifetime for a prefix
Do we really need an extra config option to indicate a configured
preferred lifetime needs to be used ?
Can't we just initialize preferred_lifetime to 43200 and just check
for ra_useleasetime in router.c when setting the preferred lifetime ?
>
> ra_preferred_lft:
>   Use the limit for preferred lifetime of a prefix
This is confusing to prefix the config option with ra as it's used
both for RA and DHCPv6; I would just call it preferred_lifetime
>
> If only "useleasetime" is set odhcpd will still set the "preferred_lft"
> to the leasetime. If "ra_use_preferred_lft" is also set the
> "preferred_lft" will be set to "ra_preferred_lft".
>
> Signed-off-by: Nick Hainke <vincent at systemli.org>
> ---
>  README          |  4 ++++
>  src/config.c    | 15 +++++++++++++++
>  src/dhcpv6-ia.c | 20 ++++++++++++++++----
>  src/odhcpd.h    |  3 +++
>  src/router.c    |  4 ++++
>  5 files changed, 42 insertions(+), 4 deletions(-)
>
> diff --git a/README b/README
> index a34a93c..6a5c6cf 100644
> --- a/README
> +++ b/README
> @@ -129,6 +129,10 @@ ra_lifetime                integer 1800                    Value to be placed in Router
>  ra_useleasetime                bool    0                       Use configured leasetime as
>                                                         limit for the preferred and
>                                                         valid lifetime of a prefix
> +ra_preferred_lft       string  12h             Value for the preferred lifetime
> +                                                       for a prefix
> +ra_use_preferred_lft   bool    0               Use the limit for preferred
> +                                                       lifetime of a prefix
>  ra_reachabletime       integer 0                       Reachable Time in milliseconds to be
>                                                         advertised in RA messages
>  ra_retranstime         integer 0                       Retransmit Time in milliseconds to be
> diff --git a/src/config.c b/src/config.c
> index 015a716..cb06dfe 100644
> --- a/src/config.c
> +++ b/src/config.c
> @@ -82,6 +82,8 @@ enum {
>         IFACE_ATTR_NDPROXY_ROUTING,
>         IFACE_ATTR_NDPROXY_SLAVE,
>         IFACE_ATTR_PREFIX_FILTER,
> +       IFACE_ATTR_RA_USE_PREFERRED_LFT,
> +       IFACE_ATTR_RA_PREFERRED_LFT,
>         IFACE_ATTR_MAX
>  };
>
> @@ -130,6 +132,8 @@ static const struct blobmsg_policy iface_attrs[IFACE_ATTR_MAX] = {
>         [IFACE_ATTR_NDPROXY_ROUTING] = { .name = "ndproxy_routing", .type = BLOBMSG_TYPE_BOOL },
>         [IFACE_ATTR_NDPROXY_SLAVE] = { .name = "ndproxy_slave", .type = BLOBMSG_TYPE_BOOL },
>         [IFACE_ATTR_PREFIX_FILTER] = { .name = "prefix_filter", .type = BLOBMSG_TYPE_STRING },
> +       [IFACE_ATTR_RA_USE_PREFERRED_LFT] = { .name = "ra_use_preferred_lft", .type = BLOBMSG_TYPE_BOOL },
> +       [IFACE_ATTR_RA_PREFERRED_LFT] = { .name = "ra_preferred_lft", .type = BLOBMSG_TYPE_STRING },
>  };
>
>  static const struct uci_blob_param_info iface_attr_info[IFACE_ATTR_MAX] = {
> @@ -525,6 +529,14 @@ int config_parse_interface(void *data, size_t len, const char *name, bool overwr
>                 iface->dhcp_leasetime = time;
>         }
>
> +       if ((c = tb[IFACE_ATTR_RA_PREFERRED_LFT])) {
> +               double time = parse_leasetime(c);
> +               if (time < 0)
> +                       goto err;
> +
> +               iface->ra_preferred_lft = time;
> +       }
> +
>         if ((c = tb[IFACE_ATTR_START])) {
>                 iface->dhcpv4_start.s_addr = htonl(blobmsg_get_u32(c));
>                 iface->dhcpv4_end.s_addr = htonl(ntohl(iface->dhcpv4_start.s_addr) +
> @@ -795,6 +807,9 @@ int config_parse_interface(void *data, size_t len, const char *name, bool overwr
>         if ((c = tb[IFACE_ATTR_RA_USELEASETIME]))
>                 iface->ra_useleasetime = blobmsg_get_bool(c);
>
> +       if ((c = tb[IFACE_ATTR_RA_USE_PREFERRED_LFT]))
> +               iface->ra_use_preferred_lft = blobmsg_get_bool(c);
> +
>         if ((c = tb[IFACE_ATTR_RA_DNS]))
>                 iface->ra_dns = blobmsg_get_bool(c);
>
> diff --git a/src/dhcpv6-ia.c b/src/dhcpv6-ia.c
> index d7848de..8fffeb7 100644
> --- a/src/dhcpv6-ia.c
> +++ b/src/dhcpv6-ia.c
> @@ -247,6 +247,9 @@ void dhcpv6_ia_enum_addrs(struct interface *iface, struct dhcp_assignment *c,
>                         addr.s6_addr32[2] = addr.s6_addr32[3] = 0;
>                 }
>
> +               if (pref > (uint32_t)c->preferred_until)
> +                       pref = c->preferred_until;
> +
>                 if (pref > (uint32_t)c->valid_until)
>                         pref = c->valid_until;
>
> @@ -827,14 +830,18 @@ static size_t build_ia(uint8_t *buf, size_t buflen, uint16_t status,
>         }
>
>         if (a) {
> -               uint32_t leasetime;
> +               uint32_t leasetime, pref;
>
>                 if (a->leasetime)
>                         leasetime = a->leasetime;
>                 else
>                         leasetime = iface->dhcp_leasetime;
> +
white space error here
> +               if (iface->ra_use_preferred_lft)
> +                       pref = iface->ra_preferred_lft;
> +               else
> +                       pref = leasetime;
>
> -               uint32_t pref = leasetime;
>                 uint32_t valid = leasetime;
>
>                 struct odhcpd_ipaddr *addrs = (a->managed) ? a->managed : iface->addr6;
> @@ -851,8 +858,8 @@ static size_t build_ia(uint8_t *buf, size_t buflen, uint16_t status,
>                         if (prefix_pref != UINT32_MAX)
>                                 prefix_pref -= now;
>
> -                       if (prefix_pref > leasetime)
> -                               prefix_pref = leasetime;
> +                       if (prefix_pref > pref)
> +                               prefix_pref = pref;
>
>                         if (prefix_valid != UINT32_MAX)
>                                 prefix_valid -= now;
> @@ -918,6 +925,10 @@ static size_t build_ia(uint8_t *buf, size_t buflen, uint16_t status,
>                         /* UINT32_MAX is considered as infinite leasetime */
>                         a->valid_until = (valid == UINT32_MAX) ? 0 : valid + now;
>
> +               if (!INFINITE_VALID(a->preferred_until))
> +                       /* UINT32_MAX is considered as infinite leasetime */
> +                       a->preferred_until = (pref == UINT32_MAX) ? 0 : pref + now;
> +
>                 o_ia.t1 = htonl((pref == UINT32_MAX) ? pref : pref * 5 / 10);
>                 o_ia.t2 = htonl((pref == UINT32_MAX) ? pref : pref * 8 / 10);
>
> @@ -1261,6 +1272,7 @@ ssize_t dhcpv6_ia_handle_IAs(uint8_t *buf, size_t buflen, struct interface *ifac
>                                                 a->peer = *addr;
>                                                 a->assigned = is_na && l ? l->hostid : reqhint;
>                                                 a->valid_until =  now;
> +                                               a->preferred_until =  now;
>                                                 a->dhcp_free_cb = dhcpv6_ia_free_assignment;
>                                                 a->iface = iface;
>                                                 a->flags = (is_pd ? OAF_DHCPV6_PD : OAF_DHCPV6_NA);
> diff --git a/src/odhcpd.h b/src/odhcpd.h
> index 2f7dd25..9df53a8 100644
> --- a/src/odhcpd.h
> +++ b/src/odhcpd.h
> @@ -182,6 +182,7 @@ struct dhcp_assignment {
>
>         struct sockaddr_in6 peer;
>         time_t valid_until;
> +       time_t preferred_until;
>
>  #define fr_timer       reconf_timer
>         struct uloop_timeout reconf_timer;
> @@ -286,6 +287,8 @@ struct interface {
>         uint32_t ra_retranstime;
>         uint32_t ra_hoplimit;
>         int ra_mtu;
> +       bool ra_use_preferred_lft;
> +       uint32_t ra_preferred_lft;
>
>         // DHCP
>         uint32_t dhcp_leasetime;
> diff --git a/src/router.c b/src/router.c
> index 06f3a66..244e600 100644
> --- a/src/router.c
> +++ b/src/router.c
> @@ -554,6 +554,10 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
>                         if (iface->ra_useleasetime &&
>                             preferred > iface->dhcp_leasetime)
>                                 preferred = iface->dhcp_leasetime;
> +
> +                       if (iface->ra_use_preferred_lft &&
> +                           preferred > iface->ra_preferred_lft)
> +                               preferred = iface->ra_preferred_lft;
>                 }
>
>                 valid = TIME_LEFT(addr->valid, now);
> --
> 2.29.2
>
>
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