[OpenWrt-Devel] [PATCH] [odhcp6c] ra: clear RA information and request new after link-up event or SIGUSR2
Pavel Merzlyakov
pavel.merzlyakov at gmail.com
Wed Mar 20 07:44:36 EDT 2019
>Can you share the network config you're using ?
I'm sorry I can't do this.
>I would prefer to use another signal to trigger the sending of RS.
Of course, it's up to you.
But I think there should be some signal witch restart both RA and DHCPv6.
Regarding to the patch
do you agree that we must clear STATE_RA_ on link-up event
before we trigger Router Solicitation message (see ra.c:247 ->
https://git.openwrt.org/?p=project/odhcp6c.git;a=blob;f=src/ra.c;h=898f449168e29bae08e48e9395f420d13b2ec899;hb=HEAD#l247
)?
Br,
Pavel
On Wed, 20 Mar 2019 at 10:52, Hans Dedecker <dedeckeh at gmail.com> wrote:
> On Tue, Mar 19, 2019 at 1:15 PM Pavel Merzlyakov
> <pavel.merzlyakov at gmail.com> wrote:
> >
> > >why is this not the case in your setup ?
> > Because sometimes odhcp6c miss restart, probably because of Bridge Mode
> (it's attached to bridge interface).
> Can you share the network config you're using ?
>
> > Anyway, I use a hotplug script which sends SIGUSR2 signal to odhcp6c on
> link-up event.
> > Of course I could send SIGTERM, but I think it's not the proper way to
> solve problem.
> >
> > I thought that it is an obvious bug because I see a lack of consistency.
> > Why odhcp6c on SIGUSR2
> > clear STATE_IA_ and resend DHCPV6_MSG_
> > and don't do same with RA - clear STATE_RA_ and resend Router
> Solicitation message?
> This was the approach by the original author of the code to control
> only DHCPv6 via SIGUSR1 and SIGUSR2.
> I understand your need to trigger the sending of RS via a signal but
> I'm reluctant to change the current behavior of the SIGUSR2 signal as
> I would prefer to use another signal to trigger the sending of RS.
>
> Hans
> >
> > Br,
> > Pavel
> >
> > On Tue, 19 Mar 2019 at 12:36, Hans Dedecker <dedeckeh at gmail.com> wrote:
> >>
> >> Hi,
> >>
> >> On Mon, Mar 18, 2019 at 8:51 PM Pavel Merzlyakov
> >> <pavel.merzlyakov at gmail.com> wrote:
> >> >
> >> > Hi,
> >> >
> >> > >Can you be elaborate more in detail what use case you want to cover
> >> > >with this patch; in other words what is not working now ?
> >> > Ok,
> >> > my setup:
> >> > Two peer routers A and B which both connected to gateway C.
> >> > Routers A and B have public IPv6 addresses on WAN interfaces from
> same subnet (because of RA on C) and private IPv6 addresses on LAN
> interfaces.
> >> > and issue:
> >> > If I unplug router B from C and then plug it in LAN port of router A:
> >> > 1) Router B does not send Router Solicitation message. So router B
> does not have a valid gateway for some time.
> >> Since we've linksensing support in netifd the wan/wan6 interface
> >> should be brought down when the cable is unplugged; the wan/wan6
> >> interface will be brought up again when the cable is plugged in. This
> >> means odhcp6c will be restarted and will start sending RS; why is this
> >> not the case in your setup ?
> >>
> >> Hans
> >> > 2) Router B does not delete old IPv6 address on the WAN. After first
> Router Advertisement message router B is capable to send a request via new
> gateway A, but it can't receive responses because of invalid/old source
> address in request.
> >> >
> >> >
> >> > >Why do you want to restart RA if an SIGUSR2 signal is received ?
> >> > Because I assume that SIGUSR2 signal is equivalent to link-up event
> (see odhcp6c:674 ->
> https://git.openwrt.org/?p=project/odhcp6c.git;a=blob;f=src/odhcp6c.c;h=19a86f2654bf3c59b0f47cf0aedd87235187bf89;hb=d2e247d8d87ecf8c60fcf0acdad05667bd379521#l674
> ).
> >> > In my case I use hotplug script witch on link-up sends SIGUSR2 signal
> to odhcp6c (it's connected to bridge interface).
> >> > ra_restart () could be called without condition in beginning of the
> main loop.
> >> >
> >> > Br,
> >> > Pavel
> >> >
> >> > On Mon, 18 Mar 2019 at 18:26, Hans Dedecker <dedeckeh at gmail.com>
> wrote:
> >> >>
> >> >> Hi,
> >> >>
> >> >> On Mon, Mar 18, 2019 at 2:43 PM <pavel.merzlyakov at gmail.com> wrote:
> >> >> >
> >> >> > From: Pavel Merzlyakov <pavel.merzlyakov at gmail.com>
> >> >> >
> >> >> > A subnet may be changed after link-up event
> >> >> Can you be elaborate more in detail what use case you want to cover
> >> >> with this patch; in other words what is not working now ?
> >> >> >
> >> >> > Signed-off-by: Pavel Merzlyakov <pavel.merzlyakov at gmail.com>
> >> >> > ---
> >> >> > src/odhcp6c.c | 3 +++
> >> >> > src/ra.c | 20 +++++++++++++++++---
> >> >> > src/ra.h | 1 +
> >> >> > 3 files changed, 21 insertions(+), 3 deletions(-)
> >> >> >
> >> >> > diff --git a/src/odhcp6c.c b/src/odhcp6c.c
> >> >> > index 19a86f2..dd20f39 100644
> >> >> > --- a/src/odhcp6c.c
> >> >> > +++ b/src/odhcp6c.c
> >> >> > @@ -455,6 +455,9 @@ int main(_unused int argc, char* const argv[])
> >> >> >
> >> >> > syslog(LOG_NOTICE, "(re)starting transaction on
> %s", ifname);
> >> >> >
> >> >> > + if (signal_usr2)
> >> >> > + ra_restart();
> >> >> Why do you want to restart RA if an SIGUSR2 signal is received ?
> >> >>
> >> >> Hans
> >> >> > +
> >> >> > signal_usr1 = signal_usr2 = false;
> >> >> > int mode = dhcpv6_set_ia_mode(ia_na_mode,
> ia_pd_mode);
> >> >> > if (mode != DHCPV6_STATELESS)
> >> >> > diff --git a/src/ra.c b/src/ra.c
> >> >> > index 898f449..917df11 100644
> >> >> > --- a/src/ra.c
> >> >> > +++ b/src/ra.c
> >> >> > @@ -55,6 +55,7 @@ static int sock = -1, rtnl = -1;
> >> >> > static int if_index = 0;
> >> >> > static char if_name[IF_NAMESIZE] = {0};
> >> >> > static volatile int rs_attempt = 0;
> >> >> > +static const int rs_attempt_limit = 4;
> >> >> > static struct in6_addr lladdr = IN6ADDR_ANY_INIT;
> >> >> > static unsigned int ra_options = 0;
> >> >> > static unsigned int ra_holdoff_interval = 0;
> >> >> > @@ -179,6 +180,20 @@ failure:
> >> >> > return -1;
> >> >> > }
> >> >> >
> >> >> > +void ra_restart(void)
> >> >> > +{
> >> >> > + const int rs_attempt_old = rs_attempt;
> >> >> > +
> >> >> > + odhcp6c_clear_state(STATE_RA_PREFIX);
> >> >> > + odhcp6c_clear_state(STATE_RA_ROUTE);
> >> >> > + odhcp6c_clear_state(STATE_RA_DNS);
> >> >> > + odhcp6c_clear_state(STATE_RA_SEARCH);
> >> >> > +
> >> >> > + rs_attempt = 0;
> >> >> > + if (rs_attempt_old == 0 || rs_attempt_old >=
> rs_attempt_limit)
> >> >> > + ra_send_rs(SIGALRM);
> >> >> > +}
> >> >> > +
> >> >> > static void ra_send_rs(int signal __attribute__((unused)))
> >> >> > {
> >> >> > const struct sockaddr_in6 dest = {AF_INET6, 0, 0,
> ALL_IPV6_ROUTERS, if_index};
> >> >> > @@ -193,7 +208,7 @@ static void ra_send_rs(int signal
> __attribute__((unused)))
> >> >> > if (sendto(sock, &rs, len, MSG_DONTWAIT, (struct
> sockaddr*)&dest, sizeof(dest)) < 0)
> >> >> > syslog(LOG_ERR, "Failed to send RS (%s)",
> strerror(errno));
> >> >> >
> >> >> > - if (++rs_attempt <= 3)
> >> >> > + if (++rs_attempt < rs_attempt_limit)
> >> >> > alarm(4);
> >> >> > }
> >> >> >
> >> >> > @@ -243,8 +258,7 @@ bool ra_link_up(void)
> >> >> > if (ret) {
> >> >> > syslog(LOG_NOTICE, "carrier => %i event on %s",
> (int)!nocarrier, if_name);
> >> >> >
> >> >> > - rs_attempt = 0;
> >> >> > - ra_send_rs(SIGALRM);
> >> >> > + ra_restart();
> >> >> > }
> >> >> >
> >> >> > return ret;
> >> >> > diff --git a/src/ra.h b/src/ra.h
> >> >> > index 9acc8cd..4ec208f 100644
> >> >> > --- a/src/ra.h
> >> >> > +++ b/src/ra.h
> >> >> > @@ -46,5 +46,6 @@ struct icmpv6_opt_route_info {
> >> >> >
> >> >> > int ra_init(const char *ifname, const struct in6_addr *ifid,
> >> >> > unsigned int options, unsigned int
> holdoff_interval);
> >> >> > +void ra_restart(void);
> >> >> > bool ra_link_up(void);
> >> >> > bool ra_process(void);
> >> >> > --
> >> >> > 2.21.0
> >> >> >
> >> >> >
> >> >> > _______________________________________________
> >> >> > openwrt-devel mailing list
> >> >> > openwrt-devel at lists.openwrt.org
> >> >> > https://lists.openwrt.org/mailman/listinfo/openwrt-devel
>
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