dhcpcd-discuss

On 05/03/2019 15:03, Donald Sharp wrote:
> Roy -
>
> I could not figure out how to make debug's work so I just changed the
> logdebugx to logerrx:

Use the -d flag or add the word debug to /etc/dhcpcd.conf

> diff --git a/src/route.c b/src/route.c
> index dbe2b5a5..6963837d 100644
> --- a/src/route.c
> +++ b/src/route.c
> @@ -258,8 +258,8 @@ rt_dispose(struct dhcpcd_ctx *ctx)
>    rt_headfree(&ctx->routes);
>   #ifdef RT_FREE_ROUTE_TABLE
>    rt_headfree(&ctx->froutes);
> - logdebugx("free route list used %zu times", froutes);
> - logdebugx("new routes from free list %zu", nroutes);
> + logerrx("free route list used %zu times", froutes);
> + logerrx("new routes from free list %zu", nroutes);
>   #endif
>   }
>
>
> And only see this:
>
> Mar 05 14:41:19 janelle dhcpcd[20151]: free route list used 7 times
> Mar 05 14:41:19 janelle dhcpcd[20168]: dummy0: soliciting an IPv6 router
> Mar 05 14:41:19 janelle dhcpcd[20151]: new routes from free list 0
>
> On startup.  After startup when I install/remove 1 million routes I
> never see the message again.

Cause dhcpcd to exit and then check syslog.
You'll see it then.

> Another issue that has popped up during testing is that now that I am
> looking at the syslog is that I am seeing frequent messges from dhcpd
> that say this:
>
> Mar 05 14:34:40 janelle dhcpcd[19931]: route socket overflowed -
> learning interface state
> Mar 05 14:34:41 janelle dhcpcd[19931]: route socket overflowed -
> learning interface state
>
> during route install/removal.
>
> I added this bit of code:
>
> diff --git a/src/if-linux.c b/src/if-linux.c
> index b912c171..4b5dda54 100644
> --- a/src/if-linux.c
> +++ b/src/if-linux.c
> @@ -323,12 +323,15 @@ if_opensockets_os(struct dhcpcd_ctx *ctx)
>        &on, sizeof(on));
>   #endif
>
> + int rcvbufsize = 16 * 1024 * 1024;
> + setsockopt(ctx->link_fd, SOL_SOCKET, SO_RCVBUFFORCE, &rcvbufsize,
> sizeof(rcvbufsize));
>    if ((priv = calloc(1, sizeof(*priv))) == NULL)
>    return -1;
>
>    ctx->priv = priv;
>    memset(&snl, 0, sizeof(snl));
>    priv->route_fd = _open_link_socket(&snl, NETLINK_ROUTE);
> + setsockopt(priv->route_fd, SOL_SOCKET, SO_RCVBUFFORCE, &rcvbufsize,
> sizeof(rcvbufsize));
>    if (priv->route_fd == -1)
>    return -1;
>    len = sizeof(snl);
>
> and the error message has gone away.  Perhaps some cli option is
> needed for linux when it is planned to be used in a large scale
> routing env?

While the error itself is indeed scary, dhcpcd does have the logic to 
work around it.
Each time it happens it will re-sync interfaces and addresses with a 
single call to getifaddrs(3).
It doens't resync routes, but that's not overly important.

Do you only see the message on system boot, or when dhcpcd is actually 
running as well?
I'm curious as that's quite a large kernel buffer you're reserving, and 
that will be for each instance of dhcpcd.

Roy