[PATCH] dhcp: Actually note down the length of options received by the client

[PATCH] dhcp: Actually note down the length of options received by the client

[Stefano Brivio]

It turns out we never used 'clen' until commit 1f24d3efb499 ("dhcp:
support BOOTP clients"), and we always ignored option 55 (Parameter
Request List), while, according to RFC 2132, we MUST try to insert
the requested options in the order requested by the client.

The commit mentioned above made this visible because now every client
is reported as sending a DHCPREQUEST as an old BOOTP client, based on
the lack of option 53 (that is, zero length).

Fixes: b439984641ed ("merd: ARP and DHCP handlers, connection tracking fixes")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 dhcp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/dhcp.c b/dhcp.c
index c1ac95e..46c258e 100644
--- a/dhcp.c
+++ b/dhcp.c
@@ -317,6 +317,7 @@ int dhcp(const struct ctx *c, const struct pool *p)
 			return -1;
 
 		memcpy(&opts[*type].c, val, *olen);
+		opts[*type].clen = *olen;
 		opt_off += *olen + 2;
 	}
 
-- 
@@ -317,6 +317,7 @@ int dhcp(const struct ctx *c, const struct pool *p)
 			return -1;
 
 		memcpy(&opts[*type].c, val, *olen);
+		opts[*type].clen = *olen;
 		opt_off += *olen + 2;
 	}
 
-- 
2.39.2

Re: [PATCH] dhcp: Actually note down the length of options received by the client

[David Gibson]

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On Thu, Sep 21, 2023 at 06:50:56PM +0200, Stefano Brivio wrote:
> It turns out we never used 'clen' until commit 1f24d3efb499 ("dhcp:
> support BOOTP clients"), and we always ignored option 55 (Parameter
> Request List), while, according to RFC 2132, we MUST try to insert
> the requested options in the order requested by the client.
> 
> The commit mentioned above made this visible because now every client
> is reported as sending a DHCPREQUEST as an old BOOTP client, based on
> the lack of option 53 (that is, zero length).
> 
> Fixes: b439984641ed ("merd: ARP and DHCP handlers, connection tracking fixes")
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  dhcp.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/dhcp.c b/dhcp.c
> index c1ac95e..46c258e 100644
> --- a/dhcp.c
> +++ b/dhcp.c
> @@ -317,6 +317,7 @@ int dhcp(const struct ctx *c, const struct pool *p)
>  			return -1;
>  
>  		memcpy(&opts[*type].c, val, *olen);
> +		opts[*type].clen = *olen;
>  		opt_off += *olen + 2;
>  	}
>  

-- 
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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