Re: [PATCH 06/14] Add helpers for normal inbound packet destination addresses

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Oct 18, 2022 at 05:04:41AM +0200, Stefano Brivio wrote:
11;rgb:ffff/ffff/ffff> On Mon, 17 Oct 2022 19:57:59 +1100
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
> > tap_ip_send() doesn't take a destination address, because it's specifically
> > for inbound packets, and the IP addresses of the guest/namespace are
> > already known to us.  Rather than open-coding this destination address
> > logic, make helper functions for it which will enable some later cleanups.
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  tap.c | 29 ++++++++++++++++++++++++-----
> >  tap.h |  3 +++
> >  2 files changed, 27 insertions(+), 5 deletions(-)
> > 
> > diff --git a/tap.c b/tap.c
> > index de02c56..41e8ff2 100644
> > --- a/tap.c
> > +++ b/tap.c
> > @@ -96,6 +96,28 @@ int tap_send(const struct ctx *c, const void *data, size_t len, int vnet_pre)
> >  	return write(c->fd_tap, (char *)data + (vnet_pre ? 4 : 0), len);
> >  }
> >  
> > +/**
> > + * tap_ip4_daddr() - Normal IPv4 destination address for inbound packets
> > + * @c:		Execution context
> 
> Given that the address is returned in network order, I think this would
> be relevant here:
> 
>  * Return: IPv4 address, network order

Done.

> > + */
> > +in_addr_t tap_ip4_daddr(const struct ctx *c)
> > +{
> > +	return c->ip4.addr_seen;
> > +}
> > +
> > +/**
> > + * tap_ip6_daddr() - Normal IPv4 destination address for inbound packets
> > + * @c:		Execution context
> > + * @src:	Source address
> 
>  * Return: pointer to IPv6 address

Done.

> > + */
> > +const struct in6_addr *tap_ip6_daddr(const struct ctx *c,
> > +				     const struct in6_addr *src)
> > +{
> > +	if (IN6_IS_ADDR_LINKLOCAL(src))
> > +		return &c->ip6.addr_ll_seen;
> > +	return &c->ip6.addr_seen;
> > +}
> > +
> >  /**
> >   * tap_ip_send() - Send IP packet, with L2 headers, calculating L3/L4 checksums
> >   * @c:		Execution context
> > @@ -132,7 +154,7 @@ void tap_ip_send(const struct ctx *c, const struct in6_addr *src, uint8_t proto,
> >  		iph->frag_off = 0;
> >  		iph->ttl = 255;
> >  		iph->protocol = proto;
> > -		iph->daddr = c->ip4.addr_seen;
> > +		iph->daddr = tap_ip4_daddr(c);
> >  		memcpy(&iph->saddr, &src->s6_addr[12], 4);
> >  
> >  		csum_ip4_header(iph);
> > @@ -163,10 +185,7 @@ void tap_ip_send(const struct ctx *c, const struct in6_addr *src, uint8_t proto,
> >  		ip6h->priority = 0;
> >  
> >  		ip6h->saddr = *src;
> > -		if (IN6_IS_ADDR_LINKLOCAL(src))
> > -			ip6h->daddr = c->ip6.addr_ll_seen;
> > -		else
> > -			ip6h->daddr = c->ip6.addr_seen;
> > +		ip6h->daddr = *tap_ip6_daddr(c, src);
> >  
> >  		memcpy(data, in, len);
> >  
> > diff --git a/tap.h b/tap.h
> > index df3aec0..a6764b4 100644
> > --- a/tap.h
> > +++ b/tap.h
> > @@ -6,6 +6,9 @@
> >  #ifndef TAP_H
> >  #define TAP_H
> >  
> > +in_addr_t tap_ip4_daddr(const struct ctx *c);
> > +const struct in6_addr *tap_ip6_daddr(const struct ctx *c,
> > +				     const struct in6_addr *src);
> >  void tap_ip_send(const struct ctx *c, const struct in6_addr *src, uint8_t proto,
> >  		 const char *in, size_t len, uint32_t flow);
> >  int tap_send(const struct ctx *c, const void *data, size_t len, int vnet_pre);
> 

-- 
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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