Re: [PATCH v7 15/27] flow: Helper to create sockets based on flowside

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

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On Wed, Jul 10, 2024 at 11:32:01PM +0200, Stefano Brivio wrote:
> On Fri,  5 Jul 2024 12:07:12 +1000
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
> > We have upcoming use cases where it's useful to create new bound socket
> > based on information from the flow table.  Add flowside_sock_l4() to do
> > this for either PIF_HOST or PIF_SPLICE sockets.
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  flow.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  flow.h |  3 ++
> >  util.c |  6 ++--
> >  util.h |  3 ++
> >  4 files changed, 101 insertions(+), 3 deletions(-)
> > 
> > diff --git a/flow.c b/flow.c
> > index 6f09781a..2d0a8a32 100644
> > --- a/flow.c
> > +++ b/flow.c
> > @@ -5,9 +5,11 @@
> >   * Tracking for logical "flows" of packets.
> >   */
> >  
> > +#include <errno.h>
> >  #include <stdint.h>
> >  #include <stdio.h>
> >  #include <unistd.h>
> > +#include <sched.h>
> >  #include <string.h>
> >  
> >  #include "util.h"
> > @@ -143,6 +145,96 @@ static void flowside_from_af(struct flowside *fside, sa_family_t af,
> >  	fside->eport = eport;
> >  }
> >  
> > +/**
> > + * struct flowside_sock_args - Parameters for flowside_sock_splice()
> > + * @c:		Execution context
> > + * @fd:		Filled in with new socket fd
> > + * @err:	Filled in with errno if something failed
> > + * @type:	Socket epoll type
> > + * @sa:		Socket address
> > + * @sl:		Length of @sa
> > + * @data:	epoll reference data
> > + */
> > +struct flowside_sock_args {
> > +	const struct ctx *c;
> > +	int fd;
> > +	int err;
> > +	enum epoll_type type;
> > +	const struct sockaddr *sa;
> > +	socklen_t sl;
> > +	const char *path;
> > +	uint32_t data;
> > +};
> > +
> > +/** flowside_sock_splice() - Create and bind socket for PIF_SPLICE based on flowside
> > + * @arg:	Argument as a struct flowside_sock_args
> > + *
> > + * Return: 0
> > + */
> > +static int flowside_sock_splice(void *arg)
> > +{
> > +	struct flowside_sock_args *a = arg;
> > +
> > +	ns_enter(a->c);
> > +
> > +	a->fd =  sock_l4_sa(a->c, a->type, a->sa, a->sl, NULL,
> 
> Nit: assuming you wanted the extra whitespace here to align the
> assignment with the one of a->err below, I'd rather write this
> (at least for consistency) as "a->fd  = ...".

Actually, I think it was just a boring old typo.

> 
> > +			    a->sa->sa_family == AF_INET6, a->data);
> > +	a->err = errno;
> 
> 
> > +
> > +	return 0;
> > +}
> > +
> > +/** flowside_sock_l4() - Create and bind socket based on flowside
> > + * @c:		Execution context
> > + * @type:	Socket epoll type
> > + * @pif:	Interface for this socket
> > + * @tgt:	Target flowside
> > + * @data:	epoll reference portion for protocol handlers
> > + *
> > + * Return: socket fd of protocol @proto bound to the forwarding address and port
> > + *         from @tgt (if specified).
> > + */
> > +/* cppcheck-suppress unusedFunction */
> > +int flowside_sock_l4(const struct ctx *c, enum epoll_type type, uint8_t pif,
> > +		     const struct flowside *tgt, uint32_t data)
> > +{
> > +	const char *ifname = NULL;
> > +	union sockaddr_inany sa;
> > +	socklen_t sl;
> > +
> > +	ASSERT(pif_is_socket(pif));
> > +
> > +	pif_sockaddr(c, &sa, &sl, pif, &tgt->faddr, tgt->fport);
> > +
> > +	switch (pif) {
> > +	case PIF_HOST:
> > +		if (inany_is_loopback(&tgt->faddr))
> > +			ifname = NULL;
> > +		else if (sa.sa_family == AF_INET)
> > +			ifname = c->ip4.ifname_out;
> > +		else if (sa.sa_family == AF_INET6)
> > +			ifname = c->ip6.ifname_out;
> > +
> > +		return sock_l4_sa(c, type, &sa, sl, ifname,
> > +				  sa.sa_family == AF_INET6, data);
> > +
> > +	case PIF_SPLICE: {
> > +		struct flowside_sock_args args = {
> > +			.c = c, .type = type,
> > +			.sa = &sa.sa, .sl = sl, .data = data,
> > +		};
> > +		NS_CALL(flowside_sock_splice, &args);
> > +		errno = args.err;
> > +		return args.fd;
> > +	}
> > +
> > +	default:
> > +		/* If we add new socket pifs, they'll need to be implemented
> > +		 * here */
> 
> For consistency:
> 
> 		/* If we add new socket pifs, they'll need to be implemented
> 		 * here
> 		 */

Done.

> 
> there are a few occurrences in the next patches, not so important I
> guess, I can also do a pass later at some point.
> 
> > +		ASSERT(0);
> > +	}
> > +}
> > +
> >  /** flow_log_ - Log flow-related message
> >   * @f:		flow the message is related to
> >   * @pri:	Log priority
> > diff --git a/flow.h b/flow.h
> > index c3a15ca6..e27f99be 100644
> > --- a/flow.h
> > +++ b/flow.h
> > @@ -164,6 +164,9 @@ static inline bool flowside_eq(const struct flowside *left,
> >  	       left->fport == right->fport;
> >  }
> >  
> > +int flowside_sock_l4(const struct ctx *c, enum epoll_type type, uint8_t pif,
> > +		     const struct flowside *tgt, uint32_t data);
> > +
> >  /**
> >   * struct flow_common - Common fields for packet flows
> >   * @state:	State of the flow table entry
> > diff --git a/util.c b/util.c
> > index 9a73fbb9..f2994a79 100644
> > --- a/util.c
> > +++ b/util.c
> > @@ -44,9 +44,9 @@
> >   *
> >   * Return: newly created socket, negative error code on failure
> >   */
> > -static int sock_l4_sa(const struct ctx *c, enum epoll_type type,
> > -		      const void *sa, socklen_t sl,
> > -		      const char *ifname, bool v6only, uint32_t data)
> > +int sock_l4_sa(const struct ctx *c, enum epoll_type type,
> > +	       const void *sa, socklen_t sl,
> > +	       const char *ifname, bool v6only, uint32_t data)
> >  {
> >  	sa_family_t af = ((const struct sockaddr *)sa)->sa_family;
> >  	union epoll_ref ref = { .type = type, .data = data };
> > diff --git a/util.h b/util.h
> > index d0150396..f2e4f8cf 100644
> > --- a/util.h
> > +++ b/util.h
> > @@ -144,6 +144,9 @@ struct ctx;
> >  
> >  /* cppcheck-suppress funcArgNamesDifferent */
> >  __attribute__ ((weak)) int ffsl(long int i) { return __builtin_ffsl(i); }
> > +int sock_l4_sa(const struct ctx *c, enum epoll_type type,
> > +	       const void *sa, socklen_t sl,
> > +	       const char *ifname, bool v6only, uint32_t data);
> >  int sock_l4(const struct ctx *c, sa_family_t af, enum epoll_type type,
> >  	    const void *bind_addr, const char *ifname, uint16_t port,
> >  	    uint32_t data);
> 

-- 
David Gibson (he or they)	| 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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