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passt/pif.c
David Gibson b8d4fac6a2 util, pif: Replace sock_l4() with pif_sock_l4()
The sock_l4() function is very convenient for creating sockets bound to
a given address, but its interface has some problems.

Most importantly, the address and port alone aren't enough in some cases.
For link-local addresses (at least) we also need the pif in order to
properly construct a socket adddress.  This case doesn't yet arise, but
it might cause us trouble in future.

Additionally, sock_l4() can take AF_UNSPEC with the special meaning that it
should attempt to create a "dual stack" socket which will respond to both
IPv4 and IPv6 traffic.  This only makes sense if there is no specific
address given.  We verify this at runtime, but it would be nicer if we
could enforce it structurally.

For sockets associated specifically with a single flow we already replaced
sock_l4() with flowside_sock_l4() which avoids those problems.  Now,
replace all the remaining users with a new pif_sock_l4() which also takes
an explicit pif.

The new function takes the address as an inany *, with NULL indicating the
dual stack case.  This does add some complexity in some of the callers,
however future planned cleanups should make this go away again.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2024-09-25 19:03:15 +02:00

104 lines
2.7 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later
* Copyright Red Hat
* Author: David Gibson <david@gibson.dropbear.id.au>
*
* Passt/pasta interface types and IDs
*/
#include <stdint.h>
#include <assert.h>
#include <netinet/in.h>
#include "util.h"
#include "pif.h"
#include "siphash.h"
#include "ip.h"
#include "inany.h"
#include "passt.h"
const char *pif_type_str[] = {
[PIF_NONE] = "<none>",
[PIF_HOST] = "HOST",
[PIF_TAP] = "TAP",
[PIF_SPLICE] = "SPLICE",
};
static_assert(ARRAY_SIZE(pif_type_str) == PIF_NUM_TYPES,
"pif_type_str[] doesn't match enum pif_type");
/** pif_sockaddr() - Construct a socket address suitable for an interface
* @c: Execution context
* @sa: Pointer to sockaddr to fill in
* @sl: Updated to relevant length of initialised @sa
* @pif: Interface to create the socket address
* @addr: IPv[46] address
* @port: Port (host byte order)
*/
void pif_sockaddr(const struct ctx *c, union sockaddr_inany *sa, socklen_t *sl,
uint8_t pif, const union inany_addr *addr, in_port_t port)
{
const struct in_addr *v4 = inany_v4(addr);
ASSERT(pif_is_socket(pif));
if (v4) {
sa->sa_family = AF_INET;
sa->sa4.sin_addr = *v4;
sa->sa4.sin_port = htons(port);
memset(&sa->sa4.sin_zero, 0, sizeof(sa->sa4.sin_zero));
*sl = sizeof(sa->sa4);
} else {
sa->sa_family = AF_INET6;
sa->sa6.sin6_addr = addr->a6;
sa->sa6.sin6_port = htons(port);
if (pif == PIF_HOST && IN6_IS_ADDR_LINKLOCAL(&addr->a6))
sa->sa6.sin6_scope_id = c->ifi6;
else
sa->sa6.sin6_scope_id = 0;
sa->sa6.sin6_flowinfo = 0;
*sl = sizeof(sa->sa6);
}
}
/** pif_sock_l4() - Open a socket bound to an address on a specified interface
* @c: Execution context
* @type: Socket epoll type
* @pif: Interface for this socket
* @addr: Address to bind to, or NULL for dual-stack any
* @ifname: Interface for binding, NULL for any
* @port: Port number to bind to (host byte order)
* @data: epoll reference portion for protocol handlers
*
* NOTE: For namespace pifs, this must be called having already entered the
* relevant namespace.
*
* Return: newly created socket, negative error code on failure
*/
int pif_sock_l4(const struct ctx *c, enum epoll_type type, uint8_t pif,
const union inany_addr *addr, const char *ifname,
in_port_t port, uint32_t data)
{
union sockaddr_inany sa = {
.sa6.sin6_family = AF_INET6,
.sa6.sin6_addr = in6addr_any,
.sa6.sin6_port = htons(port),
};
socklen_t sl;
ASSERT(pif_is_socket(pif));
if (pif == PIF_SPLICE) {
/* Sanity checks */
ASSERT(!ifname);
ASSERT(addr && inany_is_loopback(addr));
}
if (!addr)
return sock_l4_sa(c, type, &sa, sizeof(sa.sa6),
ifname, false, data);
pif_sockaddr(c, &sa, &sl, pif, addr, port);
return sock_l4_sa(c, type, &sa, sl,
ifname, sa.sa_family == AF_INET6, data);
}