conf, tcp, udp: Allow specification of interface to bind to

Since kernel version 5.7, commit c427bfec18f2 ("net: core: enable
SO_BINDTODEVICE for non-root users"), we can bind sockets to
interfaces, if they haven't been bound yet (as in bind()).

Introduce an optional interface specification for forwarded ports,
prefixed by %, that can be passed together with an address.

Reported use case: running local services that use ports we want
to have externally forwarded:
  https://github.com/containers/podman/issues/14425

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 2 insertions, 1 deletions

diff --git a/util.h b/util.h
index f9a8ec6..7dc3d18 100644
--- a/util.h
+++ b/util.h
@@ -194,7 +194,8 @@ __attribute__ ((weak)) int ffsl(long int i) { return __builtin_ffsl(i); }
 char *ipv6_l4hdr(const struct pool *p, int index, size_t offset, uint8_t *proto,
 		 size_t *dlen);
 int sock_l4(const struct ctx *c, int af, uint8_t proto,
-	    const void *bind_addr, uint16_t port, uint32_t data);
+	    const void *bind_addr, const char *ifname, uint16_t port,
+	    uint32_t data);
 void sock_probe_mem(struct ctx *c);
 int timespec_diff_ms(const struct timespec *a, const struct timespec *b);
 void bitmap_set(uint8_t *map, int bit);