Re: [PATCH v2 06/12] icmp: Use -1 to represent "missing" sockets

On Sat, Jan 06, 2024 at 04:59:32PM +0100, Stefano Brivio wrote:

On Thu, 21 Dec 2023 17:53:21 +1100 David Gibson wrote:

...

icmp_id_map[] contains, amongst other things, fds for "ping" sockets associated with various ICMP echo ids. However, we only lazily open() those sockets, so many will be missing. We currently represent that with a 0, which isn't great, since that's technically a valid fd. Use -1 instead. This does require initializing the fields in icmp_id_map[] but we already have an obvious place to do that.

Signed-off-by: David Gibson --- icmp.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/icmp.c b/icmp.c index 7a505b4..dd98c7f 100644 --- a/icmp.c +++ b/icmp.c @@ -179,7 +179,7 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, int af,

iref.id = id = ntohs(ih->un.echo.id);

- if ((s = icmp_id_map[V4][id].sock) <= 0) { + if ((s = icmp_id_map[V4][id].sock) < 0) { s = sock_l4(c, AF_INET, IPPROTO_ICMP, &c->ip4.addr_out, c->ip4.ifname_out, 0, iref.u32); if (s < 0) @@ -221,7 +221,7 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, int af, return 1;

iref.id = id = ntohs(ih->icmp6_identifier); - if ((s = icmp_id_map[V6][id].sock) <= 0) { + if ((s = icmp_id_map[V6][id].sock) < 0) { s = sock_l4(c, AF_INET6, IPPROTO_ICMPV6, &c->ip6.addr_out, c->ip6.ifname_out, 0, iref.u32); @@ -277,7 +277,7 @@ static void icmp_timer_one(const struct ctx *c, int v6, uint16_t id,

epoll_ctl(c->epollfd, EPOLL_CTL_DEL, id_map->sock, NULL); close(id_map->sock); - id_map->sock = 0; + id_map->sock = -1; id_map->seq = -1; }

@@ -315,6 +315,8 @@ void icmp_init(void) { unsigned i;

- for (i = 0; i < ICMP_NUM_IDS; i++) + for (i = 0; i < ICMP_NUM_IDS; i++) { icmp_id_map[V4][i].seq = icmp_id_map[V6][i].seq = -1; + icmp_id_map[V4][i].sock = icmp_id_map[V6][i].sock = -1; + }

Another (well, kind of existing) use case for a 0xff-initialising helper.

Hm.. it's still not every field, so only sorta. -- 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