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udp: Consistently use -1 to indicate un-opened sockets in maps

udp uses the udp_tap_map, udp_splice_ns and udp_splice_init tables to keep
track of already opened sockets bound to specific ports.  We need a way to
indicate entries where a socket hasn't been opened, but the code isn't
consistent if this is indicated by a 0 or a -1:
  * udp_splice_sendfrom() and udp_tap_handler() assume that 0 indicates
    an unopened socket
  * udp_sock_init() fills in -1 for a failure to open a socket
  * udp_timer_one() is somewhere in between, treating only strictly
    positive fds as valid

-1 (or, at least, negative) is really the correct choice here, since 0 is
a theoretically valid fd value (if very unlikely in practice).  Change to
use that consistently throughout.

The table does need to be initialised to all -1 values before any calls to
udp_sock_init() which can happen from conf_ports().  Because C doesn't make
it easy to statically initialise non zero values in large tables, this does
require a somewhat awkward call to initialise the table from conf().  This
is the best approach I could see for the short term, with any luck it will
go away at some point when those socket tables are replaced by a unified
flow table.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2023-11-06 13:17:08 +11:00 committed by Stefano Brivio
parent c0426ff10b
commit 480aa4a108
3 changed files with 23 additions and 5 deletions

1
conf.c
View file

@ -1675,6 +1675,7 @@ void conf(struct ctx *c, int argc, char **argv)
c->no_map_gw = 1;
/* Inbound port options can be parsed now (after IPv4/IPv6 settings) */
udp_portmap_clear();
optind = 1;
do {
name = getopt_long(argc, argv, optstring, options, NULL);