diff options
Diffstat (limited to 'fw/src/ether.c')
| -rw-r--r-- | fw/src/ether.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/fw/src/ether.c b/fw/src/ether.c index d77143a..48f69b9 100644 --- a/fw/src/ether.c +++ b/fw/src/ether.c @@ -292,6 +292,29 @@ arpin(uchar *f, int n) write(efd, r, sizeof r); } +/* + * Is this frame ours to look at? + * + * The card is promiscuous and has to be: the stack behind fw joins + * multicast groups on a pkt interface, which has no way to tell a card + * about them, so without it the groups would never be received. What + * promiscuous adds beyond that is other machines' unicast, and handing + * that to the protected stack means judging it, counting it and + * tracking flows for conversations that were never ours. ethermux + * would have given us frames addressed to this card plus broadcast and + * multicast for nothing; this puts back the filter that asking for + * promiscuous took away. + */ +int +etherforme(uchar *f, int n) +{ + if(n < Ehdrlen) + return 0; + if((f[0] & 1) != 0) /* group: broadcast or multicast */ + return 1; + return memcmp(f, ourmac, Eaddrlen) == 0; +} + int etherisarp(uchar *f, int n) { |