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etharp_arp_input: stricter checking of hwtype, proto, hwlen & protolen allows us to leave some header fields like they are when sending ARP reply (only changing the addresses is needed)

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goldsimon 2007-06-25 18:03:23 +00:00
parent dcc2247a90
commit 1b5d3466ba
1 changed files with 16 additions and 7 deletions
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23
src/netif/etharp.c
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@ -598,6 +598,19 @@ etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
hdr = p->payload;
/* RFC 826 "Packet Reception": */
if ((hdr->hwtype != htons(HWTYPE_ETHERNET)) ||
(ARPH_HWLEN(hdr) != ETHARP_HWADDR_LEN) ||
(hdr->proto != htons(ETHTYPE_IP)) ||
(ARPH_PROTOLEN(hdr) != sizeof(struct ip_addr)) ||
(hdr->ethhdr.type != htons(ETHTYPE_ARP))) {
LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 1,
("etharp_arp_input: packet dropped, wrong hw type, hwlen, proto, protolen or ethernet type (%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F")\n",
hdr->hwtype, ARPH_HWLEN(hdr), hdr->proto, ARPH_PROTOLEN(hdr), hdr->ethhdr.type));
pbuf_free(p);
return;
}
#if LWIP_AUTOIP
/* We have to check if a host already has configured our random
* created link local address and continously check if there is
@ -657,18 +670,14 @@ etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
while(i > 0) {
i--;
hdr->dhwaddr.addr[i] = hdr->shwaddr.addr[i];
hdr->ethhdr.dest.addr[i] = hdr->shwaddr.addr[i];
hdr->shwaddr.addr[i] = ethaddr->addr[i];
hdr->ethhdr.dest.addr[i] = hdr->dhwaddr.addr[i];
hdr->ethhdr.src.addr[i] = ethaddr->addr[i];
}
hdr->hwtype = htons(HWTYPE_ETHERNET);
ARPH_HWLEN_SET(hdr, netif->hwaddr_len);
/* hwtype, hwaddr_len, proto, protolen and the type in the ethernet header
are already correct, we tested that before */
hdr->proto = htons(ETHTYPE_IP);
ARPH_PROTOLEN_SET(hdr, sizeof(struct ip_addr));
hdr->ethhdr.type = htons(ETHTYPE_ARP);
/* return ARP reply */
netif->linkoutput(netif, p);
/* we are not configured? */