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allow SLIRP to make an ARP request to get the client MAC address. It is useful if an inbound connection is done to a VM which did not send outbound IP packets 

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5498 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
bellard 2008-10-17 17:28:58 +00:00
parent 89c0f6438d
commit de806f0786
1 changed files with 51 additions and 7 deletions
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58
slirp/slirp.c
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@ -16,7 +16,11 @@ static const uint8_t special_ethaddr[6] = {
0x52, 0x54, 0x00, 0x12, 0x35, 0x00
};
/* ARP cache for the guest IP addresses (XXX: allow many entries) */
uint8_t client_ethaddr[6];
static struct in_addr client_ipaddr;
static const uint8_t zero_ethaddr[6] = { 0, 0, 0, 0, 0, 0 };
int do_slowtimo;
int link_up;
@ -597,6 +601,13 @@ static void arp_input(const uint8_t *pkt, int pkt_len)
slirp_output(arp_reply, sizeof(arp_reply));
}
break;
case ARPOP_REPLY:
/* reply to request of client mac address ? */
if (!memcmp(client_ethaddr, zero_ethaddr, ETH_ALEN) &&
!memcmp(ah->ar_sip, &client_ipaddr.s_addr, 4)) {
memcpy(client_ethaddr, ah->ar_sha, ETH_ALEN);
}
break;
default:
break;
}
@ -641,14 +652,47 @@ void if_encap(const uint8_t *ip_data, int ip_data_len)
if (ip_data_len + ETH_HLEN > sizeof(buf))
return;
if (!memcmp(client_ethaddr, zero_ethaddr, ETH_ALEN)) {
uint8_t arp_req[ETH_HLEN + sizeof(struct arphdr)];
struct ethhdr *reh = (struct ethhdr *)arp_req;
struct arphdr *rah = (struct arphdr *)(arp_req + ETH_HLEN);
const struct ip *iph = (const struct ip *)ip_data;
memcpy(eh->h_dest, client_ethaddr, ETH_ALEN);
memcpy(eh->h_source, special_ethaddr, ETH_ALEN - 1);
/* XXX: not correct */
eh->h_source[5] = CTL_ALIAS;
eh->h_proto = htons(ETH_P_IP);
memcpy(buf + sizeof(struct ethhdr), ip_data, ip_data_len);
slirp_output(buf, ip_data_len + ETH_HLEN);
/* If the client addr is not known, there is no point in
sending the packet to it. Normally the sender should have
done an ARP request to get its MAC address. Here we do it
in place of sending the packet and we hope that the sender
will retry sending its packet. */
memset(reh->h_dest, 0xff, ETH_ALEN);
memcpy(reh->h_source, special_ethaddr, ETH_ALEN - 1);
reh->h_source[5] = CTL_ALIAS;
reh->h_proto = htons(ETH_P_ARP);
rah->ar_hrd = htons(1);
rah->ar_pro = htons(ETH_P_IP);
rah->ar_hln = ETH_ALEN;
rah->ar_pln = 4;
rah->ar_op = htons(ARPOP_REQUEST);
/* source hw addr */
memcpy(rah->ar_sha, special_ethaddr, ETH_ALEN - 1);
rah->ar_sha[5] = CTL_ALIAS;
/* source IP */
memcpy(rah->ar_sip, &alias_addr, 4);
/* target hw addr (none) */
memset(rah->ar_tha, 0, ETH_ALEN);
/* target IP */
memcpy(rah->ar_tip, &iph->ip_dst, 4);
client_ipaddr = iph->ip_dst;
slirp_output(arp_req, sizeof(arp_req));
} else {
memcpy(eh->h_dest, client_ethaddr, ETH_ALEN);
memcpy(eh->h_source, special_ethaddr, ETH_ALEN - 1);
/* XXX: not correct */
eh->h_source[5] = CTL_ALIAS;
eh->h_proto = htons(ETH_P_IP);
memcpy(buf + sizeof(struct ethhdr), ip_data, ip_data_len);
slirp_output(buf, ip_data_len + ETH_HLEN);
}
}
int slirp_redir(int is_udp, int host_port,