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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

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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 0x52, 0x54, 0x00, 0x12, 0x35, 0x00
}; };
/* ARP cache for the guest IP addresses (XXX: allow many entries) */
uint8_t client_ethaddr[6]; 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 do_slowtimo;
int link_up; 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)); slirp_output(arp_reply, sizeof(arp_reply));
} }
break; 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: default:
break; 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)) if (ip_data_len + ETH_HLEN > sizeof(buf))
return; 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); /* If the client addr is not known, there is no point in
memcpy(eh->h_source, special_ethaddr, ETH_ALEN - 1); sending the packet to it. Normally the sender should have
/* XXX: not correct */ done an ARP request to get its MAC address. Here we do it
eh->h_source[5] = CTL_ALIAS; in place of sending the packet and we hope that the sender
eh->h_proto = htons(ETH_P_IP); will retry sending its packet. */
memcpy(buf + sizeof(struct ethhdr), ip_data, ip_data_len); memset(reh->h_dest, 0xff, ETH_ALEN);
slirp_output(buf, ip_data_len + ETH_HLEN); 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, int slirp_redir(int is_udp, int host_port,