Delayed IP packets
In the current implementation, if Slirp tries to send an IP packet to a client
with an unknown hardware address, the packet is simply dropped and an ARP
request is sent (if_encap in slirp/slirp.c).
With this patch, Slirp will send the ARP request, re-queue the packet and try
to send it later. The packet is dropped after one second if the ARP reply is
not received.
Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
diff --git a/slirp/slirp.c b/slirp/slirp.c
index 4a9a4d5..a86cc6e 100644
--- a/slirp/slirp.c
+++ b/slirp/slirp.c
@@ -692,55 +692,63 @@
}
}
-/* output the IP packet to the ethernet device */
-void if_encap(Slirp *slirp, const uint8_t *ip_data, int ip_data_len)
+/* Output the IP packet to the ethernet device. Returns 0 if the packet must be
+ * re-queued.
+ */
+int if_encap(Slirp *slirp, struct mbuf *ifm)
{
uint8_t buf[1600];
struct ethhdr *eh = (struct ethhdr *)buf;
uint8_t ethaddr[ETH_ALEN];
- const struct ip *iph = (const struct ip *)ip_data;
+ const struct ip *iph = (const struct ip *)ifm->m_data;
- if (ip_data_len + ETH_HLEN > sizeof(buf))
- return;
+ if (ifm->m_len + ETH_HLEN > sizeof(buf)) {
+ return 1;
+ }
if (!arp_table_search(slirp, iph->ip_dst.s_addr, ethaddr)) {
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);
- /* 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 - 4);
- memcpy(&reh->h_source[2], &slirp->vhost_addr, 4);
- 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 - 4);
- memcpy(&rah->ar_sha[2], &slirp->vhost_addr, 4);
- /* source IP */
- rah->ar_sip = slirp->vhost_addr.s_addr;
- /* target hw addr (none) */
- memset(rah->ar_tha, 0, ETH_ALEN);
- /* target IP */
- rah->ar_tip = iph->ip_dst.s_addr;
- slirp->client_ipaddr = iph->ip_dst;
- slirp_output(slirp->opaque, arp_req, sizeof(arp_req));
+ if (!ifm->arp_requested) {
+ /* If the client addr is not known, send an ARP request */
+ memset(reh->h_dest, 0xff, ETH_ALEN);
+ memcpy(reh->h_source, special_ethaddr, ETH_ALEN - 4);
+ memcpy(&reh->h_source[2], &slirp->vhost_addr, 4);
+ 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 - 4);
+ memcpy(&rah->ar_sha[2], &slirp->vhost_addr, 4);
+
+ /* source IP */
+ rah->ar_sip = slirp->vhost_addr.s_addr;
+
+ /* target hw addr (none) */
+ memset(rah->ar_tha, 0, ETH_ALEN);
+
+ /* target IP */
+ rah->ar_tip = iph->ip_dst.s_addr;
+ slirp->client_ipaddr = iph->ip_dst;
+ slirp_output(slirp->opaque, arp_req, sizeof(arp_req));
+ ifm->arp_requested = true;
+ }
+ return 0;
} else {
memcpy(eh->h_dest, ethaddr, ETH_ALEN);
memcpy(eh->h_source, special_ethaddr, ETH_ALEN - 4);
/* XXX: not correct */
memcpy(&eh->h_source[2], &slirp->vhost_addr, 4);
eh->h_proto = htons(ETH_P_IP);
- memcpy(buf + sizeof(struct ethhdr), ip_data, ip_data_len);
- slirp_output(slirp->opaque, buf, ip_data_len + ETH_HLEN);
+ memcpy(buf + sizeof(struct ethhdr), ifm->m_data, ifm->m_len);
+ slirp_output(slirp->opaque, buf, ifm->m_len + ETH_HLEN);
+ return 1;
}
}
