From 1ab74cea060d776b19857c3babc64d729bbdba5c Mon Sep 17 00:00:00 2001 From: Fabien Chouteau Date: Mon, 1 Aug 2011 18:18:37 +0200 Subject: [PATCH] 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 Signed-off-by: Jan Kiszka --- slirp/if.c | 28 +++++++++++++++++--- slirp/main.h | 2 +- slirp/mbuf.c | 2 ++ slirp/mbuf.h | 2 ++ slirp/slirp.c | 72 ++++++++++++++++++++++++++++----------------------- 5 files changed, 69 insertions(+), 37 deletions(-) diff --git a/slirp/if.c b/slirp/if.c index 0f04e13989..2d79e45bcd 100644 --- a/slirp/if.c +++ b/slirp/if.c @@ -6,6 +6,7 @@ */ #include +#include "qemu-timer.h" #define ifs_init(ifm) ((ifm)->ifs_next = (ifm)->ifs_prev = (ifm)) @@ -105,6 +106,9 @@ if_output(struct socket *so, struct mbuf *ifm) ifs_init(ifm); insque(ifm, ifq); + /* Expiration date = Now + 1 second */ + ifm->expiration_date = qemu_get_clock_ns(rt_clock) + 1000000000ULL; + diddit: slirp->if_queued++; @@ -153,6 +157,9 @@ diddit: void if_start(Slirp *slirp) { + int requeued = 0; + uint64_t now; + struct mbuf *ifm, *ifqt; DEBUG_CALL("if_start"); @@ -165,6 +172,8 @@ if_start(Slirp *slirp) if (!slirp_can_output(slirp->opaque)) return; + now = qemu_get_clock_ns(rt_clock); + /* * See which queue to get next packet from * If there's something in the fastq, select it immediately @@ -199,11 +208,22 @@ if_start(Slirp *slirp) ifm->ifq_so->so_nqueued = 0; } - /* Encapsulate the packet for sending */ - if_encap(slirp, (uint8_t *)ifm->m_data, ifm->m_len); - - m_free(ifm); + if (ifm->expiration_date < now) { + /* Expired */ + m_free(ifm); + } else { + /* Encapsulate the packet for sending */ + if (if_encap(slirp, ifm)) { + m_free(ifm); + } else { + /* re-queue */ + insque(ifm, ifqt); + requeued++; + } + } if (slirp->if_queued) goto again; + + slirp->if_queued = requeued; } diff --git a/slirp/main.h b/slirp/main.h index 0dd8d81ce4..028df4b361 100644 --- a/slirp/main.h +++ b/slirp/main.h @@ -42,5 +42,5 @@ extern int tcp_keepintvl; #define PROTO_PPP 0x2 #endif -void if_encap(Slirp *slirp, const uint8_t *ip_data, int ip_data_len); +int if_encap(Slirp *slirp, struct mbuf *ifm); ssize_t slirp_send(struct socket *so, const void *buf, size_t len, int flags); diff --git a/slirp/mbuf.c b/slirp/mbuf.c index ce2eb843f5..c699c75096 100644 --- a/slirp/mbuf.c +++ b/slirp/mbuf.c @@ -70,6 +70,8 @@ m_get(Slirp *slirp) m->m_len = 0; m->m_nextpkt = NULL; m->m_prevpkt = NULL; + m->arp_requested = false; + m->expiration_date = (uint64_t)-1; end_error: DEBUG_ARG("m = %lx", (long )m); return m; diff --git a/slirp/mbuf.h b/slirp/mbuf.h index b74544b42b..55170e517b 100644 --- a/slirp/mbuf.h +++ b/slirp/mbuf.h @@ -86,6 +86,8 @@ struct mbuf { char m_dat_[1]; /* ANSI don't like 0 sized arrays */ char *m_ext_; } M_dat; + bool arp_requested; + uint64_t expiration_date; }; #define m_next m_hdr.mh_next diff --git a/slirp/slirp.c b/slirp/slirp.c index 4a9a4d5121..a86cc6eb2d 100644 --- a/slirp/slirp.c +++ b/slirp/slirp.c @@ -692,55 +692,63 @@ void slirp_input(Slirp *slirp, const uint8_t *pkt, int pkt_len) } } -/* 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; } }