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Simple ARP table

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This patch adds a simple ARP table in Slirp and also adds handling of
gratuitous ARP requests.

Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
This commit is contained in:
Fabien Chouteau 2011-08-03 12:52:54 +02:00 committed by Jan Kiszka
parent bafc72ab01
commit 1a0ca1e1f6
5 changed files with 169 additions and 59 deletions
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2
Makefile.objs
View file

@ -151,7 +151,7 @@ common-obj-y += qemu-timer.o qemu-timer-common.o
slirp-obj-y = cksum.o if.o ip_icmp.o ip_input.o ip_output.o
slirp-obj-y += slirp.o mbuf.o misc.o sbuf.o socket.o tcp_input.o tcp_output.o
slirp-obj-y += tcp_subr.o tcp_timer.o udp.o bootp.o tftp.o
slirp-obj-y += tcp_subr.o tcp_timer.o udp.o bootp.o tftp.o arp_table.o
common-obj-$(CONFIG_SLIRP) += $(addprefix slirp/, $(slirp-obj-y))
# xen backend driver support

95
slirp/arp_table.c Normal file
View file

@ -0,0 +1,95 @@
/*
* ARP table
*
* Copyright (c) 2011 AdaCore
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "slirp.h"
void arp_table_add(Slirp *slirp, int ip_addr, uint8_t ethaddr[ETH_ALEN])
{
const in_addr_t broadcast_addr =
~slirp->vnetwork_mask.s_addr | slirp->vnetwork_addr.s_addr;
ArpTable *arptbl = &slirp->arp_table;
int i;
DEBUG_CALL("arp_table_add");
DEBUG_ARG("ip = 0x%x", ip_addr);
DEBUG_ARGS((dfd, " hw addr = %02x:%02x:%02x:%02x:%02x:%02x\n",
ethaddr[0], ethaddr[1], ethaddr[2],
ethaddr[3], ethaddr[4], ethaddr[5]));
/* Check 0.0.0.0/8 invalid source-only addresses */
assert((ip_addr & htonl(~(0xf << 28))) != 0);
if (ip_addr == 0xffffffff || ip_addr == broadcast_addr) {
/* Do not register broadcast addresses */
return;
}
/* Search for an entry */
for (i = 0; i < ARP_TABLE_SIZE; i++) {
if (arptbl->table[i].ar_sip == ip_addr) {
/* Update the entry */
memcpy(arptbl->table[i].ar_sha, ethaddr, ETH_ALEN);
return;
}
}
/* No entry found, create a new one */
arptbl->table[arptbl->next_victim].ar_sip = ip_addr;
memcpy(arptbl->table[arptbl->next_victim].ar_sha, ethaddr, ETH_ALEN);
arptbl->next_victim = (arptbl->next_victim + 1) % ARP_TABLE_SIZE;
}
bool arp_table_search(Slirp *slirp, int in_ip_addr,
uint8_t out_ethaddr[ETH_ALEN])
{
const in_addr_t broadcast_addr =
~slirp->vnetwork_mask.s_addr | slirp->vnetwork_addr.s_addr;
ArpTable *arptbl = &slirp->arp_table;
int i;
DEBUG_CALL("arp_table_search");
DEBUG_ARG("ip = 0x%x", in_ip_addr);
/* Check 0.0.0.0/8 invalid source-only addresses */
assert((in_ip_addr & htonl(~(0xf << 28))) != 0);
/* If broadcast address */
if (in_ip_addr == 0xffffffff || in_ip_addr == broadcast_addr) {
/* return Ethernet broadcast address */
memset(out_ethaddr, 0xff, ETH_ALEN);
return 1;
}
for (i = 0; i < ARP_TABLE_SIZE; i++) {
if (arptbl->table[i].ar_sip == in_ip_addr) {
memcpy(out_ethaddr, arptbl->table[i].ar_sha, ETH_ALEN);
DEBUG_ARGS((dfd, " found hw addr = %02x:%02x:%02x:%02x:%02x:%02x\n",
out_ethaddr[0], out_ethaddr[1], out_ethaddr[2],
out_ethaddr[3], out_ethaddr[4], out_ethaddr[5]));
return 1;
}
}
return 0;
}

21
slirp/bootp.c
View file

@ -149,6 +149,7 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
struct in_addr preq_addr;
int dhcp_msg_type, val;
uint8_t *q;
uint8_t client_ethaddr[ETH_ALEN];
/* extract exact DHCP msg type */
dhcp_decode(bp, &dhcp_msg_type, &preq_addr);
@ -164,8 +165,9 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
if (dhcp_msg_type != DHCPDISCOVER &&
dhcp_msg_type != DHCPREQUEST)
return;
/* XXX: this is a hack to get the client mac address */
memcpy(slirp->client_ethaddr, bp->bp_hwaddr, 6);
/* Get client's hardware address from bootp request */
memcpy(client_ethaddr, bp->bp_hwaddr, ETH_ALEN);
m = m_get(slirp);
if (!m) {
@ -178,25 +180,25 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
if (dhcp_msg_type == DHCPDISCOVER) {
if (preq_addr.s_addr != htonl(0L)) {
bc = request_addr(slirp, &preq_addr, slirp->client_ethaddr);
bc = request_addr(slirp, &preq_addr, client_ethaddr);
if (bc) {
daddr.sin_addr = preq_addr;
}
}
if (!bc) {
new_addr:
bc = get_new_addr(slirp, &daddr.sin_addr, slirp->client_ethaddr);
bc = get_new_addr(slirp, &daddr.sin_addr, client_ethaddr);
if (!bc) {
DPRINTF("no address left\n");
return;
}
}
memcpy(bc->macaddr, slirp->client_ethaddr, 6);
memcpy(bc->macaddr, client_ethaddr, ETH_ALEN);
} else if (preq_addr.s_addr != htonl(0L)) {
bc = request_addr(slirp, &preq_addr, slirp->client_ethaddr);
bc = request_addr(slirp, &preq_addr, client_ethaddr);
if (bc) {
daddr.sin_addr = preq_addr;
memcpy(bc->macaddr, slirp->client_ethaddr, 6);
memcpy(bc->macaddr, client_ethaddr, ETH_ALEN);
} else {
daddr.sin_addr.s_addr = 0;
}
@ -209,6 +211,9 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
}
}
/* Update ARP table for this IP address */
arp_table_add(slirp, daddr.sin_addr.s_addr, client_ethaddr);
saddr.sin_addr = slirp->vhost_addr;
saddr.sin_port = htons(BOOTP_SERVER);
@ -218,7 +223,7 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
rbp->bp_xid = bp->bp_xid;
rbp->bp_htype = 1;
rbp->bp_hlen = 6;
memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6);
memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, ETH_ALEN);
rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */
rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */

63
slirp/slirp.c
View file

@ -31,11 +31,11 @@
struct in_addr loopback_addr;
/* emulated hosts use the MAC addr 52:55:IP:IP:IP:IP */
static const uint8_t special_ethaddr[6] = {
static const uint8_t special_ethaddr[ETH_ALEN] = {
0x52, 0x55, 0x00, 0x00, 0x00, 0x00
};
static const uint8_t zero_ethaddr[6] = { 0, 0, 0, 0, 0, 0 };
static const uint8_t zero_ethaddr[ETH_ALEN] = { 0, 0, 0, 0, 0, 0 };
/* XXX: suppress those select globals */
fd_set *global_readfds, *global_writefds, *global_xfds;
@ -599,42 +599,8 @@ void slirp_select_poll(fd_set *readfds, fd_set *writefds, fd_set *xfds,
global_xfds = NULL;
}
#define ETH_ALEN 6
#define ETH_HLEN 14
#define ETH_P_IP 0x0800 /* Internet Protocol packet */
#define ETH_P_ARP 0x0806 /* Address Resolution packet */
#define ARPOP_REQUEST 1 /* ARP request */
#define ARPOP_REPLY 2 /* ARP reply */
struct ethhdr
{
unsigned char h_dest[ETH_ALEN]; /* destination eth addr */
unsigned char h_source[ETH_ALEN]; /* source ether addr */
unsigned short h_proto; /* packet type ID field */
};
struct arphdr
{
unsigned short ar_hrd; /* format of hardware address */
unsigned short ar_pro; /* format of protocol address */
unsigned char ar_hln; /* length of hardware address */
unsigned char ar_pln; /* length of protocol address */
unsigned short ar_op; /* ARP opcode (command) */
/*
* Ethernet looks like this : This bit is variable sized however...
*/
unsigned char ar_sha[ETH_ALEN]; /* sender hardware address */
uint32_t ar_sip; /* sender IP address */
unsigned char ar_tha[ETH_ALEN]; /* target hardware address */
uint32_t ar_tip ; /* target IP address */
} __attribute__((packed));
static void arp_input(Slirp *slirp, const uint8_t *pkt, int pkt_len)
{
struct ethhdr *eh = (struct ethhdr *)pkt;
struct arphdr *ah = (struct arphdr *)(pkt + ETH_HLEN);
uint8_t arp_reply[max(ETH_HLEN + sizeof(struct arphdr), 64)];
struct ethhdr *reh = (struct ethhdr *)arp_reply;
@ -645,6 +611,12 @@ static void arp_input(Slirp *slirp, const uint8_t *pkt, int pkt_len)
ar_op = ntohs(ah->ar_op);
switch(ar_op) {
case ARPOP_REQUEST:
if (ah->ar_tip == ah->ar_sip) {
/* Gratuitous ARP */
arp_table_add(slirp, ah->ar_sip, ah->ar_sha);
return;
}
if ((ah->ar_tip & slirp->vnetwork_mask.s_addr) ==
slirp->vnetwork_addr.s_addr) {
if (ah->ar_tip == slirp->vnameserver_addr.s_addr ||
@ -657,8 +629,8 @@ static void arp_input(Slirp *slirp, const uint8_t *pkt, int pkt_len)
return;
arp_ok:
memset(arp_reply, 0, sizeof(arp_reply));
/* XXX: make an ARP request to have the client address */
memcpy(slirp->client_ethaddr, eh->h_source, ETH_ALEN);
arp_table_add(slirp, ah->ar_sip, ah->ar_sha);
/* ARP request for alias/dns mac address */
memcpy(reh->h_dest, pkt + ETH_ALEN, ETH_ALEN);
@ -679,11 +651,7 @@ static void arp_input(Slirp *slirp, const uint8_t *pkt, int pkt_len)
}
break;
case ARPOP_REPLY:
/* reply to request of client mac address ? */
if (!memcmp(slirp->client_ethaddr, zero_ethaddr, ETH_ALEN) &&
ah->ar_sip == slirp->client_ipaddr.s_addr) {
memcpy(slirp->client_ethaddr, ah->ar_sha, ETH_ALEN);
}
arp_table_add(slirp, ah->ar_sip, ah->ar_sha);
break;
default:
break;
@ -729,15 +697,16 @@ void if_encap(Slirp *slirp, const uint8_t *ip_data, int ip_data_len)
{
uint8_t buf[1600];
struct ethhdr *eh = (struct ethhdr *)buf;
uint8_t ethaddr[ETH_ALEN];
const struct ip *iph = (const struct ip *)ip_data;
if (ip_data_len + ETH_HLEN > sizeof(buf))
return;
if (!memcmp(slirp->client_ethaddr, zero_ethaddr, ETH_ALEN)) {
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);
const struct ip *iph = (const struct ip *)ip_data;
/* If the client addr is not known, there is no point in
sending the packet to it. Normally the sender should have
@ -765,7 +734,7 @@ void if_encap(Slirp *slirp, const uint8_t *ip_data, int ip_data_len)
slirp->client_ipaddr = iph->ip_dst;
slirp_output(slirp->opaque, arp_req, sizeof(arp_req));
} else {
memcpy(eh->h_dest, slirp->client_ethaddr, ETH_ALEN);
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);

47
slirp/slirp.h
View file

@ -170,6 +170,48 @@ int inet_aton(const char *cp, struct in_addr *ia);
/* osdep.c */
int qemu_socket(int domain, int type, int protocol);
#define ETH_ALEN 6
#define ETH_HLEN 14
#define ETH_P_IP 0x0800 /* Internet Protocol packet */
#define ETH_P_ARP 0x0806 /* Address Resolution packet */
#define ARPOP_REQUEST 1 /* ARP request */
#define ARPOP_REPLY 2 /* ARP reply */
struct ethhdr {
unsigned char h_dest[ETH_ALEN]; /* destination eth addr */
unsigned char h_source[ETH_ALEN]; /* source ether addr */
unsigned short h_proto; /* packet type ID field */
};
struct arphdr {
unsigned short ar_hrd; /* format of hardware address */
unsigned short ar_pro; /* format of protocol address */
unsigned char ar_hln; /* length of hardware address */
unsigned char ar_pln; /* length of protocol address */
unsigned short ar_op; /* ARP opcode (command) */
/*
* Ethernet looks like this : This bit is variable sized however...
*/
unsigned char ar_sha[ETH_ALEN]; /* sender hardware address */
uint32_t ar_sip; /* sender IP address */
unsigned char ar_tha[ETH_ALEN]; /* target hardware address */
uint32_t ar_tip; /* target IP address */
} __attribute__((packed));
#define ARP_TABLE_SIZE 16
typedef struct ArpTable {
struct arphdr table[ARP_TABLE_SIZE];
int next_victim;
} ArpTable;
void arp_table_add(Slirp *slirp, int ip_addr, uint8_t ethaddr[ETH_ALEN]);
bool arp_table_search(Slirp *slirp, int in_ip_addr,
uint8_t out_ethaddr[ETH_ALEN]);
struct Slirp {
QTAILQ_ENTRY(Slirp) entry;
@ -181,9 +223,6 @@ struct Slirp {
struct in_addr vdhcp_startaddr;
struct in_addr vnameserver_addr;
/* ARP cache for the guest IP addresses (XXX: allow many entries) */
uint8_t client_ethaddr[6];
struct in_addr client_ipaddr;
char client_hostname[33];
@ -227,6 +266,8 @@ struct Slirp {
char *tftp_prefix;
struct tftp_session tftp_sessions[TFTP_SESSIONS_MAX];
ArpTable arp_table;
void *opaque;
};