Simple ARP table
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>
diff --git a/Makefile.objs b/Makefile.objs
index 6991a9f..0c10557 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -151,7 +151,7 @@
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
diff --git a/slirp/arp_table.c b/slirp/arp_table.c
new file mode 100644
index 0000000..820dee2
--- /dev/null
+++ b/slirp/arp_table.c
@@ -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;
+}
diff --git a/slirp/bootp.c b/slirp/bootp.c
index 1eb2ed1..efd1fe7 100644
--- a/slirp/bootp.c
+++ b/slirp/bootp.c
@@ -149,6 +149,7 @@
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 @@
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 @@
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 @@
}
}
+ /* 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 @@
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 */
diff --git a/slirp/slirp.c b/slirp/slirp.c
index df787ea..4a9a4d5 100644
--- a/slirp/slirp.c
+++ b/slirp/slirp.c
@@ -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 @@
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 @@
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 @@
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 @@
}
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 @@
{
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 @@
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);
diff --git a/slirp/slirp.h b/slirp/slirp.h
index 16bb6ba..2a070e6 100644
--- a/slirp/slirp.h
+++ b/slirp/slirp.h
@@ -170,6 +170,48 @@
/* 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 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 @@
char *tftp_prefix;
struct tftp_session tftp_sessions[TFTP_SESSIONS_MAX];
+ ArpTable arp_table;
+
void *opaque;
};
