On 2011-08-02 15:19, Fabien Chouteau wrote:
> This patch adds a simple ARP table in Slirp and also adds handling of
> gratuitous ARP requests.
>
> Signed-off-by: Fabien Chouteau <chout...@adacore.com>
> ---
> Makefile.objs | 2 +-
> slirp/arp_table.c | 71
> +++++++++++++++++++++++++++++++++++++++++++++++++++++
> slirp/bootp.c | 21 +++++++++------
> slirp/slirp.c | 63 ++++++++++++-----------------------------------
> slirp/slirp.h | 47 ++++++++++++++++++++++++++++++++--
> 5 files changed, 145 insertions(+), 59 deletions(-)
> create mode 100644 slirp/arp_table.c
>
> diff --git a/Makefile.objs b/Makefile.objs
> index 6991a9f..0c10557 100644
> --- a/Makefile.objs
> +++ b/Makefile.objs
> @@ -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
> diff --git a/slirp/arp_table.c b/slirp/arp_table.c
> new file mode 100644
> index 0000000..c259b42
> --- /dev/null
> +++ b/slirp/arp_table.c
> @@ -0,0 +1,71 @@
> +#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 @@ 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 */
> 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 @@ 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);
> 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 @@ 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;
> };
>
> --
> 1.7.4.1
>
Looks good now and work here as well.
One last thing (I swear): We need a proper license header for
arp_table.c. Then I'll apply this and v3 of 2/2 and send out a pull
request (Anthony asked me to look after slirp).
Thanks,
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
