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Re: [Qemu-devel] [PATCH V3 1/2] [SLIRP] Simple ARP table
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [PATCH V3 1/2] [SLIRP] Simple ARP table |
Date: |
Mon, 01 Aug 2011 22:16:44 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2011-08-01 18:18, 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 <address@hidden>
> ---
> Makefile.objs | 2 +-
> slirp/arp_table.c | 72
> +++++++++++++++++++++++++++++++++++++++++++++++++++++
> slirp/bootp.c | 21 +++++++++------
> slirp/slirp.c | 63 +++++++++++----------------------------------
> slirp/slirp.h | 47 ++++++++++++++++++++++++++++++++--
> 5 files changed, 146 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..c7034ee
> --- /dev/null
> +++ b/slirp/arp_table.c
> @@ -0,0 +1,72 @@
> +#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;
That's only part of the picture. 255.255.255.255 is a valid broadcast
address as well.
> + 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]));
> +
> + if ((ip_addr & ~(0xf << 28)) == 0 ||
> + ip_addr == broadcast_addr) {
> + /* Do not register 0.0.0.0/8 or broadcast addresses */
> + return;
> + }
> +
> + /* Search for an entry */
> + for (i = 0; i < ARP_TABLE_SIZE && arptbl->table[i].ar_sip != 0; i++) {
Forgot to remove the test for ar_sip != 0.
> + 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;
Same as above. That means DCHP is still broken. Please include that
scenario in your tests before sending the next round.
> + ArpTable *arptbl = &slirp->arp_table;
> + int i;
> +
> + DEBUG_CALL("arp_table_search");
> + DEBUG_ARG("ip = 0x%x", in_ip_addr);
> +
> + /* If address in 0.0.0.0/8 */
> + if ((in_ip_addr & ~(0xf << 28)) == 0) {
Should rather be an assert() as it means the caller is about to send a
frame to that source-only address.
Jan
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