net: Add support for capturing VLANs (Jan Kiszka)

This patch is derived from Tristan Gingold's patch. It adds a new VLAN
client type that writes all traffic on the VLAN it is attached to into a
pcap file. Such a file can then be analyzed offline with Wireshark or
tcpdump.

Besides rebasing and some minor cleanups, the major differences to the
original version are:
 - support for enabling/disabling via the monitor (host_net_add/remove)
 - no special ordering of VLAN client list, qemu_send_packet now takes
   care of properly ordered packets
 - 64k default capturing limit (I hate tcpdump's default)

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7200 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
aliguori 2009-04-21 19:56:28 +00:00
parent 1030021681
commit bb9ea79e7a
3 changed files with 121 additions and 3 deletions

View file

@ -1731,7 +1731,7 @@ static const mon_cmd_t mon_cmds[] = {
{ "pci_add", "sss", pci_device_hot_add, "pci_addr=auto|[[<domain>:]<bus>:]<slot> nic|storage [[vlan=n][,macaddr=addr][,model=type]] [file=file][,if=type][,bus=nr]...", "hot-add PCI device" },
{ "pci_del", "s", pci_device_hot_remove, "pci_addr=[[<domain>:]<bus>:]<slot>", "hot remove PCI device" },
{ "host_net_add", "ss", net_host_device_add,
"[tap,user,socket,vde] options", "add host VLAN client" },
"[tap,user,socket,vde,dump] options", "add host VLAN client" },
{ "host_net_remove", "is", net_host_device_remove,
"vlan_id name", "remove host VLAN client" },
#endif

115
net.c
View file

@ -118,6 +118,7 @@
#include "qemu-char.h"
#include "audio/audio.h"
#include "qemu_socket.h"
#include "qemu-log.h"
#if defined(CONFIG_SLIRP)
#include "libslirp.h"
@ -1558,6 +1559,106 @@ static int net_socket_mcast_init(VLANState *vlan,
}
typedef struct DumpState {
VLANClientState *pcap_vc;
int fd;
int pcap_caplen;
} DumpState;
#define PCAP_MAGIC 0xa1b2c3d4
struct pcap_file_hdr {
uint32_t magic;
uint16_t version_major;
uint16_t version_minor;
int32_t thiszone;
uint32_t sigfigs;
uint32_t snaplen;
uint32_t linktype;
};
struct pcap_sf_pkthdr {
struct {
int32_t tv_sec;
int32_t tv_usec;
} ts;
uint32_t caplen;
uint32_t len;
};
static void dump_receive(void *opaque, const uint8_t *buf, int size)
{
DumpState *s = opaque;
struct pcap_sf_pkthdr hdr;
int64_t ts;
int caplen;
/* Early return in case of previous error. */
if (s->fd < 0) {
return;
}
ts = muldiv64 (qemu_get_clock(vm_clock),1000000, ticks_per_sec);
caplen = size > s->pcap_caplen ? s->pcap_caplen : size;
hdr.ts.tv_sec = ts / 1000000000LL;
hdr.ts.tv_usec = ts % 1000000;
hdr.caplen = caplen;
hdr.len = size;
if (write(s->fd, &hdr, sizeof(hdr)) != sizeof(hdr) ||
write(s->fd, buf, caplen) != caplen) {
qemu_log("-net dump write error - stop dump\n");
close(s->fd);
s->fd = -1;
}
}
static void net_dump_cleanup(VLANClientState *vc)
{
DumpState *s = vc->opaque;
close(s->fd);
qemu_free(s);
}
static int net_dump_init(VLANState *vlan, const char *device,
const char *name, const char *filename, int len)
{
struct pcap_file_hdr hdr;
DumpState *s;
s = qemu_malloc(sizeof(DumpState));
s->fd = open(filename, O_CREAT | O_WRONLY, 0644);
if (s->fd < 0) {
fprintf(stderr, "-net dump: can't open %s\n", filename);
return -1;
}
s->pcap_caplen = len;
hdr.magic = PCAP_MAGIC;
hdr.version_major = 2;
hdr.version_minor = 4;
hdr.thiszone = 0;
hdr.sigfigs = 0;
hdr.snaplen = s->pcap_caplen;
hdr.linktype = 1;
if (write(s->fd, &hdr, sizeof(hdr)) < sizeof(hdr)) {
perror("-net dump write error");
close(s->fd);
qemu_free(s);
return -1;
}
s->pcap_vc = qemu_new_vlan_client(vlan, device, name, dump_receive, NULL,
net_dump_cleanup, s);
snprintf(s->pcap_vc->info_str, sizeof(s->pcap_vc->info_str),
"dump to %s (len=%d)", filename, len);
return 0;
}
/* find or alloc a new VLAN */
VLANState *qemu_find_vlan(int id)
{
@ -1883,7 +1984,17 @@ int net_client_init(const char *device, const char *p)
ret = net_vde_init(vlan, device, name, vde_sock, vde_port, vde_group, vde_mode);
} else
#endif
{
if (!strcmp(device, "dump")) {
int len = 65536;
if (get_param_value(buf, sizeof(buf), "len", p) > 0) {
len = strtol(buf, NULL, 0);
}
if (!get_param_value(buf, sizeof(buf), "file", p)) {
snprintf(buf, sizeof(buf), "qemu-vlan%d.pcap", vlan_id);
}
ret = net_dump_init(vlan, device, name, buf, len);
} else {
fprintf(stderr, "Unknown network device: %s\n", device);
ret = -1;
goto out;
@ -1908,7 +2019,7 @@ void net_client_uninit(NICInfo *nd)
static int net_host_check_device(const char *device)
{
int i;
const char *valid_param_list[] = { "tap", "socket"
const char *valid_param_list[] = { "tap", "socket", "dump"
#ifdef CONFIG_SLIRP
,"user"
#endif

View file

@ -745,6 +745,8 @@ DEF("net", HAS_ARG, QEMU_OPTION_net, \
" Use group 'groupname' and mode 'octalmode' to change default\n"
" ownership and permissions for communication port.\n"
#endif
"-net dump[,vlan=n][,file=f][,len=n]\n"
" dump traffic on vlan 'n' to file 'f' (max n bytes per packet)\n"
"-net none use it alone to have zero network devices; if no -net option\n"
" is provided, the default is '-net nic -net user'\n")
STEXI
@ -865,6 +867,11 @@ vde_switch -F -sock /tmp/myswitch
qemu linux.img -net nic -net vde,sock=/tmp/myswitch
@end example
@item -net dump[,vlan=@var{n}][,file=@var{file}][,len=@var{len}]
Dump network traffic on VLAN @var{n} to file @var{file} (@file{qemu-vlan0.pcap} by default).
At most @var{len} bytes (64k by default) per packet are stored. The file format is
libpcap, so it can be analyzed with tools such as tcpdump or Wireshark.
@item -net none
Indicate that no network devices should be configured. It is used to
override the default configuration (@option{-net nic -net user}) which