zcip: apply patch from

http://bugs.busybox.net/view.php?id=1005
      zcip does not claim another IP after defending
This commit is contained in:
Denis Vlasenko 2006-09-03 12:20:36 +00:00
parent 06ab5fb6b9
commit 87d80dcc3e

View File

@ -43,12 +43,7 @@
struct arp_packet {
struct ether_header hdr;
// FIXME this part is netinet/if_ether.h "struct ether_arp"
struct arphdr arp;
struct ether_addr source_addr;
struct in_addr source_ip;
struct ether_addr target_addr;
struct in_addr target_ip;
struct ether_arp arp;
} ATTRIBUTE_PACKED;
enum {
@ -68,10 +63,19 @@ enum {
DEFEND_INTERVAL = 10
};
static const struct in_addr null_ip = { 0 };
static const struct ether_addr null_addr = { {0, 0, 0, 0, 0, 0} };
/* States during the configuration process. */
enum {
PROBE = 0,
RATE_LIMIT_PROBE,
ANNOUNCE,
MONITOR,
DEFEND
};
static int verbose = 0;
/* Implicitly zero-initialized */
static const struct in_addr null_ip;
static const struct ether_addr null_addr;
static int verbose;
#define DBG(fmt,args...) \
do { } while (0)
@ -100,6 +104,7 @@ static int arp(int fd, struct sockaddr *saddr, int op,
const struct ether_addr *target_addr, struct in_addr target_ip)
{
struct arp_packet p;
memset(&p, 0, sizeof(p));
// ether header
p.hdr.ether_type = htons(ETHERTYPE_ARP);
@ -107,15 +112,15 @@ static int arp(int fd, struct sockaddr *saddr, int op,
memset(p.hdr.ether_dhost, 0xff, ETH_ALEN);
// arp request
p.arp.ar_hrd = htons(ARPHRD_ETHER);
p.arp.ar_pro = htons(ETHERTYPE_IP);
p.arp.ar_hln = ETH_ALEN;
p.arp.ar_pln = 4;
p.arp.ar_op = htons(op);
memcpy(&p.source_addr, source_addr, ETH_ALEN);
memcpy(&p.source_ip, &source_ip, sizeof (p.source_ip));
memcpy(&p.target_addr, target_addr, ETH_ALEN);
memcpy(&p.target_ip, &target_ip, sizeof (p.target_ip));
p.arp.arp_hrd = htons(ARPHRD_ETHER);
p.arp.arp_pro = htons(ETHERTYPE_IP);
p.arp.arp_hln = ETH_ALEN;
p.arp.arp_pln = 4;
p.arp.arp_op = htons(op);
memcpy(&p.arp.arp_sha, source_addr, ETH_ALEN);
memcpy(&p.arp.arp_spa, &source_ip, sizeof (p.arp.arp_spa));
memcpy(&p.arp.arp_tha, target_addr, ETH_ALEN);
memcpy(&p.arp.arp_tpa, &target_ip, sizeof (p.arp.arp_tpa));
// send it
if (sendto(fd, &p, sizeof (p), 0, saddr, sizeof (*saddr)) < 0) {
@ -196,11 +201,11 @@ int zcip_main(int argc, char *argv[])
int fd;
int ready = 0;
suseconds_t timeout = 0; // milliseconds
time_t defend = 0;
unsigned conflicts = 0;
unsigned nprobes = 0;
unsigned nclaims = 0;
int t;
int state = PROBE;
// parse commandline: prog [options] ifname script
while ((t = getopt(argc, argv, "fqr:v")) != EOF) {
@ -307,6 +312,9 @@ fail:
fds[0].events = POLLIN;
fds[0].revents = 0;
int source_ip_conflict = 0;
int target_ip_conflict = 0;
// poll, being ready to adjust current timeout
if (!timeout) {
timeout = ms_rdelay(PROBE_WAIT);
@ -314,6 +322,7 @@ fail:
// make the kernel filter out all packets except
// ones we'd care about.
}
// set tv1 to the point in time when we timeout
gettimeofday(&tv1, NULL);
tv1.tv_usec += (timeout % 1000) * 1000;
while (tv1.tv_usec > 1000000) {
@ -326,9 +335,13 @@ fail:
timeout, intf, nprobes, nclaims);
switch (poll(fds, 1, timeout)) {
// timeouts trigger protocol transitions
// timeout
case 0:
// probes
VDBG("state = %d\n", state);
switch (state) {
case PROBE:
// timeouts in the PROBE state means no conflicting ARP packets
// have been received, so we can progress through the states
if (nprobes < PROBE_NUM) {
nprobes++;
VDBG("probe/%d %s@%s\n",
@ -336,54 +349,99 @@ fail:
(void)arp(fd, &saddr, ARPOP_REQUEST,
&addr, null_ip,
&null_addr, ip);
if (nprobes < PROBE_NUM) {
timeout = PROBE_MIN * 1000;
timeout += ms_rdelay(PROBE_MAX
- PROBE_MIN);
} else
timeout = ANNOUNCE_WAIT * 1000;
}
// then announcements
else if (nclaims < ANNOUNCE_NUM) {
else {
// Switch to announce state.
state = ANNOUNCE;
nclaims = 0;
VDBG("announce/%d %s@%s\n",
nclaims, intf, inet_ntoa(ip));
(void)arp(fd, &saddr, ARPOP_REQUEST,
&addr, ip,
&addr, ip);
timeout = ANNOUNCE_INTERVAL * 1000;
}
break;
case RATE_LIMIT_PROBE:
// timeouts in the RATE_LIMIT_PROBE state means no conflicting ARP packets
// have been received, so we can move immediately to the announce state
state = ANNOUNCE;
nclaims = 0;
VDBG("announce/%d %s@%s\n",
nclaims, intf, inet_ntoa(ip));
(void)arp(fd, &saddr, ARPOP_REQUEST,
&addr, ip,
&addr, ip);
timeout = ANNOUNCE_INTERVAL * 1000;
break;
case ANNOUNCE:
// timeouts in the ANNOUNCE state means no conflicting ARP packets
// have been received, so we can progress through the states
if (nclaims < ANNOUNCE_NUM) {
nclaims++;
VDBG("announce/%d %s@%s\n",
nclaims, intf, inet_ntoa(ip));
(void)arp(fd, &saddr, ARPOP_REQUEST,
&addr, ip,
&addr, ip);
if (nclaims < ANNOUNCE_NUM) {
timeout = ANNOUNCE_INTERVAL * 1000;
} else {
}
else {
// Switch to monitor state.
state = MONITOR;
// link is ok to use earlier
// FIXME update filters
run(script, "config", intf, &ip);
ready = 1;
conflicts = 0;
timeout = -1;
timeout = -1; // Never timeout in the monitor state.
// NOTE: all other exit paths
// should deconfig ...
if (quit)
return EXIT_SUCCESS;
// FIXME update filters
}
}
break;
case DEFEND:
// We won! No ARP replies, so just go back to monitor.
state = MONITOR;
timeout = -1;
conflicts = 0;
break;
default:
// Invalid, should never happen. Restart the whole protocol.
state = PROBE;
pick(&ip);
timeout = 0;
nprobes = 0;
nclaims = 0;
break;
} // switch (state)
break; // case 0 (timeout)
// packets arriving
case 1:
// maybe adjust timeout
// We need to adjust the timeout in case we didn't receive
// a conflicting packet.
if (timeout > 0) {
struct timeval tv2;
gettimeofday(&tv2, NULL);
if (timercmp(&tv1, &tv2, <)) {
// Current time is greater than the expected timeout time.
// Should never happen.
VDBG("missed an expected timeout\n");
timeout = 0;
} else {
VDBG("adjusting timeout\n");
timersub(&tv1, &tv2, &tv1);
timeout = 1000 * tv1.tv_sec
+ tv1.tv_usec / 1000;
}
}
if ((fds[0].revents & POLLIN) == 0) {
if (fds[0].revents & POLLERR) {
// FIXME: links routinely go down;
@ -397,6 +455,7 @@ fail:
}
continue;
}
// read ARP packet
if (recv(fd, &p, sizeof (p), 0) < 0) {
why = "recv";
@ -405,71 +464,102 @@ fail:
if (p.hdr.ether_type != htons(ETHERTYPE_ARP))
continue;
#ifdef DEBUG
{
struct ether_addr * sha = (struct ether_addr *) p.arp.arp_sha;
struct ether_addr * tha = (struct ether_addr *) p.arp.arp_tha;
struct in_addr * spa = (struct in_addr *) p.arp.arp_spa;
struct in_addr * tpa = (struct in_addr *) p.arp.arp_tpa;
VDBG("%s recv arp type=%d, op=%d,\n",
intf, ntohs(p.hdr.ether_type),
ntohs(p.arp.ar_op));
ntohs(p.arp.arp_op));
VDBG("\tsource=%s %s\n",
ether_ntoa(&p.source_addr),
inet_ntoa(p.source_ip));
ether_ntoa(sha),
inet_ntoa(*spa));
VDBG("\ttarget=%s %s\n",
ether_ntoa(&p.target_addr),
inet_ntoa(p.target_ip));
if (p.arp.ar_op != htons(ARPOP_REQUEST)
&& p.arp.ar_op != htons(ARPOP_REPLY))
ether_ntoa(tha),
inet_ntoa(*tpa));
}
#endif
if (p.arp.arp_op != htons(ARPOP_REQUEST)
&& p.arp.arp_op != htons(ARPOP_REPLY))
continue;
// some cases are always conflicts
if ((p.source_ip.s_addr == ip.s_addr)
&& (memcmp(&addr, &p.source_addr,
ETH_ALEN) != 0)) {
collision:
VDBG("%s ARP conflict from %s\n", intf,
ether_ntoa(&p.source_addr));
if (ready) {
time_t now = time(0);
if (memcmp(p.arp.arp_spa, &ip.s_addr, sizeof(struct in_addr)) == 0 &&
memcmp(&addr, &p.arp.arp_sha, ETH_ALEN) != 0) {
source_ip_conflict = 1;
}
if (memcmp(p.arp.arp_tpa, &ip.s_addr, sizeof(struct in_addr)) == 0 &&
p.arp.arp_op == htons(ARPOP_REQUEST) &&
memcmp(&addr, &p.arp.arp_tha, ETH_ALEN) != 0) {
target_ip_conflict = 1;
}
if ((defend + DEFEND_INTERVAL)
< now) {
defend = now;
(void)arp(fd, &saddr,
ARPOP_REQUEST,
&addr, ip,
&addr, ip);
VDBG("%s defend\n", intf);
timeout = -1;
continue;
}
defend = now;
ready = 0;
run(script, "deconfig", intf, &ip);
// FIXME rm filters: setsockopt(fd,
// SO_DETACH_FILTER, ...)
}
VDBG("state = %d, source ip conflict = %d, target ip conflict = %d\n",
state, source_ip_conflict, target_ip_conflict);
switch (state) {
case PROBE:
case ANNOUNCE:
// When probing or announcing, check for source IP conflicts
// and other hosts doing ARP probes (target IP conflicts).
if (source_ip_conflict || target_ip_conflict) {
conflicts++;
if (conflicts >= MAX_CONFLICTS) {
VDBG("%s ratelimit\n", intf);
sleep(RATE_LIMIT_INTERVAL);
timeout = RATE_LIMIT_INTERVAL * 1000;
state = RATE_LIMIT_PROBE;
}
// restart the whole protocol
pick(&ip);
timeout = 0;
nprobes = 0;
nclaims = 0;
}
// two hosts probing one address is a collision too
else if (p.target_ip.s_addr == ip.s_addr
&& nclaims == 0
&& p.arp.ar_op == htons(ARPOP_REQUEST)
&& memcmp(&addr, &p.target_addr,
ETH_ALEN) != 0) {
goto collision;
break;
case MONITOR:
// If a conflict, we try to defend with a single ARP probe.
if (source_ip_conflict) {
VDBG("monitor conflict -- defending\n");
state = DEFEND;
timeout = DEFEND_INTERVAL * 1000;
(void)arp(fd, &saddr,
ARPOP_REQUEST,
&addr, ip,
&addr, ip);
}
break;
case DEFEND:
// Well, we tried. Start over (on conflict).
if (source_ip_conflict) {
state = PROBE;
VDBG("defend conflict -- starting over\n");
ready = 0;
run(script, "deconfig", intf, &ip);
// restart the whole protocol
pick(&ip);
timeout = 0;
nprobes = 0;
nclaims = 0;
}
break;
default:
// Invalid, should never happen. Restart the whole protocol.
VDBG("invalid state -- starting over\n");
state = PROBE;
pick(&ip);
timeout = 0;
nprobes = 0;
nclaims = 0;
break;
} // switch state
break; // case 1 (packets arriving)
default:
why = "poll";
goto bad;
}
} // switch poll
}
bad:
if (foreground)