emo/busybox
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

zcip: apply patch from

Browse Source 
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
1 changed files with 181 additions and 91 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

272
networking/zcip.c
View File

@ -15,7 +15,7 @@
* certainly be used. Its naming is built over multicast DNS. * certainly be used. Its naming is built over multicast DNS.
*/ */
// #define DEBUG //#define DEBUG
// TODO: // TODO:
// - more real-world usage/testing, especially daemon mode // - more real-world usage/testing, especially daemon mode
@ -43,12 +43,7 @@
struct arp_packet { struct arp_packet {
struct ether_header hdr; struct ether_header hdr;
// FIXME this part is netinet/if_ether.h "struct ether_arp" struct ether_arp arp;
struct arphdr arp;
struct ether_addr source_addr;
struct in_addr source_ip;
struct ether_addr target_addr;
struct in_addr target_ip;
} ATTRIBUTE_PACKED; } ATTRIBUTE_PACKED;
enum { enum {
@ -68,10 +63,19 @@ enum {
DEFEND_INTERVAL = 10 DEFEND_INTERVAL = 10
}; };
static const struct in_addr null_ip = { 0 }; /* States during the configuration process. */
static const struct ether_addr null_addr = { {0, 0, 0, 0, 0, 0} }; 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...) \ #define DBG(fmt,args...) \
do { } while (0) 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) const struct ether_addr *target_addr, struct in_addr target_ip)
{ {
struct arp_packet p; struct arp_packet p;
memset(&p, 0, sizeof(p));
// ether header // ether header
p.hdr.ether_type = htons(ETHERTYPE_ARP); 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); memset(p.hdr.ether_dhost, 0xff, ETH_ALEN);
// arp request // arp request
p.arp.ar_hrd = htons(ARPHRD_ETHER); p.arp.arp_hrd = htons(ARPHRD_ETHER);
p.arp.ar_pro = htons(ETHERTYPE_IP); p.arp.arp_pro = htons(ETHERTYPE_IP);
p.arp.ar_hln = ETH_ALEN; p.arp.arp_hln = ETH_ALEN;
p.arp.ar_pln = 4; p.arp.arp_pln = 4;
p.arp.ar_op = htons(op); p.arp.arp_op = htons(op);
memcpy(&p.source_addr, source_addr, ETH_ALEN); memcpy(&p.arp.arp_sha, source_addr, ETH_ALEN);
memcpy(&p.source_ip, &source_ip, sizeof (p.source_ip)); memcpy(&p.arp.arp_spa, &source_ip, sizeof (p.arp.arp_spa));
memcpy(&p.target_addr, target_addr, ETH_ALEN); memcpy(&p.arp.arp_tha, target_addr, ETH_ALEN);
memcpy(&p.target_ip, &target_ip, sizeof (p.target_ip)); memcpy(&p.arp.arp_tpa, &target_ip, sizeof (p.arp.arp_tpa));
// send it // send it
if (sendto(fd, &p, sizeof (p), 0, saddr, sizeof (*saddr)) < 0) { 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 fd;
int ready = 0; int ready = 0;
suseconds_t timeout = 0; // milliseconds suseconds_t timeout = 0; // milliseconds
time_t defend = 0;
unsigned conflicts = 0; unsigned conflicts = 0;
unsigned nprobes = 0; unsigned nprobes = 0;
unsigned nclaims = 0; unsigned nclaims = 0;
int t; int t;
int state = PROBE;
// parse commandline: prog [options] ifname script // parse commandline: prog [options] ifname script
while ((t = getopt(argc, argv, "fqr:v")) != EOF) { while ((t = getopt(argc, argv, "fqr:v")) != EOF) {
@ -307,6 +312,9 @@ fail:
fds[0].events = POLLIN; fds[0].events = POLLIN;
fds[0].revents = 0; fds[0].revents = 0;
int source_ip_conflict = 0;
int target_ip_conflict = 0;
// poll, being ready to adjust current timeout // poll, being ready to adjust current timeout
if (!timeout) { if (!timeout) {
timeout = ms_rdelay(PROBE_WAIT); timeout = ms_rdelay(PROBE_WAIT);
@ -314,6 +322,7 @@ fail:
// make the kernel filter out all packets except // make the kernel filter out all packets except
// ones we'd care about. // ones we'd care about.
} }
// set tv1 to the point in time when we timeout
gettimeofday(&tv1, NULL); gettimeofday(&tv1, NULL);
tv1.tv_usec += (timeout % 1000) * 1000; tv1.tv_usec += (timeout % 1000) * 1000;
while (tv1.tv_usec > 1000000) { while (tv1.tv_usec > 1000000) {
@ -326,64 +335,113 @@ fail:
timeout, intf, nprobes, nclaims); timeout, intf, nprobes, nclaims);
switch (poll(fds, 1, timeout)) { switch (poll(fds, 1, timeout)) {
// timeouts trigger protocol transitions // timeout
case 0: case 0:
// probes VDBG("state = %d\n", state);
if (nprobes < PROBE_NUM) { switch (state) {
nprobes++; case PROBE:
VDBG("probe/%d %s@%s\n", // timeouts in the PROBE state means no conflicting ARP packets
nprobes, intf, inet_ntoa(ip)); // have been received, so we can progress through the states
(void)arp(fd, &saddr, ARPOP_REQUEST,
&addr, null_ip,
&null_addr, ip);
if (nprobes < PROBE_NUM) { if (nprobes < PROBE_NUM) {
nprobes++;
VDBG("probe/%d %s@%s\n",
nprobes, intf, inet_ntoa(ip));
(void)arp(fd, &saddr, ARPOP_REQUEST,
&addr, null_ip,
&null_addr, ip);
timeout = PROBE_MIN * 1000; timeout = PROBE_MIN * 1000;
timeout += ms_rdelay(PROBE_MAX timeout += ms_rdelay(PROBE_MAX
- PROBE_MIN); - PROBE_MIN);
} else }
timeout = ANNOUNCE_WAIT * 1000; else {
} // Switch to announce state.
// then announcements state = ANNOUNCE;
else if (nclaims < ANNOUNCE_NUM) { nclaims = 0;
nclaims++; 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", VDBG("announce/%d %s@%s\n",
nclaims, intf, inet_ntoa(ip)); nclaims, intf, inet_ntoa(ip));
(void)arp(fd, &saddr, ARPOP_REQUEST, (void)arp(fd, &saddr, ARPOP_REQUEST,
&addr, ip, &addr, ip,
&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) { 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);
timeout = ANNOUNCE_INTERVAL * 1000; timeout = ANNOUNCE_INTERVAL * 1000;
} else { }
else {
// Switch to monitor state.
state = MONITOR;
// link is ok to use earlier // link is ok to use earlier
// FIXME update filters
run(script, "config", intf, &ip); run(script, "config", intf, &ip);
ready = 1; ready = 1;
conflicts = 0; conflicts = 0;
timeout = -1; timeout = -1; // Never timeout in the monitor state.
// NOTE: all other exit paths // NOTE: all other exit paths
// should deconfig ... // should deconfig ...
if (quit) if (quit)
return EXIT_SUCCESS; return EXIT_SUCCESS;
// FIXME update filters
} }
} break;
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 // packets arriving
case 1: case 1:
// maybe adjust timeout // We need to adjust the timeout in case we didn't receive
// a conflicting packet.
if (timeout > 0) { if (timeout > 0) {
struct timeval tv2; struct timeval tv2;
gettimeofday(&tv2, NULL); gettimeofday(&tv2, NULL);
if (timercmp(&tv1, &tv2, <)) { if (timercmp(&tv1, &tv2, <)) {
// Current time is greater than the expected timeout time.
// Should never happen.
VDBG("missed an expected timeout\n");
timeout = 0; timeout = 0;
} else { } else {
VDBG("adjusting timeout\n");
timersub(&tv1, &tv2, &tv1); timersub(&tv1, &tv2, &tv1);
timeout = 1000 * tv1.tv_sec timeout = 1000 * tv1.tv_sec
+ tv1.tv_usec / 1000; + tv1.tv_usec / 1000;
} }
} }
if ((fds[0].revents & POLLIN) == 0) { if ((fds[0].revents & POLLIN) == 0) {
if (fds[0].revents & POLLERR) { if (fds[0].revents & POLLERR) {
// FIXME: links routinely go down; // FIXME: links routinely go down;
@ -397,6 +455,7 @@ fail:
} }
continue; continue;
} }
// read ARP packet // read ARP packet
if (recv(fd, &p, sizeof (p), 0) < 0) { if (recv(fd, &p, sizeof (p), 0) < 0) {
why = "recv"; why = "recv";
@ -405,71 +464,102 @@ fail:
if (p.hdr.ether_type != htons(ETHERTYPE_ARP)) if (p.hdr.ether_type != htons(ETHERTYPE_ARP))
continue; continue;
VDBG("%s recv arp type=%d, op=%d,\n", #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), intf, ntohs(p.hdr.ether_type),
ntohs(p.arp.ar_op)); ntohs(p.arp.arp_op));
VDBG("\tsource=%s %s\n", VDBG("\tsource=%s %s\n",
ether_ntoa(&p.source_addr), ether_ntoa(sha),
inet_ntoa(p.source_ip)); inet_ntoa(*spa));
VDBG("\ttarget=%s %s\n", VDBG("\ttarget=%s %s\n",
ether_ntoa(&p.target_addr), ether_ntoa(tha),
inet_ntoa(p.target_ip)); inet_ntoa(*tpa));
if (p.arp.ar_op != htons(ARPOP_REQUEST) }
&& p.arp.ar_op != htons(ARPOP_REPLY)) #endif
if (p.arp.arp_op != htons(ARPOP_REQUEST)
&& p.arp.arp_op != htons(ARPOP_REPLY))
continue; continue;
// some cases are always conflicts if (memcmp(p.arp.arp_spa, &ip.s_addr, sizeof(struct in_addr)) == 0 &&
if ((p.source_ip.s_addr == ip.s_addr) memcmp(&addr, &p.arp.arp_sha, ETH_ALEN) != 0) {
&& (memcmp(&addr, &p.source_addr, source_ip_conflict = 1;
ETH_ALEN) != 0)) { }
collision: if (memcmp(p.arp.arp_tpa, &ip.s_addr, sizeof(struct in_addr)) == 0 &&
VDBG("%s ARP conflict from %s\n", intf, p.arp.arp_op == htons(ARPOP_REQUEST) &&
ether_ntoa(&p.source_addr)); memcmp(&addr, &p.arp.arp_tha, ETH_ALEN) != 0) {
if (ready) { target_ip_conflict = 1;
time_t now = time(0); }
if ((defend + DEFEND_INTERVAL) VDBG("state = %d, source ip conflict = %d, target ip conflict = %d\n",
< now) { state, source_ip_conflict, target_ip_conflict);
defend = now; switch (state) {
(void)arp(fd, &saddr, case PROBE:
ARPOP_REQUEST, case ANNOUNCE:
&addr, ip, // When probing or announcing, check for source IP conflicts
&addr, ip); // and other hosts doing ARP probes (target IP conflicts).
VDBG("%s defend\n", intf); if (source_ip_conflict || target_ip_conflict) {
timeout = -1; conflicts++;
continue; if (conflicts >= MAX_CONFLICTS) {
VDBG("%s ratelimit\n", intf);
timeout = RATE_LIMIT_INTERVAL * 1000;
state = RATE_LIMIT_PROBE;
} }
defend = now;
// restart the whole protocol
pick(&ip);
timeout = 0;
nprobes = 0;
nclaims = 0;
}
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; ready = 0;
run(script, "deconfig", intf, &ip); run(script, "deconfig", intf, &ip);
// FIXME rm filters: setsockopt(fd,
// SO_DETACH_FILTER, ...) // restart the whole protocol
pick(&ip);
timeout = 0;
nprobes = 0;
nclaims = 0;
} }
conflicts++; break;
if (conflicts >= MAX_CONFLICTS) { default:
VDBG("%s ratelimit\n", intf); // Invalid, should never happen. Restart the whole protocol.
sleep(RATE_LIMIT_INTERVAL); VDBG("invalid state -- starting over\n");
} state = PROBE;
// restart the whole protocol
pick(&ip); pick(&ip);
timeout = 0; timeout = 0;
nprobes = 0; nprobes = 0;
nclaims = 0; nclaims = 0;
} break;
// two hosts probing one address is a collision too } // switch state
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;
break; // case 1 (packets arriving)
default: default:
why = "poll"; why = "poll";
goto bad; goto bad;
} } // switch poll
} }
bad: bad:
if (foreground) if (foreground)