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zcip: use low-order 4 bytes of MAC as random seed, not 4 high-order

Browse source 
arping: fix wrong roundtrip calculation
arping,zcip: cleanups and code shrink

run                                                  389     402     +13
arp                                                  195     188      -7
zcip_main                                           1524    1495     -29
arping_main                                         1874    1823     -51
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/3 up/down: 13/-87)            Total: -74 bytes
   text    data     bss     dec     hex filename
 776587     929    9100  786616   c00b8 busybox_old
 776499     929    9100  786528   c0060 busybox_unstripped
This commit is contained in:
Denis Vlasenko 2007-11-25 12:40:56 +00:00
parent 7c9d533a85
commit a09300a88c
2 changed files with 120 additions and 102 deletions
Download patch file Download diff file Expand all files Collapse all files

153
networking/zcip.c
View file

@ -39,7 +39,7 @@
#define MONOTONIC_US() ((unsigned)monotonic_us())
struct arp_packet {
struct ether_header hdr;
struct ether_header eth;
struct ether_arp arp;
} ATTRIBUTE_PACKED;
@ -69,8 +69,21 @@ enum {
DEFEND
};
#define VDBG(fmt,args...) \
do { } while (0)
#define VDBG(...) do { } while (0)
enum {
sock_fd = 3
};
struct globals {
char *intf;
struct sockaddr saddr;
};
#define G (*(struct globals*)&bb_common_bufsiz1)
#define intf (G.intf )
#define saddr (G.saddr)
/**
* Pick a random link local IP address on 169.254/16, except that
@ -89,17 +102,17 @@ static void pick(struct in_addr *ip)
/**
* Broadcast an ARP packet.
*/
static void arp(int fd, struct sockaddr *saddr, int op,
const struct ether_addr *source_addr, struct in_addr source_ip,
const struct ether_addr *target_addr, struct in_addr target_ip)
static void arp(int op,
const struct ether_addr *source_eth, struct in_addr source_ip,
const struct ether_addr *target_eth, struct in_addr target_ip)
{
struct arp_packet p;
memset(&p, 0, sizeof(p));
// ether header
p.hdr.ether_type = htons(ETHERTYPE_ARP);
memcpy(p.hdr.ether_shost, source_addr, ETH_ALEN);
memset(p.hdr.ether_dhost, 0xff, ETH_ALEN);
p.eth.ether_type = htons(ETHERTYPE_ARP);
memcpy(p.eth.ether_shost, source_eth, ETH_ALEN);
memset(p.eth.ether_dhost, 0xff, ETH_ALEN);
// arp request
p.arp.arp_hrd = htons(ARPHRD_ETHER);
@ -107,13 +120,13 @@ static void arp(int fd, struct sockaddr *saddr, int op,
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_sha, source_eth, 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_tha, target_eth, ETH_ALEN);
memcpy(&p.arp.arp_tpa, &target_ip, sizeof(p.arp.arp_tpa));
// send it
xsendto(fd, &p, sizeof(p), saddr, sizeof(*saddr));
xsendto(sock_fd, &p, sizeof(p), &saddr, sizeof(saddr));
// Currently all callers ignore errors, that's why returns are
// commented out...
@ -123,21 +136,24 @@ static void arp(int fd, struct sockaddr *saddr, int op,
/**
* Run a script. argv[2] is already NULL.
*/
static int run(char *argv[3], const char *intf, struct in_addr *ip)
static int run(char *argv[3], struct in_addr *ip)
{
int status;
char *addr = addr; /* for gcc */
const char *fmt = "%s %s %s" + 3;
VDBG("%s run %s %s\n", intf, argv[0], argv[1]);
if (ip) {
char *addr = inet_ntoa(*ip);
addr = inet_ntoa(*ip);
setenv("ip", addr, 1);
bb_info_msg("%s %s %s", argv[1], intf, addr);
fmt -= 3;
}
bb_info_msg(fmt, argv[1], intf, addr);
status = wait4pid(spawn(argv));
if (status < 0) {
bb_perror_msg("%s %s", argv[1], intf);
bb_perror_msg("%s %s %s" + 3, argv[1], intf);
return -errno;
}
if (status != 0)
@ -148,7 +164,7 @@ static int run(char *argv[3], const char *intf, struct in_addr *ip)
/**
* Return milliseconds of random delay, up to "secs" seconds.
*/
static unsigned ALWAYS_INLINE ms_rdelay(unsigned secs)
static unsigned ALWAYS_INLINE random_delay_ms(unsigned secs)
{
return rand() % (secs * 1000);
}
@ -160,10 +176,8 @@ int zcip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int zcip_main(int argc, char **argv)
{
int state = PROBE;
/* Prevent unaligned traps for ARM (see srand() below) */
struct ether_addr eth_addr __attribute__(( aligned(sizeof(unsigned)) ));
struct ether_addr eth_addr;
const char *why;
int fd;
char *r_opt;
unsigned opts;
@ -171,10 +185,8 @@ int zcip_main(int argc, char **argv)
struct {
const struct in_addr null_ip;
const struct ether_addr null_addr;
struct sockaddr saddr;
struct in_addr ip;
struct ifreq ifr;
char *intf;
char *script_av[3];
int timeout_ms; /* must be signed */
unsigned conflicts;
@ -185,10 +197,8 @@ int zcip_main(int argc, char **argv)
} L;
#define null_ip (L.null_ip )
#define null_addr (L.null_addr )
#define saddr (L.saddr )
#define ip (L.ip )
#define ifr (L.ifr )
#define intf (L.intf )
#define script_av (L.script_av )
#define timeout_ms (L.timeout_ms)
#define conflicts (L.conflicts )
@ -231,29 +241,37 @@ int zcip_main(int argc, char **argv)
// initialize the interface (modprobe, ifup, etc)
script_av[1] = (char*)"init";
if (run(script_av, intf, NULL))
if (run(script_av, NULL))
return EXIT_FAILURE;
// initialize saddr
// saddr is: { u16 sa_family; u8 sa_data[14]; }
//memset(&saddr, 0, sizeof(saddr));
//TODO: are we leaving sa_family == 0 (AF_UNSPEC)?!
safe_strncpy(saddr.sa_data, intf, sizeof(saddr.sa_data));
// open an ARP socket
fd = xsocket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP));
xmove_fd(xsocket(AF_PACKET, SOCK_PACKET, htons(ETH_P_ARP)), sock_fd);
// bind to the interface's ARP socket
xbind(fd, &saddr, sizeof(saddr));
xbind(sock_fd, &saddr, sizeof(saddr));
// get the interface's ethernet address
//memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, intf, sizeof(ifr.ifr_name));
xioctl(fd, SIOCGIFHWADDR, &ifr);
xioctl(sock_fd, SIOCGIFHWADDR, &ifr);
memcpy(&eth_addr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN);
// start with some stable ip address, either a function of
// the hardware address or else the last address we used.
// we are taking low-order four bytes, as top-order ones
// aren't random enough.
// NOTE: the sequence of addresses we try changes only
// depending on when we detect conflicts.
srand(*(unsigned*)&eth_addr);
{
uint32_t t;
memcpy(&t, (char*)&eth_addr + 2, 4);
srand(t);
}
if (ip.s_addr == 0)
pick(&ip);
@ -281,18 +299,17 @@ int zcip_main(int argc, char **argv)
struct pollfd fds[1];
unsigned deadline_us;
struct arp_packet p;
int source_ip_conflict;
int target_ip_conflict;
int source_ip_conflict = 0;
int target_ip_conflict = 0;
fds[0].fd = fd;
fds[0].fd = sock_fd;
fds[0].events = POLLIN;
fds[0].revents = 0;
// poll, being ready to adjust current timeout
if (!timeout_ms) {
timeout_ms = ms_rdelay(PROBE_WAIT);
// FIXME setsockopt(fd, SO_ATTACH_FILTER, ...) to
timeout_ms = random_delay_ms(PROBE_WAIT);
// FIXME setsockopt(sock_fd, SO_ATTACH_FILTER, ...) to
// make the kernel filter out all packets except
// ones we'd care about.
}
@ -302,6 +319,8 @@ int zcip_main(int argc, char **argv)
VDBG("...wait %d %s nprobes=%u, nclaims=%u\n",
timeout_ms, intf, nprobes, nclaims);
// FIXME: do we really receive ALL packets here??
// if yes, set up filtering to get ARPs only!!! (see arping)
switch (safe_poll(fds, 1, timeout_ms)) {
default:
@ -319,11 +338,11 @@ int zcip_main(int argc, char **argv)
nprobes++;
VDBG("probe/%u %s@%s\n",
nprobes, intf, inet_ntoa(ip));
arp(fd, &saddr, ARPOP_REQUEST,
arp(ARPOP_REQUEST,
&eth_addr, null_ip,
&null_addr, ip);
timeout_ms = PROBE_MIN * 1000;
timeout_ms += ms_rdelay(PROBE_MAX - PROBE_MIN);
timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN);
}
else {
// Switch to announce state.
@ -331,7 +350,7 @@ int zcip_main(int argc, char **argv)
nclaims = 0;
VDBG("announce/%u %s@%s\n",
nclaims, intf, inet_ntoa(ip));
arp(fd, &saddr, ARPOP_REQUEST,
arp(ARPOP_REQUEST,
&eth_addr, ip,
&eth_addr, ip);
timeout_ms = ANNOUNCE_INTERVAL * 1000;
@ -344,7 +363,7 @@ int zcip_main(int argc, char **argv)
nclaims = 0;
VDBG("announce/%u %s@%s\n",
nclaims, intf, inet_ntoa(ip));
arp(fd, &saddr, ARPOP_REQUEST,
arp(ARPOP_REQUEST,
&eth_addr, ip,
&eth_addr, ip);
timeout_ms = ANNOUNCE_INTERVAL * 1000;
@ -356,7 +375,7 @@ int zcip_main(int argc, char **argv)
nclaims++;
VDBG("announce/%u %s@%s\n",
nclaims, intf, inet_ntoa(ip));
arp(fd, &saddr, ARPOP_REQUEST,
arp(ARPOP_REQUEST,
&eth_addr, ip,
&eth_addr, ip);
timeout_ms = ANNOUNCE_INTERVAL * 1000;
@ -367,7 +386,7 @@ int zcip_main(int argc, char **argv)
// link is ok to use earlier
// FIXME update filters
script_av[1] = (char*)"config";
run(script_av, intf, &ip);
run(script_av, &ip);
ready = 1;
conflicts = 0;
timeout_ms = -1; // Never timeout in the monitor state.
@ -395,7 +414,7 @@ int zcip_main(int argc, char **argv)
} // switch (state)
break; // case 0 (timeout)
// packets arriving
// packets arriving, or link went down
case 1:
// We need to adjust the timeout in case we didn't receive
// a conflicting packet.
@ -408,8 +427,7 @@ int zcip_main(int argc, char **argv)
timeout_ms = 0;
} else {
VDBG("adjusting timeout\n");
timeout_ms = diff / 1000;
if (!timeout_ms) timeout_ms = 1;
timeout_ms = (diff / 1000) | 1; /* never 0 */
}
}
@ -417,10 +435,10 @@ int zcip_main(int argc, char **argv)
if (fds[0].revents & POLLERR) {
// FIXME: links routinely go down;
// this shouldn't necessarily exit.
bb_error_msg("%s: poll error", intf);
bb_error_msg("iface %s is down", intf);
if (ready) {
script_av[1] = (char*)"deconfig";
run(script_av, intf, &ip);
run(script_av, &ip);
}
return EXIT_FAILURE;
}
@ -428,21 +446,20 @@ int zcip_main(int argc, char **argv)
}
// read ARP packet
if (recv(fd, &p, sizeof(p), 0) < 0) {
if (safe_read(sock_fd, &p, sizeof(p)) < 0) {
why = "recv";
goto bad;
}
if (p.hdr.ether_type != htons(ETHERTYPE_ARP))
if (p.eth.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;
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.eth.ether_type),
ntohs(p.arp.arp_op));
VDBG("\tsource=%s %s\n",
ether_ntoa(sha),
@ -453,16 +470,21 @@ int zcip_main(int argc, char **argv)
}
#endif
if (p.arp.arp_op != htons(ARPOP_REQUEST)
&& p.arp.arp_op != htons(ARPOP_REPLY))
&& p.arp.arp_op != htons(ARPOP_REPLY))
continue;
if (memcmp(p.arp.arp_spa, &ip.s_addr, sizeof(struct in_addr)) == 0 &&
memcmp(&eth_addr, &p.arp.arp_sha, ETH_ALEN) != 0) {
source_ip_conflict = 0;
target_ip_conflict = 0;
if (memcmp(p.arp.arp_spa, &ip.s_addr, sizeof(struct in_addr)) == 0
&& memcmp(&p.arp.arp_sha, &eth_addr, 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(&eth_addr, &p.arp.arp_tha, ETH_ALEN) != 0) {
if (p.arp.arp_op == htons(ARPOP_REQUEST)
&& memcmp(p.arp.arp_tpa, &ip.s_addr, sizeof(struct in_addr)) == 0
&& memcmp(&p.arp.arp_tha, &eth_addr, ETH_ALEN) != 0
) {
target_ip_conflict = 1;
}
@ -494,10 +516,9 @@ int zcip_main(int argc, char **argv)
VDBG("monitor conflict -- defending\n");
state = DEFEND;
timeout_ms = DEFEND_INTERVAL * 1000;
arp(fd, &saddr,
ARPOP_REQUEST,
&eth_addr, ip,
&eth_addr, ip);
arp(ARPOP_REQUEST,
&eth_addr, ip,
&eth_addr, ip);
}
break;
case DEFEND:
@ -507,7 +528,7 @@ int zcip_main(int argc, char **argv)
VDBG("defend conflict -- starting over\n");
ready = 0;
script_av[1] = (char*)"deconfig";
run(script_av, intf, &ip);
run(script_av, &ip);
// restart the whole protocol
pick(&ip);
@ -530,6 +551,6 @@ int zcip_main(int argc, char **argv)
} // switch poll
} // while (1)
bad:
bb_perror_msg("%s, %s", intf, why);
bb_perror_msg("%s: %s", intf, why);
return EXIT_FAILURE;
}