From a09300a88c68f72bae2a4f25bb0f8620e560832c Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Sun, 25 Nov 2007 12:40:56 +0000 Subject: zcip: use low-order 4 bytes of MAC as random seed, not 4 high-order 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 --- networking/zcip.c | 153 +++++++++++++++++++++++++++++++----------------------- 1 file changed, 87 insertions(+), 66 deletions(-) (limited to 'networking/zcip.c') diff --git a/networking/zcip.c b/networking/zcip.c index a16a6420c..129155fe5 100644 --- a/networking/zcip.c +++ b/networking/zcip.c @@ -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(ð_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*)ð_addr); + { + uint32_t t; + memcpy(&t, (char*)ð_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, ð_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, ð_addr, ip, ð_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, ð_addr, ip, ð_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, ð_addr, ip, ð_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(ð_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, ð_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(ð_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, ð_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, - ð_addr, ip, - ð_addr, ip); + arp(ARPOP_REQUEST, + ð_addr, ip, + ð_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; } -- cgit v1.2.3