mirror of
https://github.com/topjohnwu/ndk-busybox.git
synced 2024-12-11 05:24:04 +00:00
zcip: another code shrink
function old new delta send_arp_request - 185 +185 zcip_main 1273 1272 -1 pick_nip 40 - -40 arp 185 - -185 ------------------------------------------------------------------------------ (add/remove: 1/2 grow/shrink: 0/1 up/down: 185/-226) Total: -41 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
parent
99e30be38b
commit
e347583835
@ -90,7 +90,7 @@ enum {
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struct globals {
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struct sockaddr iface_sockaddr;
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struct ether_addr eth_addr;
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struct ether_addr our_ethaddr;
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uint32_t localnet_ip;
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} FIX_ALIASING;
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#define G (*(struct globals*)&bb_common_bufsiz1)
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@ -121,14 +121,14 @@ static const char *nip_to_a(uint32_t nip)
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/**
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* Broadcast an ARP packet.
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*/
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static void arp(
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static void send_arp_request(
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/* int op, - always ARPOP_REQUEST */
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/* const struct ether_addr *source_eth, - always &G.eth_addr */
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/* const struct ether_addr *source_eth, - always &G.our_ethaddr */
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uint32_t source_nip,
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const struct ether_addr *target_eth, uint32_t target_nip)
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{
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enum { op = ARPOP_REQUEST };
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#define source_eth (&G.eth_addr)
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#define source_eth (&G.our_ethaddr)
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struct arp_packet p;
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memset(&p, 0, sizeof(p));
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@ -205,35 +205,34 @@ static ALWAYS_INLINE unsigned random_delay_ms(unsigned secs)
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int zcip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int zcip_main(int argc UNUSED_PARAM, char **argv)
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{
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int state;
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char *r_opt;
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const char *l_opt = "169.254.0.0";
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int state;
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int nsent;
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unsigned opts;
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// ugly trick, but I want these zeroed in one go
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// Ugly trick, but I want these zeroed in one go
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struct {
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const struct ether_addr null_addr;
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const struct ether_addr null_ethaddr;
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struct ifreq ifr;
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uint32_t chosen_nip;
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int conflicts;
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int timeout_ms; // must be signed
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unsigned conflicts;
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unsigned nsent;
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int verbose;
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} L;
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#define null_addr (L.null_addr )
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#define ifr (L.ifr )
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#define chosen_nip (L.chosen_nip)
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#define timeout_ms (L.timeout_ms)
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#define conflicts (L.conflicts )
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#define nsent (L.nsent )
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#define verbose (L.verbose )
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#define null_ethaddr (L.null_ethaddr)
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#define ifr (L.ifr )
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#define chosen_nip (L.chosen_nip )
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#define conflicts (L.conflicts )
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#define timeout_ms (L.timeout_ms )
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#define verbose (L.verbose )
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memset(&L, 0, sizeof(L));
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INIT_G();
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#define FOREGROUND (opts & 1)
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#define QUIT (opts & 2)
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// parse commandline: prog [options] ifname script
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// Parse commandline: prog [options] ifname script
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// exactly 2 args; -v accumulates and implies -f
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opt_complementary = "=2:vv:vf";
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opts = getopt32(argv, "fqr:l:v", &r_opt, &l_opt, &verbose);
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@ -242,7 +241,7 @@ int zcip_main(int argc UNUSED_PARAM, char **argv)
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if (!FOREGROUND)
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bb_daemonize_or_rexec(0 /*was: DAEMON_CHDIR_ROOT*/, argv);
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#endif
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// open an ARP socket
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// Open an ARP socket
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// (need to do it before openlog to prevent openlog from taking
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// fd 3 (sock_fd==3))
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xmove_fd(xsocket(AF_PACKET, SOCK_PACKET, htons(ETH_P_ARP)), sock_fd);
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@ -282,26 +281,26 @@ int zcip_main(int argc UNUSED_PARAM, char **argv)
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xsetenv("interface", argv_intf);
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// initialize the interface (modprobe, ifup, etc)
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// Initialize the interface (modprobe, ifup, etc)
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if (run(argv, "init", 0))
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return EXIT_FAILURE;
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// initialize G.iface_sockaddr
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// Initialize G.iface_sockaddr
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// G.iface_sockaddr is: { u16 sa_family; u8 sa_data[14]; }
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//memset(&G.iface_sockaddr, 0, sizeof(G.iface_sockaddr));
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//TODO: are we leaving sa_family == 0 (AF_UNSPEC)?!
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safe_strncpy(G.iface_sockaddr.sa_data, argv_intf, sizeof(G.iface_sockaddr.sa_data));
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// bind to the interface's ARP socket
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// Bind to the interface's ARP socket
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xbind(sock_fd, &G.iface_sockaddr, sizeof(G.iface_sockaddr));
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// get the interface's ethernet address
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// Get the interface's ethernet address
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//memset(&ifr, 0, sizeof(ifr));
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strncpy_IFNAMSIZ(ifr.ifr_name, argv_intf);
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xioctl(sock_fd, SIOCGIFHWADDR, &ifr);
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memcpy(&G.eth_addr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN);
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memcpy(&G.our_ethaddr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN);
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// start with some stable ip address, either a function of
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// Start with some stable ip address, either a function of
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// the hardware address or else the last address we used.
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// we are taking low-order four bytes, as top-order ones
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// aren't random enough.
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@ -309,17 +308,14 @@ int zcip_main(int argc UNUSED_PARAM, char **argv)
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// depending on when we detect conflicts.
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{
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uint32_t t;
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move_from_unaligned32(t, ((char *)&G.eth_addr + 2));
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move_from_unaligned32(t, ((char *)&G.our_ethaddr + 2));
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srand(t);
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}
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if (chosen_nip == 0)
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chosen_nip = pick_nip();
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// FIXME cases to handle:
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// - zcip already running!
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// - link already has local address... just defend/update
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// daemonize now; don't delay system startup
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// Daemonize now; don't delay system startup
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if (!FOREGROUND) {
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#if BB_MMU
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bb_daemonize(0 /*was: DAEMON_CHDIR_ROOT*/);
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@ -327,14 +323,14 @@ int zcip_main(int argc UNUSED_PARAM, char **argv)
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bb_info_msg("start, interface %s", argv_intf);
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}
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// run the dynamic address negotiation protocol,
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// Run the dynamic address negotiation protocol,
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// restarting after address conflicts:
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// - start with some address we want to try
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// - short random delay
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// - arp probes to see if another host uses it
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// 00:04:e2:64:23:c2 > ff:ff:ff:ff:ff:ff, ARP (0x0806): arp who-has 169.254.194.171 tell 0.0.0.0
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// 00:04:e2:64:23:c2 > ff:ff:ff:ff:ff:ff: arp who-has 169.254.194.171 tell 0.0.0.0
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// - arp announcements that we're claiming it
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// 00:04:e2:64:23:c2 > ff:ff:ff:ff:ff:ff, ARP (0x0806): arp who-has 169.254.194.171 (00:04:e2:64:23:c2) tell 169.254.194.171
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// 00:04:e2:64:23:c2 > ff:ff:ff:ff:ff:ff: arp who-has 169.254.194.171 (00:04:e2:64:23:c2) tell 169.254.194.171
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// - use it
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// - defend it, within limits
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// exit if:
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@ -342,73 +338,73 @@ int zcip_main(int argc UNUSED_PARAM, char **argv)
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// run "<script> config", then exit with exitcode 0
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// - poll error (when does this happen?)
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// - read error (when does this happen?)
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// - sendto error (in arp()) (when does this happen?)
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// - sendto error (in send_arp_request()) (when does this happen?)
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// - revents & POLLERR (link down). run "<script> deconfig" first
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if (chosen_nip == 0) {
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new_nip_and_PROBE:
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chosen_nip = pick_nip();
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}
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nsent = 0;
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state = PROBE;
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while (1) {
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struct pollfd fds[1];
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unsigned deadline_us;
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struct arp_packet p;
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int ip_conflict;
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int n;
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fds[0].fd = sock_fd;
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fds[0].events = POLLIN;
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fds[0].revents = 0;
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// poll, being ready to adjust current timeout
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// Poll, being ready to adjust current timeout
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if (!timeout_ms) {
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timeout_ms = random_delay_ms(PROBE_WAIT);
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// FIXME setsockopt(sock_fd, SO_ATTACH_FILTER, ...) to
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// make the kernel filter out all packets except
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// ones we'd care about.
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}
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// set deadline_us to the point in time when we timeout
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// Set deadline_us to the point in time when we timeout
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deadline_us = MONOTONIC_US() + timeout_ms * 1000;
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VDBG("...wait %d %s nsent=%u\n",
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timeout_ms, argv_intf, nsent);
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switch (safe_poll(fds, 1, timeout_ms)) {
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default:
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n = safe_poll(fds, 1, timeout_ms);
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if (n < 0) {
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//bb_perror_msg("poll"); - done in safe_poll
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return EXIT_FAILURE;
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// timeout
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case 0:
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VDBG("state = %d\n", state);
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}
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if (n == 0) { // timed out?
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VDBG("state:%d\n", state);
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switch (state) {
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case PROBE:
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// timeouts in the PROBE state mean no conflicting ARP packets
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// have been received, so we can progress through the states
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// No conflicting ARP packets were seen:
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// we can progress through the states
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if (nsent < PROBE_NUM) {
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nsent++;
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VDBG("probe/%u %s@%s\n",
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nsent, argv_intf, nip_to_a(chosen_nip));
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timeout_ms = PROBE_MIN * 1000;
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timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN);
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arp(/* ARPOP_REQUEST, */
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/* &G.eth_addr, */ 0,
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&null_addr, chosen_nip);
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break;
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send_arp_request(0, &null_ethaddr, chosen_nip);
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continue;
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}
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// Switch to announce state
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nsent = 0;
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state = ANNOUNCE;
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goto send_announce;
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case ANNOUNCE:
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// timeouts in the ANNOUNCE state mean no conflicting ARP packets
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// have been received, so we can progress through the states
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// No conflicting ARP packets were seen:
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// we can progress through the states
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if (nsent < ANNOUNCE_NUM) {
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send_announce:
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nsent++;
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VDBG("announce/%u %s@%s\n",
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nsent, argv_intf, nip_to_a(chosen_nip));
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timeout_ms = ANNOUNCE_INTERVAL * 1000;
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arp(/* ARPOP_REQUEST, */
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/* &G.eth_addr, */ chosen_nip,
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&G.eth_addr, chosen_nip);
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break;
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send_arp_request(chosen_nip, &G.our_ethaddr, chosen_nip);
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continue;
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}
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// Switch to monitor state
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// FIXME update filters
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@ -416,124 +412,117 @@ int zcip_main(int argc UNUSED_PARAM, char **argv)
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// NOTE: all other exit paths should deconfig...
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if (QUIT)
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return EXIT_SUCCESS;
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conflicts = 0;
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timeout_ms = -1; // Never timeout in the monitor state.
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state = MONITOR;
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break;
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case DEFEND:
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// fall through: switch_to_MONITOR
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default:
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// case DEFEND:
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// case MONITOR: (shouldn't happen, MONITOR timeout is infinite)
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// Defend period ended with no ARP replies - we won
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conflicts = 0;
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timeout_ms = -1;
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timeout_ms = -1; // never timeout in monitor state
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state = MONITOR;
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break;
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} // switch (state)
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break; // case 0 (timeout)
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continue;
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}
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}
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// packets arriving, or link went down
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case 1:
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// We need to adjust the timeout in case we didn't receive
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// a conflicting packet.
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if (timeout_ms > 0) {
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unsigned diff = deadline_us - MONOTONIC_US();
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if ((int)(diff) < 0) {
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// Current time is greater than the expected timeout time.
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diff = 0;
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// Packet arrived, or link went down.
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// We need to adjust the timeout in case we didn't receive
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// a conflicting packet.
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if (timeout_ms > 0) {
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unsigned diff = deadline_us - MONOTONIC_US();
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if ((int)(diff) < 0) {
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// Current time is greater than the expected timeout time.
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diff = 0;
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}
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VDBG("adjusting timeout\n");
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timeout_ms = (diff / 1000) | 1; // never 0
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}
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if ((fds[0].revents & POLLIN) == 0) {
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if (fds[0].revents & POLLERR) {
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// FIXME: links routinely go down;
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// this shouldn't necessarily exit.
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bb_error_msg("iface %s is down", argv_intf);
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if (state >= MONITOR) {
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// Only if we are in MONITOR or DEFEND
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run(argv, "deconfig", chosen_nip);
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}
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VDBG("adjusting timeout\n");
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timeout_ms = (diff / 1000) | 1; // never 0
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return EXIT_FAILURE;
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}
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continue;
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}
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if ((fds[0].revents & POLLIN) == 0) {
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if (fds[0].revents & POLLERR) {
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// FIXME: links routinely go down;
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// this shouldn't necessarily exit.
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bb_error_msg("iface %s is down", argv_intf);
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if (state >= MONITOR) {
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// only if we are in MONITOR or DEFEND
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run(argv, "deconfig", chosen_nip);
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}
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return EXIT_FAILURE;
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}
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continue;
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}
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// Read ARP packet
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if (safe_read(sock_fd, &p, sizeof(p)) < 0) {
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bb_perror_msg_and_die(bb_msg_read_error);
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}
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// read ARP packet
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if (safe_read(sock_fd, &p, sizeof(p)) < 0) {
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bb_perror_msg_and_die(bb_msg_read_error);
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}
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if (p.eth.ether_type != htons(ETHERTYPE_ARP))
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continue;
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if (p.arp.arp_op != htons(ARPOP_REQUEST)
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&& p.arp.arp_op != htons(ARPOP_REPLY)
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) {
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continue;
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}
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if (p.eth.ether_type != htons(ETHERTYPE_ARP))
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continue;
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if (p.arp.arp_op != htons(ARPOP_REQUEST)
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&& p.arp.arp_op != htons(ARPOP_REPLY)
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) {
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continue;
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}
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#ifdef DEBUG
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{
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struct ether_addr *sha = (struct ether_addr *) p.arp.arp_sha;
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struct ether_addr *tha = (struct ether_addr *) p.arp.arp_tha;
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struct in_addr *spa = (struct in_addr *) p.arp.arp_spa;
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struct in_addr *tpa = (struct in_addr *) p.arp.arp_tpa;
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VDBG("source=%s %s\n", ether_ntoa(sha), inet_ntoa(*spa));
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VDBG("target=%s %s\n", ether_ntoa(tha), inet_ntoa(*tpa));
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}
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{
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struct ether_addr *sha = (struct ether_addr *) p.arp.arp_sha;
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struct ether_addr *tha = (struct ether_addr *) p.arp.arp_tha;
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struct in_addr *spa = (struct in_addr *) p.arp.arp_spa;
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struct in_addr *tpa = (struct in_addr *) p.arp.arp_tpa;
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VDBG("source=%s %s\n", ether_ntoa(sha), inet_ntoa(*spa));
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VDBG("target=%s %s\n", ether_ntoa(tha), inet_ntoa(*tpa));
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}
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#endif
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ip_conflict = 0;
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if (memcmp(&p.arp.arp_sha, &G.eth_addr, ETH_ALEN) != 0) {
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if (memcmp(p.arp.arp_spa, &chosen_nip, 4) == 0) {
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// A probe or reply with source_ip == chosen ip
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ip_conflict = 1;
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}
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if (p.arp.arp_op == htons(ARPOP_REQUEST)
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&& memcmp(p.arp.arp_spa, &const_int_0, 4) == 0
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&& memcmp(p.arp.arp_tpa, &chosen_nip, 4) == 0
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) {
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// A probe with source_ip == 0.0.0.0, target_ip == chosen ip:
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// another host trying to claim this ip!
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ip_conflict |= 2;
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}
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ip_conflict = 0;
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if (memcmp(&p.arp.arp_sha, &G.our_ethaddr, ETH_ALEN) != 0) {
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if (memcmp(p.arp.arp_spa, &chosen_nip, 4) == 0) {
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// A probe or reply with source_ip == chosen ip
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ip_conflict = 1;
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}
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VDBG("state:%d ip_conflict:%d\n", state, ip_conflict);
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if (!ip_conflict)
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break;
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if (p.arp.arp_op == htons(ARPOP_REQUEST)
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&& memcmp(p.arp.arp_spa, &const_int_0, 4) == 0
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&& memcmp(p.arp.arp_tpa, &chosen_nip, 4) == 0
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) {
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// A probe with source_ip == 0.0.0.0, target_ip == chosen ip:
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// another host trying to claim this ip!
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ip_conflict |= 2;
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}
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}
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VDBG("state:%d ip_conflict:%d\n", state, ip_conflict);
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if (!ip_conflict)
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continue;
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// Either src or target IP conflict exists
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if (state <= ANNOUNCE) {
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// PROBE or ANNOUNCE
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conflicts++;
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timeout_ms = PROBE_MIN * 1000
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+ CONFLICT_MULTIPLIER * random_delay_ms(conflicts);
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chosen_nip = pick_nip();
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nsent = 0;
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state = PROBE;
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break;
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}
|
||||
// MONITOR or DEFEND: only src IP conflict is a problem
|
||||
if (ip_conflict & 1) {
|
||||
if (state == MONITOR) {
|
||||
// Src IP conflict, defend with a single ARP probe
|
||||
VDBG("monitor conflict - defending\n");
|
||||
timeout_ms = DEFEND_INTERVAL * 1000;
|
||||
state = DEFEND;
|
||||
arp(/* ARPOP_REQUEST, */
|
||||
/* &G.eth_addr, */ chosen_nip,
|
||||
&G.eth_addr, chosen_nip);
|
||||
break;
|
||||
}
|
||||
// state == DEFEND
|
||||
// Another src IP conflict, start over
|
||||
VDBG("defend conflict - starting over\n");
|
||||
run(argv, "deconfig", chosen_nip);
|
||||
// Either src or target IP conflict exists
|
||||
if (state <= ANNOUNCE) {
|
||||
// PROBE or ANNOUNCE
|
||||
conflicts++;
|
||||
timeout_ms = PROBE_MIN * 1000
|
||||
+ CONFLICT_MULTIPLIER * random_delay_ms(conflicts);
|
||||
goto new_nip_and_PROBE;
|
||||
}
|
||||
|
||||
// restart the whole protocol
|
||||
timeout_ms = 0;
|
||||
chosen_nip = pick_nip();
|
||||
nsent = 0;
|
||||
state = PROBE;
|
||||
// MONITOR or DEFEND: only src IP conflict is a problem
|
||||
if (ip_conflict & 1) {
|
||||
if (state == MONITOR) {
|
||||
// Src IP conflict, defend with a single ARP probe
|
||||
VDBG("monitor conflict - defending\n");
|
||||
timeout_ms = DEFEND_INTERVAL * 1000;
|
||||
state = DEFEND;
|
||||
send_arp_request(chosen_nip, &G.our_ethaddr, chosen_nip);
|
||||
continue;
|
||||
}
|
||||
break; // case 1 (packet arrived)
|
||||
} // switch (poll)
|
||||
// state == DEFEND
|
||||
// Another src IP conflict, start over
|
||||
VDBG("defend conflict - starting over\n");
|
||||
run(argv, "deconfig", chosen_nip);
|
||||
conflicts = 0;
|
||||
timeout_ms = 0;
|
||||
goto new_nip_and_PROBE;
|
||||
}
|
||||
// Note: if we only have a target IP conflict here (ip_conflict & 2),
|
||||
// IOW: if we just saw this sort of ARP packet:
|
||||
// aa:bb:cc:dd:ee:ff > xx:xx:xx:xx:xx:xx: arp who-has <chosen_nip> tell 0.0.0.0
|
||||
// we expect _kernel_ to respond to that, because <chosen_nip>
|
||||
// is (expected to be) configured on this iface.
|
||||
} // while (1)
|
||||
#undef argv_intf
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user