zcip: code size optimizations, improved help text and comments

function                                             old     new   delta
packed_usage                                       24750   24787     +37
run                                                  658     655      -3
pick                                                  40      34      -6
arp                                                  186     177      -9
zcip_main                                           1402    1356     -46
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/4 up/down: 37/-64)            Total: -27 bytes

diff --git a/include/usage.h b/include/usage.h
index 8f6013ede6f8ef4d1ea4591d6d0fa9654978330c..d2478641c9491d541887b042765fd388008f0d81 100644 (file)
--- a/include/usage.h
+++ b/include/usage.h
@@ -4680,8 +4680,11 @@
        "Manage a ZeroConf IPv4 link-local address\n" \
      "\nOptions:" \
      "\n       -f              Run in foreground" \
-     "\n       -q              Quit after address (no daemon)" \
+     "\n       -q              Quit after obtaining address" \
      "\n       -r 169.254.x.x  Request this address first" \
      "\n       -v              Verbose" \
+     "\n" \
+     "\nWith no -q, runs continuously monitoring for ARP conflicts," \
+     "\nexits only on I/O errors (link down etc)" \
 
 #endif /* __BB_USAGE_H__ */

diff --git a/networking/zcip.c b/networking/zcip.c
index f406b6c16e9a01ddc660f74aafc441710fcb5e61..ff9c83dc7b3965c1a040f65a3c1d346390420ae4 100644 (file)
--- a/networking/zcip.c
+++ b/networking/zcip.c
@@ -75,35 +75,40 @@ enum {
 };
 
 struct globals {
-       char *intf;
        struct sockaddr saddr;
+       struct ether_addr eth_addr;
 };
 #define G (*(struct globals*)&bb_common_bufsiz1)
-#define intf  (G.intf )
-#define saddr (G.saddr)
+#define saddr    (G.saddr   )
+#define eth_addr (G.eth_addr)
 
 
 /**
  * Pick a random link local IP address on 169.254/16, except that
  * the first and last 256 addresses are reserved.
  */
-static void pick(struct in_addr *ip)
+static uint32_t pick(void)
 {
        unsigned tmp;
 
        do {
                tmp = rand() & IN_CLASSB_HOST;
        } while (tmp > (IN_CLASSB_HOST - 0x0200));
-       ip->s_addr = htonl((LINKLOCAL_ADDR + 0x0100) + tmp);
+       return htonl((LINKLOCAL_ADDR + 0x0100) + tmp);
 }
 
 /**
  * Broadcast an ARP packet.
  */
-static void arp(int op,
-       const struct ether_addr *source_eth, struct in_addr source_ip,
+static void arp(
+       /* int op, - always ARPOP_REQUEST */
+       /* const struct ether_addr *source_eth, - always &eth_addr */
+                                       struct in_addr source_ip,
        const struct ether_addr *target_eth, struct in_addr target_ip)
 {
+       enum { op = ARPOP_REQUEST };
+#define source_eth (&eth_addr)
+
        struct arp_packet p;
        memset(&p, 0, sizeof(p));
 
@@ -124,38 +129,44 @@ static void arp(int op,
        memcpy(&p.arp.arp_tpa, &target_ip, sizeof(p.arp.arp_tpa));
 
        // send it
+       // Even though sock_fd is already bound to saddr, just send()
+       // won't work, because "socket is not connected"
+       // (and connect() won't fix that, "operation not supported").
+       // Thus we sendto() to saddr. I wonder which sockaddr
+       // (from bind() or from sendto()?) kernel actually uses
+       // to determine iface to emit the packet from...
        xsendto(sock_fd, &p, sizeof(p), &saddr, sizeof(saddr));
-
-       // Currently all callers ignore errors, that's why returns are
-       // commented out...
-       //return 0;
+#undef source_eth
 }
 
 /**
- * Run a script. argv[2] is already NULL.
+ * Run a script.
+ * argv[0]:intf argv[1]:script_name argv[2]:junk argv[3]:NULL
  */
-static int run(char *argv[3], struct in_addr *ip)
+static int run(char *argv[3], const char *param, 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]);
+       argv[2] = (char*)param;
+
+       VDBG("%s run %s %s\n", argv[0], argv[1], argv[2]);
 
        if (ip) {
                addr = inet_ntoa(*ip);
                xsetenv("ip", addr);
                fmt -= 3;
        }
-       bb_info_msg(fmt, argv[1], intf, addr);
+       bb_info_msg(fmt, argv[2], argv[0], addr);
 
-       status = wait4pid(spawn(argv));
+       status = wait4pid(spawn(argv + 1));
        if (status < 0) {
-               bb_perror_msg("%s %s %s" + 3, argv[1], intf);
+               bb_perror_msg("%s %s %s" + 3, argv[2], argv[0]);
                return -errno;
        }
        if (status != 0)
-               bb_error_msg("script %s %s failed, exitcode=%d", argv[0], argv[1], status);
+               bb_error_msg("script %s %s failed, exitcode=%d", argv[1], argv[2], status);
        return status;
 }
 
@@ -173,8 +184,7 @@ static ALWAYS_INLINE unsigned random_delay_ms(unsigned secs)
 int zcip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int zcip_main(int argc, char **argv)
 {
-       int state = PROBE;
-       struct ether_addr eth_addr;
+       int state;
        char *r_opt;
        unsigned opts;
 
@@ -184,7 +194,6 @@ int zcip_main(int argc, char **argv)
                const struct ether_addr null_addr;
                struct in_addr ip;
                struct ifreq ifr;
-               char *script_av[3];
                int timeout_ms; /* must be signed */
                unsigned conflicts;
                unsigned nprobes;
@@ -196,7 +205,6 @@ int zcip_main(int argc, char **argv)
 #define null_addr  (L.null_addr )
 #define ip         (L.ip        )
 #define ifr        (L.ifr       )
-#define script_av  (L.script_av )
 #define timeout_ms (L.timeout_ms)
 #define conflicts  (L.conflicts )
 #define nprobes    (L.nprobes   )
@@ -234,29 +242,33 @@ int zcip_main(int argc, char **argv)
                }
        }
        argc -= optind;
-       argv += optind;
+       argv += optind - 1;
+
+       /* Now: argv[0]:junk argv[1]:intf argv[2]:script argv[3]:NULL */
+       /* We need to make space for script argument: */
+       argv[0] = argv[1];
+       argv[1] = argv[2];
+       /* Now: argv[0]:intf argv[1]:script argv[2]:junk argv[3]:NULL */
+#define argv_intf (argv[0])
 
-       intf = argv[0];
-       script_av[0] = argv[1];
-       xsetenv("interface", intf);
+       xsetenv("interface", argv_intf);
 
        // initialize the interface (modprobe, ifup, etc)
-       script_av[1] = (char*)"init";
-       if (run(script_av, NULL))
+       if (run(argv, "init", 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));
+       safe_strncpy(saddr.sa_data, argv_intf, sizeof(saddr.sa_data));
 
        // bind to the interface's ARP socket
        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));
+       strncpy(ifr.ifr_name, argv_intf, sizeof(ifr.ifr_name));
        xioctl(sock_fd, SIOCGIFHWADDR, &ifr);
        memcpy(&eth_addr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN);
 
@@ -267,12 +279,11 @@ int zcip_main(int argc, char **argv)
        // NOTE: the sequence of addresses we try changes only
        // depending on when we detect conflicts.
        {
-               uint32_t t;
-               memcpy(&t, (char*)&eth_addr + 2, 4);
+               uint32_t t = get_unaligned_u32p((uint32_t *) ((char *)&eth_addr + 2));
                srand(t);
        }
        if (ip.s_addr == 0)
-               pick(&ip);
+               ip.s_addr = pick();
 
        // FIXME cases to handle:
        //  - zcip already running!
@@ -283,7 +294,7 @@ int zcip_main(int argc, char **argv)
 #if BB_MMU
                bb_daemonize(0 /*was: DAEMON_CHDIR_ROOT*/);
 #endif
-               bb_info_msg("start, interface %s", intf);
+               bb_info_msg("start, interface %s", argv_intf);
        }
 
        // run the dynamic address negotiation protocol,
@@ -294,6 +305,14 @@ int zcip_main(int argc, char **argv)
        //  - arp announcements that we're claiming it
        //  - use it
        //  - defend it, within limits
+       // exit if:
+       // - address is successfully obtained and -q was given:
+       //   run "<script> config", then exit with exitcode 0
+       // - poll error (when does this happen?)
+       // - read error (when does this happen?)
+       // - sendto error (in arp()) (when does this happen?)
+       // - revents & POLLERR (link down). run "<script> deconfig" first
+       state = PROBE;
        while (1) {
                struct pollfd fds[1];
                unsigned deadline_us;
@@ -316,7 +335,7 @@ int zcip_main(int argc, char **argv)
                deadline_us = MONOTONIC_US() + timeout_ms * 1000;
 
                VDBG("...wait %d %s nprobes=%u, nclaims=%u\n",
-                               timeout_ms, intf, nprobes, nclaims);
+                               timeout_ms, argv_intf, nprobes, nclaims);
 
                switch (safe_poll(fds, 1, timeout_ms)) {
 
@@ -334,9 +353,9 @@ int zcip_main(int argc, char **argv)
                                if (nprobes < PROBE_NUM) {
                                        nprobes++;
                                        VDBG("probe/%u %s@%s\n",
-                                                       nprobes, intf, inet_ntoa(ip));
-                                       arp(ARPOP_REQUEST,
-                                                       &eth_addr, null_ip,
+                                                       nprobes, argv_intf, inet_ntoa(ip));
+                                       arp(/* ARPOP_REQUEST, */
+                                                       /* &eth_addr, */ null_ip,
                                                        &null_addr, ip);
                                        timeout_ms = PROBE_MIN * 1000;
                                        timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN);
@@ -346,9 +365,9 @@ int zcip_main(int argc, char **argv)
                                        state = ANNOUNCE;
                                        nclaims = 0;
                                        VDBG("announce/%u %s@%s\n",
-                                                       nclaims, intf, inet_ntoa(ip));
-                                       arp(ARPOP_REQUEST,
-                                                       &eth_addr, ip,
+                                                       nclaims, argv_intf, inet_ntoa(ip));
+                                       arp(/* ARPOP_REQUEST, */
+                                                       /* &eth_addr, */ ip,
                                                        &eth_addr, ip);
                                        timeout_ms = ANNOUNCE_INTERVAL * 1000;
                                }
@@ -359,9 +378,9 @@ int zcip_main(int argc, char **argv)
                                state = ANNOUNCE;
                                nclaims = 0;
                                VDBG("announce/%u %s@%s\n",
-                                               nclaims, intf, inet_ntoa(ip));
-                               arp(ARPOP_REQUEST,
-                                               &eth_addr, ip,
+                                               nclaims, argv_intf, inet_ntoa(ip));
+                               arp(/* ARPOP_REQUEST, */
+                                               /* &eth_addr, */ ip,
                                                &eth_addr, ip);
                                timeout_ms = ANNOUNCE_INTERVAL * 1000;
                                break;
@@ -371,9 +390,9 @@ int zcip_main(int argc, char **argv)
                                if (nclaims < ANNOUNCE_NUM) {
                                        nclaims++;
                                        VDBG("announce/%u %s@%s\n",
-                                                       nclaims, intf, inet_ntoa(ip));
-                                       arp(ARPOP_REQUEST,
-                                                       &eth_addr, ip,
+                                                       nclaims, argv_intf, inet_ntoa(ip));
+                                       arp(/* ARPOP_REQUEST, */
+                                                       /* &eth_addr, */ ip,
                                                        &eth_addr, ip);
                                        timeout_ms = ANNOUNCE_INTERVAL * 1000;
                                }
@@ -382,8 +401,7 @@ int zcip_main(int argc, char **argv)
                                        state = MONITOR;
                                        // link is ok to use earlier
                                        // FIXME update filters
-                                       script_av[1] = (char*)"config";
-                                       run(script_av, &ip);
+                                       run(argv, "config", &ip);
                                        ready = 1;
                                        conflicts = 0;
                                        timeout_ms = -1; // Never timeout in the monitor state.
@@ -403,7 +421,7 @@ int zcip_main(int argc, char **argv)
                        default:
                                // Invalid, should never happen.  Restart the whole protocol.
                                state = PROBE;
-                               pick(&ip);
+                               ip.s_addr = pick();
                                timeout_ms = 0;
                                nprobes = 0;
                                nclaims = 0;
@@ -432,10 +450,9 @@ 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("iface %s is down", intf);
+                                       bb_error_msg("iface %s is down", argv_intf);
                                        if (ready) {
-                                               script_av[1] = (char*)"deconfig";
-                                               run(script_av, &ip);
+                                               run(argv, "deconfig", &ip);
                                        }
                                        return EXIT_FAILURE;
                                }
@@ -455,7 +472,7 @@ int zcip_main(int argc, char **argv)
                                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.eth.ether_type),
+                                       argv_intf, ntohs(p.eth.ether_type),
                                        ntohs(p.arp.arp_op));
                                VDBG("\tsource=%s %s\n",
                                        ether_ntoa(sha),
@@ -494,13 +511,13 @@ int zcip_main(int argc, char **argv)
                                if (source_ip_conflict || target_ip_conflict) {
                                        conflicts++;
                                        if (conflicts >= MAX_CONFLICTS) {
-                                               VDBG("%s ratelimit\n", intf);
+                                               VDBG("%s ratelimit\n", argv_intf);
                                                timeout_ms = RATE_LIMIT_INTERVAL * 1000;
                                                state = RATE_LIMIT_PROBE;
                                        }
 
                                        // restart the whole protocol
-                                       pick(&ip);
+                                       ip.s_addr = pick();
                                        timeout_ms = 0;
                                        nprobes = 0;
                                        nclaims = 0;
@@ -512,8 +529,8 @@ int zcip_main(int argc, char **argv)
                                        VDBG("monitor conflict -- defending\n");
                                        state = DEFEND;
                                        timeout_ms = DEFEND_INTERVAL * 1000;
-                                       arp(ARPOP_REQUEST,
-                                               &eth_addr, ip,
+                                       arp(/* ARPOP_REQUEST, */
+                                               /* &eth_addr, */ ip,
                                                &eth_addr, ip);
                                }
                                break;
@@ -523,11 +540,10 @@ int zcip_main(int argc, char **argv)
                                        state = PROBE;
                                        VDBG("defend conflict -- starting over\n");
                                        ready = 0;
-                                       script_av[1] = (char*)"deconfig";
-                                       run(script_av, &ip);
+                                       run(argv, "deconfig", &ip);
 
                                        // restart the whole protocol
-                                       pick(&ip);
+                                       ip.s_addr = pick();
                                        timeout_ms = 0;
                                        nprobes = 0;
                                        nclaims = 0;
@@ -537,7 +553,7 @@ int zcip_main(int argc, char **argv)
                                // Invalid, should never happen.  Restart the whole protocol.
                                VDBG("invalid state -- starting over\n");
                                state = PROBE;
-                               pick(&ip);
+                               ip.s_addr = pick();
                                timeout_ms = 0;
                                nprobes = 0;
                                nclaims = 0;
@@ -546,4 +562,5 @@ int zcip_main(int argc, char **argv)
                        break; // case 1 (packets arriving)
                } // switch poll
        } // while (1)
+#undef argv_intf
 }