Someone filed a bug at bugs.gentoo.org reflecting a possible enhancement to arping. In short the patches author felt that select should be used instead of signals to avoid missing a timeout.
The bug is located at: http://bugs.gentoo.org/show_bug.cgi?id=144526 The diff follows: --- arping.c 2006-08-20 19:14:39.000000000 -0500 +++ /var/tmp/portage/iputils-021109-r3/work/iputils/arping.c 2006-08-20 19:17:40.000000000 -0500 @@ -7,9 +7,6 @@ * 2 of the License, or (at your option) any later version. * * Authors: Alexey Kuznetsov, <[EMAIL PROTECTED]> - * 2006.08.18 erik quanstrom <[EMAIL PROTECTED]> - * use select instead of signals so timeouts will work. - * */ #include <stdlib.h> @@ -18,6 +15,7 @@ #include <linux/sockios.h> #include <sys/file.h> #include <sys/time.h> +#include <sys/signal.h> #include <sys/ioctl.h> #include <linux/if.h> #include <linux/if_arp.h> @@ -31,12 +29,12 @@ #include <string.h> #include <netinet/in.h> #include <arpa/inet.h> -#include <stdarg.h> #include "SNAPSHOT.h" static void usage(void) __attribute__((noreturn)); +int quit_on_reply=0; char *device="eth0"; int ifindex; char *source; @@ -45,10 +43,7 @@ int dad, unsolicited, advert; int quiet; int count=-1; -int ntosend=-1; -int ntorecv=-1; int timeout; -struct timeval timeouttv; int unicasting; int s; int broadcast_only; @@ -64,19 +59,6 @@ #define MS_TDIFF(tv1,tv2) ( ((tv1).tv_sec-(tv2).tv_sec)*1000 + \ ((tv1).tv_usec-(tv2).tv_usec)/1000 ) -#define pkttrace(...) /* fprintf(stderr, __VA_ARGS__) */ - -void -errexit(int err, const char* fmt, ...) -{ - va_list ap; - - va_start(ap, fmt); - vfprintf(stderr, fmt, ap); - va_end(ap); - exit(err); -} - void usage(void) { fprintf(stderr, @@ -97,6 +79,16 @@ exit(2); } +void set_signal(int signo, void (*handler)(void)) +{ + struct sigaction sa; + + memset(&sa, 0, sizeof(sa)); + sa.sa_handler = (void (*)(int))handler; + sa.sa_flags = SA_RESTART; + sigaction(signo, &sa, NULL); +} + int send_pack(int s, struct in_addr src, struct in_addr dst, struct sockaddr_ll *ME, struct sockaddr_ll *HE) { @@ -130,9 +122,7 @@ p+=4; gettimeofday(&now, NULL); - pkttrace("sendto->\n"); err = sendto(s, buf, p-buf, 0, (struct sockaddr*)HE, sizeof(*HE)); - pkttrace("sendto<-\n"); if (err == p-buf) { last = now; sent++; @@ -145,20 +135,20 @@ void finish(void) { if (!quiet) { - fflush(stdout); - fprintf(stderr, "Sent %d probes (%d broadcast(s))\n", sent, brd_sent); - fprintf(stderr, "Received %d response(s)", received); + printf("Sent %d probes (%d broadcast(s))\n", sent, brd_sent); + printf("Received %d response(s)", received); if (brd_recv || req_recv) { - fprintf(stderr, " ("); + printf(" ("); if (req_recv) - fprintf(stderr, "%d request(s)", req_recv); + printf("%d request(s)", req_recv); if (brd_recv) - fprintf(stderr, "%s%d broadcast(s)", + printf("%s%d broadcast(s)", req_recv ? ", " : "", brd_recv); - fprintf(stderr, ")"); + printf(")"); } - fprintf(stderr, "\n"); + printf("\n"); + fflush(stdout); } if (dad) exit(!!received); @@ -167,13 +157,34 @@ exit(!received); } +void catcher(void) +{ + struct timeval tv; + + gettimeofday(&tv, NULL); + + if (start.tv_sec==0) + start = tv; + + if (count-- == 0 || (timeout && MS_TDIFF(tv,start) > timeout*1000 + 500)) + finish(); + + if (last.tv_sec==0 || MS_TDIFF(tv,last) > 500) { + send_pack(s, src, dst, &me, &he); + if (count == 0 && unsolicited) + finish(); + } + alarm(1); +} + void print_hex(unsigned char *p, int len) { int i; - for (i=0; i<len-1; i++) - printf("%02X:", p[i]); - if(len) + for (i=0; i<len; i++) { printf("%02X", p[i]); + if (i != len-1) + printf(":"); + } } int recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM) @@ -274,6 +285,8 @@ brd_recv++; if (ah->ar_op == htons(ARPOP_REQUEST)) req_recv++; + if (quit_on_reply) + finish(); if(!broadcast_only) { memcpy(he.sll_addr, p, me.sll_halen); unicasting=1; @@ -281,75 +294,26 @@ return 1; } - -unsigned char packet[4096]; // too big for stack on some arch. - -void -pktloop(void) -{ - struct sockaddr_ll from; - socklen_t alen = sizeof(from); - fd_set rset; - struct timeval tmo; - int cc, i; - - for(;;){ - if(ntosend-- == 0) - break; - send_pack(s, src, dst, &me, &he); - - gettimeofday(&tmo, 0); - if(timeout) - i = MS_TDIFF(timeouttv, tmo) ; - else - i = 1000; - if(i < 0) - break; - if(i > 1000) - i = 1000; // maximum select 1s. - tmo.tv_sec = i/1000; - tmo.tv_usec = (i%1000)*1000; - - FD_ZERO(&rset); - FD_SET(s, &rset); - pkttrace("select %d ; %d\n", (int)tmo.tv_sec, (int)tmo.tv_usec); - i = select(s+1, &rset, 0, 0, &tmo); - pkttrace("<- select\n"); - if(i == -1){ - perror("arping: select"); - exit(1); - } - if(i == 0){ - gettimeofday(&tmo, 0); - i = MS_TDIFF(timeouttv, tmo); - if(timeout && i <= 0) - break; - continue; - } - if ((cc = recvfrom(s, packet, sizeof(packet), 0, - (struct sockaddr *)&from, &alen)) < 0) { - perror("arping: recvfrom"); - continue; - } - if(recv_pack(packet, cc, &from)) - if(--ntorecv == 0) - break; - } -} - int main(int argc, char **argv) { - int ch, onereply; + int socket_errno; + int ch; + uid_t uid = getuid(); + + s = socket(PF_PACKET, SOCK_DGRAM, 0); + socket_errno = errno; + + setuid(uid); while ((ch = getopt(argc, argv, "h?bfDUAqc:w:s:I:V")) != EOF) { switch(ch) { case 'b': - broadcast_only = 1; + broadcast_only=1; break; case 'D': dad++; - onereply = 1; + quit_on_reply=1; break; case 'U': unsolicited++; @@ -365,15 +329,13 @@ count = atoi(optarg); break; case 'w': - gettimeofday(&timeouttv, 0); - timeouttv.tv_sec += atoi(optarg); - timeout = 1; + timeout = atoi(optarg); break; case 'I': device = optarg; break; case 'f': - onereply = 1; + quit_on_reply=1; break; case 's': source = optarg; @@ -392,26 +354,19 @@ if (argc != 1) usage(); - target = *argv; - if(onereply) - ntorecv = 1; - if(timeout) // strange ping compatability. - ntorecv = count; - else - ntosend = count; + target = *argv; - if (device == 0) { + if (device == NULL) { fprintf(stderr, "arping: device (option -I) is required\n"); usage(); } - s = socket(PF_PACKET, SOCK_DGRAM, 0); if (s < 0) { + errno = socket_errno; perror("arping: socket"); exit(2); } - setuid(getuid()); if (1) { struct ifreq ifr; @@ -424,13 +379,19 @@ ifindex = ifr.ifr_ifindex; if (ioctl(s, SIOCGIFFLAGS, (char*)&ifr)) { - perror("arping: ioctl(SIOCGIFFLAGS)"); + perror("ioctl(SIOCGIFFLAGS)"); exit(2); } - if (!(ifr.ifr_flags&IFF_UP)) - errexit(2, "Interface \"%s\" is down\n", device); - if (ifr.ifr_flags&(IFF_NOARP|IFF_LOOPBACK)) - errexit(dad ? 0 : 2, "Interface \"%s\" is not ARPable\n", device); + if (!(ifr.ifr_flags&IFF_UP)) { + if (!quiet) + printf("Interface \"%s\" is down\n", device); + exit(2); + } + if (ifr.ifr_flags&(IFF_NOARP|IFF_LOOPBACK)) { + if (!quiet) + printf("Interface \"%s\" is not ARPable\n", device); + exit(dad?0:2); + } } if (inet_aton(target, &dst) != 1) { @@ -456,7 +417,7 @@ int probe_fd = socket(AF_INET, SOCK_DGRAM, 0); if (probe_fd < 0) { - perror("arping: socket"); + perror("socket"); exit(2); } if (device) { @@ -468,7 +429,7 @@ if (src.s_addr) { saddr.sin_addr = src; if (bind(probe_fd, (struct sockaddr*)&saddr, sizeof(saddr)) == -1) { - perror("arping: bind"); + perror("bind"); exit(2); } } else if (!dad) { @@ -481,11 +442,11 @@ if (setsockopt(probe_fd, SOL_SOCKET, SO_DONTROUTE, (char*)&on, sizeof(on)) == -1) perror("WARNING: setsockopt(SO_DONTROUTE)"); if (connect(probe_fd, (struct sockaddr*)&saddr, sizeof(saddr)) == -1) { - perror("arping: connect"); + perror("connect"); exit(2); } if (getsockname(probe_fd, (struct sockaddr*)&saddr, &alen) == -1) { - perror("arping: getsockname"); + perror("getsockname"); exit(2); } src = saddr.sin_addr; @@ -497,34 +458,60 @@ me.sll_ifindex = ifindex; me.sll_protocol = htons(ETH_P_ARP); if (bind(s, (struct sockaddr*)&me, sizeof(me)) == -1) { - perror("arping: bind"); + perror("bind"); exit(2); } if (1) { socklen_t alen = sizeof(me); if (getsockname(s, (struct sockaddr*)&me, &alen) == -1) { - perror("arping: getsockname"); + perror("getsockname"); exit(2); } } - if (me.sll_halen == 0) - errexit(dad ? 0 : 2, "Interface \"%s\" is not ARPable (no ll address)\n", device); + if (me.sll_halen == 0) { + if (!quiet) + printf("Interface \"%s\" is not ARPable (no ll address)\n", device); + exit(dad?0:2); + } he = me; memset(he.sll_addr, -1, he.sll_halen); if (!quiet) { - fprintf(stderr, "ARPING %s ", inet_ntoa(dst)); - fprintf(stderr, "from %s %s\n", inet_ntoa(src), device ? : ""); + printf("ARPING %s ", inet_ntoa(dst)); + printf("from %s %s\n", inet_ntoa(src), device ? : ""); } - if (!src.s_addr && !dad) - errexit(2, "arping: no source address in not-DAD mode\n"); + if (!src.s_addr && !dad) { + fprintf(stderr, "arping: no source address in not-DAD mode\n"); + exit(2); + } + + set_signal(SIGINT, finish); + set_signal(SIGALRM, catcher); + + catcher(); - pktloop(); - finish(); - return 1; // shut up gcc. + while(1) { + sigset_t sset, osset; + unsigned char packet[4096]; + struct sockaddr_ll from; + socklen_t alen = sizeof(from); + int cc; + + if ((cc = recvfrom(s, packet, sizeof(packet), 0, + (struct sockaddr *)&from, &alen)) < 0) { + perror("arping: recvfrom"); + continue; + } + sigemptyset(&sset); + sigaddset(&sset, SIGALRM); + sigaddset(&sset, SIGINT); + sigprocmask(SIG_BLOCK, &sset, &osset); + recv_pack(packet, cc, &from); + sigprocmask(SIG_SETMASK, &osset, NULL); + } } -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
