117 lines
3.9 KiB
C
117 lines
3.9 KiB
C
/*
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* fping: fast-ping, file-ping, favorite-ping, funky-ping
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*
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* Ping a list of target hosts in a round robin fashion.
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* A better ping overall.
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*
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* fping website: http://www.fping.org
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*
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* Current maintainer of fping: David Schweikert
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* Please send suggestions and patches to: david@schweikert.ch
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*
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*
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* Original author: Roland Schemers <schemers@stanford.edu>
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* IPv6 Support: Jeroen Massar <jeroen@unfix.org / jeroen@ipng.nl>
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* Improved main loop: David Schweikert <david@schweikert.ch>
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* Debian Merge, TOS settings: Tobi Oetiker <tobi@oetiker.ch>
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* Bugfixes, byte order & senseful seq.-numbers: Stephan Fuhrmann (stephan.fuhrmann AT 1und1.de)
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*
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*
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* Redistribution and use in source and binary forms are permitted
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* provided that the above copyright notice and this paragraph are
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* duplicated in all such forms and that any documentation,
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* advertising materials, and other materials related to such
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* distribution and use acknowledge that the software was developed
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* by Stanford University. The name of the University may not be used
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* to endorse or promote products derived from this software without
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* specific prior written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*
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* seqmap.c: implementation of a mapping between sequence number and (host, ping_nr)
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* we can't just use ping_nr*host_count + host_nr, because it can
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* overflow the 16 bit of the icmp header field. See also:
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* https://github.com/schweikert/fping/issues/48
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*/
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#include "seqmap.h"
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#include "options.h"
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#include <limits.h>
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#include <stdlib.h>
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#include <stdio.h>
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/* description of the data structure used:
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*
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* - we assume that no more than SEQMAP_MAXSEQ (65535) pings are sent in
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* the timeout interval (SEQMAP_TIMEOUT_IN_S)
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* - we store the values in an array with SEQMAP_MAXSEQ elements
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* - current sequence number % SEQMAP_MAXSEQ gives the current index
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* - when entering a value, we check that the current entry is expired
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*/
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static SEQMAP_VALUE *seqmap_map = NULL;
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static unsigned int seqmap_next_id = 0;
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#define SEQMAP_TIMEOUT_IN_S 10
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#define SEQMAP_UNASSIGNED_HOST_NR UINT_MAX
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void seqmap_init()
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{
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seqmap_map = calloc(SEQMAP_MAXSEQ, sizeof(SEQMAP_VALUE));
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if(seqmap_map == NULL) {
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perror("malloc error (can't allocate seqmap_map)");
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}
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}
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unsigned int seqmap_add(unsigned int host_nr, unsigned int ping_count, struct timeval *now)
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{
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unsigned int current_id;
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SEQMAP_VALUE *next_value;
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if(!seqmap_map) {
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fprintf(stderr, "fping internal error: seqmap not initialized.\n");
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exit(4);
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}
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/* check if expired (note that unused seqmap values will have fields set to
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* 0, so will be seen as expired */
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next_value = &seqmap_map[seqmap_next_id];
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if(next_value->ping_ts.tv_sec != 0 && (now->tv_sec - next_value->ping_ts.tv_sec) < SEQMAP_TIMEOUT_IN_S) {
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fprintf(stderr, "fping error: not enough sequence numbers available! (expire_timeout=%d, host_nr=%d, ping_count=%d, seqmap_next_id=%d)\n",
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SEQMAP_TIMEOUT_IN_S, host_nr, ping_count, seqmap_next_id);
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exit(4);
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}
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/* store the value */
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next_value->host_nr = host_nr;
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next_value->ping_count = ping_count;
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next_value->ping_ts.tv_sec = now->tv_sec;
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next_value->ping_ts.tv_usec = now->tv_usec;
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/* increase next id */
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current_id = seqmap_next_id;
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seqmap_next_id = (seqmap_next_id + 1) % SEQMAP_MAXSEQ;
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return current_id;
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}
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SEQMAP_VALUE *seqmap_fetch(unsigned int id, struct timeval *now)
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{
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SEQMAP_VALUE *value;
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if(id > SEQMAP_MAXSEQ) {
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return NULL;
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}
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value = &seqmap_map[id];
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/* verify that value is not expired */
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if(now->tv_sec - value->ping_ts.tv_sec >= SEQMAP_TIMEOUT_IN_S) {
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return NULL;
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}
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return value;
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}
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