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/*
* $Id: host.c,v 1.2 1997/08/12 19:17:13 begemot Exp begemot $
* $Log: host.c,v $
* Revision 1.2 1997/08/12 19:17:13 begemot
* New modes, new options (show speed, sort).
*
* Revision 1.1 1997/08/12 16:37:50 begemot
* Initial revision
*
* Revision 1.8 1995/11/09 15:30:00 begemot
* Bug caused "Internal hash management error" msg fixed, I hope.
*
* Revision 1.7 1995/02/26 19:21:02 begemot
* Some improvements (?) in hash management.
*
* Revision 1.6 1995/02/26 18:59:25 begemot
* Added RCS Id & Log entries into the all source files.
*
*/
/*
* Copyright (C) 1994-1996 D.Gorodchanin. See COPYING for more info.
*/
#include "trafshow.h"
#include <setjmp.h>
#include <signal.h>
#define HASH_BITS 8
#define HASH_SIZE (1 << HASH_BITS)
#define HASH(x) ((x ^ (x >> 8) ^ (x >> 16) ^ (x >> 24)) & (HASH_SIZE - 1))
#define TABLE_SIZE (HOSTS_COUNT + 1)
#define MAX_TRY 10
struct hash_entry {
unsigned long key;
unsigned long seq;
unsigned int next;
unsigned int try;
char name[MAX_HOST_NAME + 1];
};
static struct hash_entry table[TABLE_SIZE];
static unsigned int hash_table[HASH_SIZE];
static unsigned long lookup_no = 0;
static jmp_buf resolv_buf;
static void do_alarm(int sig)
{
longjmp(resolv_buf, 0);
}
static char const * resolve(unsigned long const addr)
{
struct hostent * h;
gettimeofday(&now, NULL);
if (now.tv_sec >= next.tv_sec - 1)
return NULL;
if (setjmp(resolv_buf))
return NULL;
signal(SIGALRM, do_alarm);
alarm(next.tv_sec - now.tv_sec - 1);
h = gethostbyaddr((char *) &addr, 4, AF_INET);
alarm(0);
if (h)
return h->h_name;
return NULL;
}
static char const * lookup(unsigned long const key)
{
int h;
unsigned const char * n;
h = hash_table[HASH(key)];
while ( h ) {
if (key == table[h].key) {
struct hash_entry * t = table + h;
t->seq = ++lookup_no;
/* gettimeofday(&now); no need in this */
if (now.tv_sec >= next.tv_sec - 2)
return t->name;
if (t->try <= MAX_TRY) {
if ((n = resolve(key))) {
strncpy(t->name,n,MAX_HOST_NAME);
t->name[MAX_HOST_NAME] = 0;
t->try = MAX_TRY + 1;
} else if (t->try++ == MAX_TRY) {
t->name[strlen(t->name)-1] = 0;
}
}
return t->name;
}
h = table[h].next;
}
return NULL;
}
static char * insert(unsigned long const key, char const * const name)
{
unsigned int i;
unsigned long minseq = lookup_no;
unsigned int minno = 0;
for (i = 1; i < TABLE_SIZE; i++) {
if (table[i].seq < minseq) {
minno = i;
if (!(minseq = table[i].seq)) {
break;
}
}
}
if (minseq) {
i = hash_table[HASH(table[minno].key)];
if (i == minno) {
hash_table[HASH(table[minno].key)] = table[i].next;
} else {
while (table[i].next != minno) {
if (!table[i].next) {
fprintf (stderr,"host: Internal logic error in hash management!!!!\n");
exit(1);
}
i = table[i].next;
}
table[i].next = table[minno].next;
}
}
table[minno].try = 0;
table[minno].key = key;
table[minno].seq = ++lookup_no;
strncpy(table[minno].name, name, MAX_HOST_NAME - 1);
table[minno].name[MAX_HOST_NAME - 1] = '\0';
strcat(table[minno].name, "*");
table[minno].name[MAX_HOST_NAME] = '\0';
table[minno].next = hash_table[HASH(key)];
hash_table[HASH(key)] = minno;
return table[minno].name;
}
char const * get_host_name(unsigned long const addr)
{
char const *name;
if ((name = lookup(addr))) {
return name;
}
#if 0
_res.retrans = 0;
_res.retry = 1;
#endif
name = inet_ntoa(*((struct in_addr *) &addr));
return insert(addr, name);
}
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