1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
/* Copyright 2002 Yon Uriarte and Jeff Dike
* Licensed under the GPL
*/
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/signal.h>
#include "switch.h"
#include "hash.h"
#define HASH_SIZE 128
#define HASH_MOD 11
struct hash_entry {
struct hash_entry *next;
struct hash_entry *prev;
time_t last_seen;
void *port;
unsigned char dst[ETH_ALEN];
};
static struct hash_entry *h[HASH_SIZE];
static int calc_hash(unsigned char *src)
{
return ((*(u_int32_t *) &src[0] % HASH_MOD) ^ src[4] ^ src[5] ) % HASH_SIZE ;
}
static struct hash_entry *find_entry(unsigned char *dst)
{
struct hash_entry *e;
int k = calc_hash(dst);
for(e = h[k]; e; e = e->next){
if(!memcmp(&e->dst, dst, ETH_ALEN)) return(e);
}
return(NULL);
}
void *find_in_hash(unsigned char *dst)
{
struct hash_entry *e = find_entry(dst);
if(e == NULL) return(NULL);
return(e->port);
}
void insert_into_hash(unsigned char *src, void *port)
{
struct hash_entry *new;
int k = calc_hash(src);
new = find_in_hash(src);
if(new != NULL) return;
new = malloc(sizeof(*new));
if(new == NULL){
perror("Failed to malloc hash entry");
return;
}
memcpy(&new->dst, src, ETH_ALEN );
if(h[k] != NULL) h[k]->prev = new;
new->next = h[k];
new->prev = NULL;
new->port = port;
new->last_seen = 0;
h[k] = new;
}
void update_entry_time(unsigned char *src)
{
struct hash_entry *e;
e = find_entry(src);
if(e == NULL) return;
e->last_seen = time(NULL);
}
static void delete_hash_entry(struct hash_entry *old)
{
int k = calc_hash(old->dst);
if(old->prev != NULL) old->prev->next = old->next;
if(old->next != NULL) old->next->prev = old->prev;
if(h[k] == old) h[k] = old->next;
free(old);
}
void delete_hash(unsigned char *dst)
{
struct hash_entry *old = find_entry(dst);
if(old == NULL) return;
delete_hash_entry(old);
}
static void for_all_hash(void (*f)(struct hash_entry *, void *), void *arg)
{
int i;
struct hash_entry *e, *next;
for(i = 0; i < HASH_SIZE; i++){
for(e = h[i]; e; e = next){
next = e->next;
(*f)(e, arg);
}
}
}
struct printer {
time_t now;
char *(*port_id)(void *);
};
static void print_hash_entry(struct hash_entry *e, void *arg)
{
struct printer *p = arg;
printf("Hash: %d Addr: %02x:%02x:%02x:%02x:%02x:%02x to port: %s "
"age %ld secs\n", calc_hash(e->dst),
e->dst[0], e->dst[1], e->dst[2], e->dst[3], e->dst[4], e->dst[5],
(*p->port_id)(e->port), (int) p->now - e->last_seen);
}
void print_hash(char *(*port_id)(void *))
{
struct printer p = ((struct printer) { now : time(NULL),
port_id : port_id });
for_all_hash(print_hash_entry, &p);
}
#define GC_INTERVAL 2
#define GC_EXPIRE 100
static void gc(struct hash_entry *e, void *now)
{
time_t t = *(time_t *) now;
if(e->last_seen + GC_EXPIRE < t)
delete_hash_entry(e);
}
static void sig_alarm(int sig)
{
struct itimerval it;
time_t t = time(NULL);
for_all_hash(&gc, &t);
it.it_value.tv_sec = GC_INTERVAL;
it.it_value.tv_usec = 0 ;
it.it_interval.tv_sec = 0;
it.it_interval.tv_usec = 0 ;
setitimer(ITIMER_REAL, &it, NULL);
}
void hash_init(void)
{
struct sigaction sa;
sa.sa_handler = sig_alarm;
sa.sa_flags = SA_RESTART;
if(sigaction(SIGALRM, &sa, NULL) < 0){
perror("Setting handler for SIGALRM");
return;
}
kill(getpid(), SIGALRM);
}
|
