1 #include <sys/types.h>
2 #include <sys/socket.h>
3
4 #include <arpa/inet.h>
5 #include <netinet/in.h>
6
7 #include <stdint.h>
8 #include <stdio.h>
9 #include <stdlib.h>
10 #include <string.h>
11 #include <unistd.h>
12
13 #ifndef NBBY
14 #define NBBY __NBBY
15 #endif
16
17 #define HASHMASK 0x7f
18
19 #define KEYLEN 40
20 #define HASHLEN 12
21
22 static uint8_t toeplitz_key[KEYLEN];
23 static uint32_t hash_table[HASHLEN][256];
24
25 static void toeplitz_init(uint32_t[][256], int, const uint8_t[], int);
26 static void getaddrport(char *, uint32_t *, uint16_t *);
27
28 static void
usage(const char * cmd)29 usage(const char *cmd)
30 {
31 fprintf(stderr, "%s [-s s1_hex [-s s2_hex]] [-p] [-m mask] [-d div] "
32 "addr1.port1 addr2.port2\n", cmd);
33 exit(1);
34 }
35
36 int
main(int argc,char * argv[])37 main(int argc, char *argv[])
38 {
39 uint32_t saddr, daddr;
40 uint16_t sport, dport;
41 uint32_t res, mask, divisor;
42
43 const char *cmd = argv[0];
44 uint8_t seeds[2] = { 0x6d, 0x5a };
45 int i, opt, use_port;
46
47 i = 0;
48 use_port = 0;
49 mask = 0xffffffff;
50 divisor = 0;
51
52 while ((opt = getopt(argc, argv, "d:m:ps:")) != -1) {
53 switch (opt) {
54 case 'd':
55 divisor = strtoul(optarg, NULL, 10);
56 break;
57
58 case 'm':
59 mask = strtoul(optarg, NULL, 16);
60 break;
61
62 case 'p':
63 use_port = 1;
64 break;
65
66 case 's':
67 if (i >= 2)
68 usage(cmd);
69 seeds[i++] = strtoul(optarg, NULL, 16);
70 break;
71
72 default:
73 usage(cmd);
74 }
75 }
76 argc -= optind;
77 argv += optind;
78
79 if (argc != 2)
80 usage(cmd);
81
82 for (i = 0; i < KEYLEN; ++i) {
83 if (i & 1)
84 toeplitz_key[i] = seeds[1];
85 else
86 toeplitz_key[i] = seeds[0];
87 }
88
89 getaddrport(argv[0], &saddr, &sport);
90 getaddrport(argv[1], &daddr, &dport);
91
92 toeplitz_init(hash_table, HASHLEN, toeplitz_key, KEYLEN);
93
94 res = hash_table[0][(saddr >> 0) & 0xff];
95 res ^= hash_table[1][(saddr >> 8) & 0xff];
96 res ^= hash_table[2][(saddr >> 16) & 0xff];
97 res ^= hash_table[3][(saddr >> 24) & 0xff];
98 res ^= hash_table[4][(daddr >> 0) & 0xff];
99 res ^= hash_table[5][(daddr >> 8) & 0xff];
100 res ^= hash_table[6][(daddr >> 16) & 0xff];
101 res ^= hash_table[7][(daddr >> 24) & 0xff];
102 if (use_port) {
103 res ^= hash_table[8][(sport >> 0) & 0xff];
104 res ^= hash_table[9][(sport >> 8) & 0xff];
105 res ^= hash_table[10][(dport >> 0) & 0xff];
106 res ^= hash_table[11][(dport >> 8) & 0xff];
107 }
108
109 printf("0x%08x, masked 0x%08x", res, res & mask);
110 if (divisor == 0)
111 printf("\n");
112 else
113 printf(", modulo %u\n", (res & HASHMASK) % divisor);
114 exit(0);
115 }
116
117 static void
toeplitz_init(uint32_t cache[][256],int cache_len,const uint8_t key_str[],int key_strlen)118 toeplitz_init(uint32_t cache[][256], int cache_len,
119 const uint8_t key_str[], int key_strlen)
120 {
121 int i;
122
123 if (key_strlen < cache_len + (int)sizeof(uint32_t))
124 exit(1);
125
126 for (i = 0; i < cache_len; ++i) {
127 uint32_t key[NBBY];
128 int j, b, shift, val;
129
130 bzero(key, sizeof(key));
131
132 /*
133 * Calculate 32bit keys for one byte; one key for each bit.
134 */
135 for (b = 0; b < NBBY; ++b) {
136 for (j = 0; j < 32; ++j) {
137 uint8_t k;
138 int bit;
139
140 bit = (i * NBBY) + b + j;
141
142 k = key_str[bit / NBBY];
143 shift = NBBY - (bit % NBBY) - 1;
144 if (k & (1 << shift))
145 key[b] |= 1 << (31 - j);
146 }
147 }
148
149 /*
150 * Cache the results of all possible bit combination of
151 * one byte.
152 */
153 for (val = 0; val < 256; ++val) {
154 uint32_t res = 0;
155
156 for (b = 0; b < NBBY; ++b) {
157 shift = NBBY - b - 1;
158 if (val & (1 << shift))
159 res ^= key[b];
160 }
161 cache[i][val] = res;
162 }
163 }
164 }
165
166 static void
getaddrport(char * ap_str,uint32_t * addr,uint16_t * port0)167 getaddrport(char *ap_str, uint32_t *addr, uint16_t *port0)
168 {
169 uint16_t port;
170 char *p;
171
172 p = strrchr(ap_str, '.');
173 if (p == NULL) {
174 fprintf(stderr, "invalid addr.port %s\n", ap_str);
175 exit(1);
176 }
177
178 *p = '\0';
179 ++p;
180
181 port = strtoul(p, NULL, 10);
182 *port0 = htons(port);
183
184 if (inet_pton(AF_INET, ap_str, addr) <= 0) {
185 fprintf(stderr, "invalid addr %s\n", ap_str);
186 exit(1);
187 }
188 }
189