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1.1 root 1: /*
2: * Copyright (c) 1983 Regents of the University of California.
3: * All rights reserved.
4: *
5: * Redistribution and use in source and binary forms are permitted
6: * provided that: (1) source distributions retain this entire copyright
7: * notice and comment, and (2) distributions including binaries display
8: * the following acknowledgement: ``This product includes software
9: * developed by the University of California, Berkeley and its contributors''
10: * in the documentation or other materials provided with the distribution
11: * and in all advertising materials mentioning features or use of this
12: * software. Neither the name of the University nor the names of its
13: * contributors may be used to endorse or promote products derived
14: * from this software without specific prior written permission.
15: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
16: * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
17: * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
18: */
19:
20: #ifndef lint
21: static char sccsid[] = "@(#)table.c 5.6 (Berkeley) 6/1/90";
22: #endif /* not lint */
23:
24: /*
25: * Routines to handle insertion, deletion, etc on the table
26: * of requests kept by the daemon. Nothing fancy here, linear
27: * search on a double-linked list. A time is kept with each
28: * entry so that overly old invitations can be eliminated.
29: *
30: * Consider this a mis-guided attempt at modularity
31: */
32: #include <stdio.h>
33: #include <sys/time.h>
34: #include <syslog.h>
35: #include <sys/param.h>
36:
37: #include <protocols/talkd.h>
38:
39: #define MAX_ID 16000 /* << 2^15 so I don't have sign troubles */
40:
41: #define NIL ((TABLE_ENTRY *)0)
42:
43: extern int debug;
44: struct timeval tp;
45: struct timezone *txp;
46:
47: typedef struct table_entry TABLE_ENTRY;
48:
49: struct table_entry {
50: CTL_MSG request;
51: long time;
52: TABLE_ENTRY *next;
53: TABLE_ENTRY *last;
54: };
55:
56: TABLE_ENTRY *table = NIL;
57: CTL_MSG *find_request();
58: CTL_MSG *find_match();
59: char *malloc();
60:
61: /*
62: * Look in the table for an invitation that matches the current
63: * request looking for an invitation
64: */
65: CTL_MSG *
66: find_match(request)
67: register CTL_MSG *request;
68: {
69: register TABLE_ENTRY *ptr;
70: long current_time;
71:
72: gettimeofday(&tp, &txp);
73: current_time = tp.tv_sec;
74: if (debug)
75: print_request("find_match", request);
76: for (ptr = table; ptr != NIL; ptr = ptr->next) {
77: if ((ptr->time - current_time) > MAX_LIFE) {
78: /* the entry is too old */
79: if (debug)
80: print_request("deleting expired entry",
81: &ptr->request);
82: delete(ptr);
83: continue;
84: }
85: if (debug)
86: print_request("", &ptr->request);
87: if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
88: strcmp(request->r_name, ptr->request.l_name) == 0 &&
89: ptr->request.type == LEAVE_INVITE)
90: return (&ptr->request);
91: }
92: return ((CTL_MSG *)0);
93: }
94:
95: /*
96: * Look for an identical request, as opposed to a complimentary
97: * one as find_match does
98: */
99: CTL_MSG *
100: find_request(request)
101: register CTL_MSG *request;
102: {
103: register TABLE_ENTRY *ptr;
104: long current_time;
105:
106: gettimeofday(&tp, &txp);
107: current_time = tp.tv_sec;
108: /*
109: * See if this is a repeated message, and check for
110: * out of date entries in the table while we are it.
111: */
112: if (debug)
113: print_request("find_request", request);
114: for (ptr = table; ptr != NIL; ptr = ptr->next) {
115: if ((ptr->time - current_time) > MAX_LIFE) {
116: /* the entry is too old */
117: if (debug)
118: print_request("deleting expired entry",
119: &ptr->request);
120: delete(ptr);
121: continue;
122: }
123: if (debug)
124: print_request("", &ptr->request);
125: if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
126: strcmp(request->l_name, ptr->request.l_name) == 0 &&
127: request->type == ptr->request.type &&
128: request->pid == ptr->request.pid) {
129: /* update the time if we 'touch' it */
130: ptr->time = current_time;
131: return (&ptr->request);
132: }
133: }
134: return ((CTL_MSG *)0);
135: }
136:
137: insert_table(request, response)
138: CTL_MSG *request;
139: CTL_RESPONSE *response;
140: {
141: register TABLE_ENTRY *ptr;
142: long current_time;
143:
144: gettimeofday(&tp, &txp);
145: current_time = tp.tv_sec;
146: request->id_num = new_id();
147: response->id_num = htonl(request->id_num);
148: /* insert a new entry into the top of the list */
149: ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
150: if (ptr == NIL) {
151: syslog(LOG_ERR, "insert_table: Out of memory");
152: _exit(1);
153: }
154: ptr->time = current_time;
155: ptr->request = *request;
156: ptr->next = table;
157: if (ptr->next != NIL)
158: ptr->next->last = ptr;
159: ptr->last = NIL;
160: table = ptr;
161: }
162:
163: /*
164: * Generate a unique non-zero sequence number
165: */
166: new_id()
167: {
168: static int current_id = 0;
169:
170: current_id = (current_id + 1) % MAX_ID;
171: /* 0 is reserved, helps to pick up bugs */
172: if (current_id == 0)
173: current_id = 1;
174: return (current_id);
175: }
176:
177: /*
178: * Delete the invitation with id 'id_num'
179: */
180: delete_invite(id_num)
181: int id_num;
182: {
183: register TABLE_ENTRY *ptr;
184:
185: ptr = table;
186: if (debug)
187: syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
188: for (ptr = table; ptr != NIL; ptr = ptr->next) {
189: if (ptr->request.id_num == id_num)
190: break;
191: if (debug)
192: print_request("", &ptr->request);
193: }
194: if (ptr != NIL) {
195: delete(ptr);
196: return (SUCCESS);
197: }
198: return (NOT_HERE);
199: }
200:
201: /*
202: * Classic delete from a double-linked list
203: */
204: delete(ptr)
205: register TABLE_ENTRY *ptr;
206: {
207:
208: if (debug)
209: print_request("delete", &ptr->request);
210: if (table == ptr)
211: table = ptr->next;
212: else if (ptr->last != NIL)
213: ptr->last->next = ptr->next;
214: if (ptr->next != NIL)
215: ptr->next->last = ptr->last;
216: free((char *)ptr);
217: }
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