1 /*-
2 * Copyright (c) 1983, 1985
3 * The Regents of the University of California. All rights reserved.
4 *
5 * %sccs.include.redist.c%
6 */
7
8 #ifndef lint
9 static char sccsid[] = "@(#)table.c 5.1 (Berkeley) 6/6/85";
10 #endif not lint
11
12 /*
13 * Routines to handle insertion, deletion, etc on the table
14 * of requests kept by the daemon. Nothing fancy here, linear
15 * search on a double-linked list. A time is kept with each
16 * entry so that overly old invitations can be eliminated.
17 *
18 * Consider this a mis-guided attempt at modularity
19 */
20 #include <stdio.h>
21 #include <sys/time.h>
22
23 #include "ctl.h"
24
25 #define MAX_ID 16000 /* << 2^15 so I don't have sign troubles */
26
27 #define NIL ((TABLE_ENTRY *)0)
28
29 extern int debug;
30 struct timeval tp;
31 struct timezone txp;
32
33 typedef struct table_entry TABLE_ENTRY;
34
35 struct table_entry {
36 CTL_MSG request;
37 long time;
38 TABLE_ENTRY *next;
39 TABLE_ENTRY *last;
40 };
41
42 TABLE_ENTRY *table = NIL;
43 CTL_MSG *find_request();
44 CTL_MSG *find_match();
45 char *malloc();
46
47 /*
48 * Look in the table for an invitation that matches the current
49 * request looking for an invitation
50 */
51 CTL_MSG *
find_match(request)52 find_match(request)
53 CTL_MSG *request;
54 {
55 TABLE_ENTRY *ptr;
56 extern FILE *debugout;
57 long current_time;
58
59 gettimeofday(&tp, &txp);
60 current_time = tp.tv_sec;
61 if (debug) {
62 fprintf(debugout, "Entering Look-Up with : \n");
63 print_request(request);
64 }
65 for (ptr = table; ptr != NIL; ptr = ptr->next) {
66 if ((ptr->time - current_time) > MAX_LIFE) {
67 /* the entry is too old */
68 if (debug) {
69 fprintf(debugout
70 ,"Deleting expired entry : \n");
71 print_request(&ptr->request);
72 }
73 delete(ptr);
74 continue;
75 }
76 if (debug)
77 print_request(&ptr->request);
78 if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
79 strcmp(request->r_name, ptr->request.l_name) == 0 &&
80 ptr->request.type == LEAVE_INVITE)
81 return (&ptr->request);
82 }
83 return ((CTL_MSG *)0);
84 }
85
86 /*
87 * Look for an identical request, as opposed to a complimentary
88 * one as find_match does
89 */
90 CTL_MSG *
find_request(request)91 find_request(request)
92 CTL_MSG *request;
93 {
94 TABLE_ENTRY *ptr;
95 extern FILE *debugout;
96 long current_time;
97
98 gettimeofday(&tp, &txp);
99 current_time = tp.tv_sec;
100 /*
101 * See if this is a repeated message, and check for
102 * out of date entries in the table while we are it.
103 */
104 if (debug) {
105 fprintf(debugout, "Entering find_request with : \n");
106 print_request(request);
107 }
108 for (ptr = table; ptr != NIL; ptr = ptr->next) {
109 if ((ptr->time - current_time) > MAX_LIFE) {
110 /* the entry is too old */
111 if (debug) {
112 fprintf(debugout
113 , "Deleting expired entry : \n");
114 print_request(&ptr->request);
115 }
116 delete(ptr);
117 continue;
118 }
119 if (debug)
120 print_request(&ptr->request);
121 if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
122 strcmp(request->l_name, ptr->request.l_name) == 0 &&
123 request->type == ptr->request.type &&
124 request->pid == ptr->request.pid) {
125 /* update the time if we 'touch' it */
126 ptr->time = current_time;
127 return (&ptr->request);
128 }
129 }
130 return ((CTL_MSG *)0);
131 }
132
insert_table(request,response)133 insert_table(request, response)
134 CTL_MSG *request;
135 CTL_RESPONSE *response;
136 {
137 TABLE_ENTRY *ptr;
138 long current_time;
139
140 gettimeofday(&tp, &txp);
141 current_time = tp.tv_sec;
142 response->id_num = request->id_num = new_id();
143 /* insert a new entry into the top of the list */
144 ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
145 if (ptr == NIL) {
146 fprintf(stderr, "malloc in insert_table");
147 exit(1);
148 }
149 ptr->time = current_time;
150 ptr->request = *request;
151 ptr->next = table;
152 if (ptr->next != NIL)
153 ptr->next->last = ptr;
154 ptr->last = NIL;
155 table = ptr;
156 }
157
158 /*
159 * Generate a unique non-zero sequence number
160 */
new_id()161 new_id()
162 {
163 static int current_id = 0;
164
165 current_id = (current_id + 1) % MAX_ID;
166 /* 0 is reserved, helps to pick up bugs */
167 if (current_id == 0)
168 current_id = 1;
169 return (current_id);
170 }
171
172 /*
173 * Delete the invitation with id 'id_num'
174 */
delete_invite(id_num)175 delete_invite(id_num)
176 int id_num;
177 {
178 TABLE_ENTRY *ptr;
179 extern FILE *debugout;
180
181 ptr = table;
182
183 if (debug)
184 fprintf(debugout,"Entering delete_invite with %d\n", id_num);
185 for (ptr = table; ptr != NIL; ptr = ptr->next) {
186 if (ptr->request.id_num == id_num)
187 break;
188 if (debug)
189 print_request(&ptr->request);
190 }
191 if (ptr != NIL) {
192 delete(ptr);
193 return (SUCCESS);
194 }
195 return (NOT_HERE);
196 }
197
198 /*
199 * Classic delete from a double-linked list
200 */
delete(ptr)201 delete(ptr)
202 TABLE_ENTRY *ptr;
203 {
204 extern FILE *debugout;
205
206 if (debug) {
207 fprintf(debugout, "Deleting : ");
208 print_request(&ptr->request);
209 }
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 }
218