1 /*
2 * Copyright (c) 1983, 1993
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 8.1 (Berkeley) 06/04/93";
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 <sys/param.h>
21 #include <sys/time.h>
22 #include <sys/socket.h>
23 #include <protocols/talkd.h>
24 #include <syslog.h>
25 #include <unistd.h>
26 #include <stdio.h>
27 #include <stdlib.h>
28 #include <string.h>
29
30 #define MAX_ID 16000 /* << 2^15 so I don't have sign troubles */
31
32 #define NIL ((TABLE_ENTRY *)0)
33
34 extern int debug;
35 struct timeval tp;
36 struct timezone txp;
37
38 typedef struct table_entry TABLE_ENTRY;
39
40 struct table_entry {
41 CTL_MSG request;
42 long time;
43 TABLE_ENTRY *next;
44 TABLE_ENTRY *last;
45 };
46
47 TABLE_ENTRY *table = NIL;
48 CTL_MSG *find_request();
49 CTL_MSG *find_match();
50
51 /*
52 * Look in the table for an invitation that matches the current
53 * request looking for an invitation
54 */
55 CTL_MSG *
find_match(request)56 find_match(request)
57 register CTL_MSG *request;
58 {
59 register TABLE_ENTRY *ptr;
60 time_t current_time;
61
62 gettimeofday(&tp, &txp);
63 current_time = tp.tv_sec;
64 if (debug)
65 print_request("find_match", request);
66 for (ptr = table; ptr != NIL; ptr = ptr->next) {
67 if ((ptr->time - current_time) > MAX_LIFE) {
68 /* the entry is too old */
69 if (debug)
70 print_request("deleting expired entry",
71 &ptr->request);
72 delete(ptr);
73 continue;
74 }
75 if (debug)
76 print_request("", &ptr->request);
77 if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
78 strcmp(request->r_name, ptr->request.l_name) == 0 &&
79 ptr->request.type == LEAVE_INVITE)
80 return (&ptr->request);
81 }
82 return ((CTL_MSG *)0);
83 }
84
85 /*
86 * Look for an identical request, as opposed to a complimentary
87 * one as find_match does
88 */
89 CTL_MSG *
find_request(request)90 find_request(request)
91 register CTL_MSG *request;
92 {
93 register TABLE_ENTRY *ptr;
94 time_t current_time;
95
96 gettimeofday(&tp, &txp);
97 current_time = tp.tv_sec;
98 /*
99 * See if this is a repeated message, and check for
100 * out of date entries in the table while we are it.
101 */
102 if (debug)
103 print_request("find_request", request);
104 for (ptr = table; ptr != NIL; ptr = ptr->next) {
105 if ((ptr->time - current_time) > MAX_LIFE) {
106 /* the entry is too old */
107 if (debug)
108 print_request("deleting expired entry",
109 &ptr->request);
110 delete(ptr);
111 continue;
112 }
113 if (debug)
114 print_request("", &ptr->request);
115 if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
116 strcmp(request->l_name, ptr->request.l_name) == 0 &&
117 request->type == ptr->request.type &&
118 request->pid == ptr->request.pid) {
119 /* update the time if we 'touch' it */
120 ptr->time = current_time;
121 return (&ptr->request);
122 }
123 }
124 return ((CTL_MSG *)0);
125 }
126
insert_table(request,response)127 insert_table(request, response)
128 CTL_MSG *request;
129 CTL_RESPONSE *response;
130 {
131 register TABLE_ENTRY *ptr;
132 time_t current_time;
133
134 gettimeofday(&tp, &txp);
135 current_time = tp.tv_sec;
136 request->id_num = new_id();
137 response->id_num = htonl(request->id_num);
138 /* insert a new entry into the top of the list */
139 ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
140 if (ptr == NIL) {
141 syslog(LOG_ERR, "insert_table: Out of memory");
142 _exit(1);
143 }
144 ptr->time = current_time;
145 ptr->request = *request;
146 ptr->next = table;
147 if (ptr->next != NIL)
148 ptr->next->last = ptr;
149 ptr->last = NIL;
150 table = ptr;
151 }
152
153 /*
154 * Generate a unique non-zero sequence number
155 */
new_id()156 new_id()
157 {
158 static int current_id = 0;
159
160 current_id = (current_id + 1) % MAX_ID;
161 /* 0 is reserved, helps to pick up bugs */
162 if (current_id == 0)
163 current_id = 1;
164 return (current_id);
165 }
166
167 /*
168 * Delete the invitation with id 'id_num'
169 */
delete_invite(id_num)170 delete_invite(id_num)
171 int id_num;
172 {
173 register TABLE_ENTRY *ptr;
174
175 ptr = table;
176 if (debug)
177 syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
178 for (ptr = table; ptr != NIL; ptr = ptr->next) {
179 if (ptr->request.id_num == id_num)
180 break;
181 if (debug)
182 print_request("", &ptr->request);
183 }
184 if (ptr != NIL) {
185 delete(ptr);
186 return (SUCCESS);
187 }
188 return (NOT_HERE);
189 }
190
191 /*
192 * Classic delete from a double-linked list
193 */
delete(ptr)194 delete(ptr)
195 register TABLE_ENTRY *ptr;
196 {
197
198 if (debug)
199 print_request("delete", &ptr->request);
200 if (table == ptr)
201 table = ptr->next;
202 else if (ptr->last != NIL)
203 ptr->last->next = ptr->next;
204 if (ptr->next != NIL)
205 ptr->next->last = ptr->last;
206 free((char *)ptr);
207 }
208