summary refs log tree commit diff
path: root/login/programs/connection.c
blob: 4e1663189d5d41d7b9a81c3fb44da232ba2c4a36 (plain) (blame)
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
176
177
178
179
180
/* Copyright (C) 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Mark Kettenis <kettenis@phys.uva.nl>, 1997.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>

#include "utmpd-private.h"


/* Prototypes for the local functions.  */
static client_connection *alloc_connection (void);
static void free_connection (client_connection *connection);
static int set_nonblock_flag (int desc, int value);


/* The head of the connection list.  */
static client_connection *connection_list = NULL;


/* Accept connection on SOCK, with access permissions given by ACCESS.
   Returns a pointer to a newly allocated client_connection if
   successful, NULL if not.  */
client_connection *
accept_connection (int sock, int access)
{
  client_connection *connection;

  connection = alloc_connection ();
  if (connection == NULL)
    return NULL;

  connection->sock = accept (sock, NULL, NULL);
  connection->access = access;
  if (connection->sock < 0)
    {
      free_connection (connection);
      return NULL;
    }
  
  if (set_nonblock_flag (connection->sock, 1) < 0)
    {
      close_connection (connection);
      return NULL;
    }

  return connection;  
}


/* Close CONNECTION.  */
void
close_connection (client_connection *connection)
{
  close (connection->sock);
  free_connection (connection);
}


/* Return the connection for SOCK.  */
client_connection *
find_connection (int sock)
{
  client_connection *connection;

  for (connection = connection_list; connection;
       connection = connection->next)
    {
      if (connection->sock == sock)
	return connection;
    }

  return NULL;
}


static client_connection *
alloc_connection (void)
{
  client_connection *connection;
  size_t read_bufsize = 1024;
  size_t write_bufsize = 1024;

  connection = (client_connection *)malloc (sizeof (client_connection));
  if (connection == NULL)
    return NULL;

  memset (connection, 0, sizeof (client_connection));

  /* Allocate read buffer.  */
  connection->read_base = malloc (read_bufsize);
  connection->read_ptr = connection->read_base;
  connection->read_end = connection->read_base + read_bufsize;
  if (connection->read_base == NULL)
    {
      free (connection);
      return NULL;
    }

  /* Allocate write buffer.  */
  connection->write_base = malloc (write_bufsize);
  connection->write_ptr = connection->write_base;
  connection->write_end = connection->write_base + write_bufsize;
  if (connection->write_base == NULL)
    {
      free (connection->read_base);
      free (connection);
      return NULL;
    }

  /* Link connection.  */
  connection->next = connection_list;
  connection_list = connection;
  if (connection->next)
    connection->next->prev = connection;
  
  return connection;
}


static void
free_connection (client_connection *connection)
{
  /* Unlink connection.  */
  if (connection->next)
    connection->next->prev = connection->prev;
  if (connection->prev)
    connection->prev->next = connection->next;

  /* Take care of the head of the list.  */
  if (connection == connection_list)
    connection_list = connection->next;
  
  /* Free buffers.  */
  if (connection->read_base)
    free (connection->read_base);
  if (connection->write_base)
    free (connection->write_base);

  free (connection);
}


/* Set the `O_NONBLOCK' flag of DESC if VALUE is nonzero,
   or clear the flag if VALUE is 0.
   Return 0 on success, or -1 on error with `errno' set. */
static int
set_nonblock_flag (int desc, int value)
{
  int oldflags = fcntl (desc, F_GETFL, 0);
  /* If reading the flags failed, return error indication now. */
  if (oldflags == -1)
    return -1;
  /* Set just the flag we want to set. */
  if (value != 0)
    oldflags |= O_NONBLOCK;
  else
    oldflags &= ~O_NONBLOCK;
  /* Store modified flag word in the descriptor. */
  return fcntl (desc, F_SETFL, oldflags);
}