trunk/rdesktop/readpass.c

/*
   rdesktop: A Remote Desktop Protocol client.
   User interface services - X keyboard mapping
   Copyright (C) Matthew Chapman 1999-2002
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program 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 General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <sys/types.h>
#include <signal.h>
#include <stdio.h>
#include <errno.h>
#include "rdesktop.h"
#include <assert.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <fcntl.h>

/* Execute specified askpass program and fetch password from standard
   output. Return NULL on failure, otherwise a pointer to the data
   read (which must be freed by caller) */

char *
askpass(char *askpass, const char *msg)
{
        pid_t pid;
        size_t len;
        char *pass;
        int p[2], status, ret;
        char buf[1024];
        int devnull;

        if (fflush(stdout) != 0)
                error("askpass: fflush: %s", strerror(errno));
        assert(askpass != NULL);
        if (pipe(p) < 0)
        {
                error("askpass: pipe: %s", strerror(errno));
                return NULL;
        }

        pid = fork();
        switch (pid)
        {
                case -1:
                        error("askpass: fork: %s", strerror(errno));
                        return NULL;
                        break;
                case 0:
                        /* Child */
                        seteuid(getuid());
                        setuid(getuid());
                        /* Close read end */
                        close(p[0]);

                        /* Setup stdin */
                        devnull = open("/dev/null", 0, O_RDONLY);
                        if (dup2(devnull, STDIN_FILENO) < 0)
                        {
                                error("askpass: dup2: %s", strerror(errno));
                                exit(1);
                        }
                        close(devnull);

                        /* Setup stdout */
                        if (dup2(p[1], STDOUT_FILENO) < 0)
                        {
                                error("askpass: dup2: %s", strerror(errno));
                                exit(1);
                        }
                        close(p[1]);

                        /* By now, the following fds are open: 
                           0 -> /dev/null 
                           1 -> pipe write end
                           2 -> users terminal */
                        execlp(askpass, askpass, msg, (char *) 0);
                        error("askpass: exec(%s): %s", askpass, strerror(errno));
                        exit(1);
                        break;
                default:
                        /* Parent */
                        break;
        }
        /* Close write end */
        close(p[1]);

        len = ret = 0;
        do
        {
                ret = read(p[0], buf + len, sizeof(buf) - 1 - len);

                if (ret == -1 && errno == EINTR)
                        continue;
                if (ret <= 0)
                        break;

                len += ret;
        }
        while (sizeof(buf) - 1 - len > 0);


        buf[len] = '\0';

        close(p[0]);
        while (waitpid(pid, &status, 0) < 0)
                if (errno != EINTR)
                        break;

        if (WIFEXITED(status))
        {
                if (WEXITSTATUS(status))
                {
                        error("askpass program returned %d\n", WEXITSTATUS(status));
                        return NULL;
                }
        }
        else
        {
                error("abnormal exit from askpass program");
                return NULL;
        }

        buf[strcspn(buf, "\r\n")] = '\0';
        pass = strdup(buf);
        memset(buf, 0, sizeof(buf));
        return pass;
}
1	/*
2	rdesktop: A Remote Desktop Protocol client.
3	User interface services - X keyboard mapping
4	Copyright (C) Matthew Chapman 1999-2002
5
6	This program is free software; you can redistribute it and/or modify
7	it under the terms of the GNU General Public License as published by
8	the Free Software Foundation; either version 2 of the License, or
9	(at your option) any later version.
10
11	This program is distributed in the hope that it will be useful,
12	but WITHOUT ANY WARRANTY; without even the implied warranty of
13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14	GNU General Public License for more details.
15
16	You should have received a copy of the GNU General Public License
17	along with this program; if not, write to the Free Software
18	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19	*/
20
21	#include <sys/types.h>
22	#include <signal.h>
23	#include <stdio.h>
24	#include <errno.h>
25	#include "rdesktop.h"
26	#include <assert.h>
27	#include <unistd.h>
28	#include <sys/wait.h>
29	#include <sys/stat.h>
30	#include <fcntl.h>
31
32	/* Execute specified askpass program and fetch password from standard
33	output. Return NULL on failure, otherwise a pointer to the data
34	read (which must be freed by caller) */
35
36	char *
37	askpass(char askpass, const char msg)
38	{
39	pid_t pid;
40	size_t len;
41	char *pass;
42	int p[2], status, ret;
43	char buf[1024];
44	int devnull;
45
46	if (fflush(stdout) != 0)
47	error("askpass: fflush: %s", strerror(errno));
48	assert(askpass != NULL);
49	if (pipe(p) < 0)
50	{
51	error("askpass: pipe: %s", strerror(errno));
52	return NULL;
53	}
54
55	pid = fork();
56	switch (pid)
57	{
58	case -1:
59	error("askpass: fork: %s", strerror(errno));
60	return NULL;
61	break;
62	case 0:
63	/* Child */
64	seteuid(getuid());
65	setuid(getuid());
66	/* Close read end */
67	close(p[0]);
68
69	/* Setup stdin */
70	devnull = open("/dev/null", 0, O_RDONLY);
71	if (dup2(devnull, STDIN_FILENO) < 0)
72	{
73	error("askpass: dup2: %s", strerror(errno));
74	exit(1);
75	}
76	close(devnull);
77
78	/* Setup stdout */
79	if (dup2(p[1], STDOUT_FILENO) < 0)
80	{
81	error("askpass: dup2: %s", strerror(errno));
82	exit(1);
83	}
84	close(p[1]);
85
86	/* By now, the following fds are open:
87	0 -> /dev/null
88	1 -> pipe write end
89	2 -> users terminal */
90	execlp(askpass, askpass, msg, (char *) 0);
91	error("askpass: exec(%s): %s", askpass, strerror(errno));
92	exit(1);
93	break;
94	default:
95	/* Parent */
96	break;
97	}
98	/* Close write end */
99	close(p[1]);
100
101	len = ret = 0;
102	do
103	{
104	ret = read(p[0], buf + len, sizeof(buf) - 1 - len);
105
106	if (ret == -1 && errno == EINTR)
107	continue;
108	if (ret <= 0)
109	break;
110
111	len += ret;
112	}
113	while (sizeof(buf) - 1 - len > 0);
114
115
116	buf[len] = '\0';
117
118	close(p[0]);
119	while (waitpid(pid, &status, 0) < 0)
120	if (errno != EINTR)
121	break;
122
123	if (WIFEXITED(status))
124	{
125	if (WEXITSTATUS(status))
126	{
127	error("askpass program returned %d\n", WEXITSTATUS(status));
128	return NULL;
129	}
130	}
131	else
132	{
133	error("abnormal exit from askpass program");
134	return NULL;
135	}
136
137	buf[strcspn(buf, "\r\n")] = '\0';
138	pass = strdup(buf);
139	memset(buf, 0, sizeof(buf));
140	return pass;
141	}