trunk/rdesktop/readpass.c

/*
   rdesktop: A Remote Desktop Protocol client.
   User interface services - X keyboard mapping
   Copyright (C) Matthew Chapman 1999-2001
   
   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	astrand	96	/*
2			rdesktop: A Remote Desktop Protocol client.
3			User interface services - X keyboard mapping
4			Copyright (C) Matthew Chapman 1999-2001
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	astrand	97	#include <sys/stat.h>
30			#include <fcntl.h>
31	astrand	96
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	astrand	97	int devnull;
45	astrand	96
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	astrand	97
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	astrand	96	if (dup2(p[1], STDOUT_FILENO) < 0)
80			{
81			error("askpass: dup2: %s", strerror(errno));
82			exit(1);
83			}
84	astrand	97	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	astrand	96	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			}