1 /*
2  * Please note: this implementation of openpty() is far from complete.
3  * it is just enough for portable OpenSSH's needs.
4  */
5 
6 /*
7  * Copyright (c) 2004 Damien Miller <djm@mindrot.org>
8  *
9  * Permission to use, copy, modify, and distribute this software for any
10  * purpose with or without fee is hereby granted, provided that the above
11  * copyright notice and this permission notice appear in all copies.
12  *
13  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
14  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
15  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
16  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
17  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
18  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
19  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
20  */
21 
22 /*
23  * Author: Tatu Ylonen <ylo@cs.hut.fi>
24  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
25  *                    All rights reserved
26  * Allocating a pseudo-terminal, and making it the controlling tty.
27  *
28  * As far as I am concerned, the code I have written for this software
29  * can be used freely for any purpose.  Any derived versions of this
30  * software must be clearly marked as such, and if the derived work is
31  * incompatible with the protocol description in the RFC file, it must be
32  * called by a name other than "ssh" or "Secure Shell".
33  */
34 
35 #include "includes.h"
36 #if !defined(HAVE_OPENPTY)
37 
38 #include <sys/types.h>
39 
40 #include <stdlib.h>
41 
42 #ifdef HAVE_SYS_STAT_H
43 # include <sys/stat.h>
44 #endif
45 #ifdef HAVE_SYS_IOCTL_H
46 # include <sys/ioctl.h>
47 #endif
48 
49 #ifdef HAVE_FCNTL_H
50 # include <fcntl.h>
51 #endif
52 
53 #ifdef HAVE_UTIL_H
54 # include <util.h>
55 #endif /* HAVE_UTIL_H */
56 
57 #ifdef HAVE_PTY_H
58 # include <pty.h>
59 #endif
60 #if defined(HAVE_DEV_PTMX) && defined(HAVE_SYS_STROPTS_H)
61 # include <sys/stropts.h>
62 #endif
63 
64 #include <signal.h>
65 #include <string.h>
66 #include <unistd.h>
67 
68 #ifndef O_NOCTTY
69 #define O_NOCTTY 0
70 #endif
71 
72 int
73 openpty(int *amaster, int *aslave, char *name, struct termios *termp,
74    struct winsize *winp)
75 {
76 #if defined(HAVE__GETPTY)
77 	/*
78 	 * _getpty(3) exists in SGI Irix 4.x, 5.x & 6.x -- it generates more
79 	 * pty's automagically when needed
80 	 */
81 	char *slave;
82 
83 	if ((slave = _getpty(amaster, O_RDWR, 0622, 0)) == NULL)
84 		return (-1);
85 
86 	/* Open the slave side. */
87 	if ((*aslave = open(slave, O_RDWR | O_NOCTTY)) == -1) {
88 		close(*amaster);
89 		return (-1);
90 	}
91 	return (0);
92 
93 #elif defined(HAVE_DEV_PTMX)
94 	/*
95 	 * This code is used e.g. on Solaris 2.x.  (Note that Solaris 2.3
96 	 * also has bsd-style ptys, but they simply do not work.)
97 	 */
98 	int ptm;
99 	char *pts;
100 	mysig_t old_signal;
101 
102 	if ((ptm = open("/dev/ptmx", O_RDWR | O_NOCTTY)) == -1)
103 		return (-1);
104 
105 	/* XXX: need to close ptm on error? */
106 	old_signal = signal(SIGCHLD, SIG_DFL);
107 	if (grantpt(ptm) < 0)
108 		return (-1);
109 	signal(SIGCHLD, old_signal);
110 
111 	if (unlockpt(ptm) < 0)
112 		return (-1);
113 
114 	if ((pts = ptsname(ptm)) == NULL)
115 		return (-1);
116 	*amaster = ptm;
117 
118 	/* Open the slave side. */
119 	if ((*aslave = open(pts, O_RDWR | O_NOCTTY)) == -1) {
120 		close(*amaster);
121 		return (-1);
122 	}
123 
124 # if defined(I_FIND) && defined(__SVR4)
125 	/*
126 	 * If the streams modules have already been pushed then there
127 	 * is no more work to do here.
128 	 */
129 	if (ioctl(*aslave, I_FIND, "ptem") != 0)
130 		return 0;
131 # endif
132 
133 	/*
134 	 * Try to push the appropriate streams modules, as described
135 	 * in Solaris pts(7).
136 	 */
137 	ioctl(*aslave, I_PUSH, "ptem");
138 	ioctl(*aslave, I_PUSH, "ldterm");
139 # ifndef __hpux
140 	ioctl(*aslave, I_PUSH, "ttcompat");
141 # endif /* __hpux */
142 
143 	return (0);
144 
145 #elif defined(HAVE_DEV_PTS_AND_PTC)
146 	/* AIX-style pty code. */
147 	const char *ttname;
148 
149 	if ((*amaster = open("/dev/ptc", O_RDWR | O_NOCTTY)) == -1)
150 		return (-1);
151 	if ((ttname = ttyname(*amaster)) == NULL)
152 		return (-1);
153 	if ((*aslave = open(ttname, O_RDWR | O_NOCTTY)) == -1) {
154 		close(*amaster);
155 		return (-1);
156 	}
157 	return (0);
158 
159 #else
160 	/* BSD-style pty code. */
161 	char ptbuf[64], ttbuf[64];
162 	int i;
163 	const char *ptymajors = "pqrstuvwxyzabcdefghijklmno"
164 	    "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
165 	const char *ptyminors = "0123456789abcdef";
166 	int num_minors = strlen(ptyminors);
167 	int num_ptys = strlen(ptymajors) * num_minors;
168 	struct termios tio;
169 
170 	for (i = 0; i < num_ptys; i++) {
171 		snprintf(ptbuf, sizeof(ptbuf), "/dev/pty%c%c",
172 		    ptymajors[i / num_minors], ptyminors[i % num_minors]);
173 		snprintf(ttbuf, sizeof(ttbuf), "/dev/tty%c%c",
174 		    ptymajors[i / num_minors], ptyminors[i % num_minors]);
175 
176 		if ((*amaster = open(ptbuf, O_RDWR | O_NOCTTY)) == -1) {
177 			/* Try SCO style naming */
178 			snprintf(ptbuf, sizeof(ptbuf), "/dev/ptyp%d", i);
179 			snprintf(ttbuf, sizeof(ttbuf), "/dev/ttyp%d", i);
180 			if ((*amaster = open(ptbuf, O_RDWR | O_NOCTTY)) == -1)
181 				continue;
182 		}
183 
184 		/* Open the slave side. */
185 		if ((*aslave = open(ttbuf, O_RDWR | O_NOCTTY)) == -1) {
186 			close(*amaster);
187 			return (-1);
188 		}
189 		/* set tty modes to a sane state for broken clients */
190 		if (tcgetattr(*amaster, &tio) != -1) {
191 			tio.c_lflag |= (ECHO | ISIG | ICANON);
192 			tio.c_oflag |= (OPOST | ONLCR);
193 			tio.c_iflag |= ICRNL;
194 			tcsetattr(*amaster, TCSANOW, &tio);
195 		}
196 
197 		return (0);
198 	}
199 	return (-1);
200 #endif
201 }
202 
203 #endif /* !defined(HAVE_OPENPTY) */
204 
205