xref: /freebsd/usr.bin/finger/net.c (revision 06c3fb2749bda94cb5201f81ffdb8fa6c3161b2e)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1989, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * Tony Nardo of the Johns Hopkins University/Applied Physics Lab.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 #include <sys/param.h>
36 #include <sys/socket.h>
37 #include <sys/uio.h>
38 #include <wctype.h>
39 #include <db.h>
40 #include <err.h>
41 #include <netdb.h>
42 #include <pwd.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <unistd.h>
47 #include <utmpx.h>
48 #include <wchar.h>
49 #include "finger.h"
50 
51 static void cleanup(int sig);
52 static int do_protocol(const char *name, const struct addrinfo *ai);
53 static void trying(const struct addrinfo *ai);
54 
55 void
56 netfinger(char *name)
57 {
58 	int error, multi;
59 	char *host;
60 	struct addrinfo *ai, *ai0;
61 	static struct addrinfo hint;
62 
63 	host = strrchr(name, '@');
64 	if (host == NULL)
65 		return;
66 	*host++ = '\0';
67 	signal(SIGALRM, cleanup);
68 	alarm(TIME_LIMIT);
69 
70 	hint.ai_flags = AI_CANONNAME;
71 	hint.ai_family = family;
72 	hint.ai_socktype = SOCK_STREAM;
73 
74 	error = getaddrinfo(host, "finger", &hint, &ai0);
75 	if (error) {
76 		warnx("%s: %s", host, gai_strerror(error));
77 		return;
78 	}
79 
80 	multi = (ai0->ai_next) != 0;
81 
82 	/* ai_canonname may not be filled in if the user specified an IP. */
83 	if (ai0->ai_canonname == 0)
84 		printf("[%s]\n", host);
85 	else
86 		printf("[%s]\n", ai0->ai_canonname);
87 
88 	for (ai = ai0; ai != NULL; ai = ai->ai_next) {
89 		if (multi)
90 			trying(ai);
91 
92 		error = do_protocol(name, ai);
93 		if (!error)
94 			break;
95 	}
96 	alarm(0);
97 	freeaddrinfo(ai0);
98 }
99 
100 static int
101 do_protocol(const char *name, const struct addrinfo *ai)
102 {
103 	int cnt, line_len, s;
104 	FILE *fp;
105 	wint_t c, lastc;
106 	struct iovec iov[3];
107 	struct msghdr msg;
108 	static char slash_w[] = "/W ";
109 	static char neteol[] = "\r\n";
110 
111 	s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
112 	if (s < 0) {
113 		warn("socket(%d, %d, %d)", ai->ai_family, ai->ai_socktype,
114 		     ai->ai_protocol);
115 		return -1;
116 	}
117 
118 	msg.msg_name = (void *)ai->ai_addr;
119 	msg.msg_namelen = ai->ai_addrlen;
120 	msg.msg_iov = iov;
121 	msg.msg_iovlen = 0;
122 	msg.msg_control = 0;
123 	msg.msg_controllen = 0;
124 	msg.msg_flags = 0;
125 
126 	/* -l flag for remote fingerd  */
127 	if (lflag) {
128 		iov[msg.msg_iovlen].iov_base = slash_w;
129 		iov[msg.msg_iovlen++].iov_len = 3;
130 	}
131 	/* send the name followed by <CR><LF> */
132 	iov[msg.msg_iovlen].iov_base = strdup(name);
133 	iov[msg.msg_iovlen++].iov_len = strlen(name);
134 	iov[msg.msg_iovlen].iov_base = neteol;
135 	iov[msg.msg_iovlen++].iov_len = 2;
136 
137 	if (connect(s, ai->ai_addr, ai->ai_addrlen) < 0) {
138 		warn("connect");
139 		close(s);
140 		return -1;
141 	}
142 
143 	if (sendmsg(s, &msg, 0) < 0) {
144 		warn("sendmsg");
145 		close(s);
146 		return -1;
147 	}
148 
149 	/*
150 	 * Read from the remote system; once we're connected, we assume some
151 	 * data.  If none arrives, we hang until the user interrupts.
152 	 *
153 	 * If we see a <CR> or a <CR> with the high bit set, treat it as
154 	 * a newline; if followed by a newline character, only output one
155 	 * newline.
156 	 *
157 	 * Otherwise, all high bits are stripped; if it isn't printable and
158 	 * it isn't a space, we can simply set the 7th bit.  Every ASCII
159 	 * character with bit 7 set is printable.
160 	 */
161 	lastc = 0;
162 	if ((fp = fdopen(s, "r")) != NULL) {
163 		cnt = 0;
164 		line_len = 0;
165 		while ((c = getwc(fp)) != EOF) {
166 			if (++cnt > OUTPUT_MAX) {
167 				printf("\n\n Output truncated at %d bytes...\n",
168 					cnt - 1);
169 				break;
170 			}
171 			if (c == 0x0d) {
172 				if (lastc == '\r')	/* ^M^M - skip dupes */
173 					continue;
174 				c = '\n';
175 				lastc = '\r';
176 			} else {
177 				if (!iswprint(c) && !iswspace(c)) {
178 					c &= 0x7f;
179 					c |= 0x40;
180 				}
181 				if (lastc != '\r' || c != '\n')
182 					lastc = c;
183 				else {
184 					lastc = '\n';
185 					continue;
186 				}
187 			}
188 			putwchar(c);
189 			if (c != '\n' && ++line_len > _POSIX2_LINE_MAX) {
190 				putchar('\\');
191 				putchar('\n');
192 				lastc = '\r';
193 			}
194 			if (lastc == '\n' || lastc == '\r')
195 				line_len = 0;
196 		}
197 		if (ferror(fp)) {
198 			/*
199 			 * Assume that whatever it was set errno...
200 			 */
201 			warn("reading from network");
202 		}
203 		if (lastc != L'\n')
204 			putchar('\n');
205 
206 		fclose(fp);
207 	}
208 	return 0;
209 }
210 
211 static void
212 trying(const struct addrinfo *ai)
213 {
214 	char buf[NI_MAXHOST];
215 
216 	if (getnameinfo(ai->ai_addr, ai->ai_addrlen, buf, sizeof buf,
217 			(char *)0, 0, NI_NUMERICHOST) != 0)
218 		return;		/* XXX can't happen */
219 
220 	printf("Trying %s...\n", buf);
221 }
222 
223 static void
224 cleanup(int sig __unused)
225 {
226 #define	ERRSTR	"Timed out.\n"
227 	write(STDERR_FILENO, ERRSTR, sizeof ERRSTR);
228 	exit(1);
229 }
230 
231