xref: /freebsd/lib/libc/rpc/getnetconfig.c (revision c9dbb1cc52b063bbd9ab078a7afc89a8696da659)
1 /*	$NetBSD: getnetconfig.c,v 1.3 2000/07/06 03:10:34 christos Exp $	*/
2 
3 /*-
4  * Copyright (c) 2009, Sun Microsystems, Inc.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions are met:
9  * - Redistributions of source code must retain the above copyright notice,
10  *   this list of conditions and the following disclaimer.
11  * - Redistributions in binary form must reproduce the above copyright notice,
12  *   this list of conditions and the following disclaimer in the documentation
13  *   and/or other materials provided with the distribution.
14  * - Neither the name of Sun Microsystems, Inc. nor the names of its
15  *   contributors may be used to endorse or promote products derived
16  *   from this software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
22  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28  * POSSIBILITY OF SUCH DAMAGE.
29  */
30 
31 #if defined(LIBC_SCCS) && !defined(lint)
32 static char sccsid[] = "@(#)getnetconfig.c	1.12 91/12/19 SMI";
33 #endif
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36 
37 /*
38  * Copyright (c) 1989 by Sun Microsystems, Inc.
39  */
40 
41 #include "namespace.h"
42 #include "reentrant.h"
43 #include <stdio.h>
44 #include <errno.h>
45 #include <netconfig.h>
46 #include <stddef.h>
47 #include <stdlib.h>
48 #include <string.h>
49 #include <rpc/rpc.h>
50 #include <unistd.h>
51 #include "un-namespace.h"
52 #include "rpc_com.h"
53 
54 /*
55  * The five library routines in this file provide application access to the
56  * system network configuration database, /etc/netconfig.  In addition to the
57  * netconfig database and the routines for accessing it, the environment
58  * variable NETPATH and its corresponding routines in getnetpath.c may also be
59  * used to specify the network transport to be used.
60  */
61 
62 
63 /*
64  * netconfig errors
65  */
66 
67 #define NC_NONETCONFIG	ENOENT
68 #define NC_NOMEM	ENOMEM
69 #define NC_NOTINIT	EINVAL	    /* setnetconfig was not called first */
70 #define NC_BADFILE	EBADF	    /* format for netconfig file is bad */
71 #define NC_NOTFOUND	ENOPROTOOPT /* specified netid was not found */
72 
73 /*
74  * semantics as strings (should be in netconfig.h)
75  */
76 #define NC_TPI_CLTS_S	    "tpi_clts"
77 #define	NC_TPI_COTS_S	    "tpi_cots"
78 #define	NC_TPI_COTS_ORD_S   "tpi_cots_ord"
79 #define	NC_TPI_RAW_S        "tpi_raw"
80 
81 /*
82  * flags as characters (also should be in netconfig.h)
83  */
84 #define	NC_NOFLAG_C	'-'
85 #define	NC_VISIBLE_C	'v'
86 #define	NC_BROADCAST_C	'b'
87 
88 /*
89  * Character used to indicate there is no name-to-address lookup library
90  */
91 #define NC_NOLOOKUP	"-"
92 
93 static const char * const _nc_errors[] = {
94     "Netconfig database not found",
95     "Not enough memory",
96     "Not initialized",
97     "Netconfig database has invalid format",
98     "Netid not found in netconfig database"
99 };
100 
101 struct netconfig_info {
102     int		eof;	/* all entries has been read */
103     int		ref;	/* # of times setnetconfig() has been called */
104     struct netconfig_list	*head;	/* head of the list */
105     struct netconfig_list	*tail;	/* last of the list */
106 };
107 
108 struct netconfig_list {
109     char			*linep;	/* hold line read from netconfig */
110     struct netconfig		*ncp;
111     struct netconfig_list	*next;
112 };
113 
114 struct netconfig_vars {
115     int   valid;	/* token that indicates a valid netconfig_vars */
116     int   flag;		/* first time flag */
117     struct netconfig_list *nc_configs;  /* pointer to the current netconfig entry */
118 };
119 
120 #define NC_VALID	0xfeed
121 #define NC_STORAGE	0xf00d
122 #define NC_INVALID	0
123 
124 
125 static int *__nc_error(void);
126 static int parse_ncp(char *, struct netconfig *);
127 static struct netconfig *dup_ncp(struct netconfig *);
128 
129 
130 static FILE *nc_file;		/* for netconfig db */
131 static mutex_t nc_file_lock = MUTEX_INITIALIZER;
132 
133 static struct netconfig_info	ni = { 0, 0, NULL, NULL};
134 static mutex_t ni_lock = MUTEX_INITIALIZER;
135 
136 static thread_key_t nc_key;
137 static once_t nc_once = ONCE_INITIALIZER;
138 static int nc_key_error;
139 
140 static void
141 nc_key_init(void)
142 {
143 
144 	nc_key_error = thr_keycreate(&nc_key, free);
145 }
146 
147 #define MAXNETCONFIGLINE    1000
148 
149 static int *
150 __nc_error(void)
151 {
152 	static int nc_error = 0;
153 	int *nc_addr;
154 
155 	/*
156 	 * Use the static `nc_error' if we are the main thread
157 	 * (including non-threaded programs), or if an allocation
158 	 * fails.
159 	 */
160 	if (thr_main())
161 		return (&nc_error);
162 	if (thr_once(&nc_once, nc_key_init) != 0 || nc_key_error != 0)
163 		return (&nc_error);
164 	if ((nc_addr = (int *)thr_getspecific(nc_key)) == NULL) {
165 		nc_addr = (int *)malloc(sizeof (int));
166 		if (thr_setspecific(nc_key, (void *) nc_addr) != 0) {
167 			if (nc_addr)
168 				free(nc_addr);
169 			return (&nc_error);
170 		}
171 		*nc_addr = 0;
172 	}
173 	return (nc_addr);
174 }
175 
176 #define nc_error        (*(__nc_error()))
177 /*
178  * A call to setnetconfig() establishes a /etc/netconfig "session".  A session
179  * "handle" is returned on a successful call.  At the start of a session (after
180  * a call to setnetconfig()) searches through the /etc/netconfig database will
181  * proceed from the start of the file.  The session handle must be passed to
182  * getnetconfig() to parse the file.  Each call to getnetconfig() using the
183  * current handle will process one subsequent entry in /etc/netconfig.
184  * setnetconfig() must be called before the first call to getnetconfig().
185  * (Handles are used to allow for nested calls to setnetpath()).
186  *
187  * A new session is established with each call to setnetconfig(), with a new
188  * handle being returned on each call.  Previously established sessions remain
189  * active until endnetconfig() is called with that session's handle as an
190  * argument.
191  *
192  * setnetconfig() need *not* be called before a call to getnetconfigent().
193  * setnetconfig() returns a NULL pointer on failure (for example, if
194  * the netconfig database is not present).
195  */
196 void *
197 setnetconfig(void)
198 {
199     struct netconfig_vars *nc_vars;
200 
201     if ((nc_vars = (struct netconfig_vars *)malloc(sizeof
202 		(struct netconfig_vars))) == NULL) {
203 	return(NULL);
204     }
205 
206     /*
207      * For multiple calls, i.e. nc_file is not NULL, we just return the
208      * handle without reopening the netconfig db.
209      */
210     mutex_lock(&ni_lock);
211     ni.ref++;
212     mutex_unlock(&ni_lock);
213 
214     mutex_lock(&nc_file_lock);
215     if ((nc_file != NULL) || (nc_file = fopen(NETCONFIG, "r")) != NULL) {
216 	nc_vars->valid = NC_VALID;
217 	nc_vars->flag = 0;
218 	nc_vars->nc_configs = ni.head;
219 	mutex_unlock(&nc_file_lock);
220 	return ((void *)nc_vars);
221     }
222     mutex_unlock(&nc_file_lock);
223 
224     mutex_lock(&ni_lock);
225     ni.ref--;
226     mutex_unlock(&ni_lock);
227 
228     nc_error = NC_NONETCONFIG;
229     free(nc_vars);
230     return (NULL);
231 }
232 
233 
234 /*
235  * When first called, getnetconfig() returns a pointer to the first entry in
236  * the netconfig database, formatted as a struct netconfig.  On each subsequent
237  * call, getnetconfig() returns a pointer to the next entry in the database.
238  * getnetconfig() can thus be used to search the entire netconfig file.
239  * getnetconfig() returns NULL at end of file.
240  */
241 
242 struct netconfig *
243 getnetconfig(void *handlep)
244 {
245     struct netconfig_vars *ncp = (struct netconfig_vars *)handlep;
246     char *stringp;		/* tmp string pointer */
247     struct netconfig_list	*list;
248     struct netconfig *np;
249     struct netconfig *result;
250 
251     /*
252      * Verify that handle is valid
253      */
254     mutex_lock(&nc_file_lock);
255     if (ncp == NULL || nc_file == NULL) {
256 	nc_error = NC_NOTINIT;
257 	mutex_unlock(&nc_file_lock);
258 	return (NULL);
259     }
260     mutex_unlock(&nc_file_lock);
261 
262     switch (ncp->valid) {
263     case NC_VALID:
264 	/*
265 	 * If entry has already been read into the list,
266 	 * we return the entry in the linked list.
267 	 * If this is the first time call, check if there are any entries in
268 	 * linked list.  If no entries, we need to read the netconfig db.
269 	 * If we have been here and the next entry is there, we just return
270 	 * it.
271 	 */
272 	if (ncp->flag == 0) {	/* first time */
273 	    ncp->flag = 1;
274 	    mutex_lock(&ni_lock);
275 	    ncp->nc_configs = ni.head;
276 	    mutex_unlock(&ni_lock);
277 	    if (ncp->nc_configs != NULL)	/* entry already exist */
278 		return(ncp->nc_configs->ncp);
279 	}
280 	else if (ncp->nc_configs != NULL && ncp->nc_configs->next != NULL) {
281 	    ncp->nc_configs = ncp->nc_configs->next;
282 	    return(ncp->nc_configs->ncp);
283 	}
284 
285 	/*
286 	 * If we cannot find the entry in the list and is end of file,
287 	 * we give up.
288 	 */
289 	mutex_lock(&ni_lock);
290 	if (ni.eof == 1) {
291 		mutex_unlock(&ni_lock);
292 		return(NULL);
293 	}
294 	mutex_unlock(&ni_lock);
295 
296 	break;
297     default:
298 	nc_error = NC_NOTINIT;
299 	return (NULL);
300     }
301 
302     stringp = (char *) malloc(MAXNETCONFIGLINE);
303     if (stringp == NULL)
304     	return (NULL);
305 
306 #ifdef MEM_CHK
307     if (malloc_verify() == 0) {
308 	fprintf(stderr, "memory heap corrupted in getnetconfig\n");
309 	exit(1);
310     }
311 #endif
312 
313     /*
314      * Read a line from netconfig file.
315      */
316     mutex_lock(&nc_file_lock);
317     do {
318 	if (fgets(stringp, MAXNETCONFIGLINE, nc_file) == NULL) {
319 	    free(stringp);
320 	    mutex_lock(&ni_lock);
321 	    ni.eof = 1;
322 	    mutex_unlock(&ni_lock);
323 	    mutex_unlock(&nc_file_lock);
324 	    return (NULL);
325         }
326     } while (*stringp == '#');
327     mutex_unlock(&nc_file_lock);
328 
329     list = (struct netconfig_list *) malloc(sizeof (struct netconfig_list));
330     if (list == NULL) {
331     	free(stringp);
332     	return(NULL);
333     }
334     np = (struct netconfig *) malloc(sizeof (struct netconfig));
335     if (np == NULL) {
336     	free(stringp);
337 	free(list);
338     	return(NULL);
339     }
340     list->ncp = np;
341     list->next = NULL;
342     list->ncp->nc_lookups = NULL;
343     list->linep = stringp;
344     if (parse_ncp(stringp, list->ncp) == -1) {
345 	free(stringp);
346 	free(np);
347 	free(list);
348 	return (NULL);
349     }
350     else {
351 	/*
352 	 * If this is the first entry that's been read, it is the head of
353 	 * the list.  If not, put the entry at the end of the list.
354 	 * Reposition the current pointer of the handle to the last entry
355 	 * in the list.
356 	 */
357 	mutex_lock(&ni_lock);
358 	if (ni.head == NULL) {	/* first entry */
359 	    ni.head = ni.tail = list;
360 	}
361     	else {
362     	    ni.tail->next = list;
363     	    ni.tail = ni.tail->next;
364     	}
365 	ncp->nc_configs = ni.tail;
366 	result = ni.tail->ncp;
367 	mutex_unlock(&ni_lock);
368 	return(result);
369     }
370 }
371 
372 /*
373  * endnetconfig() may be called to "unbind" or "close" the netconfig database
374  * when processing is complete, releasing resources for reuse.  endnetconfig()
375  * may not be called before setnetconfig().  endnetconfig() returns 0 on
376  * success and -1 on failure (for example, if setnetconfig() was not called
377  * previously).
378  */
379 int
380 endnetconfig(void *handlep)
381 {
382     struct netconfig_vars *nc_handlep = (struct netconfig_vars *)handlep;
383 
384     struct netconfig_list *q, *p;
385 
386     /*
387      * Verify that handle is valid
388      */
389     if (nc_handlep == NULL || (nc_handlep->valid != NC_VALID &&
390 	    nc_handlep->valid != NC_STORAGE)) {
391 	nc_error = NC_NOTINIT;
392 	return (-1);
393     }
394 
395     /*
396      * Return 0 if anyone still needs it.
397      */
398     nc_handlep->valid = NC_INVALID;
399     nc_handlep->flag = 0;
400     nc_handlep->nc_configs = NULL;
401     mutex_lock(&ni_lock);
402     if (--ni.ref > 0) {
403 	mutex_unlock(&ni_lock);
404     	free(nc_handlep);
405 	return(0);
406     }
407 
408     /*
409      * Noone needs these entries anymore, then frees them.
410      * Make sure all info in netconfig_info structure has been reinitialized.
411      */
412     q = ni.head;
413     ni.eof = ni.ref = 0;
414     ni.head = NULL;
415     ni.tail = NULL;
416     mutex_unlock(&ni_lock);
417 
418     while (q != NULL) {
419 	p = q->next;
420 	if (q->ncp->nc_lookups != NULL) free(q->ncp->nc_lookups);
421 	free(q->ncp);
422 	free(q->linep);
423 	free(q);
424 	q = p;
425     }
426     free(nc_handlep);
427 
428     mutex_lock(&nc_file_lock);
429     fclose(nc_file);
430     nc_file = NULL;
431     mutex_unlock(&nc_file_lock);
432 
433     return (0);
434 }
435 
436 /*
437  * getnetconfigent(netid) returns a pointer to the struct netconfig structure
438  * corresponding to netid.  It returns NULL if netid is invalid (that is, does
439  * not name an entry in the netconfig database).  It returns NULL and sets
440  * errno in case of failure (for example, if the netconfig database cannot be
441  * opened).
442  */
443 
444 struct netconfig *
445 getnetconfigent(const char *netid)
446 {
447     FILE *file;		/* NETCONFIG db's file pointer */
448     char *linep;	/* holds current netconfig line */
449     char *stringp;	/* temporary string pointer */
450     struct netconfig *ncp = NULL;   /* returned value */
451     struct netconfig_list *list;	/* pointer to cache list */
452 
453     nc_error = NC_NOTFOUND;	/* default error. */
454     if (netid == NULL || strlen(netid) == 0) {
455 	return (NULL);
456     }
457 
458     /*
459      * Look up table if the entries have already been read and parsed in
460      * getnetconfig(), then copy this entry into a buffer and return it.
461      * If we cannot find the entry in the current list and there are more
462      * entries in the netconfig db that has not been read, we then read the
463      * db and try find the match netid.
464      * If all the netconfig db has been read and placed into the list and
465      * there is no match for the netid, return NULL.
466      */
467     mutex_lock(&ni_lock);
468     if (ni.head != NULL) {
469 	for (list = ni.head; list; list = list->next) {
470 	    if (strcmp(list->ncp->nc_netid, netid) == 0) {
471 		mutex_unlock(&ni_lock);
472 	        return(dup_ncp(list->ncp));
473 	    }
474 	}
475 	if (ni.eof == 1) {	/* that's all the entries */
476 		mutex_unlock(&ni_lock);
477 		return(NULL);
478 	}
479     }
480     mutex_unlock(&ni_lock);
481 
482 
483     if ((file = fopen(NETCONFIG, "r")) == NULL) {
484 	nc_error = NC_NONETCONFIG;
485 	return (NULL);
486     }
487 
488     if ((linep = malloc(MAXNETCONFIGLINE)) == NULL) {
489 	fclose(file);
490 	nc_error = NC_NOMEM;
491 	return (NULL);
492     }
493     do {
494 	ptrdiff_t len;
495 	char *tmpp;	/* tmp string pointer */
496 
497 	do {
498 	    if ((stringp = fgets(linep, MAXNETCONFIGLINE, file)) == NULL) {
499 		break;
500 	    }
501 	} while (*stringp == '#');
502 	if (stringp == NULL) {	    /* eof */
503 	    break;
504 	}
505 	if ((tmpp = strpbrk(stringp, "\t ")) == NULL) {	/* can't parse file */
506 	    nc_error = NC_BADFILE;
507 	    break;
508 	}
509 	if (strlen(netid) == (size_t) (len = tmpp - stringp) &&	/* a match */
510 		strncmp(stringp, netid, (size_t)len) == 0) {
511 	    if ((ncp = (struct netconfig *)
512 		    malloc(sizeof (struct netconfig))) == NULL) {
513 		break;
514 	    }
515 	    ncp->nc_lookups = NULL;
516 	    if (parse_ncp(linep, ncp) == -1) {
517 		free(ncp);
518 		ncp = NULL;
519 	    }
520 	    break;
521 	}
522     } while (stringp != NULL);
523     if (ncp == NULL) {
524 	free(linep);
525     }
526     fclose(file);
527     return(ncp);
528 }
529 
530 /*
531  * freenetconfigent(netconfigp) frees the netconfig structure pointed to by
532  * netconfigp (previously returned by getnetconfigent()).
533  */
534 
535 void
536 freenetconfigent(struct netconfig *netconfigp)
537 {
538     if (netconfigp != NULL) {
539 	free(netconfigp->nc_netid);	/* holds all netconfigp's strings */
540 	if (netconfigp->nc_lookups != NULL)
541 	    free(netconfigp->nc_lookups);
542 	free(netconfigp);
543     }
544     return;
545 }
546 
547 /*
548  * Parse line and stuff it in a struct netconfig
549  * Typical line might look like:
550  *	udp tpi_cots vb inet udp /dev/udp /usr/lib/ip.so,/usr/local/ip.so
551  *
552  * We return -1 if any of the tokens don't parse, or malloc fails.
553  *
554  * Note that we modify stringp (putting NULLs after tokens) and
555  * we set the ncp's string field pointers to point to these tokens within
556  * stringp.
557  *
558  * stringp - string to parse
559  * ncp     - where to put results
560  */
561 
562 static int
563 parse_ncp(char *stringp, struct netconfig *ncp)
564 {
565     char    *tokenp;	/* for processing tokens */
566     char    *lasts;
567     char    **nc_lookups;
568 
569     nc_error = NC_BADFILE;	/* nearly anything that breaks is for this reason */
570     stringp[strlen(stringp)-1] = '\0';	/* get rid of newline */
571     /* netid */
572     if ((ncp->nc_netid = strtok_r(stringp, "\t ", &lasts)) == NULL) {
573 	return (-1);
574     }
575 
576     /* semantics */
577     if ((tokenp = strtok_r(NULL, "\t ", &lasts)) == NULL) {
578 	return (-1);
579     }
580     if (strcmp(tokenp, NC_TPI_COTS_ORD_S) == 0)
581 	ncp->nc_semantics = NC_TPI_COTS_ORD;
582     else if (strcmp(tokenp, NC_TPI_COTS_S) == 0)
583 	ncp->nc_semantics = NC_TPI_COTS;
584     else if (strcmp(tokenp, NC_TPI_CLTS_S) == 0)
585 	ncp->nc_semantics = NC_TPI_CLTS;
586     else if (strcmp(tokenp, NC_TPI_RAW_S) == 0)
587 	ncp->nc_semantics = NC_TPI_RAW;
588     else
589 	return (-1);
590 
591     /* flags */
592     if ((tokenp = strtok_r(NULL, "\t ", &lasts)) == NULL) {
593 	return (-1);
594     }
595     for (ncp->nc_flag = NC_NOFLAG; *tokenp != '\0';
596 	    tokenp++) {
597 	switch (*tokenp) {
598 	case NC_NOFLAG_C:
599 	    break;
600 	case NC_VISIBLE_C:
601 	    ncp->nc_flag |= NC_VISIBLE;
602 	    break;
603 	case NC_BROADCAST_C:
604 	    ncp->nc_flag |= NC_BROADCAST;
605 	    break;
606 	default:
607 	    return (-1);
608 	}
609     }
610     /* protocol family */
611     if ((ncp->nc_protofmly = strtok_r(NULL, "\t ", &lasts)) == NULL) {
612 	return (-1);
613     }
614     /* protocol name */
615     if ((ncp->nc_proto = strtok_r(NULL, "\t ", &lasts)) == NULL) {
616 	return (-1);
617     }
618     /* network device */
619     if ((ncp->nc_device = strtok_r(NULL, "\t ", &lasts)) == NULL) {
620 	return (-1);
621     }
622     if ((tokenp = strtok_r(NULL, "\t ", &lasts)) == NULL) {
623 	return (-1);
624     }
625     if (strcmp(tokenp, NC_NOLOOKUP) == 0) {
626 	ncp->nc_nlookups = 0;
627 	ncp->nc_lookups = NULL;
628     } else {
629 	char *cp;	    /* tmp string */
630 
631 	if (ncp->nc_lookups != NULL)	/* from last visit */
632 	    free(ncp->nc_lookups);
633 	ncp->nc_lookups = NULL;
634 	ncp->nc_nlookups = 0;
635 	while ((cp = tokenp) != NULL) {
636 	    if ((nc_lookups = realloc(ncp->nc_lookups,
637 		(ncp->nc_nlookups + 1) * sizeof *ncp->nc_lookups)) == NULL) {
638 		    free(ncp->nc_lookups);
639 		    ncp->nc_lookups = NULL;
640 		    return (-1);
641 	    }
642 	    tokenp = _get_next_token(cp, ',');
643 	    ncp->nc_lookups = nc_lookups;
644 	    ncp->nc_lookups[ncp->nc_nlookups++] = cp;
645 	}
646     }
647     return (0);
648 }
649 
650 
651 /*
652  * Returns a string describing the reason for failure.
653  */
654 char *
655 nc_sperror(void)
656 {
657     const char *message;
658 
659     switch(nc_error) {
660     case NC_NONETCONFIG:
661 	message = _nc_errors[0];
662 	break;
663     case NC_NOMEM:
664 	message = _nc_errors[1];
665 	break;
666     case NC_NOTINIT:
667 	message = _nc_errors[2];
668 	break;
669     case NC_BADFILE:
670 	message = _nc_errors[3];
671 	break;
672     case NC_NOTFOUND:
673 	message = _nc_errors[4];
674 	break;
675     default:
676 	message = "Unknown network selection error";
677     }
678     /* LINTED const castaway */
679     return ((char *)message);
680 }
681 
682 /*
683  * Prints a message onto standard error describing the reason for failure.
684  */
685 void
686 nc_perror(const char *s)
687 {
688     fprintf(stderr, "%s: %s\n", s, nc_sperror());
689 }
690 
691 /*
692  * Duplicates the matched netconfig buffer.
693  */
694 static struct netconfig *
695 dup_ncp(struct netconfig *ncp)
696 {
697     struct netconfig	*p;
698     char	*tmp;
699     u_int	i;
700 
701     if ((tmp=malloc(MAXNETCONFIGLINE)) == NULL)
702 	return(NULL);
703     if ((p=(struct netconfig *)malloc(sizeof(struct netconfig))) == NULL) {
704 	free(tmp);
705 	return(NULL);
706     }
707     /*
708      * First we dup all the data from matched netconfig buffer.  Then we
709      * adjust some of the member pointer to a pre-allocated buffer where
710      * contains part of the data.
711      * To follow the convention used in parse_ncp(), we store all the
712      * necessary information in the pre-allocated buffer and let each
713      * of the netconfig char pointer member point to the right address
714      * in the buffer.
715      */
716     *p = *ncp;
717     p->nc_netid = (char *)strcpy(tmp,ncp->nc_netid);
718     tmp = strchr(tmp, '\0') + 1;
719     p->nc_protofmly = (char *)strcpy(tmp,ncp->nc_protofmly);
720     tmp = strchr(tmp, '\0') + 1;
721     p->nc_proto = (char *)strcpy(tmp,ncp->nc_proto);
722     tmp = strchr(tmp, '\0') + 1;
723     p->nc_device = (char *)strcpy(tmp,ncp->nc_device);
724     p->nc_lookups = (char **)malloc((size_t)(p->nc_nlookups+1) * sizeof(char *));
725     if (p->nc_lookups == NULL) {
726 	free(p->nc_netid);
727 	free(p);
728 	return(NULL);
729     }
730     for (i=0; i < p->nc_nlookups; i++) {
731     	tmp = strchr(tmp, '\0') + 1;
732     	p->nc_lookups[i] = (char *)strcpy(tmp,ncp->nc_lookups[i]);
733     }
734     return(p);
735 }
736