xref: /freebsd/lib/libc/rpc/getnetconfig.c (revision 4ed925457ab06e83238a5db33e89ccc94b99a713)
1 /*	$NetBSD: getnetconfig.c,v 1.3 2000/07/06 03:10:34 christos Exp $	*/
2 
3 /*
4  * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
5  * unrestricted use provided that this legend is included on all tape
6  * media and as a part of the software program in whole or part.  Users
7  * may copy or modify Sun RPC without charge, but are not authorized
8  * to license or distribute it to anyone else except as part of a product or
9  * program developed by the user or with the express written consent of
10  * Sun Microsystems, Inc.
11  *
12  * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
13  * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
14  * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
15  *
16  * Sun RPC is provided with no support and without any obligation on the
17  * part of Sun Microsystems, Inc. to assist in its use, correction,
18  * modification or enhancement.
19  *
20  * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
21  * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
22  * OR ANY PART THEREOF.
23  *
24  * In no event will Sun Microsystems, Inc. be liable for any lost revenue
25  * or profits or other special, indirect and consequential damages, even if
26  * Sun has been advised of the possibility of such damages.
27  *
28  * Sun Microsystems, Inc.
29  * 2550 Garcia Avenue
30  * Mountain View, California  94043
31  */
32 
33 #if defined(LIBC_SCCS) && !defined(lint)
34 static char sccsid[] = "@(#)getnetconfig.c	1.12 91/12/19 SMI";
35 #endif
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38 
39 /*
40  * Copyright (c) 1989 by Sun Microsystems, Inc.
41  */
42 
43 #include "namespace.h"
44 #include "reentrant.h"
45 #include <stdio.h>
46 #include <errno.h>
47 #include <netconfig.h>
48 #include <stddef.h>
49 #include <stdlib.h>
50 #include <string.h>
51 #include <rpc/rpc.h>
52 #include <unistd.h>
53 #include "un-namespace.h"
54 #include "rpc_com.h"
55 
56 /*
57  * The five library routines in this file provide application access to the
58  * system network configuration database, /etc/netconfig.  In addition to the
59  * netconfig database and the routines for accessing it, the environment
60  * variable NETPATH and its corresponding routines in getnetpath.c may also be
61  * used to specify the network transport to be used.
62  */
63 
64 
65 /*
66  * netconfig errors
67  */
68 
69 #define NC_NONETCONFIG	ENOENT
70 #define NC_NOMEM	ENOMEM
71 #define NC_NOTINIT	EINVAL	    /* setnetconfig was not called first */
72 #define NC_BADFILE	EBADF	    /* format for netconfig file is bad */
73 #define NC_NOTFOUND	ENOPROTOOPT /* specified netid was not found */
74 
75 /*
76  * semantics as strings (should be in netconfig.h)
77  */
78 #define NC_TPI_CLTS_S	    "tpi_clts"
79 #define	NC_TPI_COTS_S	    "tpi_cots"
80 #define	NC_TPI_COTS_ORD_S   "tpi_cots_ord"
81 #define	NC_TPI_RAW_S        "tpi_raw"
82 
83 /*
84  * flags as characters (also should be in netconfig.h)
85  */
86 #define	NC_NOFLAG_C	'-'
87 #define	NC_VISIBLE_C	'v'
88 #define	NC_BROADCAST_C	'b'
89 
90 /*
91  * Character used to indicate there is no name-to-address lookup library
92  */
93 #define NC_NOLOOKUP	"-"
94 
95 static const char * const _nc_errors[] = {
96     "Netconfig database not found",
97     "Not enough memory",
98     "Not initialized",
99     "Netconfig database has invalid format",
100     "Netid not found in netconfig database"
101 };
102 
103 struct netconfig_info {
104     int		eof;	/* all entries has been read */
105     int		ref;	/* # of times setnetconfig() has been called */
106     struct netconfig_list	*head;	/* head of the list */
107     struct netconfig_list	*tail;	/* last of the list */
108 };
109 
110 struct netconfig_list {
111     char			*linep;	/* hold line read from netconfig */
112     struct netconfig		*ncp;
113     struct netconfig_list	*next;
114 };
115 
116 struct netconfig_vars {
117     int   valid;	/* token that indicates a valid netconfig_vars */
118     int   flag;		/* first time flag */
119     struct netconfig_list *nc_configs;  /* pointer to the current netconfig entry */
120 };
121 
122 #define NC_VALID	0xfeed
123 #define NC_STORAGE	0xf00d
124 #define NC_INVALID	0
125 
126 
127 static int *__nc_error(void);
128 static int parse_ncp(char *, struct netconfig *);
129 static struct netconfig *dup_ncp(struct netconfig *);
130 
131 
132 static FILE *nc_file;		/* for netconfig db */
133 static pthread_mutex_t nc_file_lock = PTHREAD_MUTEX_INITIALIZER;
134 
135 static struct netconfig_info	ni = { 0, 0, NULL, NULL};
136 static pthread_mutex_t ni_lock = PTHREAD_MUTEX_INITIALIZER;
137 
138 
139 #define MAXNETCONFIGLINE    1000
140 
141 static int *
142 __nc_error()
143 {
144 	static pthread_mutex_t nc_lock = PTHREAD_MUTEX_INITIALIZER;
145 	static thread_key_t nc_key = 0;
146 	static int nc_error = 0;
147 	int error, *nc_addr;
148 
149 	/*
150 	 * Use the static `nc_error' if we are the main thread
151 	 * (including non-threaded programs), or if an allocation
152 	 * fails.
153 	 */
154 	if (thr_main())
155 		return (&nc_error);
156 	if (nc_key == 0) {
157 		error = 0;
158 		mutex_lock(&nc_lock);
159 		if (nc_key == 0)
160 			error = thr_keycreate(&nc_key, free);
161 		mutex_unlock(&nc_lock);
162 		if (error)
163 			return (&nc_error);
164 	}
165 	if ((nc_addr = (int *)thr_getspecific(nc_key)) == NULL) {
166 		nc_addr = (int *)malloc(sizeof (int));
167 		if (thr_setspecific(nc_key, (void *) nc_addr) != 0) {
168 			if (nc_addr)
169 				free(nc_addr);
170 			return (&nc_error);
171 		}
172 		*nc_addr = 0;
173 	}
174 	return (nc_addr);
175 }
176 
177 #define nc_error        (*(__nc_error()))
178 /*
179  * A call to setnetconfig() establishes a /etc/netconfig "session".  A session
180  * "handle" is returned on a successful call.  At the start of a session (after
181  * a call to setnetconfig()) searches through the /etc/netconfig database will
182  * proceed from the start of the file.  The session handle must be passed to
183  * getnetconfig() to parse the file.  Each call to getnetconfig() using the
184  * current handle will process one subsequent entry in /etc/netconfig.
185  * setnetconfig() must be called before the first call to getnetconfig().
186  * (Handles are used to allow for nested calls to setnetpath()).
187  *
188  * A new session is established with each call to setnetconfig(), with a new
189  * handle being returned on each call.  Previously established sessions remain
190  * active until endnetconfig() is called with that session's handle as an
191  * argument.
192  *
193  * setnetconfig() need *not* be called before a call to getnetconfigent().
194  * setnetconfig() returns a NULL pointer on failure (for example, if
195  * the netconfig database is not present).
196  */
197 void *
198 setnetconfig()
199 {
200     struct netconfig_vars *nc_vars;
201 
202     if ((nc_vars = (struct netconfig_vars *)malloc(sizeof
203 		(struct netconfig_vars))) == NULL) {
204 	return(NULL);
205     }
206 
207     /*
208      * For multiple calls, i.e. nc_file is not NULL, we just return the
209      * handle without reopening the netconfig db.
210      */
211     mutex_lock(&ni_lock);
212     ni.ref++;
213     mutex_unlock(&ni_lock);
214 
215     mutex_lock(&nc_file_lock);
216     if ((nc_file != NULL) || (nc_file = fopen(NETCONFIG, "r")) != NULL) {
217 	nc_vars->valid = NC_VALID;
218 	nc_vars->flag = 0;
219 	nc_vars->nc_configs = ni.head;
220 	mutex_unlock(&nc_file_lock);
221 	return ((void *)nc_vars);
222     }
223     mutex_unlock(&nc_file_lock);
224 
225     mutex_lock(&ni_lock);
226     ni.ref--;
227     mutex_unlock(&ni_lock);
228 
229     nc_error = NC_NONETCONFIG;
230     free(nc_vars);
231     return (NULL);
232 }
233 
234 
235 /*
236  * When first called, getnetconfig() returns a pointer to the first entry in
237  * the netconfig database, formatted as a struct netconfig.  On each subsequent
238  * call, getnetconfig() returns a pointer to the next entry in the database.
239  * getnetconfig() can thus be used to search the entire netconfig file.
240  * getnetconfig() returns NULL at end of file.
241  */
242 
243 struct netconfig *
244 getnetconfig(handlep)
245 void *handlep;
246 {
247     struct netconfig_vars *ncp = (struct netconfig_vars *)handlep;
248     char *stringp;		/* tmp string pointer */
249     struct netconfig_list	*list;
250     struct netconfig *np;
251     struct netconfig *result;
252 
253     /*
254      * Verify that handle is valid
255      */
256     mutex_lock(&nc_file_lock);
257     if (ncp == NULL || nc_file == NULL) {
258 	nc_error = NC_NOTINIT;
259 	mutex_unlock(&nc_file_lock);
260 	return (NULL);
261     }
262     mutex_unlock(&nc_file_lock);
263 
264     switch (ncp->valid) {
265     case NC_VALID:
266 	/*
267 	 * If entry has already been read into the list,
268 	 * we return the entry in the linked list.
269 	 * If this is the first time call, check if there are any entries in
270 	 * linked list.  If no entries, we need to read the netconfig db.
271 	 * If we have been here and the next entry is there, we just return
272 	 * it.
273 	 */
274 	if (ncp->flag == 0) {	/* first time */
275 	    ncp->flag = 1;
276 	    mutex_lock(&ni_lock);
277 	    ncp->nc_configs = ni.head;
278 	    mutex_unlock(&ni_lock);
279 	    if (ncp->nc_configs != NULL)	/* entry already exist */
280 		return(ncp->nc_configs->ncp);
281 	}
282 	else if (ncp->nc_configs != NULL && ncp->nc_configs->next != NULL) {
283 	    ncp->nc_configs = ncp->nc_configs->next;
284 	    return(ncp->nc_configs->ncp);
285 	}
286 
287 	/*
288 	 * If we cannot find the entry in the list and is end of file,
289 	 * we give up.
290 	 */
291 	mutex_lock(&ni_lock);
292 	if (ni.eof == 1) {
293 		mutex_unlock(&ni_lock);
294 		return(NULL);
295 	}
296 	mutex_unlock(&ni_lock);
297 
298 	break;
299     default:
300 	nc_error = NC_NOTINIT;
301 	return (NULL);
302     }
303 
304     stringp = (char *) malloc(MAXNETCONFIGLINE);
305     if (stringp == NULL)
306     	return (NULL);
307 
308 #ifdef MEM_CHK
309     if (malloc_verify() == 0) {
310 	fprintf(stderr, "memory heap corrupted in getnetconfig\n");
311 	exit(1);
312     }
313 #endif
314 
315     /*
316      * Read a line from netconfig file.
317      */
318     mutex_lock(&nc_file_lock);
319     do {
320 	if (fgets(stringp, MAXNETCONFIGLINE, nc_file) == NULL) {
321 	    free(stringp);
322 	    mutex_lock(&ni_lock);
323 	    ni.eof = 1;
324 	    mutex_unlock(&ni_lock);
325 	    mutex_unlock(&nc_file_lock);
326 	    return (NULL);
327         }
328     } while (*stringp == '#');
329     mutex_unlock(&nc_file_lock);
330 
331     list = (struct netconfig_list *) malloc(sizeof (struct netconfig_list));
332     if (list == NULL) {
333     	free(stringp);
334     	return(NULL);
335     }
336     np = (struct netconfig *) malloc(sizeof (struct netconfig));
337     if (np == NULL) {
338     	free(stringp);
339 	free(list);
340     	return(NULL);
341     }
342     list->ncp = np;
343     list->next = NULL;
344     list->ncp->nc_lookups = NULL;
345     list->linep = stringp;
346     if (parse_ncp(stringp, list->ncp) == -1) {
347 	free(stringp);
348 	free(np);
349 	free(list);
350 	return (NULL);
351     }
352     else {
353 	/*
354 	 * If this is the first entry that's been read, it is the head of
355 	 * the list.  If not, put the entry at the end of the list.
356 	 * Reposition the current pointer of the handle to the last entry
357 	 * in the list.
358 	 */
359 	mutex_lock(&ni_lock);
360 	if (ni.head == NULL) {	/* first entry */
361 	    ni.head = ni.tail = list;
362 	}
363     	else {
364     	    ni.tail->next = list;
365     	    ni.tail = ni.tail->next;
366     	}
367 	ncp->nc_configs = ni.tail;
368 	result = ni.tail->ncp;
369 	mutex_unlock(&ni_lock);
370 	return(result);
371     }
372 }
373 
374 /*
375  * endnetconfig() may be called to "unbind" or "close" the netconfig database
376  * when processing is complete, releasing resources for reuse.  endnetconfig()
377  * may not be called before setnetconfig().  endnetconfig() returns 0 on
378  * success and -1 on failure (for example, if setnetconfig() was not called
379  * previously).
380  */
381 int
382 endnetconfig(handlep)
383 void *handlep;
384 {
385     struct netconfig_vars *nc_handlep = (struct netconfig_vars *)handlep;
386 
387     struct netconfig_list *q, *p;
388 
389     /*
390      * Verify that handle is valid
391      */
392     if (nc_handlep == NULL || (nc_handlep->valid != NC_VALID &&
393 	    nc_handlep->valid != NC_STORAGE)) {
394 	nc_error = NC_NOTINIT;
395 	return (-1);
396     }
397 
398     /*
399      * Return 0 if anyone still needs it.
400      */
401     nc_handlep->valid = NC_INVALID;
402     nc_handlep->flag = 0;
403     nc_handlep->nc_configs = NULL;
404     mutex_lock(&ni_lock);
405     if (--ni.ref > 0) {
406 	mutex_unlock(&ni_lock);
407     	free(nc_handlep);
408 	return(0);
409     }
410 
411     /*
412      * Noone needs these entries anymore, then frees them.
413      * Make sure all info in netconfig_info structure has been reinitialized.
414      */
415     q = ni.head;
416     ni.eof = ni.ref = 0;
417     ni.head = NULL;
418     ni.tail = NULL;
419     mutex_unlock(&ni_lock);
420 
421     while (q != NULL) {
422 	p = q->next;
423 	if (q->ncp->nc_lookups != NULL) free(q->ncp->nc_lookups);
424 	free(q->ncp);
425 	free(q->linep);
426 	free(q);
427 	q = p;
428     }
429     free(nc_handlep);
430 
431     mutex_lock(&nc_file_lock);
432     fclose(nc_file);
433     nc_file = NULL;
434     mutex_unlock(&nc_file_lock);
435 
436     return (0);
437 }
438 
439 /*
440  * getnetconfigent(netid) returns a pointer to the struct netconfig structure
441  * corresponding to netid.  It returns NULL if netid is invalid (that is, does
442  * not name an entry in the netconfig database).  It returns NULL and sets
443  * errno in case of failure (for example, if the netconfig database cannot be
444  * opened).
445  */
446 
447 struct netconfig *
448 getnetconfigent(netid)
449 	const char *netid;
450 {
451     FILE *file;		/* NETCONFIG db's file pointer */
452     char *linep;	/* holds current netconfig line */
453     char *stringp;	/* temporary string pointer */
454     struct netconfig *ncp = NULL;   /* returned value */
455     struct netconfig_list *list;	/* pointer to cache list */
456 
457     nc_error = NC_NOTFOUND;	/* default error. */
458     if (netid == NULL || strlen(netid) == 0) {
459 	return (NULL);
460     }
461 
462     /*
463      * Look up table if the entries have already been read and parsed in
464      * getnetconfig(), then copy this entry into a buffer and return it.
465      * If we cannot find the entry in the current list and there are more
466      * entries in the netconfig db that has not been read, we then read the
467      * db and try find the match netid.
468      * If all the netconfig db has been read and placed into the list and
469      * there is no match for the netid, return NULL.
470      */
471     mutex_lock(&ni_lock);
472     if (ni.head != NULL) {
473 	for (list = ni.head; list; list = list->next) {
474 	    if (strcmp(list->ncp->nc_netid, netid) == 0) {
475 		mutex_unlock(&ni_lock);
476 	        return(dup_ncp(list->ncp));
477 	    }
478 	}
479 	if (ni.eof == 1) {	/* that's all the entries */
480 		mutex_unlock(&ni_lock);
481 		return(NULL);
482 	}
483     }
484     mutex_unlock(&ni_lock);
485 
486 
487     if ((file = fopen(NETCONFIG, "r")) == NULL) {
488 	nc_error = NC_NONETCONFIG;
489 	return (NULL);
490     }
491 
492     if ((linep = malloc(MAXNETCONFIGLINE)) == NULL) {
493 	fclose(file);
494 	nc_error = NC_NOMEM;
495 	return (NULL);
496     }
497     do {
498 	ptrdiff_t len;
499 	char *tmpp;	/* tmp string pointer */
500 
501 	do {
502 	    if ((stringp = fgets(linep, MAXNETCONFIGLINE, file)) == NULL) {
503 		break;
504 	    }
505 	} while (*stringp == '#');
506 	if (stringp == NULL) {	    /* eof */
507 	    break;
508 	}
509 	if ((tmpp = strpbrk(stringp, "\t ")) == NULL) {	/* can't parse file */
510 	    nc_error = NC_BADFILE;
511 	    break;
512 	}
513 	if (strlen(netid) == (size_t) (len = tmpp - stringp) &&	/* a match */
514 		strncmp(stringp, netid, (size_t)len) == 0) {
515 	    if ((ncp = (struct netconfig *)
516 		    malloc(sizeof (struct netconfig))) == NULL) {
517 		break;
518 	    }
519 	    ncp->nc_lookups = NULL;
520 	    if (parse_ncp(linep, ncp) == -1) {
521 		free(ncp);
522 		ncp = NULL;
523 	    }
524 	    break;
525 	}
526     } while (stringp != NULL);
527     if (ncp == NULL) {
528 	free(linep);
529     }
530     fclose(file);
531     return(ncp);
532 }
533 
534 /*
535  * freenetconfigent(netconfigp) frees the netconfig structure pointed to by
536  * netconfigp (previously returned by getnetconfigent()).
537  */
538 
539 void
540 freenetconfigent(netconfigp)
541 	struct netconfig *netconfigp;
542 {
543     if (netconfigp != NULL) {
544 	free(netconfigp->nc_netid);	/* holds all netconfigp's strings */
545 	if (netconfigp->nc_lookups != NULL)
546 	    free(netconfigp->nc_lookups);
547 	free(netconfigp);
548     }
549     return;
550 }
551 
552 /*
553  * Parse line and stuff it in a struct netconfig
554  * Typical line might look like:
555  *	udp tpi_cots vb inet udp /dev/udp /usr/lib/ip.so,/usr/local/ip.so
556  *
557  * We return -1 if any of the tokens don't parse, or malloc fails.
558  *
559  * Note that we modify stringp (putting NULLs after tokens) and
560  * we set the ncp's string field pointers to point to these tokens within
561  * stringp.
562  */
563 
564 static int
565 parse_ncp(stringp, ncp)
566 char *stringp;		/* string to parse */
567 struct netconfig *ncp;	/* where to put results */
568 {
569     char    *tokenp;	/* for processing tokens */
570     char    *lasts;
571     char    **nc_lookups;
572 
573     nc_error = NC_BADFILE;	/* nearly anything that breaks is for this reason */
574     stringp[strlen(stringp)-1] = '\0';	/* get rid of newline */
575     /* netid */
576     if ((ncp->nc_netid = strtok_r(stringp, "\t ", &lasts)) == NULL) {
577 	return (-1);
578     }
579 
580     /* semantics */
581     if ((tokenp = strtok_r(NULL, "\t ", &lasts)) == NULL) {
582 	return (-1);
583     }
584     if (strcmp(tokenp, NC_TPI_COTS_ORD_S) == 0)
585 	ncp->nc_semantics = NC_TPI_COTS_ORD;
586     else if (strcmp(tokenp, NC_TPI_COTS_S) == 0)
587 	ncp->nc_semantics = NC_TPI_COTS;
588     else if (strcmp(tokenp, NC_TPI_CLTS_S) == 0)
589 	ncp->nc_semantics = NC_TPI_CLTS;
590     else if (strcmp(tokenp, NC_TPI_RAW_S) == 0)
591 	ncp->nc_semantics = NC_TPI_RAW;
592     else
593 	return (-1);
594 
595     /* flags */
596     if ((tokenp = strtok_r(NULL, "\t ", &lasts)) == NULL) {
597 	return (-1);
598     }
599     for (ncp->nc_flag = NC_NOFLAG; *tokenp != '\0';
600 	    tokenp++) {
601 	switch (*tokenp) {
602 	case NC_NOFLAG_C:
603 	    break;
604 	case NC_VISIBLE_C:
605 	    ncp->nc_flag |= NC_VISIBLE;
606 	    break;
607 	case NC_BROADCAST_C:
608 	    ncp->nc_flag |= NC_BROADCAST;
609 	    break;
610 	default:
611 	    return (-1);
612 	}
613     }
614     /* protocol family */
615     if ((ncp->nc_protofmly = strtok_r(NULL, "\t ", &lasts)) == NULL) {
616 	return (-1);
617     }
618     /* protocol name */
619     if ((ncp->nc_proto = strtok_r(NULL, "\t ", &lasts)) == NULL) {
620 	return (-1);
621     }
622     /* network device */
623     if ((ncp->nc_device = strtok_r(NULL, "\t ", &lasts)) == NULL) {
624 	return (-1);
625     }
626     if ((tokenp = strtok_r(NULL, "\t ", &lasts)) == NULL) {
627 	return (-1);
628     }
629     if (strcmp(tokenp, NC_NOLOOKUP) == 0) {
630 	ncp->nc_nlookups = 0;
631 	ncp->nc_lookups = NULL;
632     } else {
633 	char *cp;	    /* tmp string */
634 
635 	if (ncp->nc_lookups != NULL)	/* from last visit */
636 	    free(ncp->nc_lookups);
637 	ncp->nc_lookups = NULL;
638 	ncp->nc_nlookups = 0;
639 	while ((cp = tokenp) != NULL) {
640 	    if ((nc_lookups = realloc(ncp->nc_lookups,
641 		(ncp->nc_nlookups + 1) * sizeof *ncp->nc_lookups)) == NULL) {
642 		    free(ncp->nc_lookups);
643 		    ncp->nc_lookups = NULL;
644 		    return (-1);
645 	    }
646 	    tokenp = _get_next_token(cp, ',');
647 	    ncp->nc_lookups = nc_lookups;
648 	    ncp->nc_lookups[ncp->nc_nlookups++] = cp;
649 	}
650     }
651     return (0);
652 }
653 
654 
655 /*
656  * Returns a string describing the reason for failure.
657  */
658 char *
659 nc_sperror()
660 {
661     const char *message;
662 
663     switch(nc_error) {
664     case NC_NONETCONFIG:
665 	message = _nc_errors[0];
666 	break;
667     case NC_NOMEM:
668 	message = _nc_errors[1];
669 	break;
670     case NC_NOTINIT:
671 	message = _nc_errors[2];
672 	break;
673     case NC_BADFILE:
674 	message = _nc_errors[3];
675 	break;
676     case NC_NOTFOUND:
677 	message = _nc_errors[4];
678 	break;
679     default:
680 	message = "Unknown network selection error";
681     }
682     /* LINTED const castaway */
683     return ((char *)message);
684 }
685 
686 /*
687  * Prints a message onto standard error describing the reason for failure.
688  */
689 void
690 nc_perror(s)
691 	const char *s;
692 {
693     fprintf(stderr, "%s: %s\n", s, nc_sperror());
694 }
695 
696 /*
697  * Duplicates the matched netconfig buffer.
698  */
699 static struct netconfig *
700 dup_ncp(ncp)
701 struct netconfig	*ncp;
702 {
703     struct netconfig	*p;
704     char	*tmp;
705     u_int	i;
706 
707     if ((tmp=malloc(MAXNETCONFIGLINE)) == NULL)
708 	return(NULL);
709     if ((p=(struct netconfig *)malloc(sizeof(struct netconfig))) == NULL) {
710 	free(tmp);
711 	return(NULL);
712     }
713     /*
714      * First we dup all the data from matched netconfig buffer.  Then we
715      * adjust some of the member pointer to a pre-allocated buffer where
716      * contains part of the data.
717      * To follow the convention used in parse_ncp(), we store all the
718      * necessary information in the pre-allocated buffer and let each
719      * of the netconfig char pointer member point to the right address
720      * in the buffer.
721      */
722     *p = *ncp;
723     p->nc_netid = (char *)strcpy(tmp,ncp->nc_netid);
724     tmp = strchr(tmp, '\0') + 1;
725     p->nc_protofmly = (char *)strcpy(tmp,ncp->nc_protofmly);
726     tmp = strchr(tmp, '\0') + 1;
727     p->nc_proto = (char *)strcpy(tmp,ncp->nc_proto);
728     tmp = strchr(tmp, '\0') + 1;
729     p->nc_device = (char *)strcpy(tmp,ncp->nc_device);
730     p->nc_lookups = (char **)malloc((size_t)(p->nc_nlookups+1) * sizeof(char *));
731     if (p->nc_lookups == NULL) {
732 	free(p->nc_netid);
733 	free(p);
734 	return(NULL);
735     }
736     for (i=0; i < p->nc_nlookups; i++) {
737     	tmp = strchr(tmp, '\0') + 1;
738     	p->nc_lookups[i] = (char *)strcpy(tmp,ncp->nc_lookups[i]);
739     }
740     return(p);
741 }
742