/*	$NetBSD: getnetpath.c,v 1.17 2013/03/11 20:19:29 tron Exp $	*/

/*
 * Copyright (c) 2010, Oracle America, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 *       copyright notice, this list of conditions and the following
 *       disclaimer in the documentation and/or other materials
 *       provided with the distribution.
 *     * Neither the name of the "Oracle America, Inc." nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 *   FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 *   COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 *   INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 *   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 *   GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 *   WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static        char sccsid[] = "@(#)getnetpath.c	1.11 91/12/19 SMI";
#else
__RCSID("$NetBSD: getnetpath.c,v 1.17 2013/03/11 20:19:29 tron Exp $");
#endif
#endif

/*
 * Copyright (c) 1989 by Sun Microsystems, Inc.
 */

#include "namespace.h"
#include <stdio.h>
#include <assert.h>
#include <errno.h>
#include <netconfig.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>

#ifdef __weak_alias
__weak_alias(getnetpath,_getnetpath)
__weak_alias(setnetpath,_setnetpath)
__weak_alias(endnetpath,_endnetpath)
#endif

/*
 * internal structure to keep track of a netpath "session"
 */
struct netpath_chain {
	struct netconfig *ncp;  		/* an nconf entry */
	struct netpath_chain *nchain_next;	/* next nconf entry allocated */
};


struct netpath_vars {
	int   valid;		/* token that indicates a valid netpath_vars */
	void *nc_handlep;	/* handle for current netconfig "session" */
	char *netpath;		/* pointer to current view-point in NETPATH */
	char *netpath_start;	/* pointer to start of our copy of NETPATH */
	struct netpath_chain *ncp_list;  /* list of nconfs allocated this session*/
};

#define NP_VALID	0xf00d
#define NP_INVALID	0

char *_get_next_token(char *, int);


/*
 * A call to setnetpath() establishes a NETPATH "session".  setnetpath()
 * must be called before the first call to getnetpath().  A "handle" is
 * returned to distinguish the session; this handle should be passed
 * subsequently to getnetpath().  (Handles are used to allow for nested calls
 * to setnetpath()).
 * If setnetpath() is unable to establish a session (due to lack of memory
 * resources, or the absence of the /etc/netconfig file), a NULL pointer is
 * returned.
 */

void *
setnetpath(void)
{
	struct netpath_vars *np_sessionp;   /* this session's variables */
	char *npp;				/* NETPATH env variable */

#ifdef MEM_CHK
	malloc_debug(1);
#endif

	if ((np_sessionp = malloc(sizeof(*np_sessionp))) == NULL)
		return (NULL);
	if ((np_sessionp->nc_handlep = setnetconfig()) == NULL) {
		free(np_sessionp);
		syslog (LOG_ERR, "rpc: failed to open " NETCONFIG);
		return (NULL);
	}
	np_sessionp->valid = NP_VALID;
	np_sessionp->ncp_list = NULL;
	if ((npp = getenv(NETPATH)) == NULL)
		np_sessionp->netpath = NULL;
	else {
		(void) endnetconfig(np_sessionp->nc_handlep);
					/* won't need nc session*/
		np_sessionp->nc_handlep = NULL;
		if ((np_sessionp->netpath = malloc(strlen(npp)+1)) == NULL) {
			free(np_sessionp);
			return (NULL);
		} else
			(void) strcpy(np_sessionp->netpath, npp);
	}
	np_sessionp->netpath_start = np_sessionp->netpath;
	return ((void *)np_sessionp);
}

/*
 * When first called, getnetpath() returns a pointer to the netconfig
 * database entry corresponding to the first valid NETPATH component.  The
 * netconfig entry is formatted as a struct netconfig.
 * On each subsequent call, getnetpath returns a pointer to the netconfig
 * entry that corresponds to the next valid NETPATH component.  getnetpath
 * can thus be used to search the netconfig database for all networks
 * included in the NETPATH variable.
 * When NETPATH has been exhausted, getnetpath() returns NULL.  It returns
 * NULL and sets errno in case of an error (e.g., setnetpath was not called
 * previously).
 * getnetpath() silently ignores invalid NETPATH components.  A NETPATH
 * compnent is invalid if there is no corresponding entry in the netconfig
 * database.
 * If the NETPATH variable is unset, getnetpath() behaves as if NETPATH
 * were set to the sequence of default or visible networks in the netconfig
 * database, in the order in which they are listed.
 */

struct netconfig *
getnetpath(void *handlep)
{
	struct netpath_vars *np_sessionp = (struct netpath_vars *)handlep;
	struct netconfig *ncp = NULL;   /* temp. holds a netconfig session */
	struct netpath_chain *chainp;   /* holds chain of ncp's we alloc */
	char  *npp;		/* holds current NETPATH */

	if (np_sessionp == NULL || np_sessionp->valid != NP_VALID) {
		errno = EINVAL;
		return (NULL);
	}
	if (np_sessionp->netpath_start == NULL) { /* NETPATH was not set */
		do {                /* select next visible network */
			if (np_sessionp->nc_handlep == NULL) {
				np_sessionp->nc_handlep = setnetconfig();
				if (np_sessionp->nc_handlep == NULL)
					syslog (LOG_ERR,
					    "rpc: failed to open " NETCONFIG);
			}
			if ((ncp = getnetconfig(np_sessionp->nc_handlep))
			    == NULL)
				return(NULL);
		} while ((ncp->nc_flag & NC_VISIBLE) == 0);
		return (ncp);
	}
	/*
	 * Find first valid network ID in netpath.
	 */
	while ((npp = np_sessionp->netpath) != NULL && strlen(npp) != 0) {
		np_sessionp->netpath = _get_next_token(npp, ':');
		/*
		 * npp is a network identifier.
		 */
		if ((ncp = getnetconfigent(npp)) != NULL) {
					/* cobble alloc chain entry */
			chainp = malloc(sizeof (struct netpath_chain));
			if (chainp == NULL) {
				freenetconfigent(ncp);
				return NULL;
			}
			chainp->ncp = ncp;
			chainp->nchain_next = NULL;
			if (np_sessionp->ncp_list == NULL)
				np_sessionp->ncp_list = chainp;
			else
				np_sessionp->ncp_list->nchain_next = chainp;
			return (ncp);
		}
		/* couldn't find this token in the database; go to next one. */
	}
	return (NULL);
}

/*
 * endnetpath() may be called to unbind NETPATH when processing is complete,
 * releasing resources for reuse.  It returns 0 on success and -1 on failure
 * (e.g. if setnetpath() was not called previously.
 */
int
endnetpath(void *handlep)
{
	struct netpath_vars *np_sessionp = (struct netpath_vars *)handlep;
	struct netpath_chain *chainp, *lastp;

	if (np_sessionp == NULL || np_sessionp->valid != NP_VALID) {
		errno = EINVAL;
		return (-1);
	}
	if (np_sessionp->nc_handlep != NULL)
		endnetconfig(np_sessionp->nc_handlep);
	if (np_sessionp->netpath_start != NULL)
		free(np_sessionp->netpath_start);
	for (chainp = np_sessionp->ncp_list; chainp != NULL;
	    lastp=chainp, chainp=chainp->nchain_next, free(lastp)) {
		freenetconfigent(chainp->ncp);
	}
	free(np_sessionp);
#ifdef MEM_CHK
	if (malloc_verify() == 0) {
		fprintf(stderr, "memory heap corrupted in endnetpath\n");
		exit(1);
	}
#endif
	return (0);
}


/*
 * Returns pointer to the rest-of-the-string after the current token.
 * The token itself starts at arg, and we null terminate it.  We return NULL
 * if either the arg is empty, or if this is the last token.
 */

char *
_get_next_token(
	char *npp,		/* string */
	int token		/* char to parse string for */
)
{
	char  *cp;		/* char pointer */
	char  *np;		/* netpath pointer */
	char  *ep;		/* escape pointer */

	_DIAGASSERT(npp != NULL);

	if ((cp = strchr(npp, token)) == NULL)
		return (NULL);
	/*
	 * did find a token, but it might be escaped.
	 */
	if ((cp > npp) && (cp[-1] == '\\')) {
		/*
		 * if slash was also escaped, carry on, otherwise find
		 * next token
		 */
		if ((cp > npp + 1) && (cp[-2] != '\\')) {
			/* shift r-o-s  onto the escaped token */
			strcpy(&cp[-1], cp);  /* XXX: overlapping string copy */
			/*
			 * Do a recursive call.
			 * We don't know how many escaped tokens there might be.
			 */
			return (_get_next_token(cp, token));
		}
	}

	*cp++ = '\0';		/* null-terminate token */
	/* get rid of any backslash escapes */
	ep = npp;
	while ((np = strchr(ep, '\\')) != 0) {
		if (np[1] == '\\')
			np++;
		strcpy(np, (ep = &np[1]));  /* XXX: overlapping string copy */
	}
	return (cp);		/* return ptr to r-o-s */
}
