src/getnetpath.c

/*
 * Copyright (c) 2009, Sun Microsystems, Inc.
 * All rights reserved.
 *
 * 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 Sun Microsystems, 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 <config.h>
#include <sys/cdefs.h>

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

#include <sys/cdefs.h>
#include <stdio.h>
#include <errno.h>
#include <netconfig.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>

#include <rpc/types.h>

/*
 * 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 alloc. 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

	np_sessionp = (struct netpath_vars *)
		mem_zalloc(sizeof(struct netpath_vars));

	np_sessionp->nc_handlep = setnetconfig();
	if (!np_sessionp->nc_handlep) {
		mem_free(np_sessionp, sizeof(struct netpath_vars));
		syslog(LOG_ERR, "rpc: failed to open " NETCONFIG);
		return (NULL);
	}
	np_sessionp->valid = NP_VALID;
	np_sessionp->ncp_list = NULL;
	npp = getenv(NETPATH);
	if (!npp)
		np_sessionp->netpath = NULL;
	else {
		(void)endnetconfig(np_sessionp->nc_handlep);
			/* won't need nc session */
		np_sessionp->nc_handlep = NULL;
		np_sessionp->netpath = mem_zalloc(strlen(npp) + 1);
		(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);
			}
			ncp = getnetconfig(np_sessionp->nc_handlep);
			if (!ncp)
				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.
		 */
		ncp = getnetconfigent(npp);
		if (ncp) {
			/* cobble alloc chain entry */
			chainp = (struct netpath_chain *)
				mem_zalloc(sizeof(struct netpath_chain));
			chainp->ncp = ncp;
			chainp->nchain_next = NULL;
			if (!np_sessionp->ncp_list)
				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)
		mem_free(np_sessionp->netpath_start, 0);
	for (chainp = np_sessionp->ncp_list; chainp != NULL;
	     lastp = chainp, chainp = chainp->nchain_next, mem_free(lastp, 0)) {
		freenetconfigent(chainp->ncp);
	}

	mem_free(np_sessionp, sizeof(*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 */

	cp = strchr(npp, token);
	if (!cp)
		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 */
			int n = strlen(cp);
			memmove(&cp[-1], cp, n); /* XXX: was overlapping
						  * strcpy */
			/*
			 * 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 */
}