/*
 * support/export/export.c
 *
 * Maintain list of exported file systems.
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/param.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <limits.h>
#include <stdlib.h>
#include <dirent.h>
#include <errno.h>
#include "xmalloc.h"
#include "nfslib.h"
#include "exportfs.h"
#include "nfsd_path.h"
#include "xlog.h"
#include "reexport.h"

exp_hash_table exportlist[MCL_MAXTYPES] = {{NULL, {{NULL,NULL}, }}, }; 
static int export_hash(char *);

static void	export_init(nfs_export *exp, nfs_client *clp,
					struct exportent *nep);
static void	export_add(nfs_export *exp);
static int	export_check(const nfs_export *exp, const struct addrinfo *ai,
				const char *path);

/* Return a real path for the export. */
static void
exportent_mkrealpath(struct exportent *eep)
{
	const char *chroot = nfsd_path_nfsd_rootdir();
	char *ret = NULL;

	if (chroot) {
		char buffer[PATH_MAX];
		if (realpath(chroot, buffer))
			ret = nfsd_path_prepend_dir(buffer, eep->e_path);
		else
			xlog(D_GENERAL, "%s: failed to resolve path %s: %m",
					__func__, chroot);
	}
	if (!ret)
		ret = xstrdup(eep->e_path);
	eep->e_realpath = ret;
}

char *
exportent_realpath(struct exportent *eep)
{
	if (!eep->e_realpath)
		exportent_mkrealpath(eep);
	return eep->e_realpath;
}

void
exportent_release(struct exportent *eep)
{
	xfree(eep->e_squids);
	xfree(eep->e_sqgids);
	free(eep->e_mountpoint);
	free(eep->e_fslocdata);
	free(eep->e_uuid);
	xfree(eep->e_hostname);
	xfree(eep->e_realpath);
}

static void
export_free(nfs_export *exp)
{
	exportent_release(&exp->m_export);
	xfree(exp);
}

static void warn_duplicated_exports(nfs_export *exp, struct exportent *eep)
{
	if (exp->m_export.e_flags != eep->e_flags) {
		xlog(L_ERROR, "incompatible duplicated export entries:");
		xlog(L_ERROR, "\t%s:%s (0x%x) [IGNORED]", eep->e_hostname,
				eep->e_path, eep->e_flags);
		xlog(L_ERROR, "\t%s:%s (0x%x)", exp->m_export.e_hostname,
				exp->m_export.e_path, exp->m_export.e_flags);
	} else {
		xlog(L_ERROR, "duplicated export entries:");
		xlog(L_ERROR, "\t%s:%s", eep->e_hostname, eep->e_path);
		xlog(L_ERROR, "\t%s:%s", exp->m_export.e_hostname,
				exp->m_export.e_path);
	}
}

/**
 * export_read - read entries from /etc/exports
 * @fname: name of file to read from
 * @ignore_hosts: don't check validity of host names
 *
 * Returns number of read entries.
 * @ignore_hosts can be set when the host names won't be used
 * and when getting delays or errors due to problems with
 * hostname looking is not acceptable.
 */
int
export_read(char *fname, int ignore_hosts)
{
	struct exportent	*eep;
	nfs_export		*exp;

	int volumes = 0;
	int reexport_found = 0;

	setexportent(fname, "r");
	while ((eep = getexportent(0,1)) != NULL) {
		exp = export_lookup(eep->e_hostname, eep->e_path, ignore_hosts);
		if (!exp) {
			if (export_create(eep, 0))
				/* possible complaints already logged */
				volumes++;
		}
		else
			warn_duplicated_exports(exp, eep);

		if (eep->e_reexport)
			reexport_found = 1;
	}

	if (reexport_found) {
		for (int i = 0; i < MCL_MAXTYPES; i++) {
			for (exp = exportlist[i].p_head; exp; exp = exp->m_next) {
				if (exp->m_export.e_reexport)
					continue;

				if (exp->m_export.e_flags & NFSEXP_FSID) {
					xlog(L_ERROR, "When a reexport= option is present no manully assigned numerical fsid= options are allowed");
					return -1;
				}
			}
		}
	}

	endexportent();

	return volumes;
}

/**
 * export_d_read - read entries from /etc/exports.
 * @fname: name of directory to read from
 * @ignore_hosts: don't check validity of host names
 *
 * Returns number of read entries.
 * Based on mnt_table_parse_dir() in
 *  util-linux-ng/shlibs/mount/src/tab_parse.c
 */
int
export_d_read(const char *dname, int ignore_hosts)
{
	int n = 0, i;
	struct dirent **namelist = NULL;
	int volumes = 0;


	n = scandir(dname, &namelist, NULL, versionsort);
	if (n < 0) {
		if (errno == ENOENT)
			/* Silently return */
			return volumes;
		xlog(L_NOTICE, "scandir %s: %s", dname, strerror(errno));
	} else if (n == 0)
		return volumes;

	for (i = 0; i < n; i++) {
		struct dirent *d = namelist[i];
		size_t namesz;
		char fname[PATH_MAX + 1];
		int fname_len;


		if (d->d_type != DT_UNKNOWN
		    && d->d_type != DT_REG
		    && d->d_type != DT_LNK)
			continue;
		if (*d->d_name == '.')
			continue;

#define _EXT_EXPORT_SIZ   (sizeof(_EXT_EXPORT) - 1)
		namesz = strlen(d->d_name);
		if (!namesz
		    || namesz < _EXT_EXPORT_SIZ + 1
		    || strcmp(d->d_name + (namesz - _EXT_EXPORT_SIZ),
			      _EXT_EXPORT))
			continue;

		fname_len = snprintf(fname, PATH_MAX +1, "%s/%s", dname, d->d_name);
		if (fname_len > PATH_MAX) {
			xlog(L_WARNING, "Too long file name: %s in %s", d->d_name, dname);
			continue;
		}

		volumes += export_read(fname, ignore_hosts);
	}

	for (i = 0; i < n; i++)
		free(namelist[i]);
	free(namelist);

	return volumes;
}

/**
 * export_create - create an in-core nfs_export record from an export entry
 * @xep: export entry to lookup
 * @canonical: if set, e_hostname is known to be canonical DNS name
 *
 * Returns a freshly instantiated export record, or NULL if
 * a problem occurred.
 */
nfs_export *
export_create(struct exportent *xep, int canonical)
{
	nfs_client	*clp;
	nfs_export	*exp;

	if (!(clp = client_lookup(xep->e_hostname, canonical))) {
		/* bad export entry; complaint already logged */
		return NULL;
	}
	exp = (nfs_export *) xmalloc(sizeof(*exp));
	export_init(exp, clp, xep);
	export_add(exp);

	return exp;
}

static void
export_init(nfs_export *exp, nfs_client *clp, struct exportent *nep)
{
	struct exportent	*e = &exp->m_export;

	dupexportent(e, nep);
	if (nep->e_hostname)
		e->e_hostname = xstrdup(nep->e_hostname);

	exp->m_exported = 0;
	exp->m_xtabent = 0;
	exp->m_mayexport = 0;
	exp->m_changed = 0;
	exp->m_warned = 0;
	exp->m_client = clp;
	clp->m_count++;
}

/*
 * Duplicate exports data. The in-core export struct retains the
 * original hostname from /etc/exports, while the in-core client struct
 * gets the newly found FQDN.
 */
static nfs_export *
export_dup(nfs_export *exp, const struct addrinfo *ai)
{
	nfs_export		*new;
	nfs_client		*clp;

	new = (nfs_export *) xmalloc(sizeof(*new));
	memcpy(new, exp, sizeof(*new));
	dupexportent(&new->m_export, &exp->m_export);
	if (exp->m_export.e_hostname)
		new->m_export.e_hostname = xstrdup(exp->m_export.e_hostname);
	clp = client_dup(exp->m_client, ai);
	if (clp == NULL) {
		export_free(new);
		return NULL;
	}
	clp->m_count++;
	new->m_client = clp;
	new->m_mayexport = exp->m_mayexport;
	new->m_exported = 0;
	new->m_xtabent = 0;
	new->m_changed = 0;
	new->m_warned = 0;
	export_add(new);

	return new;
}

static void
export_add(nfs_export *exp)
{
	exp_hash_table *p_tbl;
	exp_hash_entry *p_hen;
	nfs_export *p_next;

	int type = exp->m_client->m_type;
	int pos;

	pos = export_hash(exp->m_export.e_path);
	p_tbl = &(exportlist[type]); /* pointer to hash table */
	p_hen = &(p_tbl->entries[pos]); /* pointer to hash table entry */

	if (!(p_hen->p_first)) { /* hash table entry is empty */ 
 		p_hen->p_first = exp;
 		p_hen->p_last  = exp;

 		exp->m_next = p_tbl->p_head;
 		p_tbl->p_head = exp;
	} else { /* hash table entry is NOT empty */
		p_next = p_hen->p_last->m_next;
		p_hen->p_last->m_next = exp;
		exp->m_next = p_next;
		p_hen->p_last = exp;
	}
}

/**
 * export_find - find or create a suitable nfs_export for @ai and @path
 * @ai: pointer to addrinfo for client
 * @path: '\0'-terminated ASCII string containing export path
 *
 * Returns a pointer to nfs_export data matching @ai and @path,
 * or NULL if an error occurs.
 */
nfs_export *
export_find(const struct addrinfo *ai, const char *path)
{
	nfs_export	*exp;
	int		i;

	for (i = 0; i < MCL_MAXTYPES; i++) {
		for (exp = exportlist[i].p_head; exp; exp = exp->m_next) {
			if (!export_check(exp, ai, path))
				continue;
			if (exp->m_client->m_type == MCL_FQDN)
				return exp;
			return export_dup(exp, ai);
		}
	}

	return NULL;
}

/**
 * export_lookup - search hash table for export entry
 * @hname: '\0'-terminated ASCII string containing client hostname to look for
 * @path: '\0'-terminated ASCII string containing export path to look for
 * @canonical: if set, @hname is known to be canonical DNS name
 *
 * Returns a pointer to nfs_export record matching @hname and @path,
 * or NULL if the export was not found.
 */
nfs_export *
export_lookup(char *hname, char *path, int canonical)
{
	nfs_client *clp;
	nfs_export *exp;
	exp_hash_entry *p_hen;

	int pos;

	clp = client_lookup(hname, canonical);
	if(clp == NULL)
		return NULL;

	pos = export_hash(path);
	p_hen = &(exportlist[clp->m_type].entries[pos]); 
	for(exp = p_hen->p_first; exp && (exp != p_hen->p_last->m_next); 
  			exp = exp->m_next) {
		if (exp->m_client == clp && !strcmp(exp->m_export.e_path, path)) {
  			return exp;
		}
	}
	return NULL;
}

static int
export_check(const nfs_export *exp, const struct addrinfo *ai, const char *path)
{
	if (strcmp(path, exp->m_export.e_path))
		return 0;

	return client_check(exp->m_client, ai);
}

/**
 * export_freeall - deallocate all nfs_export records
 *
 */
void
export_freeall(void)
{
	nfs_export	*exp, *nxt;
	int		i, j;

	for (i = 0; i < MCL_MAXTYPES; i++) {
		for (exp = exportlist[i].p_head; exp; exp = nxt) {
			nxt = exp->m_next;
			client_release(exp->m_client);
			export_free(exp);
		}
		for (j = 0; j < HASH_TABLE_SIZE; j++) {
			exportlist[i].entries[j].p_first = NULL;
			exportlist[i].entries[j].p_last = NULL;
		}
		exportlist[i].p_head = NULL;
	}
	client_freeall();
}

/*
 * Compute and returns integer from string. 
 * Note: Its understood the smae integers can be same for 
 *       different strings, but it should not matter.
 */
static unsigned int 
strtoint(char *str)
{
	int i = 0;
	unsigned int n = 0;

	while ( str[i] != '\0') {
		n+=((int)str[i])*i;
		i++;
	}
	return n;
}

/*
 * Hash function
 */
static int 
export_hash(char *str)
{
	unsigned int num = strtoint(str);

	return num % HASH_TABLE_SIZE;
}

int export_test(struct exportent *eep, int with_fsid)
{
	char *path = eep->e_path;
	int flags = eep->e_flags | (with_fsid ? NFSEXP_FSID : 0);
	/* beside max path, buf size should take protocol str into account */
	char buf[NFS_MAXPATHLEN+1+64] = { 0 };
	char *bp = buf;
	int len = sizeof(buf);
	int fd, n;

	n = snprintf(buf, len, "-test-client- ");
	bp += n;
	len -= n;
	qword_add(&bp, &len, path);
	if (len < 1)
		return 0;
	snprintf(bp, len, " 3 %d 65534 65534 0\n", flags);
	fd = open("/proc/net/rpc/nfsd.export/channel", O_WRONLY);
	if (fd < 0)
		return 0;
	n = nfsd_path_write(fd, buf, strlen(buf));
	close(fd);
	if (n < 0)
		return 0;
	return 1;
}