/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2011 Gunnar Beutner
 */

#include <stdio.h>
#include <strings.h>
#include <fcntl.h>
#include <sys/wait.h>
#include <unistd.h>
#include <libzfs.h>
#include <libshare.h>
#include "libshare_impl.h"

static sa_fstype_t *nfs_fstype;
static boolean_t nfs_available;

typedef int (*nfs_shareopt_callback_t)(const char *opt, const char *value,
    void *cookie);

typedef int (*nfs_host_callback_t)(const char *sharepath, const char *host,
    const char *security, const char *access, void *cookie);

static int
foreach_nfs_shareopt(const char *shareopts,
    nfs_shareopt_callback_t callback, void *cookie)
{
	char *shareopts_dup, *opt, *cur, *value;
	int was_nul, rc;

	if (shareopts == NULL)
		return SA_OK;

	shareopts_dup = strdup(shareopts);

	if (shareopts_dup == NULL)
		return SA_NO_MEMORY;

	opt = shareopts_dup;
	was_nul = 0;

	while (1) {
		cur = opt;

		while (*cur != ',' && *cur != '\0')
			cur++;

		if (*cur == '\0')
			was_nul = 1;

		*cur = '\0';

		if (cur > opt) {
			value = strchr(opt, '=');

			if (value != NULL) {
				*value = '\0';
				value++;
			}

			rc = callback(opt, value, cookie);

			if (rc != SA_OK) {
				free(shareopts_dup);
				return rc;
			}
		}

		opt = cur + 1;

		if (was_nul)
			break;
	}

	free(shareopts_dup);

	return 0;
}

typedef struct nfs_host_cookie_s {
	nfs_host_callback_t callback;
	const char *sharepath;
	void *cookie;
	const char *security;
} nfs_host_cookie_t;

static int
foreach_nfs_host_cb(const char *opt, const char *value, void *pcookie)
{
	int rc;
	const char *access;
	char *host_dup, *host, *next;
	nfs_host_cookie_t *udata = (nfs_host_cookie_t *)pcookie;

#ifdef DEBUG
	fprintf(stderr, "foreach_nfs_host_cb: key=%s, value=%s\n", opt, value);
#endif

	if (strcmp(opt, "sec") == 0)
		udata->security = value;

	if (strcmp(opt, "rw") == 0 || strcmp(opt, "ro") == 0) {
		if (value == NULL)
			value = "*";

		access = opt;

		host_dup = strdup(value);

		if (host_dup == NULL)
			return SA_NO_MEMORY;

		host = host_dup;

		do {
			next = strchr(host, ':');
			if (next != NULL) {
				*next = '\0';
				next++;
			}

			rc = udata->callback(udata->sharepath, host,
			    udata->security, access, udata->cookie);

			if (rc != SA_OK) {
				free(host_dup);

				return rc;
			}

			host = next;
		} while (host != NULL);

		free(host_dup);
	}

	return SA_OK;
}

static int
foreach_nfs_host(sa_share_impl_t impl_share, nfs_host_callback_t callback,
    void *cookie)
{
	nfs_host_cookie_t udata;
	char *shareopts;

	udata.callback = callback;
	udata.sharepath = impl_share->sharepath;
	udata.cookie = cookie;
	udata.security = "sys";

	shareopts = FSINFO(impl_share, nfs_fstype)->shareopts;

	return foreach_nfs_shareopt(shareopts, foreach_nfs_host_cb,
	    &udata);
}

static int
get_linux_hostspec(const char *solaris_hostspec, char **plinux_hostspec)
{
	/*
	 * For now we just support CIDR masks (e.g. @192.168.0.0/16) and host
	 * wildcards (e.g. *.example.org).
	 */
	if (solaris_hostspec[0] == '@') {
		/*
		 * Solaris host specifier, e.g. @192.168.0.0/16; we just need
		 * to skip the @ in this case
		 */
		*plinux_hostspec = strdup(solaris_hostspec + 1);
	} else {
		*plinux_hostspec = strdup(solaris_hostspec);
	}

	if (*plinux_hostspec == NULL) {
		return SA_NO_MEMORY;
	}

	return SA_OK;
}

static int
nfs_enable_share_one(const char *sharepath, const char *host,
    const char *security, const char *access, void *pcookie)
{
	pid_t pid;
	int rc, status;
	char *linuxhost, *hostpath, *opts;
	const char *linux_opts = (const char *)pcookie;

	pid = fork();

	if (pid < 0)
		return SA_SYSTEM_ERR;

	if (pid > 0) {
		while ((rc = waitpid(pid, &status, 0)) <= 0 && errno == EINTR)
			; /* empty loop body */

		if (rc <= 0)
			return SA_SYSTEM_ERR;

		if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
			return SA_CONFIG_ERR;

		return SA_OK;
	}

	/* child */

	/* exportfs -i -o sec=XX,rX,<opts> <host>:<sharepath> */

	rc = get_linux_hostspec(host, &linuxhost);

	if (rc < 0)
		exit(1);

	hostpath = malloc(strlen(linuxhost) + 1 + strlen(sharepath) + 1);

	if (hostpath == NULL) {
		free(linuxhost);

		exit(1);
	}

	sprintf(hostpath, "%s:%s", linuxhost, sharepath);

	free(linuxhost);

	if (linux_opts == NULL)
		linux_opts = "";

	opts = malloc(4 + strlen(security) + 4 + strlen(linux_opts) + 1);

	if (opts == NULL)
		exit(1);

	sprintf(opts, "sec=%s,%s,%s", security, access, linux_opts);

#ifdef DEBUG
	fprintf(stderr, "sharing %s with opts %s\n", hostpath, opts);
#endif

	rc = execlp("/usr/sbin/exportfs", "exportfs", "-i", \
	    "-o", opts, hostpath, NULL);

	if (rc < 0) {
		free(hostpath);
		free(opts);
		exit(1);
	}

	exit(0);
}

static int
add_linux_shareopt(char **plinux_opts, const char *key, const char *value)
{
	size_t len = 0;
	char *new_linux_opts;

	if (*plinux_opts != NULL)
		len = strlen(*plinux_opts);

	new_linux_opts = realloc(*plinux_opts, len + 1 + strlen(key) +
	    (value ? 1 + strlen(value) : 0) + 1);

	if (new_linux_opts == NULL)
		return SA_NO_MEMORY;

	new_linux_opts[len] = '\0';

	if (len > 0)
		strcat(new_linux_opts, ",");

	strcat(new_linux_opts, key);

	if (value != NULL) {
		strcat(new_linux_opts, "=");
		strcat(new_linux_opts, value);
	}

	*plinux_opts = new_linux_opts;

	return SA_OK;
}

static int
get_linux_shareopts_cb(const char *key, const char *value, void *cookie)
{
	char **plinux_opts = (char **)cookie;

	/* host-specific options, these are taken care of elsewhere */
	if (strcmp(key, "ro") == 0 || strcmp(key, "rw") == 0 ||
	    strcmp(key, "sec") == 0)
		return SA_OK;

	if (strcmp(key, "anon") == 0)
		key = "anonuid";

	 if (strcmp(key, "root_mapping") == 0) {
		 (void) add_linux_shareopt(plinux_opts, "root_squash", NULL);
		 key = "anonuid";
	 }

	if (strcmp(key, "nosub") == 0)
		key = "subtree_check";

	if (strcmp(key, "insecure") != 0 && strcmp(key, "secure") != 0 &&
	    strcmp(key, "async") != 0 && strcmp(key, "sync") != 0 &&
	    strcmp(key, "no_wdelay") != 0 && strcmp(key, "wdelay") != 0 &&
	    strcmp(key, "nohide") != 0 && strcmp(key, "hide") != 0 &&
	    strcmp(key, "crossmnt") != 0 &&
	    strcmp(key, "no_subtree_check") != 0 &&
	    strcmp(key, "subtree_check") != 0 &&
	    strcmp(key, "insecure_locks") != 0 &&
	    strcmp(key, "secure_locks") != 0 &&
	    strcmp(key, "no_auth_nlm") != 0 && strcmp(key, "auth_nlm") != 0 &&
	    strcmp(key, "no_acl") != 0 && strcmp(key, "mountpoint") != 0 &&
	    strcmp(key, "mp") != 0 && strcmp(key, "fsuid") != 0 &&
	    strcmp(key, "refer") != 0 && strcmp(key, "replicas") != 0 &&
	    strcmp(key, "root_squash") != 0 &&
	    strcmp(key, "no_root_squash") != 0 &&
	    strcmp(key, "all_squash") != 0 &&
	    strcmp(key, "no_all_squash") != 0 &&
	    strcmp(key, "anonuid") != 0 && strcmp(key, "anongid") != 0) {
		return SA_SYNTAX_ERR;
	}

	(void) add_linux_shareopt(plinux_opts, key, value);

	return SA_OK;
}

static int
get_linux_shareopts(const char *shareopts, char **plinux_opts)
{
	int rc;

	assert(plinux_opts != NULL);

	*plinux_opts = NULL;

	/* default options for Solaris shares */
	(void) add_linux_shareopt(plinux_opts, "no_subtree_check", NULL);
	(void) add_linux_shareopt(plinux_opts, "no_root_squash", NULL);
	(void) add_linux_shareopt(plinux_opts, "mountpoint", NULL);

	rc = foreach_nfs_shareopt(shareopts, get_linux_shareopts_cb, plinux_opts);

	if (rc != SA_OK) {
		free(*plinux_opts);
		*plinux_opts = NULL;
	}

	return rc;
}

static int
nfs_enable_share(sa_share_impl_t impl_share)
{
	char *shareopts, *linux_opts;
	int rc;

	if (!nfs_available) {
		return SA_SYSTEM_ERR;
	}

	shareopts = FSINFO(impl_share, nfs_fstype)->shareopts;

	if (shareopts == NULL)
		return SA_OK;

	rc = get_linux_shareopts(shareopts, &linux_opts);

	if (rc != SA_OK)
		return rc;

	rc = foreach_nfs_host(impl_share, nfs_enable_share_one, linux_opts);

	free(linux_opts);

	return rc;
}

static int
nfs_disable_share_one(const char *sharepath, const char *host,
    const char *security, const char *access, void *cookie)
{
	pid_t pid;
	int rc, status;
	char *linuxhost, *hostpath;

	pid = fork();

	if (pid < 0)
		return SA_SYSTEM_ERR;

	if (pid > 0) {
		while ((rc = waitpid(pid, &status, 0)) <= 0 && errno == EINTR)
			; /* empty loop body */

		if (rc <= 0)
			return SA_SYSTEM_ERR;

		if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
			return SA_CONFIG_ERR;

		return SA_OK;
	}

	/* child */

	rc = get_linux_hostspec(host, &linuxhost);

	if (rc < 0)
		exit(1);

	hostpath = malloc(strlen(linuxhost) + 1 + strlen(sharepath) + 1);

	if (hostpath == NULL) {
		free(linuxhost);
		exit(1);
	}

	sprintf(hostpath, "%s:%s", linuxhost, sharepath);

	free(linuxhost);

#ifdef DEBUG
	fprintf(stderr, "unsharing %s\n", hostpath);
#endif

	rc = execlp("/usr/sbin/exportfs", "exportfs", "-u", \
	    hostpath, NULL);

	if (rc < 0) {
		free(hostpath);
		exit(1);
	}

	exit(0);
}

static int
nfs_disable_share(sa_share_impl_t impl_share)
{
	if (!nfs_available) {
		/*
		 * The share can't possibly be active, so nothing
		 * needs to be done to disable it.
		 */
		return SA_OK;
	}

	return foreach_nfs_host(impl_share, nfs_disable_share_one, NULL);
}

static int
nfs_validate_shareopts(const char *shareopts)
{
	char *linux_opts;
	int rc;

	rc = get_linux_shareopts(shareopts, &linux_opts);

	if (rc != SA_OK)
		return rc;

	free(linux_opts);

	return SA_OK;
}

/*
 * TODO: Rather than invoking "exportfs -v" once for each share we should only
 * call it once for all shares.
 */
static boolean_t
is_share_active(sa_share_impl_t impl_share)
{
	pid_t pid;
	int rc, status;
	int pipes[2];
	FILE *exportfs_stdout;
	char line[512];
	char *tab, *cur;
	boolean_t share_active = B_FALSE;

	if (pipe(pipes) < 0)
		return B_FALSE;

	pid = fork();

	if (pid < 0)
		return B_FALSE;

	if (pid > 0) {
		share_active = B_FALSE;

		exportfs_stdout = fdopen(pipes[0], "r");
		close(pipes[1]);

		while (fgets(line, sizeof(line), exportfs_stdout) != NULL) {
			if (share_active)
				continue;

			/*
			 * exportfs uses separate lines for the share path
			 * and the export options when the share path is longer
			 * than a certain amount of characters; this ignores
			 * the option lines
			 */
			if (line[0] == '\t')
				continue;

			tab = strchr(line, '\t');

			if (tab != NULL) {
				*tab = '\0';
				cur = tab - 1;
			} else {
				/*
				 * there's no tab character, which means the
				 * NFS options are on a separate line; we just
				 * need to remove the new-line character
				 * at the end of the line
				 */
				cur = line + strlen(line) - 1;
			}

			/* remove trailing spaces and new-line characters */
			while (cur >= line &&
			    (*cur == ' ' || *cur == '\n'))
				*cur-- = '\0';

			if (strcmp(line, impl_share->sharepath) == 0) {
				share_active = B_TRUE;

				/*
				 * We can't break here just yet, otherwise
				 * exportfs might die due to write() failing
				 * with EPIPE once we've closed the pipe file
				 * descriptor - we need to read until EOF
				 * occurs on the stdout pipe.
				 */
			}
		}

		fclose(exportfs_stdout);

		while ((rc = waitpid(pid, &status, 0)) <= 0 && errno == EINTR)
			; /* empty loop body */

		if (rc <= 0)
			return B_FALSE;

		if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
			return B_FALSE;

		return share_active;
	}

	/* child */

	/* exportfs -v */

	close(pipes[0]);

	if (dup2(pipes[1], STDOUT_FILENO) < 0)
		exit(1);

	rc = execlp("/usr/sbin/exportfs", "exportfs", "-v", NULL);

	if (rc < 0) {
		exit(1);
	}

	exit(0);
}

static int
nfs_update_shareopts(sa_share_impl_t impl_share, const char *resource,
    const char *shareopts)
{
	char *shareopts_dup;
	boolean_t needs_reshare = B_FALSE;
	char *old_shareopts;

	FSINFO(impl_share, nfs_fstype)->active = is_share_active(impl_share);

	old_shareopts = FSINFO(impl_share, nfs_fstype)->shareopts;

	if (strcmp(shareopts, "on") == 0)
		shareopts = "rw";

	if (FSINFO(impl_share, nfs_fstype)->active && old_shareopts != NULL &&
	    strcmp(old_shareopts, shareopts) != 0) {
		needs_reshare = B_TRUE;
		nfs_disable_share(impl_share);
	}

	shareopts_dup = strdup(shareopts);

	if (shareopts_dup == NULL)
		return SA_NO_MEMORY;

	if (old_shareopts != NULL)
		free(old_shareopts);

	FSINFO(impl_share, nfs_fstype)->shareopts = shareopts_dup;

	if (needs_reshare)
		nfs_enable_share(impl_share);

	return SA_OK;
}


static void
nfs_clear_shareopts(sa_share_impl_t impl_share)
{
	free(FSINFO(impl_share, nfs_fstype)->shareopts);
	FSINFO(impl_share, nfs_fstype)->shareopts = NULL;
}

static const sa_share_ops_t nfs_shareops = {
	.enable_share = nfs_enable_share,
	.disable_share = nfs_disable_share,

	.validate_shareopts = nfs_validate_shareopts,
	.update_shareopts = nfs_update_shareopts,
	.clear_shareopts = nfs_clear_shareopts,
};

static int
nfs_check_exportfs(void)
{
	pid_t pid;
	int rc, status, null_fd;

	pid = fork();

	if (pid < 0)
		return SA_SYSTEM_ERR;

	if (pid > 0) {
		while ((rc = waitpid(pid, &status, 0)) <= 0 && errno == EINTR)
			; /* empty loop body */

		if (rc <= 0)
			return SA_SYSTEM_ERR;

		if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
			return SA_CONFIG_ERR;

		return SA_OK;
	}

	/* child */

	null_fd = open("/dev/null", O_RDONLY);

	if (null_fd < 0 || dup2(null_fd, 1) < 0 || dup2(null_fd, 2) < 0)
		exit(1);

	close(null_fd);

	rc = execlp("/usr/sbin/exportfs", "exportfs", NULL);

	if (rc < 0) {
		exit(1);
	}

	exit(0);
}

void
libshare_nfs_init(void)
{
	nfs_available = (nfs_check_exportfs() == SA_OK);

	nfs_fstype = register_fstype("nfs", &nfs_shareops);
}