/*
   * linux/fs/nfs/nfs4namespace.c
   *
   * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>

   * - Modified by David Howells <dhowells@redhat.com>

   *
   * NFSv4 namespace
   */

  #include <linux/dcache.h>
  #include <linux/mount.h>
  #include <linux/namei.h>
  #include <linux/nfs_fs.h>

  #include <linux/slab.h>

  #include <linux/string.h>
  #include <linux/sunrpc/clnt.h>
  #include <linux/vfs.h>
  #include <linux/inet.h>
  #include "internal.h"

  #include "nfs4_fs.h"

  #include "dns_resolve.h"

  
  #define NFSDBG_FACILITY		NFSDBG_VFS
  
  /*

   * Convert the NFSv4 pathname components into a standard posix path.
   *
   * Note that the resulting string will be placed at the end of the buffer

   */

  static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,

  					 char *buffer, ssize_t buflen)
  {
  	char *end = buffer + buflen;
  	int n;
  
  	*--end = '\0';
  	buflen--;
  
  	n = pathname->ncomponents;
  	while (--n >= 0) {

  		const struct nfs4_string *component = &pathname->components[n];

  		buflen -= component->len + 1;
  		if (buflen < 0)
  			goto Elong;
  		end -= component->len;
  		memcpy(end, component->data, component->len);
  		*--end = '/';
  	}
  	return end;
  Elong:
  	return ERR_PTR(-ENAMETOOLONG);
  }

  /*
   * Determine the mount path as a string
   */

  static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)

  {

  	char *limit;
  	char *path = nfs_path(&limit, dentry, buffer, buflen);
  	if (!IS_ERR(path)) {
  		char *colon = strchr(path, ':');
  		if (colon && colon < limit)
  			path = colon + 1;
  	}
  	return path;

  }
  
  /*
   * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
   * believe to be the server path to this dentry
   */

  static int nfs4_validate_fspath(struct dentry *dentry,

  				const struct nfs4_fs_locations *locations,
  				char *page, char *page2)
  {
  	const char *path, *fs_path;

  	path = nfs4_path(dentry, page, PAGE_SIZE);

  	if (IS_ERR(path))
  		return PTR_ERR(path);
  
  	fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
  	if (IS_ERR(fs_path))
  		return PTR_ERR(fs_path);
  
  	if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
  		dprintk("%s: path %s does not begin with fsroot %s
  ",

  			__func__, path, fs_path);

  		return -ENOENT;
  	}
  
  	return 0;
  }

  static size_t nfs_parse_server_name(char *string, size_t len,
  		struct sockaddr *sa, size_t salen)
  {
  	ssize_t ret;
  
  	ret = rpc_pton(string, len, sa, salen);
  	if (ret == 0) {
  		ret = nfs_dns_resolve_name(string, len, sa, salen);
  		if (ret < 0)
  			ret = 0;
  	}
  	return ret;
  }

  static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
  				     char *page, char *page2,
  				     const struct nfs4_fs_location *location)
  {

  	const size_t addr_bufsize = sizeof(struct sockaddr_storage);

  	struct vfsmount *mnt = ERR_PTR(-ENOENT);
  	char *mnt_path;

  	unsigned int maxbuflen;

  	unsigned int s;

  
  	mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
  	if (IS_ERR(mnt_path))

  		return ERR_CAST(mnt_path);

  	mountdata->mnt_path = mnt_path;

  	maxbuflen = mnt_path - 1 - page2;

  	mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
  	if (mountdata->addr == NULL)
  		return ERR_PTR(-ENOMEM);

  	for (s = 0; s < location->nservers; s++) {

  		const struct nfs4_string *buf = &location->servers[s];

  		if (buf->len <= 0 || buf->len >= maxbuflen)

  			continue;

  		if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
  			continue;

  
  		mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,

  				mountdata->addr, addr_bufsize);

  		if (mountdata->addrlen == 0)

  			continue;

  		rpc_set_port(mountdata->addr, NFS_PORT);

  		memcpy(page2, buf->data, buf->len);
  		page2[buf->len] = '\0';

  		mountdata->hostname = page2;

  
  		snprintf(page, PAGE_SIZE, "%s:%s",
  				mountdata->hostname,
  				mountdata->mnt_path);
  
  		mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
  		if (!IS_ERR(mnt))
  			break;

  	}

  	kfree(mountdata->addr);

  	return mnt;
  }

  /**
   * nfs_follow_referral - set up mountpoint when hitting a referral on moved error

   * @dentry - parent directory

   * @locations - array of NFSv4 server location information

   *
   */

  static struct vfsmount *nfs_follow_referral(struct dentry *dentry,

  					    const struct nfs4_fs_locations *locations)

  {
  	struct vfsmount *mnt = ERR_PTR(-ENOENT);
  	struct nfs_clone_mount mountdata = {

  		.sb = dentry->d_sb,

  		.dentry = dentry,

  		.authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,

  	};

  	char *page = NULL, *page2 = NULL;

  	int loc, error;

  
  	if (locations == NULL || locations->nlocations <= 0)
  		goto out;

  	dprintk("%s: referral at %s/%s
  ", __func__,

  		dentry->d_parent->d_name.name, dentry->d_name.name);

  	page = (char *) __get_free_page(GFP_USER);

  	if (!page)

  		goto out;

  	page2 = (char *) __get_free_page(GFP_USER);

  	if (!page2)

  		goto out;

  	/* Ensure fs path is a prefix of current dentry path */

  	error = nfs4_validate_fspath(dentry, locations, page, page2);

  	if (error < 0) {
  		mnt = ERR_PTR(error);
  		goto out;

  	}

  	for (loc = 0; loc < locations->nlocations; loc++) {

  		const struct nfs4_fs_location *location = &locations->locations[loc];

  
  		if (location == NULL || location->nservers <= 0 ||

  		    location->rootpath.ncomponents == 0)

  			continue;

  		mnt = try_location(&mountdata, page, page2, location);
  		if (!IS_ERR(mnt))
  			break;

  	}

  out:

  	free_page((unsigned long) page);
  	free_page((unsigned long) page2);

  	dprintk("%s: done
  ", __func__);

  	return mnt;
  }
  
  /*
   * nfs_do_refmount - handle crossing a referral on server
   * @dentry - dentry of referral

   *
   */

  struct vfsmount *nfs_do_refmount(struct dentry *dentry)

  {

  	struct vfsmount *mnt = ERR_PTR(-ENOMEM);

  	struct dentry *parent;
  	struct nfs4_fs_locations *fs_locations = NULL;
  	struct page *page;
  	int err;
  
  	/* BUG_ON(IS_ROOT(dentry)); */

  	dprintk("%s: enter
  ", __func__);

  
  	page = alloc_page(GFP_KERNEL);
  	if (page == NULL)
  		goto out;
  
  	fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
  	if (fs_locations == NULL)
  		goto out_free;
  
  	/* Get locations */

  	mnt = ERR_PTR(-ENOENT);

  	parent = dget_parent(dentry);

  	dprintk("%s: getting locations for %s/%s
  ",

  		__func__, parent->d_name.name, dentry->d_name.name);

  	err = nfs4_proc_fs_locations(parent->d_inode, &dentry->d_name, fs_locations, page);

  	dput(parent);

  	if (err != 0 ||
  	    fs_locations->nlocations <= 0 ||

  	    fs_locations->fs_path.ncomponents <= 0)
  		goto out_free;

  	mnt = nfs_follow_referral(dentry, fs_locations);

  out_free:
  	__free_page(page);
  	kfree(fs_locations);
  out:

  	dprintk("%s: done
  ", __func__);

  	return mnt;
  }