/* $OpenBSD$ */

/*

 * Copyright (c) 2021 Holland Schutte, Jayson Morberg

 * Copyright (c) 2021 Dallas Lyons <dallasdlyons@gmail.com>

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR

 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER

 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING

 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 */

#include <sys/types.h>

#include <sys/stat.h>

#include <sys/socket.h>

#include <ctype.h>

#include <pwd.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include "tmux.h"

struct server_acl_user {

  uid_t       uid;

  int       flags;

#define SERVER_ACL_READONLY 0x1

  RB_ENTRY(server_acl_user) entry;

};

static int

server_acl_cmp(struct server_acl_user *user1, struct server_acl_user *user2)

{

  if (user1->uid < user2->uid)

    return (-1);

  return (user1->uid > user2->uid);

}

RB_HEAD(server_acl_entries, server_acl_user) server_acl_entries;

RB_GENERATE_STATIC(server_acl_entries, server_acl_user, entry, server_acl_cmp);

/* Initialize server_acl tree. */

void

server_acl_init(void)

{

  RB_INIT(&server_acl_entries);

  if (getuid() != 0)

    server_acl_user_allow(0);

  server_acl_user_allow(getuid());

}

/* Find user entry. */

struct server_acl_user*

server_acl_user_find(uid_t uid)

{

  struct server_acl_user  find = { .uid = uid };

  return (RB_FIND(server_acl_entries, &server_acl_entries, &find));

}

/* Display the tree. */

void

server_acl_display(struct cmdq_item *item)

{

  struct server_acl_user  *loop;

  struct passwd   *pw;

  const char    *name;

  RB_FOREACH(loop, server_acl_entries, &server_acl_entries) {

    if (loop->uid == 0)

      continue;

    if ((pw = getpwuid(loop->uid)) != NULL)

      name = pw->pw_name;

    else

      name = "unknown";

    if (loop->flags == SERVER_ACL_READONLY)

      cmdq_print(item, "%s (R)", name);

    else

      cmdq_print(item, "%s (W)", name);

  }

}

/* Allow a user. */

void

server_acl_user_allow(uid_t uid)

{

  struct server_acl_user  *user;

  user = server_acl_user_find(uid);

  if (user == NULL) {

    user = xcalloc(1, sizeof *user);

    user->uid = uid;

    RB_INSERT(server_acl_entries, &server_acl_entries, user);

  }

}

/* Deny a user (remove from the tree). */

void

server_acl_user_deny(uid_t uid)

{

  struct server_acl_user  *user;

  user = server_acl_user_find(uid);

  if (user != NULL) {

    RB_REMOVE(server_acl_entries, &server_acl_entries, user);

    free(user);

  }

}

/* Allow this user write access. */

void

server_acl_user_allow_write(uid_t uid)

{

  struct server_acl_user  *user;

  struct client   *c;

  user = server_acl_user_find(uid);

  if (user == NULL)

    return;

  user->flags &= ~SERVER_ACL_READONLY;

  TAILQ_FOREACH(c, &clients, entry) {

    uid = proc_get_peer_uid(c->peer);

    if (uid != (uid_t)-1 && uid == user->uid)

      c->flags &= ~CLIENT_READONLY;

  }

}

/* Deny this user write access. */

void

server_acl_user_deny_write(uid_t uid)

{

  struct server_acl_user  *user;

  struct client   *c;

  user = server_acl_user_find(uid);

  if (user == NULL)

    return;

  user->flags |= SERVER_ACL_READONLY;

  TAILQ_FOREACH(c, &clients, entry) {

    uid = proc_get_peer_uid(c->peer);

    if (uid != (uid_t)-1 && uid == user->uid)

      c->flags |= CLIENT_READONLY;

  }

}

/*

 * Check if the client's UID exists in the ACL list and if so, set as read only

 * if needed. Return false if the user does not exist.

 */

int

server_acl_join(struct client *c)

{

  struct server_acl_user  *user;

  uid_t      uid;

  uid = proc_get_peer_uid(c->peer);

  if (uid == (uid_t)-1)

    return (0);

  user = server_acl_user_find(uid);

  if (user == NULL)

    return (0);

  if (user->flags & SERVER_ACL_READONLY)

    c->flags |= CLIENT_READONLY;

  return (1);

}

/* Get UID for user entry. */

uid_t

server_acl_get_uid(struct server_acl_user *user)

{

  return (user->uid);

}