** Author contact information:
**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*******************************************************************************
**
** This file contains code for generating the login and logout screens.
**
** Notes:
**
** There are two special-case user-ids: "anonymous" and "nobody".
** The capabilities of the nobody user are available to anyone,
** regardless of whether or not they are logged in.  The capabilities
** of anonymous are only available after logging in, but the login
** screen displays the password for the anonymous login, so this
** should not prevent a human user from doing so.
**
** The nobody user has capabilities that you want spiders to have.
** The anonymous user has capabilities that you want people without
** logins to have.
**
** Of course, a sophisticated spider could easily circumvent the
** anonymous login requirement and walk the website.  But that is
** not really the point.  The anonymous login keeps search-engine
** crawlers and site download tools like wget from walking change
** logs and downloading diffs of very version of the archive that
** has ever existed, and things like that.
*/
#include "config.h"
#include "login.h"
#include <time.h>

/*
** Return the name of the login cookie

** WEBPAGE: /logout
**
** Generate the login page
*/
void login_page(void){
  const char *zUsername, *zPasswd, *zGoto;
  const char *zNew1, *zNew2;
  const char *zAnonPw;
  char *zErrMsg = "";

  login_check_credentials();
  zUsername = P("u");
  zPasswd = P("p");
  zGoto = PD("g","index");
  if( P("out")!=0 ){
    const char *zCookieName = login_cookie_name();
    cgi_set_cookie(zCookieName, "", 0, -86400);
    cgi_redirect(zGoto);
  }
  if( g.okPassword && zPasswd && (zNew1 = P("n1"))!=0 && (zNew2 = P("n2"))!=0 ){
    if( db_int(1, "SELECT 0 FROM user"
                  " WHERE uid=%d AND pw=%Q", g.userUid, zPasswd) ){
      sleep(1);
      zErrMsg = 
         @ <p><font color="red">
         @ You entered an incorrect old password while attempting to change
         @ your password.  Your password is unchanged.

      db_multi_exec(
         "UPDATE user SET pw=%Q WHERE uid=%d", zNew1, g.userUid
      );
      cgi_redirect("index");
      return;
    }
  }
  if( zUsername!=0 && zPasswd!=0 ){
    int uid = db_int(0,
        "SELECT uid FROM user"
        " WHERE login=%Q AND pw=%Q", zUsername, zPasswd);
    if( uid<=0 || strcmp(zUsername,"nobody")==0 ){
      sleep(1);
      zErrMsg = 
         @ <p><font color="red">
         @ You entered an unknown user or an incorrect password.
         @ </font></p>
      ;
    }else{
      char *zCookie;
      const char *zCookieName = login_cookie_name();

      const char *zExpire = db_get("cookie-expire","8766");
      int expires = atoi(zExpire)*3600;
      const char *zIpAddr = PD("REMOTE_ADDR","nil");
 
      if( strcmp(zUsername, "anonymous")==0 ){
        cgi_set_cookie(zCookieName, "anonymous", 0, expires);
      }else{
        zCookie = db_text(0, "SELECT '%d/' || hex(randomblob(25))", uid);

        cgi_set_cookie(zCookieName, zCookie, 0, expires);
        db_multi_exec(
          "UPDATE user SET cookie=%Q, ipaddr=%Q, "
          "  cexpire=julianday('now')+%d/86400.0 WHERE uid=%d",
          zCookie, zIpAddr, expires, uid
        );
      }
      cgi_redirect(zGoto);
    }
  }
  style_header("Login/Logout");
  @ %s(zErrMsg)
  @ <form action="login" method="POST">
  if( P("g") ){

  @   <td><input type="password" name="p" value="" size=30></td>
  @ </tr>
  @ <tr>
  @   <td></td>
  @   <td><input type="submit" name="in" value="Login"></td>
  @ </tr>
  @ </table>
  if( g.zLogin==0 ){
    @ <p>To login
  }else{
    @ <p>You are current logged in as <b>%h(g.zLogin)</b></p>
    @ <p>To change your login to a different user
  }
  @ enter the user-id and password at the left and press the
  @ "Login" button.  Your user name will be stored in a browser cookie.
  @ You must configure your web browser to accept cookies in order for
  @ the login to take.</p>
  if( g.zLogin==0 ){
    zAnonPw = db_text(0, "SELECT pw FROM user"
                         " WHERE login='anonymous'"

                         "   AND cap!=''");
    if( zAnonPw ){
      @ <p>If you do not have a user-id, enter "<b>anonymous</b>" with a
      @ password of "<b>%h(zAnonPw)</b>".</p>
    }else{
      @ <p>A valid user-id and password is required.  Anonymous access
      @ is not allowed on this installation.</p>
    }
  }
  if( g.zLogin ){
    @ <br clear="both"><hr>
    @ <p>To log off the system (and delete your login cookie)
    @  press the following button:<br>
    @ <input type="submit" name="out" value="Logout"></p>
  }
  @ </form>
  if( g.okPassword ){
    @ <br clear="both"><hr>
    @ <p>To change your password, enter your old password and your
    @ new password twice below then press the "Change Password"
    @ button.</p>
    @ <form action="login" method="POST">
    @ <table>
    @ <tr><td align="right">Old Password:</td>

void login_check_credentials(void){
  int uid = 0;
  const char *zCookie;
  const char *zRemoteAddr;
  const char *zCap = 0;

  /* Only run this check once.  */
  if( g.userUid!=0 ) return;


  /* If the HTTP connection is coming over 127.0.0.1 and if
  ** local login is disabled, then there is no need to check
  ** user credentials.
  */
  zRemoteAddr = PD("REMOTE_ADDR","nil");
  if( strcmp(zRemoteAddr, "127.0.0.1")==0
        && db_get_int("authenticate-localhost",1)==0 ){
    uid = db_int(0, "SELECT uid FROM user WHERE cap LIKE '%%s%%'");
    g.zLogin = db_text("?", "SELECT login FROM user WHERE uid=%d", uid);
    zCap = "s";
    g.noPswd = 1;

  }

  /* Check the login cookie to see if it matches a known valid user.
  */

  if( uid==0 && (zCookie = P(login_cookie_name()))!=0 ){
    if( isdigit(zCookie[0]) ){
      uid = db_int(0, 
            "SELECT uid FROM user"
            " WHERE uid=%d"
            "   AND cookie=%Q"
            "   AND ipaddr=%Q"
            "   AND cexpire>julianday('now')",
            atoi(zCookie), zCookie, zRemoteAddr
         );
    }else if( zCookie[0]=='a' ){
      uid = db_int(0, "SELECT uid FROM user WHERE login='anonymous'");
    }
  }

  if( uid==0 ){
    uid = db_int(0, "SELECT uid FROM user WHERE login='nobody'");
    if( uid==0 ){
      uid = -1;
      zCap = "";
    }
  }
  if( zCap==0 ){
    if( uid ){
      Stmt s;
      db_prepare(&s, "SELECT login, cap FROM user WHERE uid=%d", uid);
      db_step(&s);
      g.zLogin = db_column_malloc(&s, 0);
      zCap = db_column_malloc(&s, 1);

      db_finalize(&s);
    }
    if( zCap==0 ){
      zCap = "";
    }
  }
  g.userUid = uid;
  login_set_capabilities(zCap);
}

/*
** Set the global capability flags based on a capability string.
*/
void login_set_capabilities(const char *zCap){