/*

** 2003 January 11

**

** The author disclaims copyright to this source code.  In place of

** a legal notice, here is a blessing:

**

**    May you do good and not evil.

**    May you find forgiveness for yourself and forgive others.

**    May you share freely, never taking more than you give.

**

*************************************************************************

** This file contains code used to implement the sqlite3_set_authorizer()

** API.  This facility is an optional feature of the library.  Embedded

** systems that do not need this facility may omit it by recompiling

** the library with -DSQLITE_OMIT_AUTHORIZATION=1

**

** $Id: auth.c,v 1.29 2007/09/18 15:55:07 drh Exp $

*/

#include "sqliteInt.h"

/*

** All of the code in this file may be omitted by defining a single

** macro.

*/

#ifndef SQLITE_OMIT_AUTHORIZATION

/*

** Set or clear the access authorization function.

**

** The access authorization function is be called during the compilation

** phase to verify that the user has read and/or write access permission on

** various fields of the database.  The first argument to the auth function

** is a copy of the 3rd argument to this routine.  The second argument

** to the auth function is one of these constants:

**

**       SQLITE_CREATE_INDEX

**       SQLITE_CREATE_TABLE

**       SQLITE_CREATE_TEMP_INDEX

**       SQLITE_CREATE_TEMP_TABLE

**       SQLITE_CREATE_TEMP_TRIGGER

**       SQLITE_CREATE_TEMP_VIEW

**       SQLITE_CREATE_TRIGGER

**       SQLITE_CREATE_VIEW

**       SQLITE_DELETE

**       SQLITE_DROP_INDEX

**       SQLITE_DROP_TABLE

**       SQLITE_DROP_TEMP_INDEX

**       SQLITE_DROP_TEMP_TABLE

**       SQLITE_DROP_TEMP_TRIGGER

**       SQLITE_DROP_TEMP_VIEW

**       SQLITE_DROP_TRIGGER

**       SQLITE_DROP_VIEW

**       SQLITE_INSERT

**       SQLITE_PRAGMA

**       SQLITE_READ

**       SQLITE_SELECT

**       SQLITE_TRANSACTION

**       SQLITE_UPDATE

**

** The third and fourth arguments to the auth function are the name of

** the table and the column that are being accessed.  The auth function

** should return either SQLITE_OK, SQLITE_DENY, or SQLITE_IGNORE.  If

** SQLITE_OK is returned, it means that access is allowed.  SQLITE_DENY

** means that the SQL statement will never-run - the sqlite3_exec() call

** will return with an error.  SQLITE_IGNORE means that the SQL statement

** should run but attempts to read the specified column will return NULL

** and attempts to write the column will be ignored.

**

** Setting the auth function to NULL disables this hook.  The default

** setting of the auth function is NULL.

*/

SQLITE_EXPORT int sqlite3_set_authorizer(

  sqlite3 *db,

  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),

  void *pArg

){

  sqlite3_mutex_enter(db->mutex);

  db->xAuth = xAuth;

  db->pAuthArg = pArg;

  sqlite3ExpirePreparedStatements(db);

  sqlite3_mutex_leave(db->mutex);

  return SQLITE_OK;

}

/*

** Write an error message into pParse->zErrMsg that explains that the

** user-supplied authorization function returned an illegal value.

*/

static void sqliteAuthBadReturnCode(Parse *pParse, int rc){

  sqlite3ErrorMsg(pParse, "illegal return value (%d) from the "

    "authorization function - should be SQLITE_OK, SQLITE_IGNORE, "

    "or SQLITE_DENY", rc);

  pParse->rc = SQLITE_ERROR;

}

/*

** The pExpr should be a TK_COLUMN expression.  The table referred to

** is in pTabList or else it is the NEW or OLD table of a trigger.  

** Check to see if it is OK to read this particular column.

**

** If the auth function returns SQLITE_IGNORE, change the TK_COLUMN 

** instruction into a TK_NULL.  If the auth function returns SQLITE_DENY,

** then generate an error.

*/

void sqlite3AuthRead(

  Parse *pParse,        /* The parser context */

  Expr *pExpr,          /* The expression to check authorization on */

  Schema *pSchema,      /* The schema of the expression */

  SrcList *pTabList     /* All table that pExpr might refer to */

){

  sqlite3 *db = pParse->db;

  int rc;

  Table *pTab = 0;      /* The table being read */

  const char *zCol;     /* Name of the column of the table */

  int iSrc;             /* Index in pTabList->a[] of table being read */

  const char *zDBase;   /* Name of database being accessed */

  TriggerStack *pStack; /* The stack of current triggers */

  int iDb;              /* The index of the database the expression refers to */

  if( db->xAuth==0 ) return;

  if( pExpr->op!=TK_COLUMN ) return;

  iDb = sqlite3SchemaToIndex(pParse->db, pSchema);

  if( iDb<0 ){

    /* An attempt to read a column out of a subquery or other

    ** temporary table. */

    return;

  }

  for(iSrc=0; pTabList && iSrc<pTabList->nSrc; iSrc++){

    if( pExpr->iTable==pTabList->a[iSrc].iCursor ) break;

  }

  if( iSrc>=0 && pTabList && iSrc<pTabList->nSrc ){

    pTab = pTabList->a[iSrc].pTab;

  }else if( (pStack = pParse->trigStack)!=0 ){

    /* This must be an attempt to read the NEW or OLD pseudo-tables

    ** of a trigger.

    */

    assert( pExpr->iTable==pStack->newIdx || pExpr->iTable==pStack->oldIdx );

    pTab = pStack->pTab;

  }

  if( pTab==0 ) return;

  if( pExpr->iColumn>=0 ){

    assert( pExpr->iColumn<pTab->nCol );

    zCol = pTab->aCol[pExpr->iColumn].zName;

  }else if( pTab->iPKey>=0 ){

    assert( pTab->iPKey<pTab->nCol );

    zCol = pTab->aCol[pTab->iPKey].zName;

  }else{

    zCol = "ROWID";

  }

  assert( iDb>=0 && iDb<db->nDb );

  zDBase = db->aDb[iDb].zName;

  rc = db->xAuth(db->pAuthArg, SQLITE_READ, pTab->zName, zCol, zDBase, 

                 pParse->zAuthContext);

  if( rc==SQLITE_IGNORE ){

    pExpr->op = TK_NULL;

  }else if( rc==SQLITE_DENY ){

    if( db->nDb>2 || iDb!=0 ){

      sqlite3ErrorMsg(pParse, "access to %s.%s.%s is prohibited", 

         zDBase, pTab->zName, zCol);

    }else{

      sqlite3ErrorMsg(pParse, "access to %s.%s is prohibited",pTab->zName,zCol);

    }

    pParse->rc = SQLITE_AUTH;

  }else if( rc!=SQLITE_OK ){

    sqliteAuthBadReturnCode(pParse, rc);

  }

}

/*

** Do an authorization check using the code and arguments given.  Return

** either SQLITE_OK (zero) or SQLITE_IGNORE or SQLITE_DENY.  If SQLITE_DENY

** is returned, then the error count and error message in pParse are

** modified appropriately.

*/

int sqlite3AuthCheck(

  Parse *pParse,

  int code,

  const char *zArg1,

  const char *zArg2,

  const char *zArg3

){

  sqlite3 *db = pParse->db;

  int rc;

  /* Don't do any authorization checks if the database is initialising

  ** or if the parser is being invoked from within sqlite3_declare_vtab.

  */

  if( db->init.busy || IN_DECLARE_VTAB ){

    return SQLITE_OK;

  }

  if( db->xAuth==0 ){

    return SQLITE_OK;

  }

  rc = db->xAuth(db->pAuthArg, code, zArg1, zArg2, zArg3, pParse->zAuthContext);

  if( rc==SQLITE_DENY ){

    sqlite3ErrorMsg(pParse, "not authorized");

    pParse->rc = SQLITE_AUTH;

  }else if( rc!=SQLITE_OK && rc!=SQLITE_IGNORE ){

    rc = SQLITE_DENY;

    sqliteAuthBadReturnCode(pParse, rc);

  }

  return rc;

}

/*

** Push an authorization context.  After this routine is called, the

** zArg3 argument to authorization callbacks will be zContext until

** popped.  Or if pParse==0, this routine is a no-op.

*/

void sqlite3AuthContextPush(

  Parse *pParse,

  AuthContext *pContext, 

  const char *zContext

){

  pContext->pParse = pParse;

  if( pParse ){

    pContext->zAuthContext = pParse->zAuthContext;

    pParse->zAuthContext = zContext;

  }

}

/*

** Pop an authorization context that was previously pushed

** by sqlite3AuthContextPush

*/

void sqlite3AuthContextPop(AuthContext *pContext){

  if( pContext->pParse ){

    pContext->pParse->zAuthContext = pContext->zAuthContext;

    pContext->pParse = 0;

  }

}

#endif /* SQLITE_OMIT_AUTHORIZATION */