/*

 ** 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.

 */

 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 */