/*
** 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
*/
#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
){
#ifdef SQLITE_ENABLE_API_ARMOR
 if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
#endif
 sqlite3_mutex_enter(db->mutex);
 db->xAuth = (sqlite3_xauth)xAuth;
 db->pAuthArg = pArg;
 if( db->xAuth ) sqlite3ExpirePreparedStatements(db, 1);
 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){
 sqlite3ErrorMsg(pParse, "authorizer malfunction");
 pParse->rc = SQLITE_ERROR;
}

/*
** Invoke the authorization callback for permission to read column zCol from
** table zTab in database zDb. This function assumes that an authorization
** callback has been registered (i.e. that sqlite3.xAuth is not NULL).
**
** If SQLITE_IGNORE is returned and pExpr is not NULL, then pExpr is changed
** to an SQL NULL expression. Otherwise, if pExpr is NULL, then SQLITE_IGNORE
** is treated as SQLITE_DENY. In this case an error is left in pParse.
*/
int sqlite3AuthReadCol(
 Parse *pParse, /* The parser context */
 const char *zTab, /* Table name */
 const char *zCol, /* Column name */
 int iDb /* Index of containing database. */
){
 sqlite3 *db = pParse->db; /* Database handle */
 char *zDb = db->aDb[iDb].zDbSName; /* Schema name of attached database */
 int rc; /* Auth callback return code */

 if( db->init.busy ) return SQLITE_OK;
 rc = db->xAuth(db->pAuthArg, SQLITE_READ, zTab,zCol,zDb,pParse->zAuthContext
#ifdef SQLITE_USER_AUTHENTICATION
 ,db->auth.zAuthUser
#endif
 );
 if( rc==SQLITE_DENY ){
 char *z = sqlite3_mprintf("%s.%s", zTab, zCol);
 if( db->nDb>2 || iDb!=0 ) z = sqlite3_mprintf("%s.%z", zDb, z);
 sqlite3ErrorMsg(pParse, "access to %z is prohibited", z);
 pParse->rc = SQLITE_AUTH;
 }else if( rc!=SQLITE_IGNORE && rc!=SQLITE_OK ){
 sqliteAuthBadReturnCode(pParse);
 }
 return rc;
}

/*
** 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 */
){
 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 */
 int iDb; /* The index of the database the expression refers to */
 int iCol; /* Index of column in table */

 assert( pExpr->op==TK_COLUMN || pExpr->op==TK_TRIGGER );
 assert( !IN_RENAME_OBJECT );
 assert( pParse->db->xAuth!=0 );
 iDb = sqlite3SchemaToIndex(pParse->db, pSchema);
 if( iDb<0 ){
 /* An attempt to read a column out of a subquery or other
 ** temporary table. */
 return;
 }

 if( pExpr->op==TK_TRIGGER ){
 pTab = pParse->pTriggerTab;
 }else{
 assert( pTabList );
 for(iSrc=0; iSrc<pTabList->nSrc; iSrc++){
 if( pExpr->iTable==pTabList->a[iSrc].iCursor ){
 pTab = pTabList->a[iSrc].pTab;
 break;
 }
 }
 }
 iCol = pExpr->iColumn;
 if( pTab==0 ) return;

 if( iCol>=0 ){
 assert( iCol<pTab->nCol );
 zCol = pTab->aCol[iCol].zCnName;
 }else if( pTab->iPKey>=0 ){
 assert( pTab->iPKey<pTab->nCol );
 zCol = pTab->aCol[pTab->iPKey].zCnName;
 }else{
 zCol = "ROWID";
 }
 assert( iDb>=0 && iDb<pParse->db->nDb );
 if( SQLITE_IGNORE==sqlite3AuthReadCol(pParse, pTab->zName, zCol, iDb) ){
 pExpr->op = TK_NULL;
 }
}

/*
** 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 initializing
 ** or if the parser is being invoked from within sqlite3_declare_vtab.
 */
 assert( !IN_RENAME_OBJECT || db->xAuth==0 );
 if( db->xAuth==0 || db->init.busy || IN_SPECIAL_PARSE ){
 return SQLITE_OK;
 }

 /* EVIDENCE-OF: R-43249-19882 The third through sixth parameters to the
 ** callback are either NULL pointers or zero-terminated strings that
 ** contain additional details about the action to be authorized.
 **
 ** The following testcase() macros show that any of the 3rd through 6th
 ** parameters can be either NULL or a string. */
 testcase( zArg1==0 );
 testcase( zArg2==0 );
 testcase( zArg3==0 );
 testcase( pParse->zAuthContext==0 );

 rc = db->xAuth(db->pAuthArg, code, zArg1, zArg2, zArg3, pParse->zAuthContext
#ifdef SQLITE_USER_AUTHENTICATION
 ,db->auth.zAuthUser
#endif
 );
 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);
 }
 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
){
 assert( pParse );
 pContext->pParse = 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 */