/*+
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** 2003 January 11+
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**+
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** The author disclaims copyright to this source code.  In place of+
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** a legal notice, here is a blessing:+
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**+
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**    May you do good and not evil.+
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**    May you find forgiveness for yourself and forgive others.+
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**    May you share freely, never taking more than you give.+
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**+
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*************************************************************************+
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** This file contains code used to implement the sqlite3_set_authorizer()+
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** API.  This facility is an optional feature of the library.  Embedded+
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** systems that do not need this facility may omit it by recompiling+
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** the library with -DSQLITE_OMIT_AUTHORIZATION=1+
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**+
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** $Id: auth.cpp 1282 2008-11-13 09:31:33Z LarsPson $+
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*/+
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#include "sqliteInt.h"+
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+
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/*+
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** All of the code in this file may be omitted by defining a single+
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** macro.+
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*/+
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#ifndef SQLITE_OMIT_AUTHORIZATION+
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+
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/*+
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** Set or clear the access authorization function.+
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**+
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** The access authorization function is be called during the compilation+
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** phase to verify that the user has read and/or write access permission on+
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** various fields of the database.  The first argument to the auth function+
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** is a copy of the 3rd argument to this routine.  The second argument+
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** to the auth function is one of these constants:+
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**+
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**       SQLITE_CREATE_INDEX+
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**       SQLITE_CREATE_TABLE+
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**       SQLITE_CREATE_TEMP_INDEX+
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**       SQLITE_CREATE_TEMP_TABLE+
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**       SQLITE_CREATE_TEMP_TRIGGER+
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**       SQLITE_CREATE_TEMP_VIEW+
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**       SQLITE_CREATE_TRIGGER+
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**       SQLITE_CREATE_VIEW+
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**       SQLITE_DELETE+
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**       SQLITE_DROP_INDEX+
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**       SQLITE_DROP_TABLE+
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**       SQLITE_DROP_TEMP_INDEX+
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**       SQLITE_DROP_TEMP_TABLE+
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**       SQLITE_DROP_TEMP_TRIGGER+
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**       SQLITE_DROP_TEMP_VIEW+
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**       SQLITE_DROP_TRIGGER+
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**       SQLITE_DROP_VIEW+
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**       SQLITE_INSERT+
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**       SQLITE_PRAGMA+
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**       SQLITE_READ+
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**       SQLITE_SELECT+
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**       SQLITE_TRANSACTION+
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**       SQLITE_UPDATE+
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**+
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** The third and fourth arguments to the auth function are the name of+
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** the table and the column that are being accessed.  The auth function+
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** should return either SQLITE_OK, SQLITE_DENY, or SQLITE_IGNORE.  If+
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** SQLITE_OK is returned, it means that access is allowed.  SQLITE_DENY+
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** means that the SQL statement will never-run - the sqlite3_exec() call+
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** will return with an error.  SQLITE_IGNORE means that the SQL statement+
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** should run but attempts to read the specified column will return NULL+
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** and attempts to write the column will be ignored.+
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**+
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** Setting the auth function to NULL disables this hook.  The default+
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** setting of the auth function is NULL.+
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*/+
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EXPORT_C int sqlite3_set_authorizer(+
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  sqlite3 *db,+
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  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),+
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  void *pArg+
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){+
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  sqlite3_mutex_enter(db->mutex);+
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  db->xAuth = xAuth;+
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  db->pAuthArg = pArg;+
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  sqlite3ExpirePreparedStatements(db);+
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  sqlite3_mutex_leave(db->mutex);+
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  return SQLITE_OK;+
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}+
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+
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/*+
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** Write an error message into pParse->zErrMsg that explains that the+
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** user-supplied authorization function returned an illegal value.+
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*/+
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static void sqliteAuthBadReturnCode(Parse *pParse, int rc){+
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  sqlite3ErrorMsg(pParse, "illegal return value (%d) from the "+
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    "authorization function - should be SQLITE_OK, SQLITE_IGNORE, "+
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    "or SQLITE_DENY", rc);+
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  pParse->rc = SQLITE_ERROR;+
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}+
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+
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/*+
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** The pExpr should be a TK_COLUMN expression.  The table referred to+
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** is in pTabList or else it is the NEW or OLD table of a trigger.  +
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** Check to see if it is OK to read this particular column.+
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**+
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** If the auth function returns SQLITE_IGNORE, change the TK_COLUMN +
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** instruction into a TK_NULL.  If the auth function returns SQLITE_DENY,+
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** then generate an error.+
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*/+
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void sqlite3AuthRead(+
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  Parse *pParse,        /* The parser context */+
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  Expr *pExpr,          /* The expression to check authorization on */+
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  Schema *pSchema,      /* The schema of the expression */+
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  SrcList *pTabList     /* All table that pExpr might refer to */+
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){+
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  sqlite3 *db = pParse->db;+
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  int rc;+
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  Table *pTab = 0;      /* The table being read */+
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  const char *zCol;     /* Name of the column of the table */+
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  int iSrc;             /* Index in pTabList->a[] of table being read */+
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  const char *zDBase;   /* Name of database being accessed */+
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  TriggerStack *pStack; /* The stack of current triggers */+
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  int iDb;              /* The index of the database the expression refers to */+
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+
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  if( db->xAuth==0 ) return;+
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  if( pExpr->op!=TK_COLUMN ) return;+
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  iDb = sqlite3SchemaToIndex(pParse->db, pSchema);+
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  if( iDb<0 ){+
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    /* An attempt to read a column out of a subquery or other+
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    ** temporary table. */+
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    return;+
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  }+
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  for(iSrc=0; pTabList && iSrc<pTabList->nSrc; iSrc++){+
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    if( pExpr->iTable==pTabList->a[iSrc].iCursor ) break;+
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  }+
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  if( iSrc>=0 && pTabList && iSrc<pTabList->nSrc ){+
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    pTab = pTabList->a[iSrc].pTab;+
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  }else if( (pStack = pParse->trigStack)!=0 ){+
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    /* This must be an attempt to read the NEW or OLD pseudo-tables+
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    ** of a trigger.+
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    */+
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    assert( pExpr->iTable==pStack->newIdx || pExpr->iTable==pStack->oldIdx );+
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    pTab = pStack->pTab;+
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  }+
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  if( pTab==0 ) return;+
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  if( pExpr->iColumn>=0 ){+
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    assert( pExpr->iColumn<pTab->nCol );+
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    zCol = pTab->aCol[pExpr->iColumn].zName;+
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  }else if( pTab->iPKey>=0 ){+
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    assert( pTab->iPKey<pTab->nCol );+
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    zCol = pTab->aCol[pTab->iPKey].zName;+
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  }else{+
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    zCol = "ROWID";+
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  }+
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  assert( iDb>=0 && iDb<db->nDb );+
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  zDBase = db->aDb[iDb].zName;+
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  rc = db->xAuth(db->pAuthArg, SQLITE_READ, pTab->zName, zCol, zDBase, +
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                 pParse->zAuthContext);+
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  if( rc==SQLITE_IGNORE ){+
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    pExpr->op = TK_NULL;+
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  }else if( rc==SQLITE_DENY ){+
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    if( db->nDb>2 || iDb!=0 ){+
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      sqlite3ErrorMsg(pParse, "access to %s.%s.%s is prohibited", +
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         zDBase, pTab->zName, zCol);+
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    }else{+
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      sqlite3ErrorMsg(pParse, "access to %s.%s is prohibited",pTab->zName,zCol);+
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    }+
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    pParse->rc = SQLITE_AUTH;+
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  }else if( rc!=SQLITE_OK ){+
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    sqliteAuthBadReturnCode(pParse, rc);+
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  }+
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}+
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+
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/*+
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** Do an authorization check using the code and arguments given.  Return+
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** either SQLITE_OK (zero) or SQLITE_IGNORE or SQLITE_DENY.  If SQLITE_DENY+
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** is returned, then the error count and error message in pParse are+
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** modified appropriately.+
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*/+
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int sqlite3AuthCheck(+
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  Parse *pParse,+
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  int code,+
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  const char *zArg1,+
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  const char *zArg2,+
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  const char *zArg3+
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){+
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  sqlite3 *db = pParse->db;+
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  int rc;+
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+
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  /* Don't do any authorization checks if the database is initialising+
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  ** or if the parser is being invoked from within sqlite3_declare_vtab.+
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  */+
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  if( db->init.busy || IN_DECLARE_VTAB ){+
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    return SQLITE_OK;+
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  }+
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+
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  if( db->xAuth==0 ){+
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    return SQLITE_OK;+
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  }+
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  rc = db->xAuth(db->pAuthArg, code, zArg1, zArg2, zArg3, pParse->zAuthContext);+
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  if( rc==SQLITE_DENY ){+
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    sqlite3ErrorMsg(pParse, "not authorized");+
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    pParse->rc = SQLITE_AUTH;+
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  }else if( rc!=SQLITE_OK && rc!=SQLITE_IGNORE ){+
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    rc = SQLITE_DENY;+
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    sqliteAuthBadReturnCode(pParse, rc);+
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  }+
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  return rc;+
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}+
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+
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/*+
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** Push an authorization context.  After this routine is called, the+
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** zArg3 argument to authorization callbacks will be zContext until+
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** popped.  Or if pParse==0, this routine is a no-op.+
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*/+
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void sqlite3AuthContextPush(+
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  Parse *pParse,+
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  AuthContext *pContext, +
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  const char *zContext+
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){+
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  pContext->pParse = pParse;+
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  if( pParse ){+
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    pContext->zAuthContext = pParse->zAuthContext;+
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    pParse->zAuthContext = zContext;+
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  }+
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}+
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+
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/*+
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** Pop an authorization context that was previously pushed+
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** by sqlite3AuthContextPush+
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*/+
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void sqlite3AuthContextPop(AuthContext *pContext){+
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  if( pContext->pParse ){+
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    pContext->pParse->zAuthContext = pContext->zAuthContext;+
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    pContext->pParse = 0;+
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  }+
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}+
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+
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#endif /* SQLITE_OMIT_AUTHORIZATION */+
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