/*
* Key Derivation Function (KDF) Module
*
* Provides commands to derive keys.
*
* Copyright (C) 2023 Brian O'Hagan
*
*/
#include "tlsInt.h"
#include "tclOpts.h"
#include <openssl/rand.h>
/*******************************************************************/
/* Options for Random commands */
static const char *command_opts [] = {
"-private", NULL};
enum _command_opts {
_opt_private
};
/*
*-------------------------------------------------------------------
*
* RAND_Random --
*
* Generate random byes using a random bytes using a cryptographically
* secure pseudo random generator (CSPRNG).
*
* Returns:
* TCL_OK or TCL_ERROR
*
* Side effects:
* Sets result to the random bytes, or an error message
*
*-------------------------------------------------------------------
*/
static int RAND_Random(ClientData clientData, Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]) {
int out_len = 0, res;
unsigned char *out_buf;
Tcl_Obj *resultObj;
(void) clientData;
dprintf("Called");
/* Clear errors */
Tcl_ResetResult(interp);
ERR_clear_error();
/* Validate arg count */
if (objc < 2 || objc > 3) {
Tcl_WrongNumArgs(interp, 1, objv, "?-private? length");
return TCL_ERROR;
} else if (objc == 3) {
Tcl_Size fn;
if (Tcl_GetIndexFromObj(interp, objv[1], command_opts, "option", 0, &fn) != TCL_OK) {
return TCL_ERROR;
}
}
/* Get length */
if (Tcl_GetIntFromObj(interp, objv[objc - 1], &out_len) != TCL_OK) {
return TCL_ERROR;
}
if (out_len < 0) {
Tcl_SetObjResult(interp, Tcl_ObjPrintf("bad count \"%d\": must be integer >= 0", out_len));
return TCL_ERROR;
}
/* Allocate storage for result */
resultObj = Tcl_NewObj();
out_buf = Tcl_SetByteArrayLength(resultObj, (Tcl_Size) out_len);
if (resultObj == NULL || out_buf == NULL) {
Tcl_AppendResult(interp, "Memory allocation error", (char *) NULL);
Tcl_DecrRefCount(resultObj);
return TCL_ERROR;
}
/* Get random bytes */
if (objc == 2) {
res = RAND_bytes(out_buf, out_len);
} else {
res = RAND_priv_bytes(out_buf, out_len);
}
if (!res) {
Tcl_AppendResult(interp, "Generate failed: ", GET_ERR_REASON(), (char *) NULL);
Tcl_DecrRefCount(resultObj);
return TCL_ERROR;
}
Tcl_SetObjResult(interp, resultObj);
return TCL_OK;
}
/*
*-------------------------------------------------------------------
*
* Tls_RandCommands --
*
* Create key commands
*
* Returns:
* TCL_OK or TCL_ERROR
*
* Side effects:
* Creates commands
*
*-------------------------------------------------------------------
*/
int Tls_RandCommands(Tcl_Interp *interp) {
Tcl_CreateObjCommand(interp, "tls::random", RAND_Random, (ClientData) NULL, (Tcl_CmdDeleteProc *) NULL);
return TCL_OK;
}