Quelle  xbsconst.c   Sprache: C

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * X.509 v3 Basic Constraints Extension
 */

#include "prtypes.h"
#include <limits.h> /* for LONG_MAX */
#include "seccomon.h"
#include "secdert.h"
#include "secoidt.h"
#include "secasn1t.h"
#include "secasn1.h"
#include "certt.h"
#include "secder.h"
#include "prprf.h"
#include "secerr.h"

typedef struct EncodedContext {
    SECItem isCA;
    SECItem pathLenConstraint;
    SECItem encodedValue;
    PLArenaPool *arena;
} EncodedContext;

static const SEC_ASN1Template CERTBasicConstraintsTemplate[] = {
    { SEC_ASN1_SEQUENCE, 0, NULL, sizeof(EncodedContext) },
    { SEC_ASN1_OPTIONAL | SEC_ASN1_BOOLEAN, /* XXX DER_DEFAULT */
      offsetof(EncodedContext, isCA) },
    { SEC_ASN1_OPTIONAL | SEC_ASN1_INTEGER,
      offsetof(EncodedContext, pathLenConstraint) },
    { 0 }
};

static unsigned char hexTrue = 0xff;
static unsigned char hexFalse = 0x00;

#define GEN_BREAK(status) \
    rv = status;          \
    break;

SECStatus
CERT_EncodeBasicConstraintValue(PLArenaPool *arena, CERTBasicConstraints *value,
                                SECItem *encodedValue)
{
    EncodedContext encodeContext;
    PLArenaPool *our_pool = NULL;
    SECStatus rv = SECSuccess;

    do {
        PORT_Memset(&encodeContext, 0, sizeof(encodeContext));
        if (!value->isCA && value->pathLenConstraint >= 0) {
            PORT_SetError(SEC_ERROR_EXTENSION_VALUE_INVALID);
            GEN_BREAK(SECFailure);
        }

        encodeContext.arena = arena;
        if (value->isCA == PR_TRUE) {
            encodeContext.isCA.data = &hexTrue;
            encodeContext.isCA.len = 1;
        }

        /* If the pathLenConstraint is less than 0, then it should be
         * omitted from the encoding.
         */
        if (value->isCA && value->pathLenConstraint >= 0) {
            our_pool = PORT_NewArena(SEC_ASN1_DEFAULT_ARENA_SIZE);
            if (our_pool == NULL) {
                PORT_SetError(SEC_ERROR_NO_MEMORY);
                GEN_BREAK(SECFailure);
            }
            if (SEC_ASN1EncodeUnsignedInteger(
                    our_pool, &encodeContext.pathLenConstraint,
                    (unsigned long)value->pathLenConstraint) == NULL) {
                PORT_SetError(SEC_ERROR_NO_MEMORY);
                GEN_BREAK(SECFailure);
            }
        }
        if (SEC_ASN1EncodeItem(arena, encodedValue, &encodeContext,
                               CERTBasicConstraintsTemplate) == NULL) {
            GEN_BREAK(SECFailure);
        }
    } while (0);
    if (our_pool)
        PORT_FreeArena(our_pool, PR_FALSE);
    return (rv);
}

SECStatus
CERT_DecodeBasicConstraintValue(CERTBasicConstraints *value,
                                const SECItem *encodedValue)
{
    EncodedContext decodeContext;
    PORTCheapArenaPool tmpArena;
    SECStatus rv = SECSuccess;

    do {
        PORT_Memset(&decodeContext, 0, sizeof(decodeContext));
        /* initialize the value just in case we got "0x30 00", or when the
           pathLenConstraint is omitted.
         */
        decodeContext.isCA.data = &hexFalse;
        decodeContext.isCA.len = 1;

        PORT_InitCheapArena(&tmpArena, SEC_ASN1_DEFAULT_ARENA_SIZE);

        rv = SEC_QuickDERDecodeItem(&tmpArena.arena, &decodeContext,
                                    CERTBasicConstraintsTemplate, encodedValue);
        if (rv == SECFailure)
            break;

        value->isCA = decodeContext.isCA.data
                          ? (PRBool)(decodeContext.isCA.data[0] != 0)
                          : PR_FALSE;
        if (decodeContext.pathLenConstraint.data == NULL) {
            /* if the pathLenConstraint is not encoded, and the current setting
              is CA, then the pathLenConstraint should be set to a negative
              number
              for unlimited certificate path.
             */
            if (value->isCA) {
                value->pathLenConstraint = CERT_UNLIMITED_PATH_CONSTRAINT;
            } else {
                value->pathLenConstraint = 0;
            }
        } else if (value->isCA) {
            long len = DER_GetInteger(&decodeContext.pathLenConstraint);
            if (len < 0 || len == LONG_MAX) {
                PORT_SetError(SEC_ERROR_BAD_DER);
                GEN_BREAK(SECFailure);
            }
            value->pathLenConstraint = len;
        } else {
            /* here we get an error where the subject is not a CA, but
               the pathLenConstraint is set */
            PORT_SetError(SEC_ERROR_BAD_DER);
            GEN_BREAK(SECFailure);
            break;
        }
    } while (0);

    PORT_DestroyCheapArena(&tmpArena);
    return (rv);
}