+static int check_revocation(X509_STORE_CTX *ctx)
+ {
+ int i, last, ok;
+ if (!(ctx->flags & X509_V_FLAG_CRL_CHECK))
+ return 1;
+ if (ctx->flags & X509_V_FLAG_CRL_CHECK_ALL)
+ last = 0;
+ else
+ last = sk_X509_num(ctx->chain) - 1;
+ for(i = 0; i <= last; i++)
+ {
+ ctx->error_depth = i;
+ ok = check_cert(ctx);
+ if (!ok) return ok;
+ }
+ return 1;
+ }
+
+static int check_cert(X509_STORE_CTX *ctx)
+ {
+ X509_CRL *crl = NULL;
+ X509 *x;
+ int ok, cnum;
+ cnum = ctx->error_depth;
+ x = sk_X509_value(ctx->chain, cnum);
+ ctx->current_cert = x;
+ /* Try to retrieve relevant CRL */
+ ok = ctx->get_crl(ctx, &crl, x);
+ /* If error looking up CRL, nothing we can do except
+ * notify callback
+ */
+ if(!ok)
+ {
+ ctx->error = X509_V_ERR_UNABLE_TO_GET_CRL;
+ ok = ctx->verify_cb(0, ctx);
+ goto err;
+ }
+ ctx->current_crl = crl;
+ ok = ctx->check_crl(ctx, crl);
+ if (!ok) goto err;
+ ok = ctx->cert_crl(ctx, crl, x);
+ err:
+ ctx->current_crl = NULL;
+ X509_CRL_free(crl);
+ return ok;
+
+ }
+
+/* Retrieve CRL corresponding to certificate: currently just a
+ * subject lookup: maybe use AKID later...
+ * Also might look up any included CRLs too (e.g PKCS#7 signedData).
+ */
+static int get_crl(X509_STORE_CTX *ctx, X509_CRL **crl, X509 *x)
+ {
+ int ok;
+ X509_OBJECT xobj;
+ ok = X509_STORE_get_by_subject(ctx, X509_LU_CRL, X509_get_issuer_name(x), &xobj);
+ if (!ok) return 0;
+ *crl = xobj.data.crl;
+ return 1;
+ }
+
+/* Check CRL validity */
+static int check_crl(X509_STORE_CTX *ctx, X509_CRL *crl)
+ {
+ X509 *issuer = NULL;
+ EVP_PKEY *ikey = NULL;
+ int ok = 0, chnum, cnum, i;
+ time_t *ptime;
+ cnum = ctx->error_depth;
+ chnum = sk_X509_num(ctx->chain) - 1;
+ /* Find CRL issuer: if not last certificate then issuer
+ * is next certificate in chain.
+ */
+ if(cnum < chnum)
+ issuer = sk_X509_value(ctx->chain, cnum + 1);
+ else
+ {
+ issuer = sk_X509_value(ctx->chain, chnum);
+ /* If not self signed, can't check signature */
+ if(!ctx->check_issued(ctx, issuer, issuer))
+ {
+ ctx->error = X509_V_ERR_UNABLE_TO_GET_CRL_ISSUER;
+ ok = ctx->verify_cb(0, ctx);
+ if(!ok) goto err;
+ }
+ }
+
+ if(issuer)
+ {
+
+ /* Attempt to get issuer certificate public key */
+ ikey = X509_get_pubkey(issuer);
+
+ if(!ikey)
+ {
+ ctx->error=X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY;
+ ok = ctx->verify_cb(0, ctx);
+ if (!ok) goto err;
+ }
+ else
+ {
+ /* Verify CRL signature */
+ if(X509_CRL_verify(crl, ikey) <= 0)
+ {
+ ctx->error=X509_V_ERR_CRL_SIGNATURE_FAILURE;
+ ok = ctx->verify_cb(0, ctx);
+ if (!ok) goto err;
+ }
+ }
+ }
+
+ /* OK, CRL signature valid check times */
+ if (ctx->flags & X509_V_FLAG_USE_CHECK_TIME)
+ ptime = &ctx->check_time;
+ else
+ ptime = NULL;
+
+ i=X509_cmp_time(X509_CRL_get_lastUpdate(crl), ptime);
+ if (i == 0)
+ {
+ ctx->error=X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD;
+ ok = ctx->verify_cb(0, ctx);
+ if (!ok) goto err;
+ }
+
+ if (i > 0)
+ {
+ ctx->error=X509_V_ERR_CRL_NOT_YET_VALID;
+ ok = ctx->verify_cb(0, ctx);
+ if (!ok) goto err;
+ }
+
+ if(X509_CRL_get_nextUpdate(crl))
+ {
+ i=X509_cmp_time(X509_CRL_get_nextUpdate(crl), ptime);
+
+ if (i == 0)
+ {
+ ctx->error=X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD;
+ ok = ctx->verify_cb(0, ctx);
+ if (!ok) goto err;
+ }
+
+ if (i < 0)
+ {
+ ctx->error=X509_V_ERR_CRL_HAS_EXPIRED;
+ ok = ctx->verify_cb(0, ctx);
+ if (!ok) goto err;
+ }
+ }
+
+ ok = 1;
+
+ err:
+ EVP_PKEY_free(ikey);
+ return ok;
+ }
+
+/* Check certificate against CRL */
+static int cert_crl(X509_STORE_CTX *ctx, X509_CRL *crl, X509 *x)
+ {
+ int idx, ok;
+ X509_REVOKED rtmp;
+ /* Look for serial number of certificate in CRL */
+ rtmp.serialNumber = X509_get_serialNumber(x);
+ idx = sk_X509_REVOKED_find(crl->crl->revoked, &rtmp);
+ /* Not found: OK */
+ if(idx == -1) return 1;
+ /* Otherwise revoked: want something cleverer than
+ * this to handle entry extensions in V2 CRLs.
+ */
+ ctx->error = X509_V_ERR_CERT_REVOKED;
+ ok = ctx->verify_cb(0, ctx);
+ return ok;
+ }
+