ruby--ruby/ext/openssl/ossl_x509store.c

/*
 * 'OpenSSL for Ruby' project
 * Copyright (C) 2001-2002  Michal Rokos <m.rokos@sh.cvut.cz>
 * All rights reserved.
 */
/*
 * This program is licensed under the same licence as Ruby.
 * (See the file 'LICENCE'.)
 */
#include "ossl.h"

#define NewX509Store(klass) \
    TypedData_Wrap_Struct((klass), &ossl_x509store_type, 0)
#define SetX509Store(obj, st) do { \
    if (!(st)) { \
	ossl_raise(rb_eRuntimeError, "STORE wasn't initialized!"); \
    } \
    RTYPEDDATA_DATA(obj) = (st); \
} while (0)
#define GetX509Store(obj, st) do { \
    TypedData_Get_Struct((obj), X509_STORE, &ossl_x509store_type, (st)); \
    if (!(st)) { \
	ossl_raise(rb_eRuntimeError, "STORE wasn't initialized!"); \
    } \
} while (0)
#define SafeGetX509Store(obj, st) do { \
    OSSL_Check_Kind((obj), cX509Store); \
    GetX509Store((obj), (st)); \
} while (0)

#define NewX509StCtx(klass) \
    TypedData_Wrap_Struct((klass), &ossl_x509stctx_type, 0)
#define SetX509StCtx(obj, ctx) do { \
    if (!(ctx)) { \
	ossl_raise(rb_eRuntimeError, "STORE_CTX wasn't initialized!"); \
    } \
    RTYPEDDATA_DATA(obj) = (ctx); \
} while (0)
#define GetX509StCtx(obj, ctx) do { \
    TypedData_Get_Struct((obj), X509_STORE_CTX, &ossl_x509stctx_type, (ctx)); \
    if (!(ctx)) { \
	ossl_raise(rb_eRuntimeError, "STORE_CTX is out of scope!"); \
    } \
} while (0)
#define SafeGetX509StCtx(obj, storep) do { \
    OSSL_Check_Kind((obj), cX509StoreContext); \
    GetX509Store((obj), (ctx)); \
} while (0)

/*
 * Verify callback stuff
 */
static int stctx_ex_verify_cb_idx, store_ex_verify_cb_idx;
static VALUE ossl_x509stctx_new(X509_STORE_CTX *);

struct ossl_verify_cb_args {
    VALUE proc;
    VALUE preverify_ok;
    VALUE store_ctx;
};

static VALUE
call_verify_cb_proc(struct ossl_verify_cb_args *args)
{
    return rb_funcall(args->proc, rb_intern("call"), 2,
		      args->preverify_ok, args->store_ctx);
}

int
ossl_verify_cb_call(VALUE proc, int ok, X509_STORE_CTX *ctx)
{
    VALUE rctx, ret;
    struct ossl_verify_cb_args args;
    int state;

    if (NIL_P(proc))
	return ok;

    ret = Qfalse;
    rctx = rb_protect((VALUE(*)(VALUE))ossl_x509stctx_new, (VALUE)ctx, &state);
    if (state) {
	rb_set_errinfo(Qnil);
	rb_warn("StoreContext initialization failure");
    }
    else {
	args.proc = proc;
	args.preverify_ok = ok ? Qtrue : Qfalse;
	args.store_ctx = rctx;
	ret = rb_protect((VALUE(*)(VALUE))call_verify_cb_proc, (VALUE)&args, &state);
	if (state) {
	    rb_set_errinfo(Qnil);
	    rb_warn("exception in verify_callback is ignored");
	}
	RTYPEDDATA_DATA(rctx) = NULL;
    }
    if (ret == Qtrue) {
	X509_STORE_CTX_set_error(ctx, X509_V_OK);
	ok = 1;
    }
    else {
	if (X509_STORE_CTX_get_error(ctx) == X509_V_OK)
	    X509_STORE_CTX_set_error(ctx, X509_V_ERR_CERT_REJECTED);
	ok = 0;
    }

    return ok;
}

/*
 * Classes
 */
VALUE cX509Store;
VALUE cX509StoreContext;
VALUE eX509StoreError;

static void
ossl_x509store_free(void *ptr)
{
    X509_STORE_free(ptr);
}

static const rb_data_type_t ossl_x509store_type = {
    "OpenSSL/X509/STORE",
    {
	0, ossl_x509store_free,
    },
    0, 0, RUBY_TYPED_FREE_IMMEDIATELY,
};

/*
 * Public functions
 */
VALUE
ossl_x509store_new(X509_STORE *store)
{
    VALUE obj;

    obj = NewX509Store(cX509Store);
    SetX509Store(obj, store);

    return obj;
}

X509_STORE *
GetX509StorePtr(VALUE obj)
{
    X509_STORE *store;

    SafeGetX509Store(obj, store);

    return store;
}

X509_STORE *
DupX509StorePtr(VALUE obj)
{
    X509_STORE *store;

    SafeGetX509Store(obj, store);
    X509_STORE_up_ref(store);

    return store;
}

/*
 * Private functions
 */
static int
x509store_verify_cb(int ok, X509_STORE_CTX *ctx)
{
    VALUE proc;

    proc = (VALUE)X509_STORE_CTX_get_ex_data(ctx, stctx_ex_verify_cb_idx);
    if (!proc)
	proc = (VALUE)X509_STORE_get_ex_data(X509_STORE_CTX_get0_store(ctx),
					     store_ex_verify_cb_idx);
    if (!proc)
	return ok;

    return ossl_verify_cb_call(proc, ok, ctx);
}

static VALUE
ossl_x509store_alloc(VALUE klass)
{
    X509_STORE *store;
    VALUE obj;

    obj = NewX509Store(klass);
    if((store = X509_STORE_new()) == NULL){
        ossl_raise(eX509StoreError, NULL);
    }
    SetX509Store(obj, store);

    return obj;
}

/*
 * General callback for OpenSSL verify
 */
static VALUE
ossl_x509store_set_vfy_cb(VALUE self, VALUE cb)
{
    X509_STORE *store;

    GetX509Store(self, store);
    X509_STORE_set_ex_data(store, store_ex_verify_cb_idx, (void *)cb);
    rb_iv_set(self, "@verify_callback", cb);

    return cb;
}


/*
 * call-seq:
 *    X509::Store.new => store
 *
 * Creates a new X509::Store.
 */
static VALUE
ossl_x509store_initialize(int argc, VALUE *argv, VALUE self)
{
    X509_STORE *store;

/* BUG: This method takes any number of arguments but appears to ignore them. */
    GetX509Store(self, store);
#if !defined(HAVE_OPAQUE_OPENSSL)
    /* [Bug #405] [Bug #1678] [Bug #3000]; already fixed? */
    store->ex_data.sk = NULL;
#endif
    X509_STORE_set_verify_cb(store, x509store_verify_cb);
    ossl_x509store_set_vfy_cb(self, Qnil);

    /* last verification status */
    rb_iv_set(self, "@error", Qnil);
    rb_iv_set(self, "@error_string", Qnil);
    rb_iv_set(self, "@chain", Qnil);
    rb_iv_set(self, "@time", Qnil);

    return self;
}

/*
 * call-seq:
 *   store.flags = flag
 *
 * Sets +flag+ to the Store. +flag+ consists of zero or more of the constants
 * defined in with name V_FLAG_* or'ed together.
 */
static VALUE
ossl_x509store_set_flags(VALUE self, VALUE flags)
{
    X509_STORE *store;
    long f = NUM2LONG(flags);

    GetX509Store(self, store);
    X509_STORE_set_flags(store, f);

    return flags;
}

/*
 * call-seq:
 *   store.purpose = purpose
 *
 * Sets the store's purpose to +purpose+. If specified, the verifications on
 * the store will check every untrusted certificate's extensions are consistent
 * with the purpose. The purpose is specified by constants:
 *
 * * X509::PURPOSE_SSL_CLIENT
 * * X509::PURPOSE_SSL_SERVER
 * * X509::PURPOSE_NS_SSL_SERVER
 * * X509::PURPOSE_SMIME_SIGN
 * * X509::PURPOSE_SMIME_ENCRYPT
 * * X509::PURPOSE_CRL_SIGN
 * * X509::PURPOSE_ANY
 * * X509::PURPOSE_OCSP_HELPER
 * * X509::PURPOSE_TIMESTAMP_SIGN
 */
static VALUE
ossl_x509store_set_purpose(VALUE self, VALUE purpose)
{
    X509_STORE *store;
    int p = NUM2INT(purpose);

    GetX509Store(self, store);
    X509_STORE_set_purpose(store, p);

    return purpose;
}

/*
 * call-seq:
 *   store.trust = trust
 */
static VALUE
ossl_x509store_set_trust(VALUE self, VALUE trust)
{
    X509_STORE *store;
    int t = NUM2INT(trust);

    GetX509Store(self, store);
    X509_STORE_set_trust(store, t);

    return trust;
}

/*
 * call-seq:
 *   store.time = time
 *
 * Sets the time to be used in verifications.
 */
static VALUE
ossl_x509store_set_time(VALUE self, VALUE time)
{
    rb_iv_set(self, "@time", time);
    return time;
}

/*
 * call-seq:
 *   store.add_file(file) -> self
 *
 * Adds the certificates in +file+ to the certificate store.  The +file+ can
 * contain multiple PEM-encoded certificates.
 */
static VALUE
ossl_x509store_add_file(VALUE self, VALUE file)
{
    X509_STORE *store;
    X509_LOOKUP *lookup;
    char *path = NULL;

    if(file != Qnil){
	rb_check_safe_obj(file);
	path = StringValueCStr(file);
    }
    GetX509Store(self, store);
    lookup = X509_STORE_add_lookup(store, X509_LOOKUP_file());
    if(lookup == NULL) ossl_raise(eX509StoreError, NULL);
    if(X509_LOOKUP_load_file(lookup, path, X509_FILETYPE_PEM) != 1){
        ossl_raise(eX509StoreError, NULL);
    }
#if OPENSSL_VERSION_NUMBER < 0x10101000 || defined(LIBRESSL_VERSION_NUMBER)
    /*
     * X509_load_cert_crl_file() which is called from X509_LOOKUP_load_file()
     * did not check the return value of X509_STORE_add_{cert,crl}(), leaking
     * "cert already in hash table" errors on the error queue, if duplicate
     * certificates are found. This will be fixed by OpenSSL 1.1.1.
     */
    ossl_clear_error();
#endif

    return self;
}

/*
 * call-seq:
 *   store.add_path(path) -> self
 *
 * Adds +path+ as the hash dir to be looked up by the store.
 */
static VALUE
ossl_x509store_add_path(VALUE self, VALUE dir)
{
    X509_STORE *store;
    X509_LOOKUP *lookup;
    char *path = NULL;

    if(dir != Qnil){
	rb_check_safe_obj(dir);
	path = StringValueCStr(dir);
    }
    GetX509Store(self, store);
    lookup = X509_STORE_add_lookup(store, X509_LOOKUP_hash_dir());
    if(lookup == NULL) ossl_raise(eX509StoreError, NULL);
    if(X509_LOOKUP_add_dir(lookup, path, X509_FILETYPE_PEM) != 1){
        ossl_raise(eX509StoreError, NULL);
    }

    return self;
}

/*
 * call-seq:
 *   store.set_default_paths
 *
 * Configures +store+ to look up CA certificates from the system default
 * certificate store as needed basis. The location of the store can usually be
 * determined by:
 *
 * * OpenSSL::X509::DEFAULT_CERT_FILE
 * * OpenSSL::X509::DEFAULT_CERT_DIR
 */
static VALUE
ossl_x509store_set_default_paths(VALUE self)
{
    X509_STORE *store;

    GetX509Store(self, store);
    if (X509_STORE_set_default_paths(store) != 1){
        ossl_raise(eX509StoreError, NULL);
    }

    return Qnil;
}

/*
 * call-seq:
 *   store.add_cert(cert)
 *
 * Adds the OpenSSL::X509::Certificate +cert+ to the certificate store.
 */
static VALUE
ossl_x509store_add_cert(VALUE self, VALUE arg)
{
    X509_STORE *store;
    X509 *cert;

    cert = GetX509CertPtr(arg); /* NO NEED TO DUP */
    GetX509Store(self, store);
    if (X509_STORE_add_cert(store, cert) != 1){
        ossl_raise(eX509StoreError, NULL);
    }

    return self;
}

/*
 * call-seq:
 *   store.add_crl(crl) -> self
 *
 * Adds the OpenSSL::X509::CRL +crl+ to the store.
 */
static VALUE
ossl_x509store_add_crl(VALUE self, VALUE arg)
{
    X509_STORE *store;
    X509_CRL *crl;

    crl = GetX509CRLPtr(arg); /* NO NEED TO DUP */
    GetX509Store(self, store);
    if (X509_STORE_add_crl(store, crl) != 1){
        ossl_raise(eX509StoreError, NULL);
    }

    return self;
}

static VALUE ossl_x509stctx_get_err(VALUE);
static VALUE ossl_x509stctx_get_err_string(VALUE);
static VALUE ossl_x509stctx_get_chain(VALUE);

/*
 * call-seq:
 *   store.verify(cert, chain = nil) -> true | false
 *
 * Performs a certificate verification on the OpenSSL::X509::Certificate +cert+.
 *
 * +chain+ can be an array of OpenSSL::X509::Certificate that is used to
 * construct the certificate chain.
 *
 * If a block is given, it overrides the callback set by #verify_callback=.
 *
 * After finishing the verification, the error information can be retrieved by
 * #error, #error_string, and the resuting complete certificate chain can be
 * retrieved by #chain.
 */
static VALUE
ossl_x509store_verify(int argc, VALUE *argv, VALUE self)
{
    VALUE cert, chain;
    VALUE ctx, proc, result;

    rb_scan_args(argc, argv, "11", &cert, &chain);
    ctx = rb_funcall(cX509StoreContext, rb_intern("new"), 3, self, cert, chain);
    proc = rb_block_given_p() ?  rb_block_proc() :
	   rb_iv_get(self, "@verify_callback");
    rb_iv_set(ctx, "@verify_callback", proc);
    result = rb_funcall(ctx, rb_intern("verify"), 0);

    rb_iv_set(self, "@error", ossl_x509stctx_get_err(ctx));
    rb_iv_set(self, "@error_string", ossl_x509stctx_get_err_string(ctx));
    rb_iv_set(self, "@chain", ossl_x509stctx_get_chain(ctx));

    return result;
}

/*
 * Public Functions
 */
static void ossl_x509stctx_free(void*);


static const rb_data_type_t ossl_x509stctx_type = {
    "OpenSSL/X509/STORE_CTX",
    {
	0, ossl_x509stctx_free,
    },
    0, 0, RUBY_TYPED_FREE_IMMEDIATELY,
};

/*
 * Private functions
 */
static void
ossl_x509stctx_free(void *ptr)
{
    X509_STORE_CTX *ctx = ptr;
    if (X509_STORE_CTX_get0_untrusted(ctx))
	sk_X509_pop_free(X509_STORE_CTX_get0_untrusted(ctx), X509_free);
    if (X509_STORE_CTX_get0_cert(ctx))
	X509_free(X509_STORE_CTX_get0_cert(ctx));
    X509_STORE_CTX_free(ctx);
}

static VALUE
ossl_x509stctx_alloc(VALUE klass)
{
    X509_STORE_CTX *ctx;
    VALUE obj;

    obj = NewX509StCtx(klass);
    if((ctx = X509_STORE_CTX_new()) == NULL){
        ossl_raise(eX509StoreError, NULL);
    }
    SetX509StCtx(obj, ctx);

    return obj;
}

static VALUE
ossl_x509stctx_new(X509_STORE_CTX *ctx)
{
    VALUE obj;

    obj = NewX509StCtx(cX509StoreContext);
    SetX509StCtx(obj, ctx);

    return obj;
}

static VALUE ossl_x509stctx_set_flags(VALUE, VALUE);
static VALUE ossl_x509stctx_set_purpose(VALUE, VALUE);
static VALUE ossl_x509stctx_set_trust(VALUE, VALUE);
static VALUE ossl_x509stctx_set_time(VALUE, VALUE);

/*
 * call-seq:
 *   StoreContext.new(store, cert = nil, chain = nil)
 */
static VALUE
ossl_x509stctx_initialize(int argc, VALUE *argv, VALUE self)
{
    VALUE store, cert, chain, t;
    X509_STORE_CTX *ctx;
    X509_STORE *x509st;
    X509 *x509 = NULL;
    STACK_OF(X509) *x509s = NULL;

    rb_scan_args(argc, argv, "12", &store, &cert, &chain);
    GetX509StCtx(self, ctx);
    SafeGetX509Store(store, x509st);
    if(!NIL_P(cert)) x509 = DupX509CertPtr(cert); /* NEED TO DUP */
    if(!NIL_P(chain)) x509s = ossl_x509_ary2sk(chain);
    if(X509_STORE_CTX_init(ctx, x509st, x509, x509s) != 1){
        sk_X509_pop_free(x509s, X509_free);
        ossl_raise(eX509StoreError, NULL);
    }
    if (!NIL_P(t = rb_iv_get(store, "@time")))
	ossl_x509stctx_set_time(self, t);
    rb_iv_set(self, "@verify_callback", rb_iv_get(store, "@verify_callback"));
    rb_iv_set(self, "@cert", cert);

    return self;
}

/*
 * call-seq:
 *   stctx.verify -> true | false
 */
static VALUE
ossl_x509stctx_verify(VALUE self)
{
    X509_STORE_CTX *ctx;

    GetX509StCtx(self, ctx);
    X509_STORE_CTX_set_ex_data(ctx, stctx_ex_verify_cb_idx,
			       (void *)rb_iv_get(self, "@verify_callback"));

    switch (X509_verify_cert(ctx)) {
      case 1:
	return Qtrue;
      case 0:
	ossl_clear_error();
	return Qfalse;
      default:
	ossl_raise(eX509CertError, NULL);
    }
}

/*
 * call-seq:
 *   stctx.chain -> Array of X509::Certificate
 */
static VALUE
ossl_x509stctx_get_chain(VALUE self)
{
    X509_STORE_CTX *ctx;
    STACK_OF(X509) *chain;
    X509 *x509;
    int i, num;
    VALUE ary;

    GetX509StCtx(self, ctx);
    if((chain = X509_STORE_CTX_get0_chain(ctx)) == NULL){
        return Qnil;
    }
    if((num = sk_X509_num(chain)) < 0){
	OSSL_Debug("certs in chain < 0???");
	return rb_ary_new();
    }
    ary = rb_ary_new2(num);
    for(i = 0; i < num; i++) {
	x509 = sk_X509_value(chain, i);
	rb_ary_push(ary, ossl_x509_new(x509));
    }

    return ary;
}

/*
 * call-seq:
 *   stctx.error -> Integer
 */
static VALUE
ossl_x509stctx_get_err(VALUE self)
{
    X509_STORE_CTX *ctx;

    GetX509StCtx(self, ctx);

    return INT2NUM(X509_STORE_CTX_get_error(ctx));
}

/*
 * call-seq:
 *   stctx.error = error_code
 */
static VALUE
ossl_x509stctx_set_error(VALUE self, VALUE err)
{
    X509_STORE_CTX *ctx;

    GetX509StCtx(self, ctx);
    X509_STORE_CTX_set_error(ctx, NUM2INT(err));

    return err;
}

/*
 * call-seq:
 *   stctx.error_string -> String
 *
 * Returns the error string corresponding to the error code retrieved by #error.
 */
static VALUE
ossl_x509stctx_get_err_string(VALUE self)
{
    X509_STORE_CTX *ctx;
    long err;

    GetX509StCtx(self, ctx);
    err = X509_STORE_CTX_get_error(ctx);

    return rb_str_new2(X509_verify_cert_error_string(err));
}

/*
 * call-seq:
 *   stctx.error_depth -> Integer
 */
static VALUE
ossl_x509stctx_get_err_depth(VALUE self)
{
    X509_STORE_CTX *ctx;

    GetX509StCtx(self, ctx);

    return INT2NUM(X509_STORE_CTX_get_error_depth(ctx));
}

/*
 * call-seq:
 *   stctx.current_cert -> X509::Certificate
 */
static VALUE
ossl_x509stctx_get_curr_cert(VALUE self)
{
    X509_STORE_CTX *ctx;

    GetX509StCtx(self, ctx);

    return ossl_x509_new(X509_STORE_CTX_get_current_cert(ctx));
}

/*
 * call-seq:
 *   stctx.current_crl -> X509::CRL
 */
static VALUE
ossl_x509stctx_get_curr_crl(VALUE self)
{
    X509_STORE_CTX *ctx;
    X509_CRL *crl;

    GetX509StCtx(self, ctx);
    crl = X509_STORE_CTX_get0_current_crl(ctx);
    if (!crl)
	return Qnil;

    return ossl_x509crl_new(crl);
}

/*
 * call-seq:
 *   stctx.flags = flags
 *
 * Sets the verification flags to the context. See Store#flags=.
 */
static VALUE
ossl_x509stctx_set_flags(VALUE self, VALUE flags)
{
    X509_STORE_CTX *store;
    long f = NUM2LONG(flags);

    GetX509StCtx(self, store);
    X509_STORE_CTX_set_flags(store, f);

    return flags;
}

/*
 * call-seq:
 *   stctx.purpose = purpose
 *
 * Sets the purpose of the context. See Store#purpose=.
 */
static VALUE
ossl_x509stctx_set_purpose(VALUE self, VALUE purpose)
{
    X509_STORE_CTX *store;
    int p = NUM2INT(purpose);

    GetX509StCtx(self, store);
    X509_STORE_CTX_set_purpose(store, p);

    return purpose;
}

/*
 * call-seq:
 *   stctx.trust = trust
 */
static VALUE
ossl_x509stctx_set_trust(VALUE self, VALUE trust)
{
    X509_STORE_CTX *store;
    int t = NUM2INT(trust);

    GetX509StCtx(self, store);
    X509_STORE_CTX_set_trust(store, t);

    return trust;
}

/*
 * call-seq:
 *   stctx.time = time
 *
 * Sets the time used in the verification. If not set, the current time is used.
 */
static VALUE
ossl_x509stctx_set_time(VALUE self, VALUE time)
{
    X509_STORE_CTX *store;
    long t;

    t = NUM2LONG(rb_Integer(time));
    GetX509StCtx(self, store);
    X509_STORE_CTX_set_time(store, 0, t);

    return time;
}

/*
 * INIT
 */
void
Init_ossl_x509store(void)
{
#if 0
    mOSSL = rb_define_module("OpenSSL");
    eOSSLError = rb_define_class_under(mOSSL, "OpenSSLError", rb_eStandardError);
    mX509 = rb_define_module_under(mOSSL, "X509");
#endif

    /* Register ext_data slot for verify callback Proc */
    stctx_ex_verify_cb_idx = X509_STORE_CTX_get_ex_new_index(0, (void *)"stctx_ex_verify_cb_idx", 0, 0, 0);
    if (stctx_ex_verify_cb_idx < 0)
	ossl_raise(eOSSLError, "X509_STORE_CTX_get_ex_new_index");
    store_ex_verify_cb_idx = X509_STORE_get_ex_new_index(0, (void *)"store_ex_verify_cb_idx", 0, 0, 0);
    if (store_ex_verify_cb_idx < 0)
	ossl_raise(eOSSLError, "X509_STORE_get_ex_new_index");

    eX509StoreError = rb_define_class_under(mX509, "StoreError", eOSSLError);

    /* Document-class: OpenSSL::X509::Store
     *
     * The X509 certificate store holds trusted CA certificates used to verify
     * peer certificates.
     *
     * The easiest way to create a useful certificate store is:
     *
     *   cert_store = OpenSSL::X509::Store.new
     *   cert_store.set_default_paths
     *
     * This will use your system's built-in certificates.
     *
     * If your system does not have a default set of certificates you can obtain
     * a set extracted from Mozilla CA certificate store by cURL maintainers
     * here: https://curl.haxx.se/docs/caextract.html (You may wish to use the
     * firefox-db2pem.sh script to extract the certificates from a local install
     * to avoid man-in-the-middle attacks.)
     *
     * After downloading or generating a cacert.pem from the above link you
     * can create a certificate store from the pem file like this:
     *
     *   cert_store = OpenSSL::X509::Store.new
     *   cert_store.add_file 'cacert.pem'
     *
     * The certificate store can be used with an SSLSocket like this:
     *
     *   ssl_context = OpenSSL::SSL::SSLContext.new
     *   ssl_context.verify_mode = OpenSSL::SSL::VERIFY_PEER
     *   ssl_context.cert_store = cert_store
     *
     *   tcp_socket = TCPSocket.open 'example.com', 443
     *
     *   ssl_socket = OpenSSL::SSL::SSLSocket.new tcp_socket, ssl_context
     */

    cX509Store = rb_define_class_under(mX509, "Store", rb_cObject);
    /*
     * The callback for additional certificate verification. It is invoked for
     * each untrusted certificate in the chain.
     *
     * The callback is invoked with two values, a boolean that indicates if the
     * pre-verification by OpenSSL has succeeded or not, and the StoreContext in
     * use. The callback must return either true or false.
     */
    rb_attr(cX509Store, rb_intern("verify_callback"), 1, 0, Qfalse);
    /*
     * The error code set by the last call of #verify.
     */
    rb_attr(cX509Store, rb_intern("error"), 1, 0, Qfalse);
    /*
     * The description for the error code set by the last call of #verify.
     */
    rb_attr(cX509Store, rb_intern("error_string"), 1, 0, Qfalse);
    /*
     * The certificate chain constructed by the last call of #verify.
     */
    rb_attr(cX509Store, rb_intern("chain"), 1, 0, Qfalse);
    rb_define_alloc_func(cX509Store, ossl_x509store_alloc);
    rb_define_method(cX509Store, "initialize",   ossl_x509store_initialize, -1);
    rb_undef_method(cX509Store, "initialize_copy");
    rb_define_method(cX509Store, "verify_callback=", ossl_x509store_set_vfy_cb, 1);
    rb_define_method(cX509Store, "flags=",       ossl_x509store_set_flags, 1);
    rb_define_method(cX509Store, "purpose=",     ossl_x509store_set_purpose, 1);
    rb_define_method(cX509Store, "trust=",       ossl_x509store_set_trust, 1);
    rb_define_method(cX509Store, "time=",        ossl_x509store_set_time, 1);
    rb_define_method(cX509Store, "add_path",     ossl_x509store_add_path, 1);
    rb_define_method(cX509Store, "add_file",     ossl_x509store_add_file, 1);
    rb_define_method(cX509Store, "set_default_paths", ossl_x509store_set_default_paths, 0);
    rb_define_method(cX509Store, "add_cert",     ossl_x509store_add_cert, 1);
    rb_define_method(cX509Store, "add_crl",      ossl_x509store_add_crl, 1);
    rb_define_method(cX509Store, "verify",       ossl_x509store_verify, -1);

    /*
     * Document-class: OpenSSL::X509::StoreContext
     *
     * A StoreContext is used while validating a single certificate and holds
     * the status involved.
     */
    cX509StoreContext = rb_define_class_under(mX509,"StoreContext", rb_cObject);
    rb_define_alloc_func(cX509StoreContext, ossl_x509stctx_alloc);
    rb_define_method(cX509StoreContext, "initialize", ossl_x509stctx_initialize, -1);
    rb_undef_method(cX509StoreContext, "initialize_copy");
    rb_define_method(cX509StoreContext, "verify", ossl_x509stctx_verify, 0);
    rb_define_method(cX509StoreContext, "chain", ossl_x509stctx_get_chain,0);
    rb_define_method(cX509StoreContext, "error", ossl_x509stctx_get_err, 0);
    rb_define_method(cX509StoreContext, "error=", ossl_x509stctx_set_error, 1);
    rb_define_method(cX509StoreContext, "error_string", ossl_x509stctx_get_err_string,0);
    rb_define_method(cX509StoreContext, "error_depth", ossl_x509stctx_get_err_depth, 0);
    rb_define_method(cX509StoreContext, "current_cert", ossl_x509stctx_get_curr_cert, 0);
    rb_define_method(cX509StoreContext, "current_crl", ossl_x509stctx_get_curr_crl, 0);
    rb_define_method(cX509StoreContext, "flags=", ossl_x509stctx_set_flags, 1);
    rb_define_method(cX509StoreContext, "purpose=", ossl_x509stctx_set_purpose, 1);
    rb_define_method(cX509StoreContext, "trust=", ossl_x509stctx_set_trust, 1);
    rb_define_method(cX509StoreContext, "time=", ossl_x509stctx_set_time, 1);
}