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ZPROXY(3) CZMQ Manual ZPROXY(3)

NAME

zproxy - Class for run a steerable proxy in the background

SYNOPSIS

//  Create new zproxy actor instance. The proxy switches messages between
//  a frontend socket and a backend socket; use the FRONTEND and BACKEND
//  commands to configure these:
//
//      zactor_t *proxy = zactor_new (zproxy, NULL);
//
//  Destroy zproxy instance. This destroys the two sockets and stops any
//  message flow between them:
//
//      zactor_destroy (&proxy);
//
//  Note that all zproxy commands are synchronous, so your application always
//  waits for a signal from the actor after each command.
//
//  Enable verbose logging of commands and activity:
//
//      zstr_send (proxy, "VERBOSE");
//      zsock_wait (proxy);
//
//  Specify frontend socket type -- see zsock_type_str () -- and attach to
//  endpoints, see zsock_attach (). Note that a proxy socket is always
//  serverish:
//
//      zstr_sendx (proxy, "FRONTEND", "XSUB", endpoints, NULL);
//      zsock_wait (proxy);
//
//  When the socket type is XSUB or SUB, topic(s) string(s) can be passed as
//  additional arguments (NOTE: in DRAFT state) and the socket will subscribe
//  using them.
//
//  Specify backend socket type -- see zsock_type_str () -- and attach to
//  endpoints, see zsock_attach (). Note that a proxy socket is always
//  serverish:
//
//      zstr_sendx (proxy, "BACKEND", "XPUB", endpoints, NULL);
//      zsock_wait (proxy);
//
//  Capture all proxied messages; these are delivered to the application
//  via an inproc PULL socket that you have already bound to the specified
//  endpoint:
//
//      zstr_sendx (proxy, "CAPTURE", endpoint, NULL);
//      zsock_wait (proxy);
//
//  Pause the proxy. A paused proxy will cease processing messages, causing
//  them to be queued up and potentially hit the high-water mark on the
//  frontend or backend socket, causing messages to be dropped, or writing
//  applications to block:
//
//      zstr_sendx (proxy, "PAUSE", NULL);
//      zsock_wait (proxy);
//
//  Resume the proxy. Note that the proxy starts automatically as soon as it
//  has a properly attached frontend and backend socket:
//
//      zstr_sendx (proxy, "RESUME", NULL);
//      zsock_wait (proxy);
//
//  Configure an authentication domain for the "FRONTEND" or "BACKEND" proxy
//  socket -- see zsock_set_zap_domain (). Call before binding socket:
//
//      zstr_sendx (proxy, "DOMAIN", "FRONTEND", "global", NULL);
//      zsock_wait (proxy);
//
//  Configure PLAIN authentication for the "FRONTEND" or "BACKEND" proxy
//  socket -- see zsock_set_plain_server (). Call before binding socket:
//
//      zstr_sendx (proxy, "PLAIN", "BACKEND", NULL);
//      zsock_wait (proxy);
//
//  Configure CURVE authentication for the "FRONTEND" or "BACKEND" proxy
//  socket -- see zsock_set_curve_server () -- specifying both the public and
//  secret keys of a certificate as Z85 armored strings -- see
//  zcert_public_txt () and zcert_secret_txt (). Call before binding socket:
//
//      zstr_sendx (proxy, "CURVE", "FRONTEND", public_txt, secret_txt, NULL);
//      zsock_wait (proxy);
//
//  This is the zproxy constructor as a zactor_fn; the argument is a
//  character string specifying frontend and backend socket types as two
//  uppercase strings separated by a hyphen:
CZMQ_EXPORT void

zproxy (zsock_t *pipe, void *unused); // Selftest CZMQ_EXPORT void
zproxy_test (bool verbose); Please add '@interface' section in './../src/zproxy.c'.

DESCRIPTION

A zproxy actor switches messages between a frontend and a backend socket. It acts much like the zmq_proxy_steerable method, though it makes benefit of CZMQ’s facilities, to be somewhat simpler to set-up.

This class replaces zproxy_v2, and is meant for applications that use the CZMQ v3 API (meaning, zsock).

EXAMPLE

From zproxy_test method.

//  Create and configure our proxy
zactor_t *proxy = zactor_new (zproxy, NULL);
assert (proxy);
if (verbose) {

zstr_sendx (proxy, "VERBOSE", NULL);
zsock_wait (proxy); } zstr_sendx (proxy, "FRONTEND", "PULL", "inproc://frontend", NULL); zsock_wait (proxy); zstr_sendx (proxy, "BACKEND", "PUSH", "inproc://backend", NULL); zsock_wait (proxy); // Connect application sockets to proxy zsock_t *faucet = zsock_new_push (">inproc://frontend"); assert (faucet); zsock_t *sink = zsock_new_pull (">inproc://backend"); assert (sink); // Send some messages and check they arrived char *hello, *world; zstr_sendx (faucet, "Hello", "World", NULL); zstr_recvx (sink, &hello, &world, NULL); assert (streq (hello, "Hello")); assert (streq (world, "World")); zstr_free (&hello); zstr_free (&world); // Test pause/resume functionality zstr_sendx (proxy, "PAUSE", NULL); zsock_wait (proxy); zstr_sendx (faucet, "Hello", "World", NULL); zsock_set_rcvtimeo (sink, 100); zstr_recvx (sink, &hello, &world, NULL); assert (!hello && !world); zstr_sendx (proxy, "RESUME", NULL); zsock_wait (proxy); zstr_recvx (sink, &hello, &world, NULL); assert (streq (hello, "Hello")); assert (streq (world, "World")); zstr_free (&hello); zstr_free (&world); // Test capture functionality zsock_t *capture = zsock_new_pull ("inproc://capture"); assert (capture); // Switch on capturing, check that it works zstr_sendx (proxy, "CAPTURE", "inproc://capture", NULL); zsock_wait (proxy); zstr_sendx (faucet, "Hello", "World", NULL); zstr_recvx (sink, &hello, &world, NULL); assert (streq (hello, "Hello")); assert (streq (world, "World")); zstr_free (&hello); zstr_free (&world); zstr_recvx (capture, &hello, &world, NULL); assert (streq (hello, "Hello")); assert (streq (world, "World")); zstr_free (&hello); zstr_free (&world); zsock_destroy (&faucet); zsock_destroy (&sink); zsock_destroy (&capture); zactor_destroy (&proxy); // Test socket creation dependency proxy = zactor_new (zproxy, NULL); assert (proxy); char *frontend = NULL; char *backend = NULL; backend = zsys_sprintf (LOCALENDPOINT, s_get_available_port ()); zclock_sleep (200); sink = zsock_new_sub (backend, "whatever"); assert (sink); zstr_sendx (proxy, "BACKEND", "XPUB", backend, NULL); zsock_wait (proxy); zsock_destroy(&sink); zactor_destroy(&proxy); zstr_free (&backend); #ifdef CZMQ_BUILD_DRAFT_API // Create and configure our proxy with PUB/SUB to test subscriptions proxy = zactor_new (zproxy, NULL); assert (proxy); if (verbose) {
zstr_sendx (proxy, "VERBOSE", NULL);
zsock_wait (proxy); } zstr_sendx (proxy, "FRONTEND", "SUB", "inproc://frontend", "He", "b", NULL); zsock_wait (proxy); zstr_sendx (proxy, "BACKEND", "PUB", "inproc://backend", NULL); zsock_wait (proxy); // Connect application sockets to proxy faucet = zsock_new_pub (">inproc://frontend"); assert (faucet); sink = zsock_new_sub (">inproc://backend", ""); assert (sink); // Send some messages and check they arrived zstr_sendx (faucet, "Hello", "World", NULL); // since SUB is binding, subscription might be lost see: // https://github.com/zeromq/libzmq/issues/2267 zsock_set_rcvtimeo (sink, 100); hello = zstr_recv (sink); if (hello) {
assert (streq (hello, "Hello"));
world = zstr_recv (sink);
assert (streq (world, "World"));
zstr_free (&hello);
zstr_free (&world); } zsock_destroy (&faucet); zsock_destroy (&sink); zactor_destroy(&proxy); #endif // CZMQ_BUILD_DRAFT_API #if (ZMQ_VERSION_MAJOR == 4) // Test authentication functionality const char *basedirpath = "src/selftest-rw/.test_zproxy"; const char *passfilepath = "src/selftest-rw/.test_zproxy/password-file"; const char *certfilepath = "src/selftest-rw/.test_zproxy/mycert.txt"; // Make sure old aborted tests do not hinder us zdir_t *dir = zdir_new (basedirpath, NULL); if (dir) {
zdir_remove (dir, true);
zdir_destroy (&dir); } zsys_file_delete (passfilepath); zsys_file_delete (certfilepath); zsys_dir_delete (basedirpath); // Create temporary directory for test files zsys_dir_create (basedirpath); // Check there's no authentication s_create_test_sockets (&proxy, &faucet, &sink, verbose); s_bind_test_sockets (proxy, &frontend, &backend); bool success = s_can_connect (&proxy, &faucet, &sink, frontend, backend,
verbose, true); assert (success); // Install the authenticator zactor_t *auth = zactor_new (zauth, NULL); assert (auth); if (verbose) {
zstr_sendx (auth, "VERBOSE", NULL);
zsock_wait (auth); } // Check there's no authentication on a default NULL server s_bind_test_sockets (proxy, &frontend, &backend); success = s_can_connect (&proxy, &faucet, &sink, frontend, backend, verbose,
true); assert (success); // When we set a domain on the server, we switch on authentication // for NULL sockets, but with no policies, the client connection // will be allowed. zstr_sendx (proxy, "DOMAIN", "FRONTEND", "global", NULL); zsock_wait (proxy); s_bind_test_sockets (proxy, &frontend, &backend); success = s_can_connect (&proxy, &faucet, &sink, frontend, backend, verbose,
true); assert (success); // Block 127.0.0.1, connection should fail zstr_sendx (proxy, "DOMAIN", "FRONTEND", "global", NULL); zsock_wait (proxy); s_bind_test_sockets (proxy, &frontend, &backend); zstr_sendx (auth, "DENY", "127.0.0.1", NULL); zsock_wait (auth); success = s_can_connect (&proxy, &faucet, &sink, frontend, backend, verbose,
false); assert (!success); // Allow our address, which overrides the block list zstr_sendx (proxy, "DOMAIN", "FRONTEND", "global", NULL); zsock_wait (proxy); zstr_sendx (proxy, "DOMAIN", "BACKEND", "global", NULL); zsock_wait (proxy); s_bind_test_sockets (proxy, &frontend, &backend); zstr_sendx (auth, "ALLOW", "127.0.0.1", NULL); zsock_wait (auth); success = s_can_connect (&proxy, &faucet, &sink, frontend, backend, verbose,
true); assert (success); // Try PLAIN authentication // Test negative case (no server-side passwords defined) zstr_sendx (proxy, "PLAIN", "FRONTEND", NULL); zsock_wait (proxy); zstr_sendx (proxy, "DOMAIN", "FRONTEND", "global", NULL); zsock_wait (proxy); s_bind_test_sockets (proxy, &frontend, &backend); zsock_set_plain_username (faucet, "admin"); zsock_set_plain_password (faucet, "Password"); success = s_can_connect (&proxy, &faucet, &sink, frontend, backend, verbose,
false); assert (!success); // Test positive case (server-side passwords defined) FILE *password = fopen (passfilepath, "w"); assert (password); fprintf (password, "admin=Password\n"); fclose (password); zstr_sendx (proxy, "PLAIN", "FRONTEND", NULL); zsock_wait (proxy); zstr_sendx (proxy, "DOMAIN", "FRONTEND", "global", NULL); zsock_wait (proxy); zstr_sendx (proxy, "PLAIN", "BACKEND", NULL); zsock_wait (proxy); zstr_sendx (proxy, "DOMAIN", "BACKEND", "global", NULL); zsock_wait (proxy); s_bind_test_sockets (proxy, &frontend, &backend); zsock_set_plain_username (faucet, "admin"); zsock_set_plain_password (faucet, "Password"); zsock_set_plain_username (sink, "admin"); zsock_set_plain_password (sink, "Password"); zstr_sendx (auth, "PLAIN", passfilepath, NULL); zsock_wait (auth); success = s_can_connect (&proxy, &faucet, &sink, frontend, backend, verbose,
true); assert (success); // Test negative case (bad client password) zstr_sendx (proxy, "PLAIN", "FRONTEND", NULL); zsock_wait (proxy); zstr_sendx (proxy, "DOMAIN", "FRONTEND", "global", NULL); zsock_wait (proxy); s_bind_test_sockets (proxy, &frontend, &backend); zsock_set_plain_username (faucet, "admin"); zsock_set_plain_password (faucet, "Bogus"); success = s_can_connect (&proxy, &faucet, &sink, frontend, backend, verbose,
false); assert (!success); if (zsys_has_curve ()) {
// We'll create two new certificates and save the client public
// certificate on disk
zcert_t *server_cert = zcert_new ();
assert (server_cert);
zcert_t *client_cert = zcert_new ();
assert (client_cert);
const char *public_key = zcert_public_txt (server_cert);
const char *secret_key = zcert_secret_txt (server_cert);
// Try CURVE authentication
// Test without setting-up any authentication
zstr_sendx (proxy, "CURVE", "FRONTEND", public_key, secret_key, NULL);
zsock_wait (proxy);
zstr_sendx (proxy, "DOMAIN", "FRONTEND", "global", NULL);
zsock_wait (proxy);
s_bind_test_sockets (proxy, &frontend, &backend);
zcert_apply (client_cert, faucet);
zsock_set_curve_serverkey (faucet, public_key);
success = s_can_connect (&proxy, &faucet, &sink, frontend, backend,
verbose, false);
assert (!success);
// Test CURVE_ALLOW_ANY
zstr_sendx (proxy, "CURVE", "FRONTEND", public_key, secret_key, NULL);
zsock_wait (proxy);
s_bind_test_sockets (proxy, &frontend, &backend);
zcert_apply (client_cert, faucet);
zsock_set_curve_serverkey (faucet, public_key);
zstr_sendx (auth, "CURVE", CURVE_ALLOW_ANY, NULL);
zsock_wait (auth);
success = s_can_connect (&proxy, &faucet, &sink, frontend, backend,
verbose, true);
assert (success);
// Test with client certificate file in authentication folder
zstr_sendx (proxy, "CURVE", "FRONTEND", public_key, secret_key, NULL);
zsock_wait (proxy);
zstr_sendx (proxy, "CURVE", "BACKEND", public_key, secret_key, NULL);
zsock_wait (proxy);
s_bind_test_sockets (proxy, &frontend, &backend);
zcert_apply (client_cert, faucet);
zsock_set_curve_serverkey (faucet, public_key);
zcert_apply (client_cert, sink);
zsock_set_curve_serverkey (sink, public_key);
zcert_save_public (client_cert, certfilepath);
zstr_sendx (auth, "CURVE", basedirpath, NULL);
zsock_wait (auth);
success = s_can_connect (&proxy, &faucet, &sink, frontend, backend,
verbose, true);
assert (success);
zcert_destroy (&server_cert);
zcert_destroy (&client_cert); } // Remove the authenticator and check a normal connection works zactor_destroy (&auth); s_bind_test_sockets (proxy, &frontend, &backend); success = s_can_connect (&proxy, &faucet, &sink, frontend, backend, verbose,
true); assert (success); // Cleanup zsock_destroy (&faucet); zsock_destroy (&sink); zactor_destroy (&proxy); zstr_free (&frontend); zstr_free (&backend); // Delete temporary directory and test files zsys_file_delete (passfilepath); zsys_file_delete (certfilepath); zsys_dir_delete (basedirpath); #endif #if defined (__WINDOWS__) zsys_shutdown(); #endif

AUTHORS

The czmq manual was written by the authors in the AUTHORS file.

RESOURCES

Main web site:

Report bugs to the email <zeromq-dev@lists.zeromq.org[1]>

COPYRIGHT

Copyright (c) the Contributors as noted in the AUTHORS file. This file is part of CZMQ, the high-level C binding for 0MQ: http://czmq.zeromq.org. 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/. LICENSE included with the czmq distribution.

NOTES

1.
zeromq-dev@lists.zeromq.org
mailto:zeromq-dev@lists.zeromq.org
03/05/2021 CZMQ 4.2.1