1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
//
// This software is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt). A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//
//
// Forwarder example based on https://github.com/C-o-r-E/nng_pubsub_proxy
//
// This example shows how to use raw sockets to set up a forwarder or proxy for
// pub/sub.
//
// An example setup for running this example would involve the following:
//
// - Run this example binary (in the background or a terminal, etc)
// - In a new terminal, run
// `nngcat --sub --dial "tcp://localhost:3328" --quoted`
// - In a second terminal, run
// `nngcat --sub --dial "tcp://localhost:3328" --quoted`
// - In a third terminal, run
// `for n in $(seq 0 99);`
// `do nngcat --pub --dial "tcp://localhost:3327" --data "$n";`
// `done`
//
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <nng/nng.h>
#include <nng/protocol/pubsub0/pub.h>
#include <nng/protocol/pubsub0/sub.h>
#define PROXY_FRONT_URL "tcp://localhost:3327"
#define PROXY_BACK_URL "tcp://localhost:3328"
void
panic_on_error(int should_panic, const char *format, ...)
{
if (should_panic) {
va_list args;
va_start(args, format);
vprintf(format, args);
va_end(args);
exit(EXIT_FAILURE);
}
}
int
main()
{
nng_socket sock_front_end = NNG_SOCKET_INITIALIZER;
nng_socket sock_back_end = NNG_SOCKET_INITIALIZER;
int ret = 0;
//
// First we need some nng sockets. Not to be confused with network
// sockets
//
ret = nng_sub0_open_raw(&sock_front_end);
panic_on_error(ret, "Failed to open front end socket\n");
ret = nng_pub0_open_raw(&sock_back_end);
panic_on_error(ret, "Failed to open back end socket\n");
//
// Now we need to set up a listener for each socket so that they have
// addresses
//
nng_listener front_ls = NNG_LISTENER_INITIALIZER;
nng_listener back_ls = NNG_LISTENER_INITIALIZER;
ret = nng_listener_create(&front_ls, sock_front_end, PROXY_FRONT_URL);
panic_on_error(ret, "Failed to create front listener\n");
ret = nng_listener_create(&back_ls, sock_back_end, PROXY_BACK_URL);
panic_on_error(ret, "Failed to create back listener\n");
ret = nng_listener_start(front_ls, 0);
panic_on_error(ret, "Failed to start front listener\n");
ret = nng_listener_start(back_ls, 0);
panic_on_error(ret, "Failed to start back listener\n");
//
// Finally let nng do the forwarding/proxying
//
ret = nng_device(sock_front_end, sock_back_end);
panic_on_error(
ret, "nng_device returned %d: %s\n", ret, nng_strerror(ret));
printf("done");
return 0;
}
|
