1// SPDX-License-Identifier: GPL-2.0
 2#include <stdio.h>
 3#include <assert.h>
 4#include <linux/bpf.h>
 5#include <unistd.h>
 6#include "libbpf.h"
 7#include "bpf_load.h"
 8#include <sys/socket.h>
 9#include <string.h>
10#include <netinet/in.h>
11#include <arpa/inet.h>
12
13int main(int ac, char **argv)
14{
15	int serverfd, serverconnfd, clientfd;
16	socklen_t sockaddr_len;
17	struct sockaddr serv_addr, mapped_addr, tmp_addr;
18	struct sockaddr_in *serv_addr_in, *mapped_addr_in, *tmp_addr_in;
19	char filename[256];
20	char *ip;
21
22	serv_addr_in = (struct sockaddr_in *)&serv_addr;
23	mapped_addr_in = (struct sockaddr_in *)&mapped_addr;
24	tmp_addr_in = (struct sockaddr_in *)&tmp_addr;
25
26	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
27
28	if (load_bpf_file(filename)) {
29		printf("%s", bpf_log_buf);
30		return 1;
31	}
32
33	assert((serverfd = socket(AF_INET, SOCK_STREAM, 0)) > 0);
34	assert((clientfd = socket(AF_INET, SOCK_STREAM, 0)) > 0);
35
36	/* Bind server to ephemeral port on lo */
37	memset(&serv_addr, 0, sizeof(serv_addr));
38	serv_addr_in->sin_family = AF_INET;
39	serv_addr_in->sin_port = 0;
40	serv_addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
41
42	assert(bind(serverfd, &serv_addr, sizeof(serv_addr)) == 0);
43
44	sockaddr_len = sizeof(serv_addr);
45	assert(getsockname(serverfd, &serv_addr, &sockaddr_len) == 0);
46	ip = inet_ntoa(serv_addr_in->sin_addr);
47	printf("Server bound to: %s:%d\n", ip, ntohs(serv_addr_in->sin_port));
48
49	memset(&mapped_addr, 0, sizeof(mapped_addr));
50	mapped_addr_in->sin_family = AF_INET;
51	mapped_addr_in->sin_port = htons(5555);
52	mapped_addr_in->sin_addr.s_addr = inet_addr("255.255.255.255");
53
54	assert(!bpf_map_update_elem(map_fd[0], &mapped_addr, &serv_addr, BPF_ANY));
55
56	assert(listen(serverfd, 5) == 0);
57
58	ip = inet_ntoa(mapped_addr_in->sin_addr);
59	printf("Client connecting to: %s:%d\n",
60	       ip, ntohs(mapped_addr_in->sin_port));
61	assert(connect(clientfd, &mapped_addr, sizeof(mapped_addr)) == 0);
62
63	sockaddr_len = sizeof(tmp_addr);
64	ip = inet_ntoa(tmp_addr_in->sin_addr);
65	assert((serverconnfd = accept(serverfd, &tmp_addr, &sockaddr_len)) > 0);
66	printf("Server received connection from: %s:%d\n",
67	       ip, ntohs(tmp_addr_in->sin_port));
68
69	sockaddr_len = sizeof(tmp_addr);
70	assert(getpeername(clientfd, &tmp_addr, &sockaddr_len) == 0);
71	ip = inet_ntoa(tmp_addr_in->sin_addr);
72	printf("Client's peer address: %s:%d\n",
73	       ip, ntohs(tmp_addr_in->sin_port));
74
75	/* Is the server's getsockname = the socket getpeername */
76	assert(memcmp(&serv_addr, &tmp_addr, sizeof(struct sockaddr_in)) == 0);
77
78	return 0;
79}