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