1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun #include <stdio.h>
3*4882a593Smuzhiyun #include <assert.h>
4*4882a593Smuzhiyun #include <unistd.h>
5*4882a593Smuzhiyun #include <bpf/bpf.h>
6*4882a593Smuzhiyun #include <bpf/libbpf.h>
7*4882a593Smuzhiyun #include <sys/socket.h>
8*4882a593Smuzhiyun #include <netinet/in.h>
9*4882a593Smuzhiyun #include <arpa/inet.h>
10*4882a593Smuzhiyun
main(int ac,char ** argv)11*4882a593Smuzhiyun int main(int ac, char **argv)
12*4882a593Smuzhiyun {
13*4882a593Smuzhiyun struct sockaddr_in *serv_addr_in, *mapped_addr_in, *tmp_addr_in;
14*4882a593Smuzhiyun struct sockaddr serv_addr, mapped_addr, tmp_addr;
15*4882a593Smuzhiyun int serverfd, serverconnfd, clientfd, map_fd;
16*4882a593Smuzhiyun struct bpf_link *link = NULL;
17*4882a593Smuzhiyun struct bpf_program *prog;
18*4882a593Smuzhiyun struct bpf_object *obj;
19*4882a593Smuzhiyun socklen_t sockaddr_len;
20*4882a593Smuzhiyun char filename[256];
21*4882a593Smuzhiyun char *ip;
22*4882a593Smuzhiyun
23*4882a593Smuzhiyun serv_addr_in = (struct sockaddr_in *)&serv_addr;
24*4882a593Smuzhiyun mapped_addr_in = (struct sockaddr_in *)&mapped_addr;
25*4882a593Smuzhiyun tmp_addr_in = (struct sockaddr_in *)&tmp_addr;
26*4882a593Smuzhiyun
27*4882a593Smuzhiyun snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
28*4882a593Smuzhiyun obj = bpf_object__open_file(filename, NULL);
29*4882a593Smuzhiyun if (libbpf_get_error(obj)) {
30*4882a593Smuzhiyun fprintf(stderr, "ERROR: opening BPF object file failed\n");
31*4882a593Smuzhiyun return 0;
32*4882a593Smuzhiyun }
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
35*4882a593Smuzhiyun if (libbpf_get_error(prog)) {
36*4882a593Smuzhiyun fprintf(stderr, "ERROR: finding a prog in obj file failed\n");
37*4882a593Smuzhiyun goto cleanup;
38*4882a593Smuzhiyun }
39*4882a593Smuzhiyun
40*4882a593Smuzhiyun /* load BPF program */
41*4882a593Smuzhiyun if (bpf_object__load(obj)) {
42*4882a593Smuzhiyun fprintf(stderr, "ERROR: loading BPF object file failed\n");
43*4882a593Smuzhiyun goto cleanup;
44*4882a593Smuzhiyun }
45*4882a593Smuzhiyun
46*4882a593Smuzhiyun map_fd = bpf_object__find_map_fd_by_name(obj, "dnat_map");
47*4882a593Smuzhiyun if (map_fd < 0) {
48*4882a593Smuzhiyun fprintf(stderr, "ERROR: finding a map in obj file failed\n");
49*4882a593Smuzhiyun goto cleanup;
50*4882a593Smuzhiyun }
51*4882a593Smuzhiyun
52*4882a593Smuzhiyun link = bpf_program__attach(prog);
53*4882a593Smuzhiyun if (libbpf_get_error(link)) {
54*4882a593Smuzhiyun fprintf(stderr, "ERROR: bpf_program__attach failed\n");
55*4882a593Smuzhiyun link = NULL;
56*4882a593Smuzhiyun goto cleanup;
57*4882a593Smuzhiyun }
58*4882a593Smuzhiyun
59*4882a593Smuzhiyun assert((serverfd = socket(AF_INET, SOCK_STREAM, 0)) > 0);
60*4882a593Smuzhiyun assert((clientfd = socket(AF_INET, SOCK_STREAM, 0)) > 0);
61*4882a593Smuzhiyun
62*4882a593Smuzhiyun /* Bind server to ephemeral port on lo */
63*4882a593Smuzhiyun memset(&serv_addr, 0, sizeof(serv_addr));
64*4882a593Smuzhiyun serv_addr_in->sin_family = AF_INET;
65*4882a593Smuzhiyun serv_addr_in->sin_port = 0;
66*4882a593Smuzhiyun serv_addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
67*4882a593Smuzhiyun
68*4882a593Smuzhiyun assert(bind(serverfd, &serv_addr, sizeof(serv_addr)) == 0);
69*4882a593Smuzhiyun
70*4882a593Smuzhiyun sockaddr_len = sizeof(serv_addr);
71*4882a593Smuzhiyun assert(getsockname(serverfd, &serv_addr, &sockaddr_len) == 0);
72*4882a593Smuzhiyun ip = inet_ntoa(serv_addr_in->sin_addr);
73*4882a593Smuzhiyun printf("Server bound to: %s:%d\n", ip, ntohs(serv_addr_in->sin_port));
74*4882a593Smuzhiyun
75*4882a593Smuzhiyun memset(&mapped_addr, 0, sizeof(mapped_addr));
76*4882a593Smuzhiyun mapped_addr_in->sin_family = AF_INET;
77*4882a593Smuzhiyun mapped_addr_in->sin_port = htons(5555);
78*4882a593Smuzhiyun mapped_addr_in->sin_addr.s_addr = inet_addr("255.255.255.255");
79*4882a593Smuzhiyun
80*4882a593Smuzhiyun assert(!bpf_map_update_elem(map_fd, &mapped_addr, &serv_addr, BPF_ANY));
81*4882a593Smuzhiyun
82*4882a593Smuzhiyun assert(listen(serverfd, 5) == 0);
83*4882a593Smuzhiyun
84*4882a593Smuzhiyun ip = inet_ntoa(mapped_addr_in->sin_addr);
85*4882a593Smuzhiyun printf("Client connecting to: %s:%d\n",
86*4882a593Smuzhiyun ip, ntohs(mapped_addr_in->sin_port));
87*4882a593Smuzhiyun assert(connect(clientfd, &mapped_addr, sizeof(mapped_addr)) == 0);
88*4882a593Smuzhiyun
89*4882a593Smuzhiyun sockaddr_len = sizeof(tmp_addr);
90*4882a593Smuzhiyun ip = inet_ntoa(tmp_addr_in->sin_addr);
91*4882a593Smuzhiyun assert((serverconnfd = accept(serverfd, &tmp_addr, &sockaddr_len)) > 0);
92*4882a593Smuzhiyun printf("Server received connection from: %s:%d\n",
93*4882a593Smuzhiyun ip, ntohs(tmp_addr_in->sin_port));
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun sockaddr_len = sizeof(tmp_addr);
96*4882a593Smuzhiyun assert(getpeername(clientfd, &tmp_addr, &sockaddr_len) == 0);
97*4882a593Smuzhiyun ip = inet_ntoa(tmp_addr_in->sin_addr);
98*4882a593Smuzhiyun printf("Client's peer address: %s:%d\n",
99*4882a593Smuzhiyun ip, ntohs(tmp_addr_in->sin_port));
100*4882a593Smuzhiyun
101*4882a593Smuzhiyun /* Is the server's getsockname = the socket getpeername */
102*4882a593Smuzhiyun assert(memcmp(&serv_addr, &tmp_addr, sizeof(struct sockaddr_in)) == 0);
103*4882a593Smuzhiyun
104*4882a593Smuzhiyun cleanup:
105*4882a593Smuzhiyun bpf_link__destroy(link);
106*4882a593Smuzhiyun bpf_object__close(obj);
107*4882a593Smuzhiyun return 0;
108*4882a593Smuzhiyun }
109