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