109 lines · c
1// SPDX-License-Identifier: GPL-2.02#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 11int 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(filename, sizeof(filename), "%s.bpf.o", argv[0]);28 obj = bpf_object__open_file(filename, NULL);29 if (libbpf_get_error(obj)) {30 fprintf(stderr, "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, "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, "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, "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, "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(serv_addr_in->sin_addr);73 printf("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("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(mapped_addr_in->sin_addr);85 printf("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(tmp_addr_in->sin_addr);91 assert((serverconnfd = accept(serverfd, &tmp_addr, &sockaddr_len)) > 0);92 printf("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(tmp_addr_in->sin_addr);98 printf("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 104cleanup:105 bpf_link__destroy(link);106 bpf_object__close(obj);107 return 0;108}109