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 <bpf/bpf.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 13 int 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 } 80