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 12 int 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 } 79