1 /* 2 * Copyright 2018 Google Inc. 3 * Author: Soheil Hassas Yeganeh (soheil@google.com) 4 * 5 * Simple example on how to use TCP_INQ and TCP_CM_INQ. 6 * 7 * License (GPLv2): 8 * 9 * This program is free software; you can redistribute it and/or modify it 10 * under the terms and conditions of the GNU General Public License, 11 * version 2, as published by the Free Software Foundation. 12 * 13 * This program is distributed in the hope it will be useful, but WITHOUT 14 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 15 * FITNESS FOR A PARTICULAR PURPOSE. * See the GNU General Public License for 16 * more details. 17 */ 18 #define _GNU_SOURCE 19 20 #include <error.h> 21 #include <netinet/in.h> 22 #include <netinet/tcp.h> 23 #include <pthread.h> 24 #include <stdio.h> 25 #include <errno.h> 26 #include <stdlib.h> 27 #include <string.h> 28 #include <sys/socket.h> 29 #include <unistd.h> 30 31 #ifndef TCP_INQ 32 #define TCP_INQ 36 33 #endif 34 35 #ifndef TCP_CM_INQ 36 #define TCP_CM_INQ TCP_INQ 37 #endif 38 39 #define BUF_SIZE 8192 40 #define CMSG_SIZE 32 41 42 static int family = AF_INET6; 43 static socklen_t addr_len = sizeof(struct sockaddr_in6); 44 static int port = 4974; 45 46 static void setup_loopback_addr(int family, struct sockaddr_storage *sockaddr) 47 { 48 struct sockaddr_in6 *addr6 = (void *) sockaddr; 49 struct sockaddr_in *addr4 = (void *) sockaddr; 50 51 switch (family) { 52 case PF_INET: 53 memset(addr4, 0, sizeof(*addr4)); 54 addr4->sin_family = AF_INET; 55 addr4->sin_addr.s_addr = htonl(INADDR_LOOPBACK); 56 addr4->sin_port = htons(port); 57 break; 58 case PF_INET6: 59 memset(addr6, 0, sizeof(*addr6)); 60 addr6->sin6_family = AF_INET6; 61 addr6->sin6_addr = in6addr_loopback; 62 addr6->sin6_port = htons(port); 63 break; 64 default: 65 error(1, 0, "illegal family"); 66 } 67 } 68 69 void *start_server(void *arg) 70 { 71 int server_fd = (int)(unsigned long)arg; 72 struct sockaddr_in addr; 73 socklen_t addrlen = sizeof(addr); 74 char *buf; 75 int fd; 76 int r; 77 78 buf = malloc(BUF_SIZE); 79 80 for (;;) { 81 fd = accept(server_fd, (struct sockaddr *)&addr, &addrlen); 82 if (fd == -1) { 83 perror("accept"); 84 break; 85 } 86 do { 87 r = send(fd, buf, BUF_SIZE, 0); 88 } while (r < 0 && errno == EINTR); 89 if (r < 0) 90 perror("send"); 91 if (r != BUF_SIZE) 92 fprintf(stderr, "can only send %d bytes\n", r); 93 /* TCP_INQ can overestimate in-queue by one byte if we send 94 * the FIN packet. Sleep for 1 second, so that the client 95 * likely invoked recvmsg(). 96 */ 97 sleep(1); 98 close(fd); 99 } 100 101 free(buf); 102 close(server_fd); 103 pthread_exit(0); 104 } 105 106 int main(int argc, char *argv[]) 107 { 108 struct sockaddr_storage listen_addr, addr; 109 int c, one = 1, inq = -1; 110 pthread_t server_thread; 111 char cmsgbuf[CMSG_SIZE]; 112 struct iovec iov[1]; 113 struct cmsghdr *cm; 114 struct msghdr msg; 115 int server_fd, fd; 116 char *buf; 117 118 while ((c = getopt(argc, argv, "46p:")) != -1) { 119 switch (c) { 120 case '4': 121 family = PF_INET; 122 addr_len = sizeof(struct sockaddr_in); 123 break; 124 case '6': 125 family = PF_INET6; 126 addr_len = sizeof(struct sockaddr_in6); 127 break; 128 case 'p': 129 port = atoi(optarg); 130 break; 131 } 132 } 133 134 server_fd = socket(family, SOCK_STREAM, 0); 135 if (server_fd < 0) 136 error(1, errno, "server socket"); 137 setup_loopback_addr(family, &listen_addr); 138 if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, 139 &one, sizeof(one)) != 0) 140 error(1, errno, "setsockopt(SO_REUSEADDR)"); 141 if (bind(server_fd, (const struct sockaddr *)&listen_addr, 142 addr_len) == -1) 143 error(1, errno, "bind"); 144 if (listen(server_fd, 128) == -1) 145 error(1, errno, "listen"); 146 if (pthread_create(&server_thread, NULL, start_server, 147 (void *)(unsigned long)server_fd) != 0) 148 error(1, errno, "pthread_create"); 149 150 fd = socket(family, SOCK_STREAM, 0); 151 if (fd < 0) 152 error(1, errno, "client socket"); 153 setup_loopback_addr(family, &addr); 154 if (connect(fd, (const struct sockaddr *)&addr, addr_len) == -1) 155 error(1, errno, "connect"); 156 if (setsockopt(fd, SOL_TCP, TCP_INQ, &one, sizeof(one)) != 0) 157 error(1, errno, "setsockopt(TCP_INQ)"); 158 159 msg.msg_name = NULL; 160 msg.msg_namelen = 0; 161 msg.msg_iov = iov; 162 msg.msg_iovlen = 1; 163 msg.msg_control = cmsgbuf; 164 msg.msg_controllen = sizeof(cmsgbuf); 165 msg.msg_flags = 0; 166 167 buf = malloc(BUF_SIZE); 168 iov[0].iov_base = buf; 169 iov[0].iov_len = BUF_SIZE / 2; 170 171 if (recvmsg(fd, &msg, 0) != iov[0].iov_len) 172 error(1, errno, "recvmsg"); 173 if (msg.msg_flags & MSG_CTRUNC) 174 error(1, 0, "control message is truncated"); 175 176 for (cm = CMSG_FIRSTHDR(&msg); cm; cm = CMSG_NXTHDR(&msg, cm)) 177 if (cm->cmsg_level == SOL_TCP && cm->cmsg_type == TCP_CM_INQ) 178 inq = *((int *) CMSG_DATA(cm)); 179 180 if (inq != BUF_SIZE - iov[0].iov_len) { 181 fprintf(stderr, "unexpected inq: %d\n", inq); 182 exit(1); 183 } 184 185 printf("PASSED\n"); 186 free(buf); 187 close(fd); 188 return 0; 189 } 190