1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright 2018 Google Inc. 4 * Author: Soheil Hassas Yeganeh (soheil@google.com) 5 * 6 * Simple example on how to use TCP_INQ and TCP_CM_INQ. 7 */ 8 #define _GNU_SOURCE 9 10 #include <error.h> 11 #include <netinet/in.h> 12 #include <netinet/tcp.h> 13 #include <pthread.h> 14 #include <stdio.h> 15 #include <errno.h> 16 #include <stdlib.h> 17 #include <string.h> 18 #include <sys/socket.h> 19 #include <unistd.h> 20 21 #ifndef TCP_INQ 22 #define TCP_INQ 36 23 #endif 24 25 #ifndef TCP_CM_INQ 26 #define TCP_CM_INQ TCP_INQ 27 #endif 28 29 #define BUF_SIZE 8192 30 #define CMSG_SIZE 32 31 32 static int family = AF_INET6; 33 static socklen_t addr_len = sizeof(struct sockaddr_in6); 34 static int port = 4974; 35 36 static void setup_loopback_addr(int family, struct sockaddr_storage *sockaddr) 37 { 38 struct sockaddr_in6 *addr6 = (void *) sockaddr; 39 struct sockaddr_in *addr4 = (void *) sockaddr; 40 41 switch (family) { 42 case PF_INET: 43 memset(addr4, 0, sizeof(*addr4)); 44 addr4->sin_family = AF_INET; 45 addr4->sin_addr.s_addr = htonl(INADDR_LOOPBACK); 46 addr4->sin_port = htons(port); 47 break; 48 case PF_INET6: 49 memset(addr6, 0, sizeof(*addr6)); 50 addr6->sin6_family = AF_INET6; 51 addr6->sin6_addr = in6addr_loopback; 52 addr6->sin6_port = htons(port); 53 break; 54 default: 55 error(1, 0, "illegal family"); 56 } 57 } 58 59 void *start_server(void *arg) 60 { 61 int server_fd = (int)(unsigned long)arg; 62 struct sockaddr_in addr; 63 socklen_t addrlen = sizeof(addr); 64 char *buf; 65 int fd; 66 int r; 67 68 buf = malloc(BUF_SIZE); 69 70 for (;;) { 71 fd = accept(server_fd, (struct sockaddr *)&addr, &addrlen); 72 if (fd == -1) { 73 perror("accept"); 74 break; 75 } 76 do { 77 r = send(fd, buf, BUF_SIZE, 0); 78 } while (r < 0 && errno == EINTR); 79 if (r < 0) 80 perror("send"); 81 if (r != BUF_SIZE) 82 fprintf(stderr, "can only send %d bytes\n", r); 83 /* TCP_INQ can overestimate in-queue by one byte if we send 84 * the FIN packet. Sleep for 1 second, so that the client 85 * likely invoked recvmsg(). 86 */ 87 sleep(1); 88 close(fd); 89 } 90 91 free(buf); 92 close(server_fd); 93 pthread_exit(0); 94 } 95 96 int main(int argc, char *argv[]) 97 { 98 struct sockaddr_storage listen_addr, addr; 99 int c, one = 1, inq = -1; 100 pthread_t server_thread; 101 char cmsgbuf[CMSG_SIZE]; 102 struct iovec iov[1]; 103 struct cmsghdr *cm; 104 struct msghdr msg; 105 int server_fd, fd; 106 char *buf; 107 108 while ((c = getopt(argc, argv, "46p:")) != -1) { 109 switch (c) { 110 case '4': 111 family = PF_INET; 112 addr_len = sizeof(struct sockaddr_in); 113 break; 114 case '6': 115 family = PF_INET6; 116 addr_len = sizeof(struct sockaddr_in6); 117 break; 118 case 'p': 119 port = atoi(optarg); 120 break; 121 } 122 } 123 124 server_fd = socket(family, SOCK_STREAM, 0); 125 if (server_fd < 0) 126 error(1, errno, "server socket"); 127 setup_loopback_addr(family, &listen_addr); 128 if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, 129 &one, sizeof(one)) != 0) 130 error(1, errno, "setsockopt(SO_REUSEADDR)"); 131 if (bind(server_fd, (const struct sockaddr *)&listen_addr, 132 addr_len) == -1) 133 error(1, errno, "bind"); 134 if (listen(server_fd, 128) == -1) 135 error(1, errno, "listen"); 136 if (pthread_create(&server_thread, NULL, start_server, 137 (void *)(unsigned long)server_fd) != 0) 138 error(1, errno, "pthread_create"); 139 140 fd = socket(family, SOCK_STREAM, 0); 141 if (fd < 0) 142 error(1, errno, "client socket"); 143 setup_loopback_addr(family, &addr); 144 if (connect(fd, (const struct sockaddr *)&addr, addr_len) == -1) 145 error(1, errno, "connect"); 146 if (setsockopt(fd, SOL_TCP, TCP_INQ, &one, sizeof(one)) != 0) 147 error(1, errno, "setsockopt(TCP_INQ)"); 148 149 msg.msg_name = NULL; 150 msg.msg_namelen = 0; 151 msg.msg_iov = iov; 152 msg.msg_iovlen = 1; 153 msg.msg_control = cmsgbuf; 154 msg.msg_controllen = sizeof(cmsgbuf); 155 msg.msg_flags = 0; 156 157 buf = malloc(BUF_SIZE); 158 iov[0].iov_base = buf; 159 iov[0].iov_len = BUF_SIZE / 2; 160 161 if (recvmsg(fd, &msg, 0) != iov[0].iov_len) 162 error(1, errno, "recvmsg"); 163 if (msg.msg_flags & MSG_CTRUNC) 164 error(1, 0, "control message is truncated"); 165 166 for (cm = CMSG_FIRSTHDR(&msg); cm; cm = CMSG_NXTHDR(&msg, cm)) 167 if (cm->cmsg_level == SOL_TCP && cm->cmsg_type == TCP_CM_INQ) 168 inq = *((int *) CMSG_DATA(cm)); 169 170 if (inq != BUF_SIZE - iov[0].iov_len) { 171 fprintf(stderr, "unexpected inq: %d\n", inq); 172 exit(1); 173 } 174 175 printf("PASSED\n"); 176 free(buf); 177 close(fd); 178 return 0; 179 } 180