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1// SPDX-License-Identifier: GPL-2.0-only2/*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_SOURCE9 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_INQ22#define TCP_INQ 3623#endif24 25#ifndef TCP_CM_INQ26#define TCP_CM_INQ TCP_INQ27#endif28 29#define BUF_SIZE 819230#define CMSG_SIZE 3231 32static int family = AF_INET6;33static socklen_t addr_len = sizeof(struct sockaddr_in6);34static int port = 4974;35 36static 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 59void *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 send84 * the FIN packet. Sleep for 1 second, so that the client85 * 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 96int 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