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/*
* Copyright 2018 Google Inc.
* Author: Soheil Hassas Yeganeh (soheil@google.com)
*
* Simple example on how to use TCP_INQ and TCP_CM_INQ.
*
* License (GPLv2):
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. * See the GNU General Public License for
* more details.
*/
#define _GNU_SOURCE
#include <error.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <pthread.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>
#ifndef TCP_INQ
#define TCP_INQ 36
#endif
#ifndef TCP_CM_INQ
#define TCP_CM_INQ TCP_INQ
#endif
#define BUF_SIZE 8192
#define CMSG_SIZE 32
static int family = AF_INET6;
static socklen_t addr_len = sizeof(struct sockaddr_in6);
static int port = 4974;
static void setup_loopback_addr(int family, struct sockaddr_storage *sockaddr)
{
struct sockaddr_in6 *addr6 = (void *) sockaddr;
struct sockaddr_in *addr4 = (void *) sockaddr;
switch (family) {
case PF_INET:
memset(addr4, 0, sizeof(*addr4));
addr4->sin_family = AF_INET;
addr4->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
addr4->sin_port = htons(port);
break;
case PF_INET6:
memset(addr6, 0, sizeof(*addr6));
addr6->sin6_family = AF_INET6;
addr6->sin6_addr = in6addr_loopback;
addr6->sin6_port = htons(port);
break;
default:
error(1, 0, "illegal family");
}
}
void *start_server(void *arg)
{
int server_fd = (int)(unsigned long)arg;
struct sockaddr_in addr;
socklen_t addrlen = sizeof(addr);
char *buf;
int fd;
int r;
buf = malloc(BUF_SIZE);
for (;;) {
fd = accept(server_fd, (struct sockaddr *)&addr, &addrlen);
if (fd == -1) {
perror("accept");
break;
}
do {
r = send(fd, buf, BUF_SIZE, 0);
} while (r < 0 && errno == EINTR);
if (r < 0)
perror("send");
if (r != BUF_SIZE)
fprintf(stderr, "can only send %d bytes\n", r);
/* TCP_INQ can overestimate in-queue by one byte if we send
* the FIN packet. Sleep for 1 second, so that the client
* likely invoked recvmsg().
*/
sleep(1);
close(fd);
}
free(buf);
close(server_fd);
pthread_exit(0);
}
int main(int argc, char *argv[])
{
struct sockaddr_storage listen_addr, addr;
int c, one = 1, inq = -1;
pthread_t server_thread;
char cmsgbuf[CMSG_SIZE];
struct iovec iov[1];
struct cmsghdr *cm;
struct msghdr msg;
int server_fd, fd;
char *buf;
while ((c = getopt(argc, argv, "46p:")) != -1) {
switch (c) {
case '4':
family = PF_INET;
addr_len = sizeof(struct sockaddr_in);
break;
case '6':
family = PF_INET6;
addr_len = sizeof(struct sockaddr_in6);
break;
case 'p':
port = atoi(optarg);
break;
}
}
server_fd = socket(family, SOCK_STREAM, 0);
if (server_fd < 0)
error(1, errno, "server socket");
setup_loopback_addr(family, &listen_addr);
if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR,
&one, sizeof(one)) != 0)
error(1, errno, "setsockopt(SO_REUSEADDR)");
if (bind(server_fd, (const struct sockaddr *)&listen_addr,
addr_len) == -1)
error(1, errno, "bind");
if (listen(server_fd, 128) == -1)
error(1, errno, "listen");
if (pthread_create(&server_thread, NULL, start_server,
(void *)(unsigned long)server_fd) != 0)
error(1, errno, "pthread_create");
fd = socket(family, SOCK_STREAM, 0);
if (fd < 0)
error(1, errno, "client socket");
setup_loopback_addr(family, &addr);
if (connect(fd, (const struct sockaddr *)&addr, addr_len) == -1)
error(1, errno, "connect");
if (setsockopt(fd, SOL_TCP, TCP_INQ, &one, sizeof(one)) != 0)
error(1, errno, "setsockopt(TCP_INQ)");
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iov = iov;
msg.msg_iovlen = 1;
msg.msg_control = cmsgbuf;
msg.msg_controllen = sizeof(cmsgbuf);
msg.msg_flags = 0;
buf = malloc(BUF_SIZE);
iov[0].iov_base = buf;
iov[0].iov_len = BUF_SIZE / 2;
if (recvmsg(fd, &msg, 0) != iov[0].iov_len)
error(1, errno, "recvmsg");
if (msg.msg_flags & MSG_CTRUNC)
error(1, 0, "control message is truncated");
for (cm = CMSG_FIRSTHDR(&msg); cm; cm = CMSG_NXTHDR(&msg, cm))
if (cm->cmsg_level == SOL_TCP && cm->cmsg_type == TCP_CM_INQ)
inq = *((int *) CMSG_DATA(cm));
if (inq != BUF_SIZE - iov[0].iov_len) {
fprintf(stderr, "unexpected inq: %d\n", inq);
exit(1);
}
printf("PASSED\n");
free(buf);
close(fd);
return 0;
}
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