selftests/net/tcp_inq.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright 2018 Google Inc.
0004  * Author: Soheil Hassas Yeganeh (soheil@google.com)
0005  *
0006  * Simple example on how to use TCP_INQ and TCP_CM_INQ.
0007  */
0008 #define _GNU_SOURCE
0009
0010 #include <error.h>
0011 #include <netinet/in.h>
0012 #include <netinet/tcp.h>
0013 #include <pthread.h>
0014 #include <stdio.h>
0015 #include <errno.h>
0016 #include <stdlib.h>
0017 #include <string.h>
0018 #include <sys/socket.h>
0019 #include <unistd.h>
0020
0021 #ifndef TCP_INQ
0022 #define TCP_INQ 36
0023 #endif
0024
0025 #ifndef TCP_CM_INQ
0026 #define TCP_CM_INQ TCP_INQ
0027 #endif
0028
0029 #define BUF_SIZE 8192
0030 #define CMSG_SIZE 32
0031
0032 static int family = AF_INET6;
0033 static socklen_t addr_len = sizeof(struct sockaddr_in6);
0034 static int port = 4974;
0035
0036 static void setup_loopback_addr(int family, struct sockaddr_storage *sockaddr)
0037 {
0038     struct sockaddr_in6 *addr6 = (void *) sockaddr;
0039     struct sockaddr_in *addr4 = (void *) sockaddr;
0040
0041     switch (family) {
0042     case PF_INET:
0043         memset(addr4, 0, sizeof(*addr4));
0044         addr4->sin_family = AF_INET;
0045         addr4->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
0046         addr4->sin_port = htons(port);
0047         break;
0048     case PF_INET6:
0049         memset(addr6, 0, sizeof(*addr6));
0050         addr6->sin6_family = AF_INET6;
0051         addr6->sin6_addr = in6addr_loopback;
0052         addr6->sin6_port = htons(port);
0053         break;
0054     default:
0055         error(1, 0, "illegal family");
0056     }
0057 }
0058
0059 void *start_server(void *arg)
0060 {
0061     int server_fd = (int)(unsigned long)arg;
0062     struct sockaddr_in addr;
0063     socklen_t addrlen = sizeof(addr);
0064     char *buf;
0065     int fd;
0066     int r;
0067
0068     buf = malloc(BUF_SIZE);
0069
0070     for (;;) {
0071         fd = accept(server_fd, (struct sockaddr *)&addr, &addrlen);
0072         if (fd == -1) {
0073             perror("accept");
0074             break;
0075         }
0076         do {
0077             r = send(fd, buf, BUF_SIZE, 0);
0078         } while (r < 0 && errno == EINTR);
0079         if (r < 0)
0080             perror("send");
0081         if (r != BUF_SIZE)
0082             fprintf(stderr, "can only send %d bytes\n", r);
0083         /* TCP_INQ can overestimate in-queue by one byte if we send
0084          * the FIN packet. Sleep for 1 second, so that the client
0085          * likely invoked recvmsg().
0086          */
0087         sleep(1);
0088         close(fd);
0089     }
0090
0091     free(buf);
0092     close(server_fd);
0093     pthread_exit(0);
0094 }
0095
0096 int main(int argc, char *argv[])
0097 {
0098     struct sockaddr_storage listen_addr, addr;
0099     int c, one = 1, inq = -1;
0100     pthread_t server_thread;
0101     char cmsgbuf[CMSG_SIZE];
0102     struct iovec iov[1];
0103     struct cmsghdr *cm;
0104     struct msghdr msg;
0105     int server_fd, fd;
0106     char *buf;
0107
0108     while ((c = getopt(argc, argv, "46p:")) != -1) {
0109         switch (c) {
0110         case '4':
0111             family = PF_INET;
0112             addr_len = sizeof(struct sockaddr_in);
0113             break;
0114         case '6':
0115             family = PF_INET6;
0116             addr_len = sizeof(struct sockaddr_in6);
0117             break;
0118         case 'p':
0119             port = atoi(optarg);
0120             break;
0121         }
0122     }
0123
0124     server_fd = socket(family, SOCK_STREAM, 0);
0125     if (server_fd < 0)
0126         error(1, errno, "server socket");
0127     setup_loopback_addr(family, &listen_addr);
0128     if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR,
0129                &one, sizeof(one)) != 0)
0130         error(1, errno, "setsockopt(SO_REUSEADDR)");
0131     if (bind(server_fd, (const struct sockaddr *)&listen_addr,
0132          addr_len) == -1)
0133         error(1, errno, "bind");
0134     if (listen(server_fd, 128) == -1)
0135         error(1, errno, "listen");
0136     if (pthread_create(&server_thread, NULL, start_server,
0137                (void *)(unsigned long)server_fd) != 0)
0138         error(1, errno, "pthread_create");
0139
0140     fd = socket(family, SOCK_STREAM, 0);
0141     if (fd < 0)
0142         error(1, errno, "client socket");
0143     setup_loopback_addr(family, &addr);
0144     if (connect(fd, (const struct sockaddr *)&addr, addr_len) == -1)
0145         error(1, errno, "connect");
0146     if (setsockopt(fd, SOL_TCP, TCP_INQ, &one, sizeof(one)) != 0)
0147         error(1, errno, "setsockopt(TCP_INQ)");
0148
0149     msg.msg_name = NULL;
0150     msg.msg_namelen = 0;
0151     msg.msg_iov = iov;
0152     msg.msg_iovlen = 1;
0153     msg.msg_control = cmsgbuf;
0154     msg.msg_controllen = sizeof(cmsgbuf);
0155     msg.msg_flags = 0;
0156
0157     buf = malloc(BUF_SIZE);
0158     iov[0].iov_base = buf;
0159     iov[0].iov_len = BUF_SIZE / 2;
0160
0161     if (recvmsg(fd, &msg, 0) != iov[0].iov_len)
0162         error(1, errno, "recvmsg");
0163     if (msg.msg_flags & MSG_CTRUNC)
0164         error(1, 0, "control message is truncated");
0165
0166     for (cm = CMSG_FIRSTHDR(&msg); cm; cm = CMSG_NXTHDR(&msg, cm))
0167         if (cm->cmsg_level == SOL_TCP && cm->cmsg_type == TCP_CM_INQ)
0168             inq = *((int *) CMSG_DATA(cm));
0169
0170     if (inq != BUF_SIZE - iov[0].iov_len) {
0171         fprintf(stderr, "unexpected inq: %d\n", inq);
0172         exit(1);
0173     }
0174
0175     printf("PASSED\n");
0176     free(buf);
0177     close(fd);
0178     return 0;
0179 }