1// SPDX-License-Identifier: GPL-2.0-only
 2/* Some common code for MSG_ZEROCOPY logic
 3 *
 4 * Copyright (C) 2023 SberDevices.
 5 *
 6 * Author: Arseniy Krasnov <avkrasnov@salutedevices.com>
 7 */
 8
 9#include <stdio.h>
10#include <stdlib.h>
11#include <sys/types.h>
12#include <sys/socket.h>
13#include <linux/errqueue.h>
14
15#include "msg_zerocopy_common.h"
16
17void enable_so_zerocopy(int fd)
18{
19	int val = 1;
20
21	if (setsockopt(fd, SOL_SOCKET, SO_ZEROCOPY, &val, sizeof(val))) {
22		perror("setsockopt");
23		exit(EXIT_FAILURE);
24	}
25}
26
27void vsock_recv_completion(int fd, const bool *zerocopied)
28{
29	struct sock_extended_err *serr;
30	struct msghdr msg = { 0 };
31	char cmsg_data[128];
32	struct cmsghdr *cm;
33	ssize_t res;
34
35	msg.msg_control = cmsg_data;
36	msg.msg_controllen = sizeof(cmsg_data);
37
38	res = recvmsg(fd, &msg, MSG_ERRQUEUE);
39	if (res) {
40		fprintf(stderr, "failed to read error queue: %zi\n", res);
41		exit(EXIT_FAILURE);
42	}
43
44	cm = CMSG_FIRSTHDR(&msg);
45	if (!cm) {
46		fprintf(stderr, "cmsg: no cmsg\n");
47		exit(EXIT_FAILURE);
48	}
49
50	if (cm->cmsg_level != SOL_VSOCK) {
51		fprintf(stderr, "cmsg: unexpected 'cmsg_level'\n");
52		exit(EXIT_FAILURE);
53	}
54
55	if (cm->cmsg_type != VSOCK_RECVERR) {
56		fprintf(stderr, "cmsg: unexpected 'cmsg_type'\n");
57		exit(EXIT_FAILURE);
58	}
59
60	serr = (void *)CMSG_DATA(cm);
61	if (serr->ee_origin != SO_EE_ORIGIN_ZEROCOPY) {
62		fprintf(stderr, "serr: wrong origin: %u\n", serr->ee_origin);
63		exit(EXIT_FAILURE);
64	}
65
66	if (serr->ee_errno) {
67		fprintf(stderr, "serr: wrong error code: %u\n", serr->ee_errno);
68		exit(EXIT_FAILURE);
69	}
70
71	/* This flag is used for tests, to check that transmission was
72	 * performed as expected: zerocopy or fallback to copy. If NULL
73	 * - don't care.
74	 */
75	if (!zerocopied)
76		return;
77
78	if (*zerocopied && (serr->ee_code & SO_EE_CODE_ZEROCOPY_COPIED)) {
79		fprintf(stderr, "serr: was copy instead of zerocopy\n");
80		exit(EXIT_FAILURE);
81	}
82
83	if (!*zerocopied && !(serr->ee_code & SO_EE_CODE_ZEROCOPY_COPIED)) {
84		fprintf(stderr, "serr: was zerocopy instead of copy\n");
85		exit(EXIT_FAILURE);
86	}
87}