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 vsock_recv_completion(int fd, const bool *zerocopied)
18{
19	struct sock_extended_err *serr;
20	struct msghdr msg = { 0 };
21	char cmsg_data[128];
22	struct cmsghdr *cm;
23	ssize_t res;
24
25	msg.msg_control = cmsg_data;
26	msg.msg_controllen = sizeof(cmsg_data);
27
28	res = recvmsg(fd, &msg, MSG_ERRQUEUE);
29	if (res) {
30		fprintf(stderr, "failed to read error queue: %zi\n", res);
31		exit(EXIT_FAILURE);
32	}
33
34	cm = CMSG_FIRSTHDR(&msg);
35	if (!cm) {
36		fprintf(stderr, "cmsg: no cmsg\n");
37		exit(EXIT_FAILURE);
38	}
39
40	if (cm->cmsg_level != SOL_VSOCK) {
41		fprintf(stderr, "cmsg: unexpected 'cmsg_level'\n");
42		exit(EXIT_FAILURE);
43	}
44
45	if (cm->cmsg_type != VSOCK_RECVERR) {
46		fprintf(stderr, "cmsg: unexpected 'cmsg_type'\n");
47		exit(EXIT_FAILURE);
48	}
49
50	serr = (void *)CMSG_DATA(cm);
51	if (serr->ee_origin != SO_EE_ORIGIN_ZEROCOPY) {
52		fprintf(stderr, "serr: wrong origin: %u\n", serr->ee_origin);
53		exit(EXIT_FAILURE);
54	}
55
56	if (serr->ee_errno) {
57		fprintf(stderr, "serr: wrong error code: %u\n", serr->ee_errno);
58		exit(EXIT_FAILURE);
59	}
60
61	/* This flag is used for tests, to check that transmission was
62	 * performed as expected: zerocopy or fallback to copy. If NULL
63	 * - don't care.
64	 */
65	if (!zerocopied)
66		return;
67
68	if (*zerocopied && (serr->ee_code & SO_EE_CODE_ZEROCOPY_COPIED)) {
69		fprintf(stderr, "serr: was copy instead of zerocopy\n");
70		exit(EXIT_FAILURE);
71	}
72
73	if (!*zerocopied && !(serr->ee_code & SO_EE_CODE_ZEROCOPY_COPIED)) {
74		fprintf(stderr, "serr: was zerocopy instead of copy\n");
75		exit(EXIT_FAILURE);
76	}
77}