ipv6_flowlabel.c

  1// SPDX-License-Identifier: GPL-2.0
  2/* Test IPV6_FLOWINFO cmsg on send and recv */
  3
  4#define _GNU_SOURCE
  5
  6#include <arpa/inet.h>
  7#include <asm/byteorder.h>
  8#include <error.h>
  9#include <errno.h>
 10#include <fcntl.h>
 11#include <limits.h>
 12#include <linux/icmpv6.h>
 13#include <linux/in6.h>
 14#include <stdbool.h>
 15#include <stdio.h>
 16#include <stdint.h>
 17#include <stdlib.h>
 18#include <string.h>
 19#include <sys/socket.h>
 20#include <sys/stat.h>
 21#include <sys/time.h>
 22#include <sys/types.h>
 23#include <unistd.h>
 24
 25/* uapi/glibc weirdness may leave this undefined */
 26#ifndef IPV6_FLOWINFO
 27#define IPV6_FLOWINFO 11
 28#endif
 29
 30#ifndef IPV6_FLOWLABEL_MGR
 31#define IPV6_FLOWLABEL_MGR 32
 32#endif
 33#ifndef IPV6_FLOWINFO_SEND
 34#define IPV6_FLOWINFO_SEND 33
 35#endif
 36
 37#define FLOWLABEL_WILDCARD	((uint32_t) -1)
 38
 39static const char cfg_data[]	= "a";
 40static uint32_t cfg_label	= 1;
 41static bool use_ping;
 42static bool use_flowinfo_send;
 43
 44static struct icmp6hdr icmp6 = {
 45	.icmp6_type = ICMPV6_ECHO_REQUEST
 46};
 47
 48static struct sockaddr_in6 addr = {
 49	.sin6_family = AF_INET6,
 50	.sin6_addr = IN6ADDR_LOOPBACK_INIT,
 51};
 52
 53static void do_send(int fd, bool with_flowlabel, uint32_t flowlabel)
 54{
 55	char control[CMSG_SPACE(sizeof(flowlabel))] = {0};
 56	struct msghdr msg = {0};
 57	struct iovec iov = {
 58		.iov_base = (char *)cfg_data,
 59		.iov_len = sizeof(cfg_data)
 60	};
 61	int ret;
 62
 63	if (use_ping) {
 64		iov.iov_base = &icmp6;
 65		iov.iov_len = sizeof(icmp6);
 66	}
 67
 68	msg.msg_iov = &iov;
 69	msg.msg_iovlen = 1;
 70
 71	if (use_flowinfo_send) {
 72		msg.msg_name = &addr;
 73		msg.msg_namelen = sizeof(addr);
 74	} else if (with_flowlabel) {
 75		struct cmsghdr *cm;
 76
 77		cm = (void *)control;
 78		cm->cmsg_len = CMSG_LEN(sizeof(flowlabel));
 79		cm->cmsg_level = SOL_IPV6;
 80		cm->cmsg_type = IPV6_FLOWINFO;
 81		*(uint32_t *)CMSG_DATA(cm) = htonl(flowlabel);
 82
 83		msg.msg_control = control;
 84		msg.msg_controllen = sizeof(control);
 85	}
 86
 87	ret = sendmsg(fd, &msg, 0);
 88	if (ret == -1)
 89		error(1, errno, "send");
 90
 91	if (with_flowlabel)
 92		fprintf(stderr, "sent with label %u\n", flowlabel);
 93	else
 94		fprintf(stderr, "sent without label\n");
 95}
 96
 97static void do_recv(int fd, bool with_flowlabel, uint32_t expect)
 98{
 99	char control[CMSG_SPACE(sizeof(expect))];
100	char data[sizeof(cfg_data)];
101	struct msghdr msg = {0};
102	struct iovec iov = {0};
103	struct cmsghdr *cm;
104	uint32_t flowlabel;
105	int ret;
106
107	iov.iov_base = data;
108	iov.iov_len = sizeof(data);
109
110	msg.msg_iov = &iov;
111	msg.msg_iovlen = 1;
112
113	memset(control, 0, sizeof(control));
114	msg.msg_control = control;
115	msg.msg_controllen = sizeof(control);
116
117	ret = recvmsg(fd, &msg, 0);
118	if (ret == -1)
119		error(1, errno, "recv");
120	if (use_ping)
121		goto parse_cmsg;
122	if (msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))
123		error(1, 0, "recv: truncated");
124	if (ret != sizeof(cfg_data))
125		error(1, 0, "recv: length mismatch");
126	if (memcmp(data, cfg_data, sizeof(data)))
127		error(1, 0, "recv: data mismatch");
128
129parse_cmsg:
130	cm = CMSG_FIRSTHDR(&msg);
131	if (with_flowlabel) {
132		if (!cm)
133			error(1, 0, "recv: missing cmsg");
134		if (CMSG_NXTHDR(&msg, cm))
135			error(1, 0, "recv: too many cmsg");
136		if (cm->cmsg_level != SOL_IPV6 ||
137		    cm->cmsg_type != IPV6_FLOWINFO)
138			error(1, 0, "recv: unexpected cmsg level or type");
139
140		flowlabel = ntohl(*(uint32_t *)CMSG_DATA(cm));
141		fprintf(stderr, "recv with label %u\n", flowlabel);
142
143		if (expect != FLOWLABEL_WILDCARD && expect != flowlabel) {
144			fprintf(stderr, "recv: incorrect flowlabel %u != %u\n",
145					flowlabel, expect);
146			error(1, 0, "recv: flowlabel is wrong");
147		}
148
149	} else {
150		fprintf(stderr, "recv without label\n");
151	}
152}
153
154static bool get_autoflowlabel_enabled(void)
155{
156	int fd, ret;
157	char val;
158
159	fd = open("/proc/sys/net/ipv6/auto_flowlabels", O_RDONLY);
160	if (fd == -1)
161		error(1, errno, "open sysctl");
162
163	ret = read(fd, &val, 1);
164	if (ret == -1)
165		error(1, errno, "read sysctl");
166	if (ret == 0)
167		error(1, 0, "read sysctl: 0");
168
169	if (close(fd))
170		error(1, errno, "close sysctl");
171
172	return val == '1';
173}
174
175static void flowlabel_get(int fd, uint32_t label, uint8_t share, uint16_t flags)
176{
177	struct in6_flowlabel_req req = {
178		.flr_action = IPV6_FL_A_GET,
179		.flr_label = htonl(label),
180		.flr_flags = flags,
181		.flr_share = share,
182	};
183
184	/* do not pass IPV6_ADDR_ANY or IPV6_ADDR_MAPPED */
185	req.flr_dst.s6_addr[0] = 0xfd;
186	req.flr_dst.s6_addr[15] = 0x1;
187
188	if (setsockopt(fd, SOL_IPV6, IPV6_FLOWLABEL_MGR, &req, sizeof(req)))
189		error(1, errno, "setsockopt flowlabel get");
190}
191
192static void parse_opts(int argc, char **argv)
193{
194	int c;
195
196	while ((c = getopt(argc, argv, "l:ps")) != -1) {
197		switch (c) {
198		case 'l':
199			cfg_label = strtoul(optarg, NULL, 0);
200			break;
201		case 'p':
202			use_ping = true;
203			break;
204		case 's':
205			use_flowinfo_send = true;
206			break;
207		default:
208			error(1, 0, "%s: parse error", argv[0]);
209		}
210	}
211}
212
213int main(int argc, char **argv)
214{
215	const int one = 1;
216	int fdt, fdr;
217	int prot = 0;
218
219	addr.sin6_port = htons(8000);
220
221	parse_opts(argc, argv);
222
223	if (use_ping) {
224		fprintf(stderr, "attempting to use ping sockets\n");
225		prot = IPPROTO_ICMPV6;
226	}
227
228	fdt = socket(PF_INET6, SOCK_DGRAM, prot);
229	if (fdt == -1)
230		error(1, errno, "socket t");
231
232	fdr = use_ping ? fdt : socket(PF_INET6, SOCK_DGRAM, 0);
233	if (fdr == -1)
234		error(1, errno, "socket r");
235
236	if (connect(fdt, (void *)&addr, sizeof(addr)))
237		error(1, errno, "connect");
238	if (!use_ping && bind(fdr, (void *)&addr, sizeof(addr)))
239		error(1, errno, "bind");
240
241	flowlabel_get(fdt, cfg_label, IPV6_FL_S_EXCL, IPV6_FL_F_CREATE);
242
243	if (setsockopt(fdr, SOL_IPV6, IPV6_FLOWINFO, &one, sizeof(one)))
244		error(1, errno, "setsockopt flowinfo");
245
246	if (get_autoflowlabel_enabled()) {
247		fprintf(stderr, "send no label: recv auto flowlabel\n");
248		do_send(fdt, false, 0);
249		do_recv(fdr, true, FLOWLABEL_WILDCARD);
250	} else {
251		fprintf(stderr, "send no label: recv no label (auto off)\n");
252		do_send(fdt, false, 0);
253		do_recv(fdr, false, 0);
254	}
255
256	if (use_flowinfo_send) {
257		fprintf(stderr, "using IPV6_FLOWINFO_SEND to send label\n");
258		addr.sin6_flowinfo = htonl(cfg_label);
259		if (setsockopt(fdt, SOL_IPV6, IPV6_FLOWINFO_SEND, &one,
260			       sizeof(one)) == -1)
261			error(1, errno, "setsockopt flowinfo_send");
262	}
263
264	fprintf(stderr, "send label\n");
265	do_send(fdt, true, cfg_label);
266	do_recv(fdr, true, cfg_label);
267
268	if (close(fdr))
269		error(1, errno, "close r");
270	if (!use_ping && close(fdt))
271		error(1, errno, "close t");
272
273	return 0;
274}