1
2
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/in6.h>
13#include <stdbool.h>
14#include <stdio.h>
15#include <stdint.h>
16#include <stdlib.h>
17#include <string.h>
18#include <sys/socket.h>
19#include <sys/stat.h>
20#include <sys/time.h>
21#include <sys/types.h>
22#include <unistd.h>
23
24
25#ifndef IPV6_FLOWINFO
26#define IPV6_FLOWINFO 11
27#endif
28
29#ifndef IPV6_FLOWLABEL_MGR
30#define IPV6_FLOWLABEL_MGR 32
31#endif
32
33#define FLOWLABEL_WILDCARD ((uint32_t) -1)
34
35static const char cfg_data[] = "a";
36static uint32_t cfg_label = 1;
37
38static void do_send(int fd, bool with_flowlabel, uint32_t flowlabel)
39{
40 char control[CMSG_SPACE(sizeof(flowlabel))] = {0};
41 struct msghdr msg = {0};
42 struct iovec iov = {0};
43 int ret;
44
45 iov.iov_base = (char *)cfg_data;
46 iov.iov_len = sizeof(cfg_data);
47
48 msg.msg_iov = &iov;
49 msg.msg_iovlen = 1;
50
51 if (with_flowlabel) {
52 struct cmsghdr *cm;
53
54 cm = (void *)control;
55 cm->cmsg_len = CMSG_LEN(sizeof(flowlabel));
56 cm->cmsg_level = SOL_IPV6;
57 cm->cmsg_type = IPV6_FLOWINFO;
58 *(uint32_t *)CMSG_DATA(cm) = htonl(flowlabel);
59
60 msg.msg_control = control;
61 msg.msg_controllen = sizeof(control);
62 }
63
64 ret = sendmsg(fd, &msg, 0);
65 if (ret == -1)
66 error(1, errno, "send");
67
68 if (with_flowlabel)
69 fprintf(stderr, "sent with label %u\n", flowlabel);
70 else
71 fprintf(stderr, "sent without label\n");
72}
73
74static void do_recv(int fd, bool with_flowlabel, uint32_t expect)
75{
76 char control[CMSG_SPACE(sizeof(expect))];
77 char data[sizeof(cfg_data)];
78 struct msghdr msg = {0};
79 struct iovec iov = {0};
80 struct cmsghdr *cm;
81 uint32_t flowlabel;
82 int ret;
83
84 iov.iov_base = data;
85 iov.iov_len = sizeof(data);
86
87 msg.msg_iov = &iov;
88 msg.msg_iovlen = 1;
89
90 memset(control, 0, sizeof(control));
91 msg.msg_control = control;
92 msg.msg_controllen = sizeof(control);
93
94 ret = recvmsg(fd, &msg, 0);
95 if (ret == -1)
96 error(1, errno, "recv");
97 if (msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))
98 error(1, 0, "recv: truncated");
99 if (ret != sizeof(cfg_data))
100 error(1, 0, "recv: length mismatch");
101 if (memcmp(data, cfg_data, sizeof(data)))
102 error(1, 0, "recv: data mismatch");
103
104 cm = CMSG_FIRSTHDR(&msg);
105 if (with_flowlabel) {
106 if (!cm)
107 error(1, 0, "recv: missing cmsg");
108 if (CMSG_NXTHDR(&msg, cm))
109 error(1, 0, "recv: too many cmsg");
110 if (cm->cmsg_level != SOL_IPV6 ||
111 cm->cmsg_type != IPV6_FLOWINFO)
112 error(1, 0, "recv: unexpected cmsg level or type");
113
114 flowlabel = ntohl(*(uint32_t *)CMSG_DATA(cm));
115 fprintf(stderr, "recv with label %u\n", flowlabel);
116
117 if (expect != FLOWLABEL_WILDCARD && expect != flowlabel)
118 fprintf(stderr, "recv: incorrect flowlabel %u != %u\n",
119 flowlabel, expect);
120
121 } else {
122 fprintf(stderr, "recv without label\n");
123 }
124}
125
126static bool get_autoflowlabel_enabled(void)
127{
128 int fd, ret;
129 char val;
130
131 fd = open("/proc/sys/net/ipv6/auto_flowlabels", O_RDONLY);
132 if (fd == -1)
133 error(1, errno, "open sysctl");
134
135 ret = read(fd, &val, 1);
136 if (ret == -1)
137 error(1, errno, "read sysctl");
138 if (ret == 0)
139 error(1, 0, "read sysctl: 0");
140
141 if (close(fd))
142 error(1, errno, "close sysctl");
143
144 return val == '1';
145}
146
147static void flowlabel_get(int fd, uint32_t label, uint8_t share, uint16_t flags)
148{
149 struct in6_flowlabel_req req = {
150 .flr_action = IPV6_FL_A_GET,
151 .flr_label = htonl(label),
152 .flr_flags = flags,
153 .flr_share = share,
154 };
155
156
157 req.flr_dst.s6_addr[0] = 0xfd;
158 req.flr_dst.s6_addr[15] = 0x1;
159
160 if (setsockopt(fd, SOL_IPV6, IPV6_FLOWLABEL_MGR, &req, sizeof(req)))
161 error(1, errno, "setsockopt flowlabel get");
162}
163
164static void parse_opts(int argc, char **argv)
165{
166 int c;
167
168 while ((c = getopt(argc, argv, "l:")) != -1) {
169 switch (c) {
170 case 'l':
171 cfg_label = strtoul(optarg, NULL, 0);
172 break;
173 default:
174 error(1, 0, "%s: parse error", argv[0]);
175 }
176 }
177}
178
179int main(int argc, char **argv)
180{
181 struct sockaddr_in6 addr = {
182 .sin6_family = AF_INET6,
183 .sin6_port = htons(8000),
184 .sin6_addr = IN6ADDR_LOOPBACK_INIT,
185 };
186 const int one = 1;
187 int fdt, fdr;
188
189 parse_opts(argc, argv);
190
191 fdt = socket(PF_INET6, SOCK_DGRAM, 0);
192 if (fdt == -1)
193 error(1, errno, "socket t");
194
195 fdr = socket(PF_INET6, SOCK_DGRAM, 0);
196 if (fdr == -1)
197 error(1, errno, "socket r");
198
199 if (connect(fdt, (void *)&addr, sizeof(addr)))
200 error(1, errno, "connect");
201 if (bind(fdr, (void *)&addr, sizeof(addr)))
202 error(1, errno, "bind");
203
204 flowlabel_get(fdt, cfg_label, IPV6_FL_S_EXCL, IPV6_FL_F_CREATE);
205
206 if (setsockopt(fdr, SOL_IPV6, IPV6_FLOWINFO, &one, sizeof(one)))
207 error(1, errno, "setsockopt flowinfo");
208
209 if (get_autoflowlabel_enabled()) {
210 fprintf(stderr, "send no label: recv auto flowlabel\n");
211 do_send(fdt, false, 0);
212 do_recv(fdr, true, FLOWLABEL_WILDCARD);
213 } else {
214 fprintf(stderr, "send no label: recv no label (auto off)\n");
215 do_send(fdt, false, 0);
216 do_recv(fdr, false, 0);
217 }
218
219 fprintf(stderr, "send label\n");
220 do_send(fdt, true, cfg_label);
221 do_recv(fdr, true, cfg_label);
222
223 if (close(fdr))
224 error(1, errno, "close r");
225 if (close(fdt))
226 error(1, errno, "close t");
227
228 return 0;
229}
230
