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2fb975da TT |
1 | /* Netlink helpers for zbuf |
2 | * Copyright (c) 2014-2015 Timo Teräs | |
3 | * | |
4 | * This file is free software: you may copy, redistribute and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation, either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | */ | |
9 | ||
10 | #include <fcntl.h> | |
11 | #include <errno.h> | |
12 | #include <string.h> | |
13 | #include <unistd.h> | |
14 | #include <sys/types.h> | |
15 | #include <sys/socket.h> | |
16 | #include <linux/netlink.h> | |
17 | #include <linux/rtnetlink.h> | |
18 | ||
19 | #include "znl.h" | |
20 | ||
21 | #define ZNL_ALIGN(len) (((len)+3) & ~3) | |
22 | ||
23 | void *znl_push(struct zbuf *zb, size_t n) | |
24 | { | |
25 | return zbuf_pushn(zb, ZNL_ALIGN(n)); | |
26 | } | |
27 | ||
28 | void *znl_pull(struct zbuf *zb, size_t n) | |
29 | { | |
30 | return zbuf_pulln(zb, ZNL_ALIGN(n)); | |
31 | } | |
32 | ||
33 | struct nlmsghdr *znl_nlmsg_push(struct zbuf *zb, uint16_t type, uint16_t flags) | |
34 | { | |
35 | struct nlmsghdr *n; | |
36 | ||
37 | n = znl_push(zb, sizeof(*n)); | |
996c9314 LB |
38 | if (!n) |
39 | return NULL; | |
2fb975da | 40 | |
996c9314 LB |
41 | *n = (struct nlmsghdr){ |
42 | .nlmsg_type = type, .nlmsg_flags = flags, | |
2fb975da TT |
43 | }; |
44 | return n; | |
45 | } | |
46 | ||
47 | void znl_nlmsg_complete(struct zbuf *zb, struct nlmsghdr *n) | |
48 | { | |
996c9314 | 49 | n->nlmsg_len = zb->tail - (uint8_t *)n; |
2fb975da TT |
50 | } |
51 | ||
52 | struct nlmsghdr *znl_nlmsg_pull(struct zbuf *zb, struct zbuf *payload) | |
53 | { | |
54 | struct nlmsghdr *n; | |
55 | size_t plen; | |
56 | ||
57 | n = znl_pull(zb, sizeof(*n)); | |
996c9314 LB |
58 | if (!n) |
59 | return NULL; | |
2fb975da TT |
60 | |
61 | plen = n->nlmsg_len - sizeof(*n); | |
62 | zbuf_init(payload, znl_pull(zb, plen), plen, plen); | |
63 | zbuf_may_pulln(zb, ZNL_ALIGN(plen) - plen); | |
64 | ||
65 | return n; | |
66 | } | |
67 | ||
996c9314 LB |
68 | struct rtattr *znl_rta_push(struct zbuf *zb, uint16_t type, const void *val, |
69 | size_t len) | |
2fb975da TT |
70 | { |
71 | struct rtattr *rta; | |
72 | uint8_t *dst; | |
73 | ||
74 | rta = znl_push(zb, ZNL_ALIGN(sizeof(*rta)) + ZNL_ALIGN(len)); | |
996c9314 LB |
75 | if (!rta) |
76 | return NULL; | |
2fb975da | 77 | |
996c9314 LB |
78 | *rta = (struct rtattr){ |
79 | .rta_type = type, .rta_len = ZNL_ALIGN(sizeof(*rta)) + len, | |
2fb975da TT |
80 | }; |
81 | ||
996c9314 | 82 | dst = (uint8_t *)(rta + 1); |
2fb975da | 83 | memcpy(dst, val, len); |
996c9314 | 84 | memset(dst + len, 0, ZNL_ALIGN(len) - len); |
2fb975da TT |
85 | |
86 | return rta; | |
87 | } | |
88 | ||
89 | struct rtattr *znl_rta_push_u32(struct zbuf *zb, uint16_t type, uint32_t val) | |
90 | { | |
91 | return znl_rta_push(zb, type, &val, sizeof(val)); | |
92 | } | |
93 | ||
94 | struct rtattr *znl_rta_nested_push(struct zbuf *zb, uint16_t type) | |
95 | { | |
96 | struct rtattr *rta; | |
97 | ||
98 | rta = znl_push(zb, sizeof(*rta)); | |
996c9314 LB |
99 | if (!rta) |
100 | return NULL; | |
2fb975da | 101 | |
996c9314 | 102 | *rta = (struct rtattr){ |
2fb975da TT |
103 | .rta_type = type, |
104 | }; | |
105 | return rta; | |
106 | } | |
107 | ||
108 | void znl_rta_nested_complete(struct zbuf *zb, struct rtattr *rta) | |
109 | { | |
996c9314 | 110 | size_t len = zb->tail - (uint8_t *)rta; |
2fb975da TT |
111 | size_t align = ZNL_ALIGN(len) - len; |
112 | ||
113 | if (align) { | |
114 | void *dst = zbuf_pushn(zb, align); | |
996c9314 LB |
115 | if (dst) |
116 | memset(dst, 0, align); | |
2fb975da TT |
117 | } |
118 | rta->rta_len = len; | |
119 | } | |
120 | ||
121 | struct rtattr *znl_rta_pull(struct zbuf *zb, struct zbuf *payload) | |
122 | { | |
123 | struct rtattr *rta; | |
124 | size_t plen; | |
125 | ||
126 | rta = znl_pull(zb, sizeof(*rta)); | |
996c9314 LB |
127 | if (!rta) |
128 | return NULL; | |
2fb975da TT |
129 | |
130 | if (rta->rta_len > sizeof(*rta)) { | |
131 | plen = rta->rta_len - sizeof(*rta); | |
132 | zbuf_init(payload, znl_pull(zb, plen), plen, plen); | |
133 | } else { | |
134 | zbuf_init(payload, NULL, 0, 0); | |
135 | } | |
136 | ||
137 | return rta; | |
138 | } | |
139 | ||
140 | int znl_open(int protocol, int groups) | |
141 | { | |
142 | struct sockaddr_nl addr; | |
143 | int fd, buf = 128 * 1024; | |
144 | ||
145 | fd = socket(AF_NETLINK, SOCK_RAW, protocol); | |
146 | if (fd < 0) | |
147 | return -1; | |
148 | ||
6c8ca260 JB |
149 | if (fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) | O_NONBLOCK) < 0) |
150 | goto error; | |
151 | if (fcntl(fd, F_SETFD, FD_CLOEXEC) < 0) | |
152 | goto error; | |
2fb975da TT |
153 | if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &buf, sizeof(buf)) < 0) |
154 | goto error; | |
155 | ||
156 | memset(&addr, 0, sizeof(addr)); | |
157 | addr.nl_family = AF_NETLINK; | |
158 | addr.nl_groups = groups; | |
996c9314 | 159 | if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) |
2fb975da TT |
160 | goto error; |
161 | ||
162 | return fd; | |
163 | error: | |
164 | close(fd); | |
165 | return -1; | |
166 | } |