Frank Maker | ed6b39c | 2011-05-23 21:14:58 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2011 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | /* NOTICE: This is a clean room re-implementation of libnl */ |
| 18 | |
| 19 | #include <malloc.h> |
| 20 | #include <unistd.h> |
Elliott Hughes | b77d3d7 | 2012-09-11 18:52:40 -0700 | [diff] [blame] | 21 | #include <sys/socket.h> |
Frank Maker | ed6b39c | 2011-05-23 21:14:58 -0700 | [diff] [blame] | 22 | #include <linux/netlink.h> |
| 23 | #include "netlink-types.h" |
| 24 | |
| 25 | /* Allocate a new netlink message with the default maximum payload size. */ |
| 26 | struct nl_msg *nlmsg_alloc(void) |
| 27 | { |
| 28 | /* Whole page will store nl_msg + nlmsghdr + genlmsghdr + payload */ |
| 29 | const int page_sz = getpagesize(); |
| 30 | struct nl_msg *nm; |
| 31 | struct nlmsghdr *nlh; |
| 32 | |
| 33 | /* Netlink message */ |
| 34 | nm = (struct nl_msg *) malloc(page_sz); |
| 35 | if (!nm) |
| 36 | goto fail; |
| 37 | |
| 38 | /* Netlink message header pointer */ |
| 39 | nlh = (struct nlmsghdr *) ((char *) nm + sizeof(struct nl_msg)); |
| 40 | |
| 41 | /* Initialize */ |
| 42 | memset(nm, 0, page_sz); |
| 43 | nm->nm_size = page_sz; |
| 44 | |
| 45 | nm->nm_src.nl_family = AF_NETLINK; |
| 46 | nm->nm_src.nl_pid = getpid(); |
| 47 | |
| 48 | nm->nm_dst.nl_family = AF_NETLINK; |
| 49 | nm->nm_dst.nl_pid = 0; /* Kernel */ |
| 50 | |
| 51 | /* Initialize and add to netlink message */ |
| 52 | nlh->nlmsg_len = NLMSG_HDRLEN; |
| 53 | nm->nm_nlh = nlh; |
| 54 | |
| 55 | /* Add to reference count and return nl_msg */ |
| 56 | nlmsg_get(nm); |
| 57 | return nm; |
| 58 | fail: |
| 59 | return NULL; |
| 60 | } |
| 61 | |
| 62 | /* Return pointer to message payload. */ |
| 63 | void *nlmsg_data(const struct nlmsghdr *nlh) |
| 64 | { |
| 65 | return (char *) nlh + NLMSG_HDRLEN; |
| 66 | } |
| 67 | |
| 68 | /* Add reference count to nl_msg */ |
| 69 | void nlmsg_get(struct nl_msg *nm) |
| 70 | { |
| 71 | nm->nm_refcnt++; |
| 72 | } |
| 73 | |
| 74 | /* Release a reference from an netlink message. */ |
| 75 | void nlmsg_free(struct nl_msg *nm) |
| 76 | { |
| 77 | if (nm) { |
| 78 | nm->nm_refcnt--; |
| 79 | if (nm->nm_refcnt <= 0) |
| 80 | free(nm); |
| 81 | } |
| 82 | |
| 83 | } |
| 84 | |
| 85 | /* Return actual netlink message. */ |
| 86 | struct nlmsghdr *nlmsg_hdr(struct nl_msg *n) |
| 87 | { |
| 88 | return n->nm_nlh; |
| 89 | } |
| 90 | |
| 91 | /* Return head of attributes data / payload section */ |
| 92 | struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh, int hdrlen) |
| 93 | { |
| 94 | unsigned char *data = nlmsg_data(nlh); |
Dmitry Shmidt | 64f17e8 | 2011-08-10 15:25:51 -0700 | [diff] [blame] | 95 | return (struct nlattr *)(data + NLMSG_ALIGN(hdrlen)); |
Frank Maker | ed6b39c | 2011-05-23 21:14:58 -0700 | [diff] [blame] | 96 | } |
| 97 | |
| 98 | /* Returns pointer to end of netlink message */ |
| 99 | void *nlmsg_tail(const struct nlmsghdr *nlh) |
| 100 | { |
Dmitry Shmidt | 64f17e8 | 2011-08-10 15:25:51 -0700 | [diff] [blame] | 101 | return (void *)((char *)nlh + NLMSG_ALIGN(nlh->nlmsg_len)); |
Frank Maker | ed6b39c | 2011-05-23 21:14:58 -0700 | [diff] [blame] | 102 | } |
| 103 | |
| 104 | /* Next netlink message in message stream */ |
| 105 | struct nlmsghdr *nlmsg_next(struct nlmsghdr *nlh, int *remaining) |
| 106 | { |
| 107 | struct nlmsghdr *next_nlh = NULL; |
Dmitry Shmidt | 64f17e8 | 2011-08-10 15:25:51 -0700 | [diff] [blame] | 108 | int len = nlmsg_len(nlh); |
Frank Maker | ed6b39c | 2011-05-23 21:14:58 -0700 | [diff] [blame] | 109 | |
Dmitry Shmidt | 64f17e8 | 2011-08-10 15:25:51 -0700 | [diff] [blame] | 110 | len = NLMSG_ALIGN(len); |
| 111 | if (*remaining > 0 && |
| 112 | len <= *remaining && |
| 113 | len >= (int) sizeof(struct nlmsghdr)) { |
| 114 | next_nlh = (struct nlmsghdr *)((char *)nlh + len); |
| 115 | *remaining -= len; |
Frank Maker | ed6b39c | 2011-05-23 21:14:58 -0700 | [diff] [blame] | 116 | } |
| 117 | |
| 118 | return next_nlh; |
| 119 | } |
| 120 | |
Dmitry Shmidt | 64f17e8 | 2011-08-10 15:25:51 -0700 | [diff] [blame] | 121 | int nlmsg_datalen(const struct nlmsghdr *nlh) |
| 122 | { |
| 123 | return nlh->nlmsg_len - NLMSG_HDRLEN; |
| 124 | } |
| 125 | |
Frank Maker | ed6b39c | 2011-05-23 21:14:58 -0700 | [diff] [blame] | 126 | /* Length of attributes data */ |
| 127 | int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen) |
| 128 | { |
Dmitry Shmidt | 64f17e8 | 2011-08-10 15:25:51 -0700 | [diff] [blame] | 129 | return nlmsg_datalen(nlh) - NLMSG_ALIGN(hdrlen); |
Frank Maker | ed6b39c | 2011-05-23 21:14:58 -0700 | [diff] [blame] | 130 | } |
| 131 | |
| 132 | /* Length of netlink message */ |
| 133 | int nlmsg_len(const struct nlmsghdr *nlh) |
| 134 | { |
| 135 | return nlh->nlmsg_len; |
| 136 | } |
| 137 | |
| 138 | /* Check if the netlink message fits into the remaining bytes */ |
| 139 | int nlmsg_ok(const struct nlmsghdr *nlh, int rem) |
| 140 | { |
| 141 | return rem >= (int)sizeof(struct nlmsghdr) && |
| 142 | rem >= nlmsg_len(nlh) && |
| 143 | nlmsg_len(nlh) >= (int) sizeof(struct nlmsghdr) && |
| 144 | nlmsg_len(nlh) <= (rem); |
| 145 | } |
| 146 | |
| 147 | int nlmsg_padlen(int payload) |
| 148 | { |
| 149 | return NLMSG_ALIGN(payload) - payload; |
| 150 | } |