lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame^] | 1 | .TH libnetlink 3 |
| 2 | .SH NAME |
| 3 | libnetlink \- A library for accessing the netlink service |
| 4 | .SH SYNOPSIS |
| 5 | .nf |
| 6 | #include <asm/types.h> |
| 7 | .br |
| 8 | #include <libnetlink.h> |
| 9 | .br |
| 10 | #include <linux/netlink.h> |
| 11 | .br |
| 12 | #include <linux/rtnetlink.h> |
| 13 | .sp |
| 14 | int rtnl_open(struct rtnl_handle *rth, unsigned subscriptions) |
| 15 | .sp |
| 16 | int rtnl_wilddump_request(struct rtnl_handle *rth, int family, int type) |
| 17 | .sp |
| 18 | int rtnl_send(struct rtnl_handle *rth, char *buf, int len) |
| 19 | .sp |
| 20 | int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len) |
| 21 | .sp |
| 22 | int rtnl_dump_filter(struct rtnl_handle *rth, |
| 23 | int (*filter)(struct sockaddr_nl *, struct nlmsghdr *n, void *), |
| 24 | void *arg1, |
| 25 | int (*junk)(struct sockaddr_nl *,struct nlmsghdr *n, void *), |
| 26 | void *arg2) |
| 27 | .sp |
| 28 | int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer, |
| 29 | unsigned groups, struct nlmsghdr *answer, |
| 30 | .br |
| 31 | int (*junk)(struct sockaddr_nl *,struct nlmsghdr *n, void *), |
| 32 | .br |
| 33 | void *jarg) |
| 34 | .sp |
| 35 | int rtnl_listen(struct rtnl_handle *rtnl, |
| 36 | int (*handler)(struct sockaddr_nl *,struct nlmsghdr *n, void *), |
| 37 | void *jarg) |
| 38 | .sp |
| 39 | int rtnl_from_file(FILE *rtnl, |
| 40 | int (*handler)(struct sockaddr_nl *,struct nlmsghdr *n, void *), |
| 41 | void *jarg) |
| 42 | .sp |
| 43 | int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data) |
| 44 | .sp |
| 45 | int addattr_l(struct nlmsghdr *n, int maxlen, int type, void *data, int alen) |
| 46 | .sp |
| 47 | int rta_addattr32(struct rtattr *rta, int maxlen, int type, __u32 data) |
| 48 | .sp |
| 49 | int rta_addattr_l(struct rtattr *rta, int maxlen, int type, void *data, int alen) |
| 50 | .SH DESCRIPTION |
| 51 | libnetlink provides a higher level interface to |
| 52 | .BR rtnetlink(7). |
| 53 | The read functions return 0 on success and a negative errno on failure. |
| 54 | The send functions return the amount of data sent, or -1 on error. |
| 55 | .TP |
| 56 | rtnl_open |
| 57 | Open a rtnetlink socket and save the state into the |
| 58 | .B rth |
| 59 | handle. This handle is passed to all subsequent calls. |
| 60 | .B subscriptions |
| 61 | is a bitmap of the rtnetlink multicast groups the socket will be |
| 62 | a member of. |
| 63 | |
| 64 | .TP |
| 65 | rtnl_wilddump_request |
| 66 | Request a full dump of the |
| 67 | .B type |
| 68 | database for |
| 69 | .B family |
| 70 | addresses. |
| 71 | .B type |
| 72 | is a rtnetlink message type. |
| 73 | .\" XXX |
| 74 | |
| 75 | .TP |
| 76 | rtnl_dump_request |
| 77 | Request a full dump of the |
| 78 | .B type |
| 79 | data buffer into |
| 80 | .B buf |
| 81 | with maximum length of |
| 82 | .B len. |
| 83 | .B type |
| 84 | is a rtnetlink message type. |
| 85 | |
| 86 | .TP |
| 87 | rtnl_dump_filter |
| 88 | Receive netlink data after a request and filter it. |
| 89 | The |
| 90 | .B filter |
| 91 | callback checks if the received message is wanted. It gets the source |
| 92 | address of the message, the message itself and |
| 93 | .B arg1 |
| 94 | as arguments. 0 as return means that the filter passed, a negative |
| 95 | value is returned |
| 96 | by |
| 97 | .I rtnl_dump_filter |
| 98 | in case of error. NULL for |
| 99 | .I filter |
| 100 | means to not use a filter. |
| 101 | .B junk |
| 102 | is used to filter messages not destined to the local socket. |
| 103 | Only one message bundle is received. Unless there is no message |
| 104 | pending, this function does not block. |
| 105 | |
| 106 | .TP |
| 107 | rtnl_listen |
| 108 | Receive netlink data after a request and pass it to |
| 109 | .I handler. |
| 110 | .B handler |
| 111 | is a callback that gets the message source address, the message itself, |
| 112 | and the |
| 113 | .B jarg |
| 114 | cookie as arguments. It will get called for all received messages. |
| 115 | Only one message bundle is received. Unless there is no message |
| 116 | pending this function does not block. |
| 117 | |
| 118 | .TP |
| 119 | rtnl_from_file |
| 120 | Works like |
| 121 | .I rtnl_listen, |
| 122 | but reads a netlink message bundle from the file |
| 123 | .B file |
| 124 | and passes the messages to |
| 125 | .B handler |
| 126 | for parsing. The file contains raw data as received from a rtnetlink socket. |
| 127 | .PP |
| 128 | The following functions are useful to construct custom rtnetlink messages. For |
| 129 | simple database dumping with filtering it is better to use the higher level |
| 130 | functions above. See |
| 131 | .BR rtnetlink(3) |
| 132 | and |
| 133 | .BR netlink(3) |
| 134 | on how to generate a rtnetlink message. The following utility functions |
| 135 | require a continuous buffer that already contains a netlink message header |
| 136 | and a rtnetlink request. |
| 137 | |
| 138 | .TP |
| 139 | rtnl_send |
| 140 | Send the rtnetlink message in |
| 141 | .B buf |
| 142 | of length |
| 143 | .B len |
| 144 | to handle |
| 145 | .B rth. |
| 146 | |
| 147 | .TP |
| 148 | addattr32 |
| 149 | Add a __u32 attribute of type |
| 150 | .B type |
| 151 | and with value |
| 152 | .B data |
| 153 | to netlink message |
| 154 | .B n, |
| 155 | which is part of a buffer of length |
| 156 | .B maxlen. |
| 157 | |
| 158 | .TP |
| 159 | addattr_l |
| 160 | Add a variable length attribute of type |
| 161 | .B type |
| 162 | and with value |
| 163 | .B data |
| 164 | and |
| 165 | .B alen |
| 166 | length to netlink message |
| 167 | .B n, |
| 168 | which is part of a buffer of length |
| 169 | .B maxlen. |
| 170 | .B data |
| 171 | is copied. |
| 172 | |
| 173 | .TP |
| 174 | rta_addattr32 |
| 175 | Initialize the rtnetlink attribute |
| 176 | .B rta |
| 177 | with a __u32 data value. |
| 178 | |
| 179 | .TP |
| 180 | rta_addattr32 |
| 181 | Initialize the rtnetlink attribute |
| 182 | .B rta |
| 183 | with a variable length data value. |
| 184 | |
| 185 | .SH BUGS |
| 186 | The functions sometimes use fprintf and exit when a fatal error occurs. |
| 187 | This library should be named librtnetlink. |
| 188 | |
| 189 | .SH AUTHORS |
| 190 | netlink/rtnetlink was designed and written by Alexey Kuznetsov. |
| 191 | Andi Kleen wrote the man page. |
| 192 | |
| 193 | .SH SEE ALSO |
| 194 | .BR netlink(7), |
| 195 | .BR rtnetlink(7) |
| 196 | .br |
| 197 | /usr/include/linux/rtnetlink.h |