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Diffstat (limited to 'package/libnl-tiny/src/genl.c')
| -rw-r--r-- | package/libnl-tiny/src/genl.c | 268 |
1 files changed, 268 insertions, 0 deletions
diff --git a/package/libnl-tiny/src/genl.c b/package/libnl-tiny/src/genl.c new file mode 100644 index 0000000..055be91 --- /dev/null +++ b/package/libnl-tiny/src/genl.c @@ -0,0 +1,268 @@ +/* + * lib/genl/genl.c Generic Netlink + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation version 2.1 + * of the License. + * + * Copyright (c) 2003-2008 Thomas Graf <tgraf@suug.ch> + */ + +/** + * @defgroup genl Generic Netlink + * + * @par Message Format + * @code + * <------- NLMSG_ALIGN(hlen) ------> <---- NLMSG_ALIGN(len) ---> + * +----------------------------+- - -+- - - - - - - - - - -+- - -+ + * | Header | Pad | Payload | Pad | + * | struct nlmsghdr | | | | + * +----------------------------+- - -+- - - - - - - - - - -+- - -+ + * @endcode + * @code + * <-------- GENL_HDRLEN -------> <--- hdrlen --> + * <------- genlmsg_len(ghdr) ------> + * +------------------------+- - -+---------------+- - -+------------+ + * | Generic Netlink Header | Pad | Family Header | Pad | Attributes | + * | struct genlmsghdr | | | | | + * +------------------------+- - -+---------------+- - -+------------+ + * genlmsg_data(ghdr)--------------^ ^ + * genlmsg_attrdata(ghdr, hdrlen)------------------------- + * @endcode + * + * @par Example + * @code + * #include <netlink/netlink.h> + * #include <netlink/genl/genl.h> + * #include <netlink/genl/ctrl.h> + * + * struct nl_sock *sock; + * struct nl_msg *msg; + * int family; + * + * // Allocate a new netlink socket + * sock = nl_socket_alloc(); + * + * // Connect to generic netlink socket on kernel side + * genl_connect(sock); + * + * // Ask kernel to resolve family name to family id + * family = genl_ctrl_resolve(sock, "generic_netlink_family_name"); + * + * // Construct a generic netlink by allocating a new message, fill in + * // the header and append a simple integer attribute. + * msg = nlmsg_alloc(); + * genlmsg_put(msg, NL_AUTO_PID, NL_AUTO_SEQ, family, 0, NLM_F_ECHO, + * CMD_FOO_GET, FOO_VERSION); + * nla_put_u32(msg, ATTR_FOO, 123); + * + * // Send message over netlink socket + * nl_send_auto_complete(sock, msg); + * + * // Free message + * nlmsg_free(msg); + * + * // Prepare socket to receive the answer by specifying the callback + * // function to be called for valid messages. + * nl_socket_modify_cb(sock, NL_CB_VALID, NL_CB_CUSTOM, parse_cb, NULL); + * + * // Wait for the answer and receive it + * nl_recvmsgs_default(sock); + * + * static int parse_cb(struct nl_msg *msg, void *arg) + * { + * struct nlmsghdr *nlh = nlmsg_hdr(msg); + * struct nlattr *attrs[ATTR_MAX+1]; + * + * // Validate message and parse attributes + * genlmsg_parse(nlh, 0, attrs, ATTR_MAX, policy); + * + * if (attrs[ATTR_FOO]) { + * uint32_t value = nla_get_u32(attrs[ATTR_FOO]); + * ... + * } + * + * return 0; + * } + * @endcode + * @{ + */ + +#include <netlink-generic.h> +#include <netlink/netlink.h> +#include <netlink/genl/genl.h> +#include <netlink/utils.h> + +/** + * @name Socket Creating + * @{ + */ + +int genl_connect(struct nl_sock *sk) +{ + return nl_connect(sk, NETLINK_GENERIC); +} + +/** @} */ + +/** + * @name Sending + * @{ + */ + +/** + * Send trivial generic netlink message + * @arg sk Netlink socket. + * @arg family Generic netlink family + * @arg cmd Command + * @arg version Version + * @arg flags Additional netlink message flags. + * + * Fills out a routing netlink request message and sends it out + * using nl_send_simple(). + * + * @return 0 on success or a negative error code. + */ +int genl_send_simple(struct nl_sock *sk, int family, int cmd, + int version, int flags) +{ + struct genlmsghdr hdr = { + .cmd = cmd, + .version = version, + }; + + return nl_send_simple(sk, family, flags, &hdr, sizeof(hdr)); +} + +/** @} */ + + +/** + * @name Message Parsing + * @{ + */ + +int genlmsg_valid_hdr(struct nlmsghdr *nlh, int hdrlen) +{ + struct genlmsghdr *ghdr; + + if (!nlmsg_valid_hdr(nlh, GENL_HDRLEN)) + return 0; + + ghdr = nlmsg_data(nlh); + if (genlmsg_len(ghdr) < NLMSG_ALIGN(hdrlen)) + return 0; + + return 1; +} + +int genlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype, + struct nla_policy *policy) +{ + struct genlmsghdr *ghdr; + + if (!genlmsg_valid_hdr(nlh, hdrlen)) + return -NLE_MSG_TOOSHORT; + + ghdr = nlmsg_data(nlh); + return nla_validate(genlmsg_attrdata(ghdr, hdrlen), + genlmsg_attrlen(ghdr, hdrlen), maxtype, policy); +} + +int genlmsg_parse(struct nlmsghdr *nlh, int hdrlen, struct nlattr *tb[], + int maxtype, struct nla_policy *policy) +{ + struct genlmsghdr *ghdr; + + if (!genlmsg_valid_hdr(nlh, hdrlen)) + return -NLE_MSG_TOOSHORT; + + ghdr = nlmsg_data(nlh); + return nla_parse(tb, maxtype, genlmsg_attrdata(ghdr, hdrlen), + genlmsg_attrlen(ghdr, hdrlen), policy); +} + +/** + * Get head of message payload + * @arg gnlh genetlink messsage header + */ +void *genlmsg_data(const struct genlmsghdr *gnlh) +{ + return ((unsigned char *) gnlh + GENL_HDRLEN); +} + +/** + * Get lenght of message payload + * @arg gnlh genetlink message header + */ +int genlmsg_len(const struct genlmsghdr *gnlh) +{ + struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh - + NLMSG_HDRLEN); + return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN); +} + +/** + * Get head of attribute data + * @arg gnlh generic netlink message header + * @arg hdrlen length of family specific header + */ +struct nlattr *genlmsg_attrdata(const struct genlmsghdr *gnlh, int hdrlen) +{ + return genlmsg_data(gnlh) + NLMSG_ALIGN(hdrlen); +} + +/** + * Get length of attribute data + * @arg gnlh generic netlink message header + * @arg hdrlen length of family specific header + */ +int genlmsg_attrlen(const struct genlmsghdr *gnlh, int hdrlen) +{ + return genlmsg_len(gnlh) - NLMSG_ALIGN(hdrlen); +} + +/** @} */ + +/** + * @name Message Building + * @{ + */ + +/** + * Add generic netlink header to netlink message + * @arg msg netlink message + * @arg pid netlink process id or NL_AUTO_PID + * @arg seq sequence number of message or NL_AUTO_SEQ + * @arg family generic netlink family + * @arg hdrlen length of user specific header + * @arg flags message flags + * @arg cmd generic netlink command + * @arg version protocol version + * + * Returns pointer to user specific header. + */ +void *genlmsg_put(struct nl_msg *msg, uint32_t pid, uint32_t seq, int family, + int hdrlen, int flags, uint8_t cmd, uint8_t version) +{ + struct nlmsghdr *nlh; + struct genlmsghdr hdr = { + .cmd = cmd, + .version = version, + }; + + nlh = nlmsg_put(msg, pid, seq, family, GENL_HDRLEN + hdrlen, flags); + if (nlh == NULL) + return NULL; + + memcpy(nlmsg_data(nlh), &hdr, sizeof(hdr)); + NL_DBG(2, "msg %p: Added generic netlink header cmd=%d version=%d\n", + msg, cmd, version); + + return nlmsg_data(nlh) + GENL_HDRLEN; +} + +/** @} */ + +/** @} */ |