| /* |
| * 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; |
| } |
| |
| /** @} */ |
| |
| /** @} */ |