openwrt/upstream - upstream openwrt

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Diffstat (limited to 'include/target.mk')

-rw-r--r--

1 files changed, 1 insertions, 1 deletions

/* * lib/nl.c Core Netlink Interface * * 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 core Core * * @details * @par 1) Connecting the socket * @code * // Bind and connect the socket to a protocol, NETLINK_ROUTE in this example. * nl_connect(sk, NETLINK_ROUTE); * @endcode * * @par 2) Sending data * @code * // The most rudimentary method is to use nl_sendto() simply pushing * // a piece of data to the other netlink peer. This method is not * // recommended. * const char buf[] = { 0x01, 0x02, 0x03, 0x04 }; * nl_sendto(sk, buf, sizeof(buf)); * * // A more comfortable interface is nl_send() taking a pointer to * // a netlink message. * struct nl_msg *msg = my_msg_builder(); * nl_send(sk, nlmsg_hdr(msg)); * * // nl_sendmsg() provides additional control over the sendmsg() message * // header in order to allow more specific addressing of multiple peers etc. * struct msghdr hdr = { ... }; * nl_sendmsg(sk, nlmsg_hdr(msg), &hdr); * * // You're probably too lazy to fill out the netlink pid, sequence number * // and message flags all the time. nl_send_auto_complete() automatically * // extends your message header as needed with an appropriate sequence * // number, the netlink pid stored in the netlink socket and the message * // flags NLM_F_REQUEST and NLM_F_ACK (if not disabled in the socket) * nl_send_auto_complete(sk, nlmsg_hdr(msg)); * * // Simple protocols don't require the complex message construction interface * // and may favour nl_send_simple() to easly send a bunch of payload * // encapsulated in a netlink message header. * nl_send_simple(sk, MY_MSG_TYPE, 0, buf, sizeof(buf)); * @endcode * * @par 3) Receiving data * @code * // nl_recv() receives a single message allocating a buffer for the message * // content and gives back the pointer to you. * struct sockaddr_nl peer; * unsigned char *msg; * nl_recv(sk, &peer, &msg); * * // nl_recvmsgs() receives a bunch of messages until the callback system * // orders it to state, usually after receving a compolete multi part * // message series. * nl_recvmsgs(sk, my_callback_configuration); * * // nl_recvmsgs_default() acts just like nl_recvmsg() but uses the callback * // configuration stored in the socket. * nl_recvmsgs_default(sk); * * // In case you want to wait for the ACK to be recieved that you requested * // with your latest message, you can call nl_wait_for_ack() * nl_wait_for_ack(sk); * @endcode * * @par 4) Closing * @code * // Close the socket first to release kernel memory * nl_close(sk); * @endcode * * @{ */ #include <netlink-local.h> #include <netlink/netlink.h> #include <netlink/utils.h> #include <netlink/handlers.h> #include <netlink/msg.h> #include <netlink/attr.h> /** * @name Connection Management * @{ */ /** * Create and connect netlink socket. * @arg sk Netlink socket. * @arg protocol Netlink protocol to use. * * Creates a netlink socket using the specified protocol, binds the socket * and issues a connection attempt. * * @return 0 on success or a negative error code. */ int nl_connect(struct nl_sock *sk, int protocol) { int err; socklen_t addrlen; sk->s_fd = socket(AF_NETLINK, SOCK_RAW, protocol); if (sk->s_fd < 0) { err = -nl_syserr2nlerr(errno); goto errout; } if (!(sk->s_flags & NL_SOCK_BUFSIZE_SET)) { err = nl_socket_set_buffer_size(sk, 0, 0); if (err < 0) goto errout; } err = bind(sk->s_fd, (struct sockaddr*) &sk->s_local, sizeof(sk->s_local)); if (err < 0) { err = -nl_syserr2nlerr(errno); goto errout; } addrlen = sizeof(sk->s_local); err = getsockname(sk->s_fd, (struct sockaddr *) &sk->s_local, &addrlen); if (err < 0) { err = -nl_syserr2nlerr(errno); goto errout; } if (addrlen != sizeof(sk->s_local)) { err = -NLE_NOADDR; goto errout; } if (sk->s_local.nl_family != AF_NETLINK) { err = -NLE_AF_NOSUPPORT; goto errout; } sk->s_proto = protocol; return 0; errout: close(sk->s_fd); sk->s_fd = -1; return err; } /** * Close/Disconnect netlink socket. * @arg sk Netlink socket. */ void nl_close(struct nl_sock *sk) { if (sk->s_fd >= 0) { close(sk->s_fd); sk->s_fd = -1; } sk->s_proto = 0; } /** @} */ /** * @name Send * @{ */ /** * Send raw data over netlink socket. * @arg sk Netlink socket. * @arg buf Data buffer. * @arg size Size of data buffer. * @return Number of characters written on success or a negative error code. */ int nl_sendto(struct nl_sock *sk, void *buf, size_t size) { int ret; ret = sendto(sk->s_fd, buf, size, 0, (struct sockaddr *) &sk->s_peer, sizeof(sk->s_peer)); if (ret < 0) return -nl_syserr2nlerr(errno); return ret; } /** * Send netlink message with control over sendmsg() message header. * @arg sk Netlink socket. * @arg msg Netlink message to be sent. * @arg hdr Sendmsg() message header. * @return Number of characters sent on sucess or a negative error code. */ int nl_sendmsg(struct nl_sock *sk, struct nl_msg *msg, struct msghdr *hdr) { struct nl_cb *cb; int ret; struct iovec iov = { .iov_base = (void *) nlmsg_hdr(msg), .iov_len = nlmsg_hdr(msg)->nlmsg_len, }; hdr->msg_iov = &iov; hdr->msg_iovlen = 1; nlmsg_set_src(msg, &sk->s_local); cb = sk->s_cb; if (cb->cb_set[NL_CB_MSG_OUT]) if (nl_cb_call(cb, NL_CB_MSG_OUT, msg) != NL_OK) return 0; ret = sendmsg(sk->s_fd, hdr, 0); if (ret < 0) return -nl_syserr2nlerr(errno); return ret; } /** * Send netlink message. * @arg sk Netlink socket. * @arg msg Netlink message to be sent. * @see nl_sendmsg() * @return Number of characters sent on success or a negative error code. */ int nl_send(struct nl_sock *sk, struct nl_msg *msg) { struct sockaddr_nl *dst; struct ucred *creds; struct msghdr hdr = { .msg_name = (void *) &sk->s_peer, .msg_namelen = sizeof(struct sockaddr_nl), }; /* Overwrite destination if specified in the message itself, defaults * to the peer address of the socket. */ dst = nlmsg_get_dst(msg); if (dst->nl_family == AF_NETLINK) hdr.msg_name = dst; /* Add credentials if present. */ creds = nlmsg_get_creds(msg); if (creds != NULL) { char buf[CMSG_SPACE(sizeof(struct ucred))]; struct cmsghdr *cmsg; hdr.msg_control = buf; hdr.msg_controllen = sizeof(buf); cmsg = CMSG_FIRSTHDR(&hdr); cmsg->cmsg_level = SOL_SOCKET; cmsg->cmsg_type = SCM_CREDENTIALS; cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred)); memcpy(CMSG_DATA(cmsg), creds, sizeof(struct ucred)); } return nl_sendmsg(sk, msg, &hdr); } /** * Send netlink message and check & extend header values as needed. * @arg sk Netlink socket. * @arg msg Netlink message to be sent. * * Checks the netlink message \c nlh for completness and extends it * as required before sending it out. Checked fields include pid, * sequence nr, and flags. * * @see nl_send() * @return Number of characters sent or a negative error code. */ int nl_send_auto_complete(struct nl_sock *sk, struct nl_msg *msg) { struct nlmsghdr *nlh; struct nl_cb *cb = sk->s_cb; nlh = nlmsg_hdr(msg); if (nlh->nlmsg_pid == 0) nlh->nlmsg_pid = sk->s_local.nl_pid; if (nlh->nlmsg_seq == 0) nlh->nlmsg_seq = sk->s_seq_next++; if (msg->nm_protocol == -1) msg->nm_protocol = sk->s_proto; nlh->nlmsg_flags |= NLM_F_REQUEST; if (!(sk->s_flags & NL_NO_AUTO_ACK)) nlh->nlmsg_flags |= NLM_F_ACK; if (cb->cb_send_ow) return cb->cb_send_ow(sk, msg); else return nl_send(sk, msg); } /** * Send simple netlink message using nl_send_auto_complete() * @arg sk Netlink socket. * @arg type Netlink message type. * @arg flags Netlink message flags. * @arg buf Data buffer. * @arg size Size of data buffer. * * Builds a netlink message with the specified type and flags and * appends the specified data as payload to the message. * * @see nl_send_auto_complete() * @return Number of characters sent on success or a negative error code. */ int nl_send_simple(struct nl_sock *sk, int type, int flags, void *buf, size_t size) { int err; struct nl_msg *msg; msg = nlmsg_alloc_simple(type, flags); if (!msg) return -NLE_NOMEM; if (buf && size) { err = nlmsg_append(msg, buf, size, NLMSG_ALIGNTO); if (err < 0) goto errout; } err = nl_send_auto_complete(sk, msg); errout: nlmsg_free(msg); return err; } /** @} */ /** * @name Receive * @{ */ /** * Receive data from netlink socket * @arg sk Netlink socket. * @arg nla Destination pointer for peer's netlink address. * @arg buf Destination pointer for message content. * @arg creds Destination pointer for credentials. * * Receives a netlink message, allocates a buffer in \c *buf and * stores the message content. The peer's netlink address is stored * in \c *nla. The caller is responsible for freeing the buffer allocated * in \c *buf if a positive value is returned. Interruped system calls * are handled by repeating the read. The input buffer size is determined * by peeking before the actual read is done. * * A non-blocking sockets causes the function to return immediately with * a return value of 0 if no data is available. * * @return Number of octets read, 0 on EOF or a negative error code. */ int nl_recv(struct nl_sock *sk, struct sockaddr_nl *nla, unsigned char **buf, struct ucred **creds) { int n; int flags = 0; static int page_size = 0; struct iovec iov; struct msghdr msg = { .msg_name = (void *) nla, .msg_namelen = sizeof(struct sockaddr_nl), .msg_iov = &iov, .msg_iovlen = 1, .msg_control = NULL, .msg_controllen = 0, .msg_flags = 0, }; struct cmsghdr *cmsg; if (sk->s_flags & NL_MSG_PEEK) flags |= MSG_PEEK; if (page_size == 0) page_size = getpagesize(); iov.iov_len = page_size; iov.iov_base = *buf = malloc(iov.iov_len); if (sk->s_flags & NL_SOCK_PASSCRED) { msg.msg_controllen = CMSG_SPACE(sizeof(struct ucred)); msg.msg_control = calloc(1, msg.msg_controllen); } retry: n = recvmsg(sk->s_fd, &msg, flags); if (!n) goto abort; else if (n < 0) { if (errno == EINTR) { NL_DBG(3, "recvmsg() returned EINTR, retrying\n"); goto retry; } else if (errno == EAGAIN) { NL_DBG(3, "recvmsg() returned EAGAIN, aborting\n"); goto abort; } else { free(msg.msg_control); free(*buf); return -nl_syserr2nlerr(errno); } } if (iov.iov_len < n || msg.msg_flags & MSG_TRUNC) { /* Provided buffer is not long enough, enlarge it * and try again. */ iov.iov_len *= 2; iov.iov_base = *buf = realloc(*buf, iov.iov_len); goto retry; } else if (msg.msg_flags & MSG_CTRUNC) { msg.msg_controllen *= 2; msg.msg_control = realloc(msg.msg_control, msg.msg_controllen); goto retry; } else if (flags != 0) { /* Buffer is big enough, do the actual reading */ flags = 0; goto retry; } if (msg.msg_namelen != sizeof(struct sockaddr_nl)) { free(msg.msg_control); free(*buf); return -NLE_NOADDR; } for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) { if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_CREDENTIALS) { *creds = calloc(1, sizeof(struct ucred)); memcpy(*creds, CMSG_DATA(cmsg), sizeof(struct ucred)); break; } } free(msg.msg_control); return n; abort: free(msg.msg_control); free(*buf); return 0; } #define NL_CB_CALL(cb, type, msg) \ do { \ err = nl_cb_call(cb, type, msg); \ switch (err) { \ case NL_OK: \ err = 0; \ break; \ case NL_SKIP: \ goto skip; \ case NL_STOP: \ goto stop; \ default: \ goto out; \ } \ } while (0) static int recvmsgs(struct nl_sock *sk, struct nl_cb *cb) { int n, err = 0, multipart = 0; unsigned char *buf = NULL; struct nlmsghdr *hdr; struct sockaddr_nl nla = {0}; struct nl_msg *msg = NULL; struct ucred *creds = NULL; continue_reading: NL_DBG(3, "Attempting to read from %p\n", sk); if (cb->cb_recv_ow) n = cb->cb_recv_ow(sk, &nla, &buf, &creds); else n = nl_recv(sk, &nla, &buf, &creds); if (n <= 0) return n; NL_DBG(3, "recvmsgs(%p): Read %d bytes\n", sk, n); hdr = (struct nlmsghdr *) buf; while (nlmsg_ok(hdr, n)) { NL_DBG(3, "recgmsgs(%p): Processing valid message...\n", sk); nlmsg_free(msg); msg = nlmsg_convert(hdr); if (!msg) { err = -NLE_NOMEM; goto out; } nlmsg_set_proto(msg, sk->s_proto); nlmsg_set_src(msg, &nla); if (creds) nlmsg_set_creds(msg, creds); /* Raw callback is the first, it gives the most control * to the user and he can do his very own parsing. */ if (cb->cb_set[NL_CB_MSG_IN]) NL_CB_CALL(cb, NL_CB_MSG_IN, msg); /* Sequence number checking. The check may be done by * the user, otherwise a very simple check is applied * enforcing strict ordering */ if (cb->cb_set[NL_CB_SEQ_CHECK]) NL_CB_CALL(cb, NL_CB_SEQ_CHECK, msg); else if (hdr->nlmsg_seq != sk->s_seq_expect) { if (cb->cb_set[NL_CB_INVALID]) NL_CB_CALL(cb, NL_CB_INVALID, msg); else { err = -NLE_SEQ_MISMATCH; goto out; } } if (hdr->nlmsg_type == NLMSG_DONE || hdr->nlmsg_type == NLMSG_ERROR || hdr->nlmsg_type == NLMSG_NOOP || hdr->nlmsg_type == NLMSG_OVERRUN) { /* We can't check for !NLM_F_MULTI since some netlink * users in the kernel are broken. */ sk->s_seq_expect++; NL_DBG(3, "recvmsgs(%p): Increased expected " \ "sequence number to %d\n", sk, sk->s_seq_expect); } if (hdr->nlmsg_flags & NLM_F_MULTI) multipart = 1; /* Other side wishes to see an ack for this message */ if (hdr->nlmsg_flags & NLM_F_ACK) { if (cb->cb_set[NL_CB_SEND_ACK]) NL_CB_CALL(cb, NL_CB_SEND_ACK, msg); else { /* FIXME: implement */ } } /* messages terminates a multpart message, this is * usually the end of a message and therefore we slip * out of the loop by default. the user may overrule * this action by skipping this packet. */ if (hdr->nlmsg_type == NLMSG_DONE) { multipart = 0; if (cb->cb_set[NL_CB_FINISH]) NL_CB_CALL(cb, NL_CB_FINISH, msg); } /* Message to be ignored, the default action is to * skip this message if no callback is specified. The * user may overrule this action by returning * NL_PROCEED. */ else if (hdr->nlmsg_type == NLMSG_NOOP) { if (cb->cb_set[NL_CB_SKIPPED]) NL_CB_CALL(cb, NL_CB_SKIPPED, msg); else goto skip; } /* Data got lost, report back to user. The default action is to * quit parsing. The user may overrule this action by retuning * NL_SKIP or NL_PROCEED (dangerous) */ else if (hdr->nlmsg_type == NLMSG_OVERRUN) { if (cb->cb_set[NL_CB_OVERRUN]) NL_CB_CALL(cb, NL_CB_OVERRUN, msg); else { err = -NLE_MSG_OVERFLOW; goto out; } } /* Message carries a nlmsgerr */ else if (hdr->nlmsg_type == NLMSG_ERROR) { struct nlmsgerr *e = nlmsg_data(hdr); if (hdr->nlmsg_len < nlmsg_msg_size(sizeof(*e))) { /* Truncated error message, the default action * is to stop parsing. The user may overrule * this action by returning NL_SKIP or * NL_PROCEED (dangerous) */ if (cb->cb_set[NL_CB_INVALID]) NL_CB_CALL(cb, NL_CB_INVALID, msg); else { err = -NLE_MSG_TRUNC; goto out; } } else if (e->error) { /* Error message reported back from kernel. */ if (cb->cb_err) { err = cb->cb_err(&nla, e, cb->cb_err_arg); if (err < 0) goto out; else if (err == NL_SKIP) goto skip; else if (err == NL_STOP) { err = -nl_syserr2nlerr(e->error); goto out; } } else { err = -nl_syserr2nlerr(e->error); goto out; } } else if (cb->cb_set[NL_CB_ACK]) NL_CB_CALL(cb, NL_CB_ACK, msg); } else { /* Valid message (not checking for MULTIPART bit to * get along with broken kernels. NL_SKIP has no * effect on this. */ if (cb->cb_set[NL_CB_VALID]) NL_CB_CALL(cb, NL_CB_VALID, msg); } skip: err = 0; hdr = nlmsg_next(hdr, &n); } nlmsg_free(msg); free(buf); free(creds); buf = NULL; msg = NULL; creds = NULL; if (multipart) { /* Multipart message not yet complete, continue reading */ goto continue_reading; } stop: err = 0; out: nlmsg_free(msg); free(buf); free(creds); return err; } /** * Receive a set of messages from a netlink socket. * @arg sk Netlink socket. * @arg cb set of callbacks to control behaviour. * * Repeatedly calls nl_recv() or the respective replacement if provided * by the application (see nl_cb_overwrite_recv()) and parses the * received data as netlink messages. Stops reading if one of the * callbacks returns NL_STOP or nl_recv returns either 0 or a negative error code. * * A non-blocking sockets causes the function to return immediately if * no data is available. * * @return 0 on success or a negative error code from nl_recv(). */ int nl_recvmsgs(struct nl_sock *sk, struct nl_cb *cb) { if (cb->cb_recvmsgs_ow) return cb->cb_recvmsgs_ow(sk, cb); else return recvmsgs(sk, cb); } static int ack_wait_handler(struct nl_msg *msg, void *arg) { return NL_STOP; } /** * Wait for ACK. * @arg sk Netlink socket. * @pre The netlink socket must be in blocking state. * * Waits until an ACK is received for the latest not yet acknowledged * netlink message. */ int nl_wait_for_ack(struct nl_sock *sk) { int err; struct nl_cb *cb; cb = nl_cb_clone(sk->s_cb); if (cb == NULL) return -NLE_NOMEM; nl_cb_set(cb, NL_CB_ACK, NL_CB_CUSTOM, ack_wait_handler, NULL); err = nl_recvmsgs(sk, cb); nl_cb_put(cb); return err; } /** @} */ /** @} */


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