+++ /dev/null
-/*
- * 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. Interrupted 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() * 4;
-
- 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;
-}
-
-/** @} */
-
-/** @} */
projects / openwrt / openwrt.git / blobdiff