/* * 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) 2003-2012 Thomas Graf */ /** * @defgroup core Core Library (libnl) * * Socket handling, connection management, sending and receiving of data, * message construction and parsing, object caching system, ... * * This is the API reference of the core library. It is not meant as a guide * but as a reference. Please refer to the core library guide for detailed * documentation on the library architecture and examples: * * * @ref_asciidoc{core,_,Netlink Core Library Development Guide} * * * @{ */ #include #include #include #include #include #include #include #include /** * @defgroup core_types Data Types * * Core library data types * @{ * @} * * @defgroup send_recv Send & Receive Data * * Connection management, sending & receiving of data * * Related sections in the development guide: * - @core_doc{core_send_recv, Sending & Receiving} * - @core_doc{core_sockets, Sockets} * * @{ * * Header * ------ * ~~~~{.c} * #include * ~~~~ */ /** * @name Connection Management * @{ */ /** * Create file descriptor and bind socket. * @arg sk Netlink socket (required) * @arg protocol Netlink protocol to use (required) * * Creates a new Netlink socket using `socket()` and binds the socket to the * protocol and local port specified in the `sk` socket object. Fails if * the socket is already connected. * * @note If available, the `close-on-exec` (`SOCK_CLOEXEC`) feature is enabled * automatically on the new file descriptor. This causes the socket to * be closed automatically if any of the `exec` family functions succeed. * This is essential for multi threaded programs. * * @note The local port (`nl_socket_get_local_port()`) is unspecified after * creating a new socket. It only gets determined when accessing the * port the first time or during `nl_connect()`. When nl_connect() * fails during `bind()` due to `ADDRINUSE`, it will retry with * different ports if the port is unspecified. Unless you want to enforce * the use of a specific local port, don't access the local port (or * reset it to `unspecified` by calling `nl_socket_set_local_port(sk, 0)`). * This capability is indicated by * `%NL_CAPABILITY_NL_CONNECT_RETRY_GENERATE_PORT_ON_ADDRINUSE`. * * @note nl_connect() creates and sets the file descriptor. You can setup the file * descriptor yourself by creating and binding it, and then calling * nl_socket_set_fd(). The result will be the same. * * @see nl_socket_alloc() * @see nl_close() * @see nl_socket_set_fd() * * @return 0 on success or a negative error code. * * @retval -NLE_BAD_SOCK Socket is already connected */ int nl_connect(struct nl_sock *sk, int protocol) { int err, flags = 0; int errsv; socklen_t addrlen; struct sockaddr_nl local = { 0 }; char buf[64]; #ifdef SOCK_CLOEXEC flags |= SOCK_CLOEXEC; #endif if (sk->s_fd != -1) return -NLE_BAD_SOCK; sk->s_fd = socket(AF_NETLINK, SOCK_RAW | flags, protocol); if (sk->s_fd < 0) { errsv = errno; NL_DBG(4, "nl_connect(%p): socket() failed with %d (%s)\n", sk, errsv, strerror_r(errsv, buf, sizeof(buf))); err = -nl_syserr2nlerr(errsv); goto errout; } err = nl_socket_set_buffer_size(sk, 0, 0); if (err < 0) goto errout; if (_nl_socket_is_local_port_unspecified (sk)) { uint32_t port; uint32_t used_ports[32] = { 0 }; while (1) { port = _nl_socket_generate_local_port_no_release(sk); if (port == 0) { NL_DBG(4, "nl_connect(%p): no more unused local ports.\n", sk); _nl_socket_used_ports_release_all(used_ports); err = -NLE_EXIST; goto errout; } err = bind(sk->s_fd, (struct sockaddr*) &sk->s_local, sizeof(sk->s_local)); if (err == 0) break; errsv = errno; if (errsv == EADDRINUSE) { NL_DBG(4, "nl_connect(%p): local port %u already in use. Retry.\n", sk, (unsigned) port); _nl_socket_used_ports_set(used_ports, port); } else { NL_DBG(4, "nl_connect(%p): bind() for port %u failed with %d (%s)\n", sk, (unsigned) port, errsv, strerror_r(errsv, buf, sizeof(buf))); _nl_socket_used_ports_release_all(used_ports); err = -nl_syserr2nlerr(errsv); goto errout; } } _nl_socket_used_ports_release_all(used_ports); } else { err = bind(sk->s_fd, (struct sockaddr*) &sk->s_local, sizeof(sk->s_local)); if (err != 0) { errsv = errno; NL_DBG(4, "nl_connect(%p): bind() failed with %d (%s)\n", sk, errsv, strerror_r(errsv, buf, sizeof(buf))); err = -nl_syserr2nlerr(errsv); goto errout; } } addrlen = sizeof(local); err = getsockname(sk->s_fd, (struct sockaddr *) &local, &addrlen); if (err < 0) { NL_DBG(4, "nl_connect(%p): getsockname() failed with %d (%s)\n", sk, errno, strerror_r(errno, buf, sizeof(buf))); err = -nl_syserr2nlerr(errno); goto errout; } if (addrlen != sizeof(local)) { err = -NLE_NOADDR; goto errout; } if (local.nl_family != AF_NETLINK) { err = -NLE_AF_NOSUPPORT; goto errout; } if (sk->s_local.nl_pid != local.nl_pid) { /* strange, the port id is not as expected. Set the local * port id to release a possibly generated port and un-own * it. */ nl_socket_set_local_port (sk, local.nl_pid); } sk->s_local = local; sk->s_proto = protocol; return 0; errout: if (sk->s_fd != -1) { close(sk->s_fd); sk->s_fd = -1; } return err; } /** * Close Netlink socket * @arg sk Netlink socket (required) * * Closes the Netlink socket using `close()`. * * @note The socket is closed automatically if a `struct nl_sock` object is * freed using `nl_socket_free()`. * * @see nl_connect() */ 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 * @{ */ /** * Transmit raw data over Netlink socket. * @arg sk Netlink socket (required) * @arg buf Buffer carrying data to send (required) * @arg size Size of buffer (required) * * Transmits "raw" data over the specified Netlink socket. Unlike the other * transmit functions it does not modify the data in any way. It directly * passes the buffer \c buf of \c size to sendto(). * * The message is addressed to the peer as specified in the socket by either * the nl_socket_set_peer_port() or nl_socket_set_peer_groups() function. * * @note Because there is no indication on the message boundaries of the data * being sent, the \c NL_CB_MSG_OUT callback handler will not be invoked * for data that is being sent using this function. * * @see nl_socket_set_peer_port() * @see nl_socket_set_peer_groups() * @see nl_sendmsg() * * @return Number of bytes sent or a negative error code. */ int nl_sendto(struct nl_sock *sk, void *buf, size_t size) { int ret; if (!buf) return -NLE_INVAL; if (sk->s_fd < 0) return -NLE_BAD_SOCK; ret = sendto(sk->s_fd, buf, size, 0, (struct sockaddr *) &sk->s_peer, sizeof(sk->s_peer)); if (ret < 0) { char errbuf[64]; NL_DBG(4, "nl_sendto(%p): sendto() failed with %d (%s)\n", sk, errno, strerror_r(errno, errbuf, sizeof(errbuf))); return -nl_syserr2nlerr(errno); } return ret; } /** * Transmit Netlink message using sendmsg() * @arg sk Netlink socket (required) * @arg msg Netlink message to be sent (required) * @arg hdr sendmsg() message header (required) * * Transmits the message specified in \c hdr over the Netlink socket using the * sendmsg() system call. * * @attention * The `msg` argument will *not* be used to derive the message payload that * is being sent out. The `msg` argument is *only* passed on to the * `NL_CB_MSG_OUT` callback. The caller is responsible to initialize the * `hdr` struct properly and have it point to the message payload and * socket address. * * @note * This function uses `nlmsg_set_src()` to modify the `msg` argument prior to * invoking the `NL_CB_MSG_OUT` callback to provide the local port number. * * @callback This function triggers the `NL_CB_MSG_OUT` callback. * * @attention * Think twice before using this function. It provides a low level access to * the Netlink socket. Among other limitations, it does not add credentials * even if enabled or respect the destination address specified in the `msg` * object. * * @see nl_socket_set_local_port() * @see nl_send_auto() * @see nl_send_iovec() * * @return Number of bytes sent on success or a negative error code. * * @lowlevel */ int nl_sendmsg(struct nl_sock *sk, struct nl_msg *msg, struct msghdr *hdr) { struct nl_cb *cb; int ret; if (sk->s_fd < 0) return -NLE_BAD_SOCK; nlmsg_set_src(msg, &sk->s_local); cb = sk->s_cb; if (cb->cb_set[NL_CB_MSG_OUT]) if ((ret = nl_cb_call(cb, NL_CB_MSG_OUT, msg)) != NL_OK) return ret; ret = sendmsg(sk->s_fd, hdr, 0); if (ret < 0) { char errbuf[64]; NL_DBG(4, "nl_sendmsg(%p): sendmsg() failed with %d (%s)\n", sk, errno, strerror_r(errno, errbuf, sizeof(errbuf))); return -nl_syserr2nlerr(errno); } NL_DBG(4, "sent %d bytes\n", ret); return ret; } /** * Transmit Netlink message (taking IO vector) * @arg sk Netlink socket (required) * @arg msg Netlink message to be sent (required) * @arg iov IO vector to be sent (required) * @arg iovlen Number of struct iovec to be sent (required) * * This function is identical to nl_send() except that instead of taking a * `struct nl_msg` object it takes an IO vector. Please see the description * of `nl_send()`. * * @callback This function triggers the `NL_CB_MSG_OUT` callback. * * @see nl_send() * * @return Number of bytes sent on success or a negative error code. * * @lowlevel */ int nl_send_iovec(struct nl_sock *sk, struct nl_msg *msg, struct iovec *iov, unsigned iovlen) { struct sockaddr_nl *dst; struct ucred *creds; struct msghdr hdr = { .msg_name = (void *) &sk->s_peer, .msg_namelen = sizeof(struct sockaddr_nl), .msg_iov = iov, .msg_iovlen = iovlen, }; /* 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); } /** * Transmit Netlink message * @arg sk Netlink socket (required) * @arg msg Netlink message (required) * * Transmits the Netlink message `msg` over the Netlink socket using the * `sendmsg()` system call. This function is based on `nl_send_iovec()` but * takes care of initializing a `struct iovec` based on the `msg` object. * * The message is addressed to the peer as specified in the socket by either * the nl_socket_set_peer_port() or nl_socket_set_peer_groups() function. * The peer address can be overwritten by specifying an address in the `msg` * object using nlmsg_set_dst(). * * If present in the `msg`, credentials set by the nlmsg_set_creds() function * are added to the control buffer of the message. * * @par Overwriting Capability: * Calls to this function can be overwritten by providing an alternative using * the nl_cb_overwrite_send() function. * * @callback This function triggers the `NL_CB_MSG_OUT` callback. * * @attention * Unlike `nl_send_auto()`, this function does *not* finalize the message in * terms of automatically adding needed flags or filling out port numbers. * * @see nl_send_auto() * @see nl_send_iovec() * @see nl_socket_set_peer_port() * @see nl_socket_set_peer_groups() * @see nlmsg_set_dst() * @see nlmsg_set_creds() * @see nl_cb_overwrite_send() * * @return Number of bytes sent on success or a negative error code. */ int nl_send(struct nl_sock *sk, struct nl_msg *msg) { struct nl_cb *cb = sk->s_cb; if (cb->cb_send_ow) return cb->cb_send_ow(sk, msg); else { struct iovec iov = { .iov_base = (void *) nlmsg_hdr(msg), .iov_len = nlmsg_hdr(msg)->nlmsg_len, }; return nl_send_iovec(sk, msg, &iov, 1); } } /** * Finalize Netlink message * @arg sk Netlink socket (required) * @arg msg Netlink message (required) * * This function finalizes a Netlink message by completing the message with * desirable flags and values depending on the socket configuration. * * - If not yet filled out, the source address of the message (`nlmsg_pid`) * will be set to the local port number of the socket. * - If not yet specified, the next available sequence number is assigned * to the message (`nlmsg_seq`). * - If not yet specified, the protocol field of the message will be set to * the protocol field of the socket. * - The `NLM_F_REQUEST` Netlink message flag will be set. * - The `NLM_F_ACK` flag will be set if Auto-ACK mode is enabled on the * socket. */ void nl_complete_msg(struct nl_sock *sk, struct nl_msg *msg) { struct nlmsghdr *nlh; nlh = nlmsg_hdr(msg); if (nlh->nlmsg_pid == NL_AUTO_PORT) nlh->nlmsg_pid = nl_socket_get_local_port(sk); if (nlh->nlmsg_seq == NL_AUTO_SEQ) 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; } /** * Finalize and transmit Netlink message * @arg sk Netlink socket (required) * @arg msg Netlink message (required) * * Finalizes the message by passing it to `nl_complete_msg()` and transmits it * by passing it to `nl_send()`. * * @callback This function triggers the `NL_CB_MSG_OUT` callback. * * @see nl_complete_msg() * @see nl_send() * * @return Number of bytes sent or a negative error code. */ int nl_send_auto(struct nl_sock *sk, struct nl_msg *msg) { nl_complete_msg(sk, msg); return nl_send(sk, msg); } /** * Finalize and transmit Netlink message and wait for ACK or error message * @arg sk Netlink socket (required) * @arg msg Netlink message (required) * * Passes the `msg` to `nl_send_auto()` to finalize and transmit it. Frees the * message and waits (sleeps) for the ACK or error message to be received. * * @attention * Disabling Auto-ACK (nl_socket_disable_auto_ack()) will cause this function * to return immediately after transmitting the message. However, the peer may * still be returning an error message in response to the request. It is the * responsibility of the caller to handle such messages. * * @callback This function triggers the `NL_CB_MSG_OUT` callback. * * @attention * This function frees the `msg` object after transmitting it by calling * `nlmsg_free()`. * * @see nl_send_auto(). * @see nl_wait_for_ack() * * @return 0 on success or a negative error code. */ int nl_send_sync(struct nl_sock *sk, struct nl_msg *msg) { int err; err = nl_send_auto(sk, msg); nlmsg_free(msg); if (err < 0) return err; return wait_for_ack(sk); } /** * Construct and transmit a Netlink message * @arg sk Netlink socket (required) * @arg type Netlink message type (required) * @arg flags Netlink message flags (optional) * @arg buf Data buffer (optional) * @arg size Size of data buffer (optional) * * Allocates a new Netlink message based on `type` and `flags`. If `buf` * points to payload of length `size` that payload will be appended to the * message. * * Sends out the message using `nl_send_auto()` and frees the message * afterwards. * * @see nl_send_auto() * * @return Number of characters sent on success or a negative error code. * @retval -NLE_NOMEM Unable to allocate Netlink message */ 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(sk, msg); errout: nlmsg_free(msg); return err; } /** @} */ /** * @name Receive * @{ */ /** * Receive data from netlink socket * @arg sk Netlink socket (required) * @arg nla Netlink socket structure to hold address of peer (required) * @arg buf Destination pointer for message content (required) * @arg creds Destination pointer for credentials (optional) * * Receives data from a connected netlink socket using recvmsg() and returns * the number of bytes read. The read data is stored in a newly allocated * buffer that is assigned to \c *buf. The peer's netlink address will be * stored in \c *nla. * * This function blocks until data is available to be read unless the socket * has been put into non-blocking mode using nl_socket_set_nonblocking() in * which case this function will return immediately with a return value of 0. * * The buffer size used when reading from the netlink socket and thus limiting * the maximum size of a netlink message that can be read defaults to the size * of a memory page (getpagesize()). The buffer size can be modified on a per * socket level using the function nl_socket_set_msg_buf_size(). * * If message peeking is enabled using nl_socket_enable_msg_peek() the size of * the message to be read will be determined using the MSG_PEEK flag prior to * performing the actual read. This leads to an additional recvmsg() call for * every read operation which has performance implications and is not * recommended for high throughput protocols. * * An eventual interruption of the recvmsg() system call is automatically * handled by retrying the operation. * * If receiving of credentials has been enabled using the function * nl_socket_set_passcred(), this function will allocate a new struct ucred * filled with the received credentials and assign it to \c *creds. The caller * is responsible for freeing the buffer. * * @note The caller is responsible to free the returned data buffer and if * enabled, the credentials buffer. * * @see nl_socket_set_nonblocking() * @see nl_socket_set_msg_buf_size() * @see nl_socket_enable_msg_peek() * @see nl_socket_set_passcred() * * @return Number of bytes read, 0 on EOF, 0 on no data event (non-blocking * mode), or a negative error code. */ int nl_recv(struct nl_sock *sk, struct sockaddr_nl *nla, unsigned char **buf, struct ucred **creds) { ssize_t 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, }; struct ucred* tmpcreds = NULL; int retval = 0; if (!buf || !nla) return -NLE_INVAL; if (sk->s_flags & NL_MSG_PEEK) flags |= MSG_PEEK | MSG_TRUNC; if (page_size == 0) page_size = getpagesize() * 4; iov.iov_len = sk->s_bufsize ? : page_size; iov.iov_base = malloc(iov.iov_len); if (!iov.iov_base) { retval = -NLE_NOMEM; goto abort; } if (creds && (sk->s_flags & NL_SOCK_PASSCRED)) { msg.msg_controllen = CMSG_SPACE(sizeof(struct ucred)); msg.msg_control = malloc(msg.msg_controllen); if (!msg.msg_control) { retval = -NLE_NOMEM; goto abort; } } retry: n = recvmsg(sk->s_fd, &msg, flags); if (!n) { retval = 0; goto abort; } if (n < 0) { char errbuf[64]; if (errno == EINTR) { NL_DBG(3, "recvmsg() returned EINTR, retrying\n"); goto retry; } NL_DBG(4, "nl_sendmsg(%p): nl_recv() failed with %d (%s)\n", sk, errno, strerror_r(errno, errbuf, sizeof(errbuf))); retval = -nl_syserr2nlerr(errno); goto abort; } if (msg.msg_flags & MSG_CTRUNC) { void *tmp; msg.msg_controllen *= 2; tmp = realloc(msg.msg_control, msg.msg_controllen); if (!tmp) { retval = -NLE_NOMEM; goto abort; } msg.msg_control = tmp; goto retry; } if (iov.iov_len < n || (msg.msg_flags & MSG_TRUNC)) { void *tmp; /* respond with error to an incomplete message */ if (!(sk->s_flags & NL_MSG_PEEK)) { retval = -NLE_MSG_TRUNC; goto abort; } /* Provided buffer is not long enough, enlarge it * to size of n (which should be total length of the message) * and try again. */ iov.iov_len = n; tmp = realloc(iov.iov_base, iov.iov_len); if (!tmp) { retval = -NLE_NOMEM; goto abort; } iov.iov_base = tmp; flags = 0; goto retry; } if (flags != 0) { /* Buffer is big enough, do the actual reading */ flags = 0; goto retry; } if (msg.msg_namelen != sizeof(struct sockaddr_nl)) { retval = -NLE_NOADDR; goto abort; } if (creds && (sk->s_flags & NL_SOCK_PASSCRED)) { struct cmsghdr *cmsg; for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) { if (cmsg->cmsg_level != SOL_SOCKET) continue; if (cmsg->cmsg_type != SCM_CREDENTIALS) continue; tmpcreds = malloc(sizeof(*tmpcreds)); if (!tmpcreds) { retval = -NLE_NOMEM; goto abort; } memcpy(tmpcreds, CMSG_DATA(cmsg), sizeof(*tmpcreds)); break; } } retval = n; abort: free(msg.msg_control); if (retval <= 0) { free(iov.iov_base); iov.iov_base = NULL; free(tmpcreds); tmpcreds = NULL; } else *buf = iov.iov_base; if (creds) *creds = tmpcreds; return retval; } /** @cond SKIP */ #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) /** @endcond */ static int recvmsgs(struct nl_sock *sk, struct nl_cb *cb) { int n, err = 0, multipart = 0, interrupted = 0, nrecv = 0; unsigned char *buf = NULL; struct nlmsghdr *hdr; /* nla is passed on to not only to nl_recv() but may also be passed to a function pointer provided by the caller which may or may not initialize the variable. Thomas Graf. */ 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, "recvmsgs(%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); nrecv++; /* 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); /* Only do sequence checking if auto-ack mode is enabled */ } else if (!(sk->s_flags & NL_NO_AUTO_ACK)) { 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; if (hdr->nlmsg_flags & NLM_F_DUMP_INTR) { if (cb->cb_set[NL_CB_DUMP_INTR]) NL_CB_CALL(cb, NL_CB_DUMP_INTR, msg); else { /* * We have to continue reading to clear * all messages until a NLMSG_DONE is * received and report the inconsistency. */ interrupted = 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 multipart 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_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) { char buf[64]; NL_DBG(4, "recvmsgs(%p): RTNETLINK responded with %d (%s)\n", sk, -e->error, strerror_r(-e->error, buf, sizeof(buf))); /* 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); if (interrupted) err = -NLE_DUMP_INTR; if (!err) err = nrecv; return err; } /** * Receive a set of messages from a netlink socket and report parsed messages * @arg sk Netlink socket. * @arg cb set of callbacks to control behaviour. * * This function is identical to nl_recvmsgs() to the point that it will * return the number of parsed messages instead of 0 on success. * * @see nl_recvmsgs() * * @return Number of received messages or a negative error code from nl_recv(). */ int nl_recvmsgs_report(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); } /** * 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. * * @see nl_recvmsgs_report() * * @return 0 on success or a negative error code from nl_recv(). */ int nl_recvmsgs(struct nl_sock *sk, struct nl_cb *cb) { int err; if ((err = nl_recvmsgs_report(sk, cb)) > 0) err = 0; return err; } /** * Receive a set of message from a netlink socket using handlers in nl_sock. * @arg sk Netlink socket. * * Calls nl_recvmsgs() with the handlers configured in the netlink socket. */ int nl_recvmsgs_default(struct nl_sock *sk) { return nl_recvmsgs(sk, sk->s_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; } /** @cond SKIP */ struct pickup_param { int (*parser)(struct nl_cache_ops *, struct sockaddr_nl *, struct nlmsghdr *, struct nl_parser_param *); struct nl_object *result; int *syserror; }; static int __store_answer(struct nl_object *obj, struct nl_parser_param *p) { struct pickup_param *pp = p->pp_arg; /* * the parser will put() the object at the end, expecting the cache * to take the reference. */ nl_object_get(obj); pp->result = obj; return 0; } static int __pickup_answer(struct nl_msg *msg, void *arg) { struct pickup_param *pp = arg; struct nl_parser_param parse_arg = { .pp_cb = __store_answer, .pp_arg = pp, }; return pp->parser(NULL, &msg->nm_src, msg->nm_nlh, &parse_arg); } static int __pickup_answer_syserr(struct sockaddr_nl *nla, struct nlmsgerr *nlerr, void *arg) { *(((struct pickup_param *) arg)->syserror) = nlerr->error; return -nl_syserr2nlerr(nlerr->error); } /** @endcond */ /** * Pickup netlink answer, parse is and return object * @arg sk Netlink socket * @arg parser Parser function to parse answer * @arg result Result pointer to return parsed object * * @return 0 on success or a negative error code. */ int nl_pickup(struct nl_sock *sk, int (*parser)(struct nl_cache_ops *, struct sockaddr_nl *, struct nlmsghdr *, struct nl_parser_param *), struct nl_object **result) { return nl_pickup_keep_syserr(sk, parser, result, NULL); } /** * Pickup netlink answer, parse is and return object with preserving system error * @arg sk Netlink socket * @arg parser Parser function to parse answer * @arg result Result pointer to return parsed object * @arg syserr Result pointer for the system error in case of failure * * @return 0 on success or a negative error code. */ int nl_pickup_keep_syserr(struct nl_sock *sk, int (*parser)(struct nl_cache_ops *, struct sockaddr_nl *, struct nlmsghdr *, struct nl_parser_param *), struct nl_object **result, int *syserror) { struct nl_cb *cb; int err; struct pickup_param pp = { .parser = parser, }; cb = nl_cb_clone(sk->s_cb); if (cb == NULL) return -NLE_NOMEM; nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, __pickup_answer, &pp); if (syserror) { *syserror = 0; pp.syserror = syserror; nl_cb_err(cb, NL_CB_CUSTOM, __pickup_answer_syserr, &pp); } err = nl_recvmsgs(sk, cb); if (err < 0) goto errout; *result = pp.result; errout: nl_cb_put(cb); return err; } /** @} */ /** * @name Deprecated * @{ */ /** * @deprecated Please use nl_complete_msg() */ void nl_auto_complete(struct nl_sock *sk, struct nl_msg *msg) { nl_complete_msg(sk, msg); } /** * @deprecated Please use nl_send_auto() */ int nl_send_auto_complete(struct nl_sock *sk, struct nl_msg *msg) { return nl_send_auto(sk, msg); } /** @} */ /** @} */ /** @} */