diff options
Diffstat (limited to 'src/libsystemd/sd-netlink/netlink-socket.c')
| -rw-r--r-- | src/libsystemd/sd-netlink/netlink-socket.c | 275 |
1 files changed, 275 insertions, 0 deletions
diff --git a/src/libsystemd/sd-netlink/netlink-socket.c b/src/libsystemd/sd-netlink/netlink-socket.c new file mode 100644 index 0000000000..2e2826ac63 --- /dev/null +++ b/src/libsystemd/sd-netlink/netlink-socket.c @@ -0,0 +1,275 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of systemd. + + Copyright 2013 Tom Gundersen <teg@jklm.no> + + systemd 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; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +***/ + +#include <netinet/in.h> +#include <stdbool.h> +#include <unistd.h> + +#include "util.h" +#include "socket-util.h" +#include "formats-util.h" +#include "refcnt.h" +#include "missing.h" + +#include "sd-netlink.h" +#include "netlink-util.h" +#include "netlink-internal.h" +#include "netlink-types.h" + +/* returns the number of bytes sent, or a negative error code */ +int socket_write_message(sd_netlink *nl, sd_netlink_message *m) { + union { + struct sockaddr sa; + struct sockaddr_nl nl; + } addr = { + .nl.nl_family = AF_NETLINK, + }; + ssize_t k; + + assert(nl); + assert(m); + assert(m->hdr); + + k = sendto(nl->fd, m->hdr, m->hdr->nlmsg_len, + 0, &addr.sa, sizeof(addr)); + if (k < 0) + return -errno; + + return k; +} + +static int socket_recv_message(int fd, struct iovec *iov, uint32_t *_group, bool peek) { + union sockaddr_union sender; + uint8_t cmsg_buffer[CMSG_SPACE(sizeof(struct nl_pktinfo))]; + struct msghdr msg = { + .msg_iov = iov, + .msg_iovlen = 1, + .msg_name = &sender, + .msg_namelen = sizeof(sender), + .msg_control = cmsg_buffer, + .msg_controllen = sizeof(cmsg_buffer), + }; + struct cmsghdr *cmsg; + uint32_t group = 0; + int r; + + assert(fd >= 0); + assert(iov); + + r = recvmsg(fd, &msg, MSG_TRUNC | (peek ? MSG_PEEK : 0)); + if (r < 0) { + /* no data */ + if (errno == ENOBUFS) + log_debug("rtnl: kernel receive buffer overrun"); + else if (errno == EAGAIN) + log_debug("rtnl: no data in socket"); + + return (errno == EAGAIN || errno == EINTR) ? 0 : -errno; + } + + if (sender.nl.nl_pid != 0) { + /* not from the kernel, ignore */ + log_debug("rtnl: ignoring message from portid %"PRIu32, sender.nl.nl_pid); + + if (peek) { + /* drop the message */ + r = recvmsg(fd, &msg, 0); + if (r < 0) + return (errno == EAGAIN || errno == EINTR) ? 0 : -errno; + } + + return 0; + } + + CMSG_FOREACH(cmsg, &msg) { + if (cmsg->cmsg_level == SOL_NETLINK && + cmsg->cmsg_type == NETLINK_PKTINFO && + cmsg->cmsg_len == CMSG_LEN(sizeof(struct nl_pktinfo))) { + struct nl_pktinfo *pktinfo = (void *)CMSG_DATA(cmsg); + + /* multi-cast group */ + group = pktinfo->group; + } + } + + if (_group) + *_group = group; + + return r; +} + +/* On success, the number of bytes received is returned and *ret points to the received message + * which has a valid header and the correct size. + * If nothing useful was received 0 is returned. + * On failure, a negative error code is returned. + */ +int socket_read_message(sd_netlink *rtnl) { + _cleanup_netlink_message_unref_ sd_netlink_message *first = NULL; + struct iovec iov = {}; + uint32_t group = 0; + bool multi_part = false, done = false; + struct nlmsghdr *new_msg; + size_t len; + int r; + unsigned i = 0; + + assert(rtnl); + assert(rtnl->rbuffer); + assert(rtnl->rbuffer_allocated >= sizeof(struct nlmsghdr)); + + /* read nothing, just get the pending message size */ + r = socket_recv_message(rtnl->fd, &iov, NULL, true); + if (r <= 0) + return r; + else + len = (size_t)r; + + /* make room for the pending message */ + if (!greedy_realloc((void **)&rtnl->rbuffer, + &rtnl->rbuffer_allocated, + len, sizeof(uint8_t))) + return -ENOMEM; + + iov.iov_base = rtnl->rbuffer; + iov.iov_len = rtnl->rbuffer_allocated; + + /* read the pending message */ + r = socket_recv_message(rtnl->fd, &iov, &group, false); + if (r <= 0) + return r; + else + len = (size_t)r; + + if (len > rtnl->rbuffer_allocated) + /* message did not fit in read buffer */ + return -EIO; + + if (NLMSG_OK(rtnl->rbuffer, len) && rtnl->rbuffer->nlmsg_flags & NLM_F_MULTI) { + multi_part = true; + + for (i = 0; i < rtnl->rqueue_partial_size; i++) { + if (rtnl_message_get_serial(rtnl->rqueue_partial[i]) == + rtnl->rbuffer->nlmsg_seq) { + first = rtnl->rqueue_partial[i]; + break; + } + } + } + + for (new_msg = rtnl->rbuffer; NLMSG_OK(new_msg, len) && !done; new_msg = NLMSG_NEXT(new_msg, len)) { + _cleanup_netlink_message_unref_ sd_netlink_message *m = NULL; + const NLType *nl_type; + + if (!group && new_msg->nlmsg_pid != rtnl->sockaddr.nl.nl_pid) + /* not broadcast and not for us */ + continue; + + if (new_msg->nlmsg_type == NLMSG_NOOP) + /* silently drop noop messages */ + continue; + + if (new_msg->nlmsg_type == NLMSG_DONE) { + /* finished reading multi-part message */ + done = true; + + /* if first is not defined, put NLMSG_DONE into the receive queue. */ + if (first) + continue; + } + + /* check that we support this message type */ + r = type_system_get_type(NULL, &nl_type, new_msg->nlmsg_type); + if (r < 0) { + if (r == -EOPNOTSUPP) + log_debug("sd-netlink: ignored message with unknown type: %i", + new_msg->nlmsg_type); + + continue; + } + + /* check that the size matches the message type */ + if (new_msg->nlmsg_len < NLMSG_LENGTH(nl_type->size)) { + log_debug("sd-netlink: message larger than expected, dropping"); + continue; + } + + r = message_new_empty(rtnl, &m); + if (r < 0) + return r; + + m->broadcast = !!group; + + m->hdr = memdup(new_msg, new_msg->nlmsg_len); + if (!m->hdr) + return -ENOMEM; + + /* seal and parse the top-level message */ + r = sd_netlink_message_rewind(m); + if (r < 0) + return r; + + /* push the message onto the multi-part message stack */ + if (first) + m->next = first; + first = m; + m = NULL; + } + + if (len) + log_debug("sd-netlink: discarding %zu bytes of incoming message", len); + + if (!first) + return 0; + + if (!multi_part || done) { + /* we got a complete message, push it on the read queue */ + r = rtnl_rqueue_make_room(rtnl); + if (r < 0) + return r; + + rtnl->rqueue[rtnl->rqueue_size ++] = first; + first = NULL; + + if (multi_part && (i < rtnl->rqueue_partial_size)) { + /* remove the message form the partial read queue */ + memmove(rtnl->rqueue_partial + i,rtnl->rqueue_partial + i + 1, + sizeof(sd_netlink_message*) * (rtnl->rqueue_partial_size - i - 1)); + rtnl->rqueue_partial_size --; + } + + return 1; + } else { + /* we only got a partial multi-part message, push it on the + partial read queue */ + if (i < rtnl->rqueue_partial_size) { + rtnl->rqueue_partial[i] = first; + } else { + r = rtnl_rqueue_partial_make_room(rtnl); + if (r < 0) + return r; + + rtnl->rqueue_partial[rtnl->rqueue_partial_size ++] = first; + } + first = NULL; + + return 0; + } +} |