diff options
author | Ben Pfaff <blp@nicira.com> | 2010-12-10 09:51:03 -0800 |
---|---|---|
committer | Ben Pfaff <blp@nicira.com> | 2010-12-10 11:13:27 -0800 |
commit | 2fe27d5ad27f3c7879ea696209bcf9702d9b7109 (patch) | |
tree | 943745f56a960fcd88b14205271fbf4d7d987f6f /lib/netlink-socket.c | |
parent | 365a25176bf854112b37c56888979d7755ab0d72 (diff) |
netlink: Split into generic and Linux-specific parts.
The parts of the netlink module that are related to sockets are
Linux-specific, since only Linux has AF_NETLINK sockets. The rest can be
built anywhere. This commit breaks them into two modules, and builds the
generic one on all platforms.
Acked-by: Jesse Gross <jesse@nicira.com>
Diffstat (limited to 'lib/netlink-socket.c')
-rw-r--r-- | lib/netlink-socket.c | 814 |
1 files changed, 814 insertions, 0 deletions
diff --git a/lib/netlink-socket.c b/lib/netlink-socket.c new file mode 100644 index 00000000..c9402fd9 --- /dev/null +++ b/lib/netlink-socket.c @@ -0,0 +1,814 @@ +/* + * Copyright (c) 2008, 2009, 2010 Nicira Networks. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at: + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include <config.h> +#include "netlink-socket.h" +#include <assert.h> +#include <errno.h> +#include <inttypes.h> +#include <stdlib.h> +#include <sys/types.h> +#include <unistd.h> +#include "coverage.h" +#include "dynamic-string.h" +#include "netlink.h" +#include "netlink-protocol.h" +#include "ofpbuf.h" +#include "poll-loop.h" +#include "stress.h" +#include "vlog.h" + +VLOG_DEFINE_THIS_MODULE(netlink_socket); + +COVERAGE_DEFINE(netlink_overflow); +COVERAGE_DEFINE(netlink_received); +COVERAGE_DEFINE(netlink_recv_retry); +COVERAGE_DEFINE(netlink_send); +COVERAGE_DEFINE(netlink_sent); + +/* Linux header file confusion causes this to be undefined. */ +#ifndef SOL_NETLINK +#define SOL_NETLINK 270 +#endif + +/* A single (bad) Netlink message can in theory dump out many, many log + * messages, so the burst size is set quite high here to avoid missing useful + * information. Also, at high logging levels we log *all* Netlink messages. */ +static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(60, 600); + +static void log_nlmsg(const char *function, int error, + const void *message, size_t size); + +/* Netlink sockets. */ + +struct nl_sock +{ + int fd; + uint32_t pid; +}; + +static int alloc_pid(uint32_t *); +static void free_pid(uint32_t); + +/* Creates a new netlink socket for the given netlink 'protocol' + * (NETLINK_ROUTE, NETLINK_GENERIC, ...). Returns 0 and sets '*sockp' to the + * new socket if successful, otherwise returns a positive errno value. + * + * If 'multicast_group' is nonzero, the new socket subscribes to the specified + * netlink multicast group. (A netlink socket may listen to an arbitrary + * number of multicast groups, but so far we only need one at a time.) + * + * Nonzero 'so_sndbuf' or 'so_rcvbuf' override the kernel default send or + * receive buffer size, respectively. + */ +int +nl_sock_create(int protocol, int multicast_group, + size_t so_sndbuf, size_t so_rcvbuf, struct nl_sock **sockp) +{ + struct nl_sock *sock; + struct sockaddr_nl local, remote; + int retval = 0; + + *sockp = NULL; + sock = malloc(sizeof *sock); + if (sock == NULL) { + return ENOMEM; + } + + sock->fd = socket(AF_NETLINK, SOCK_RAW, protocol); + if (sock->fd < 0) { + VLOG_ERR("fcntl: %s", strerror(errno)); + goto error; + } + + retval = alloc_pid(&sock->pid); + if (retval) { + goto error; + } + + if (so_sndbuf != 0 + && setsockopt(sock->fd, SOL_SOCKET, SO_SNDBUF, + &so_sndbuf, sizeof so_sndbuf) < 0) { + VLOG_ERR("setsockopt(SO_SNDBUF,%zu): %s", so_sndbuf, strerror(errno)); + goto error_free_pid; + } + + if (so_rcvbuf != 0 + && setsockopt(sock->fd, SOL_SOCKET, SO_RCVBUF, + &so_rcvbuf, sizeof so_rcvbuf) < 0) { + VLOG_ERR("setsockopt(SO_RCVBUF,%zu): %s", so_rcvbuf, strerror(errno)); + goto error_free_pid; + } + + /* Bind local address as our selected pid. */ + memset(&local, 0, sizeof local); + local.nl_family = AF_NETLINK; + local.nl_pid = sock->pid; + if (multicast_group > 0 && multicast_group <= 32) { + /* This method of joining multicast groups is supported by old kernels, + * but it only allows 32 multicast groups per protocol. */ + local.nl_groups |= 1ul << (multicast_group - 1); + } + if (bind(sock->fd, (struct sockaddr *) &local, sizeof local) < 0) { + VLOG_ERR("bind(%"PRIu32"): %s", sock->pid, strerror(errno)); + goto error_free_pid; + } + + /* Bind remote address as the kernel (pid 0). */ + memset(&remote, 0, sizeof remote); + remote.nl_family = AF_NETLINK; + remote.nl_pid = 0; + if (connect(sock->fd, (struct sockaddr *) &remote, sizeof remote) < 0) { + VLOG_ERR("connect(0): %s", strerror(errno)); + goto error_free_pid; + } + + /* Older kernel headers failed to define this macro. We want our programs + * to support the newer kernel features even if compiled with older + * headers, so define it ourselves in such a case. */ +#ifndef NETLINK_ADD_MEMBERSHIP +#define NETLINK_ADD_MEMBERSHIP 1 +#endif + + /* This method of joining multicast groups is only supported by newish + * kernels, but it allows for an arbitrary number of multicast groups. */ + if (multicast_group > 32 + && setsockopt(sock->fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, + &multicast_group, sizeof multicast_group) < 0) { + VLOG_ERR("setsockopt(NETLINK_ADD_MEMBERSHIP,%d): %s", + multicast_group, strerror(errno)); + goto error_free_pid; + } + + *sockp = sock; + return 0; + +error_free_pid: + free_pid(sock->pid); +error: + if (retval == 0) { + retval = errno; + if (retval == 0) { + retval = EINVAL; + } + } + if (sock->fd >= 0) { + close(sock->fd); + } + free(sock); + return retval; +} + +/* Destroys netlink socket 'sock'. */ +void +nl_sock_destroy(struct nl_sock *sock) +{ + if (sock) { + close(sock->fd); + free_pid(sock->pid); + free(sock); + } +} + +/* Tries to send 'msg', which must contain a Netlink message, to the kernel on + * 'sock'. nlmsg_len in 'msg' will be finalized to match msg->size, and + * nlmsg_pid will be set to 'sock''s pid, before the message is sent. + * + * Returns 0 if successful, otherwise a positive errno value. If + * 'wait' is true, then the send will wait until buffer space is ready; + * otherwise, returns EAGAIN if the 'sock' send buffer is full. */ +int +nl_sock_send(struct nl_sock *sock, const struct ofpbuf *msg, bool wait) +{ + struct nlmsghdr *nlmsg = nl_msg_nlmsghdr(msg); + int error; + + nlmsg->nlmsg_len = msg->size; + nlmsg->nlmsg_pid = sock->pid; + do { + int retval; + retval = send(sock->fd, msg->data, msg->size, wait ? 0 : MSG_DONTWAIT); + error = retval < 0 ? errno : 0; + } while (error == EINTR); + log_nlmsg(__func__, error, msg->data, msg->size); + if (!error) { + COVERAGE_INC(netlink_sent); + } + return error; +} + +/* Tries to send the 'n_iov' chunks of data in 'iov' to the kernel on 'sock' as + * a single Netlink message. (The message must be fully formed and not require + * finalization of its nlmsg_len or nlmsg_pid fields.) + * + * Returns 0 if successful, otherwise a positive errno value. If 'wait' is + * true, then the send will wait until buffer space is ready; otherwise, + * returns EAGAIN if the 'sock' send buffer is full. */ +int +nl_sock_sendv(struct nl_sock *sock, const struct iovec iov[], size_t n_iov, + bool wait) +{ + struct msghdr msg; + int error; + + COVERAGE_INC(netlink_send); + memset(&msg, 0, sizeof msg); + msg.msg_iov = (struct iovec *) iov; + msg.msg_iovlen = n_iov; + do { + int retval; + retval = sendmsg(sock->fd, &msg, wait ? 0 : MSG_DONTWAIT); + error = retval < 0 ? errno : 0; + } while (error == EINTR); + if (error != EAGAIN) { + log_nlmsg(__func__, error, iov[0].iov_base, iov[0].iov_len); + if (!error) { + COVERAGE_INC(netlink_sent); + } + } + return error; +} + +/* This stress option is useful for testing that OVS properly tolerates + * -ENOBUFS on NetLink sockets. Such errors are unavoidable because they can + * occur if the kernel cannot temporarily allocate enough GFP_ATOMIC memory to + * reply to a request. They can also occur if messages arrive on a multicast + * channel faster than OVS can process them. */ +STRESS_OPTION( + netlink_overflow, "simulate netlink socket receive buffer overflow", + 5, 1, -1, 100); + +/* Tries to receive a netlink message from the kernel on 'sock'. If + * successful, stores the received message into '*bufp' and returns 0. The + * caller is responsible for destroying the message with ofpbuf_delete(). On + * failure, returns a positive errno value and stores a null pointer into + * '*bufp'. + * + * If 'wait' is true, nl_sock_recv waits for a message to be ready; otherwise, + * returns EAGAIN if the 'sock' receive buffer is empty. */ +int +nl_sock_recv(struct nl_sock *sock, struct ofpbuf **bufp, bool wait) +{ + uint8_t tmp; + ssize_t bufsize = 2048; + ssize_t nbytes, nbytes2; + struct ofpbuf *buf; + struct nlmsghdr *nlmsghdr; + struct iovec iov; + struct msghdr msg = { + .msg_name = NULL, + .msg_namelen = 0, + .msg_iov = &iov, + .msg_iovlen = 1, + .msg_control = NULL, + .msg_controllen = 0, + .msg_flags = 0 + }; + + buf = ofpbuf_new(bufsize); + *bufp = NULL; + +try_again: + /* Attempt to read the message. We don't know the size of the data + * yet, so we take a guess at 2048. If we're wrong, we keep trying + * and doubling the buffer size each time. + */ + nlmsghdr = ofpbuf_put_uninit(buf, bufsize); + iov.iov_base = nlmsghdr; + iov.iov_len = bufsize; + do { + nbytes = recvmsg(sock->fd, &msg, (wait ? 0 : MSG_DONTWAIT) | MSG_PEEK); + } while (nbytes < 0 && errno == EINTR); + if (nbytes < 0) { + ofpbuf_delete(buf); + return errno; + } + if (msg.msg_flags & MSG_TRUNC) { + COVERAGE_INC(netlink_recv_retry); + bufsize *= 2; + ofpbuf_reinit(buf, bufsize); + goto try_again; + } + buf->size = nbytes; + + /* We successfully read the message, so recv again to clear the queue */ + iov.iov_base = &tmp; + iov.iov_len = 1; + do { + nbytes2 = recvmsg(sock->fd, &msg, MSG_DONTWAIT); + } while (nbytes2 < 0 && errno == EINTR); + if (nbytes2 < 0) { + if (errno == ENOBUFS) { + /* The kernel is notifying us that a message it tried to send to us + * was dropped. We have to pass this along to the caller in case + * it wants to retry a request. So kill the buffer, which we can + * re-read next time. */ + COVERAGE_INC(netlink_overflow); + ofpbuf_delete(buf); + return ENOBUFS; + } else { + VLOG_ERR_RL(&rl, "failed to remove nlmsg from socket: %s\n", + strerror(errno)); + } + } + if (nbytes < sizeof *nlmsghdr + || nlmsghdr->nlmsg_len < sizeof *nlmsghdr + || nlmsghdr->nlmsg_len > nbytes) { + VLOG_ERR_RL(&rl, "received invalid nlmsg (%zd bytes < %d)", + bufsize, NLMSG_HDRLEN); + ofpbuf_delete(buf); + return EPROTO; + } + + if (STRESS(netlink_overflow)) { + ofpbuf_delete(buf); + return ENOBUFS; + } + + *bufp = buf; + log_nlmsg(__func__, 0, buf->data, buf->size); + COVERAGE_INC(netlink_received); + + return 0; +} + +/* Sends 'request' to the kernel via 'sock' and waits for a response. If + * successful, returns 0. On failure, returns a positive errno value. + * + * If 'replyp' is nonnull, then on success '*replyp' is set to the kernel's + * reply, which the caller is responsible for freeing with ofpbuf_delete(), and + * on failure '*replyp' is set to NULL. If 'replyp' is null, then the kernel's + * reply, if any, is discarded. + * + * nlmsg_len in 'msg' will be finalized to match msg->size, and nlmsg_pid will + * be set to 'sock''s pid, before the message is sent. NLM_F_ACK will be set + * in nlmsg_flags. + * + * The caller is responsible for destroying 'request'. + * + * Bare Netlink is an unreliable transport protocol. This function layers + * reliable delivery and reply semantics on top of bare Netlink. + * + * In Netlink, sending a request to the kernel is reliable enough, because the + * kernel will tell us if the message cannot be queued (and we will in that + * case put it on the transmit queue and wait until it can be delivered). + * + * Receiving the reply is the real problem: if the socket buffer is full when + * the kernel tries to send the reply, the reply will be dropped. However, the + * kernel sets a flag that a reply has been dropped. The next call to recv + * then returns ENOBUFS. We can then re-send the request. + * + * Caveats: + * + * 1. Netlink depends on sequence numbers to match up requests and + * replies. The sender of a request supplies a sequence number, and + * the reply echos back that sequence number. + * + * This is fine, but (1) some kernel netlink implementations are + * broken, in that they fail to echo sequence numbers and (2) this + * function will drop packets with non-matching sequence numbers, so + * that only a single request can be usefully transacted at a time. + * + * 2. Resending the request causes it to be re-executed, so the request + * needs to be idempotent. + */ +int +nl_sock_transact(struct nl_sock *sock, + const struct ofpbuf *request, struct ofpbuf **replyp) +{ + uint32_t seq = nl_msg_nlmsghdr(request)->nlmsg_seq; + struct nlmsghdr *nlmsghdr; + struct ofpbuf *reply; + int retval; + + if (replyp) { + *replyp = NULL; + } + + /* Ensure that we get a reply even if this message doesn't ordinarily call + * for one. */ + nl_msg_nlmsghdr(request)->nlmsg_flags |= NLM_F_ACK; + +send: + retval = nl_sock_send(sock, request, true); + if (retval) { + return retval; + } + +recv: + retval = nl_sock_recv(sock, &reply, true); + if (retval) { + if (retval == ENOBUFS) { + COVERAGE_INC(netlink_overflow); + VLOG_DBG_RL(&rl, "receive buffer overflow, resending request"); + goto send; + } else { + return retval; + } + } + nlmsghdr = nl_msg_nlmsghdr(reply); + if (seq != nlmsghdr->nlmsg_seq) { + VLOG_DBG_RL(&rl, "ignoring seq %"PRIu32" != expected %"PRIu32, + nl_msg_nlmsghdr(reply)->nlmsg_seq, seq); + ofpbuf_delete(reply); + goto recv; + } + + /* If the reply is an error, discard the reply and return the error code. + * + * Except: if the reply is just an acknowledgement (error code of 0), and + * the caller is interested in the reply (replyp != NULL), pass the reply + * up to the caller. Otherwise the caller will get a return value of 0 + * and null '*replyp', which makes unwary callers likely to segfault. */ + if (nl_msg_nlmsgerr(reply, &retval) && (retval || !replyp)) { + ofpbuf_delete(reply); + if (retval) { + VLOG_DBG_RL(&rl, "received NAK error=%d (%s)", + retval, strerror(retval)); + } + return retval != EAGAIN ? retval : EPROTO; + } + + if (replyp) { + *replyp = reply; + } else { + ofpbuf_delete(reply); + } + return 0; +} + +/* Starts a Netlink "dump" operation, by sending 'request' to the kernel via + * 'sock', and initializes 'dump' to reflect the state of the operation. + * + * nlmsg_len in 'msg' will be finalized to match msg->size, and nlmsg_pid will + * be set to 'sock''s pid, before the message is sent. NLM_F_DUMP and + * NLM_F_ACK will be set in nlmsg_flags. + * + * The properties of Netlink make dump operations reliable as long as all of + * the following are true: + * + * - At most a single dump is in progress at a time on a given nl_sock. + * + * - The nl_sock is not subscribed to any multicast groups. + * + * - The nl_sock is not used to send any other messages before the dump + * operation is complete. + * + * This function provides no status indication. An error status for the entire + * dump operation is provided when it is completed by calling nl_dump_done(). + * + * The caller is responsible for destroying 'request'. The caller must not + * close 'sock' before it completes the dump operation (by calling + * nl_dump_done()). + */ +void +nl_dump_start(struct nl_dump *dump, + struct nl_sock *sock, const struct ofpbuf *request) +{ + struct nlmsghdr *nlmsghdr = nl_msg_nlmsghdr(request); + nlmsghdr->nlmsg_flags |= NLM_F_DUMP | NLM_F_ACK; + dump->seq = nlmsghdr->nlmsg_seq; + dump->sock = sock; + dump->status = nl_sock_send(sock, request, true); + dump->buffer = NULL; +} + +/* Helper function for nl_dump_next(). */ +static int +nl_dump_recv(struct nl_dump *dump, struct ofpbuf **bufferp) +{ + struct nlmsghdr *nlmsghdr; + struct ofpbuf *buffer; + int retval; + + retval = nl_sock_recv(dump->sock, bufferp, true); + if (retval) { + return retval == EINTR ? EAGAIN : retval; + } + buffer = *bufferp; + + nlmsghdr = nl_msg_nlmsghdr(buffer); + if (dump->seq != nlmsghdr->nlmsg_seq) { + VLOG_DBG_RL(&rl, "ignoring seq %"PRIu32" != expected %"PRIu32, + nlmsghdr->nlmsg_seq, dump->seq); + return EAGAIN; + } + + if (nl_msg_nlmsgerr(buffer, &retval)) { + VLOG_INFO_RL(&rl, "netlink dump request error (%s)", + strerror(retval)); + return retval && retval != EAGAIN ? retval : EPROTO; + } + + return 0; +} + +/* Attempts to retrieve another reply from 'dump', which must have been + * initialized with nl_dump_start(). + * + * If successful, returns true and points 'reply->data' and 'reply->size' to + * the message that was retrieved. The caller must not modify 'reply' (because + * it points into the middle of a larger buffer). + * + * On failure, returns false and sets 'reply->data' to NULL and 'reply->size' + * to 0. Failure might indicate an actual error or merely the end of replies. + * An error status for the entire dump operation is provided when it is + * completed by calling nl_dump_done(). + */ +bool +nl_dump_next(struct nl_dump *dump, struct ofpbuf *reply) +{ + struct nlmsghdr *nlmsghdr; + + reply->data = NULL; + reply->size = 0; + if (dump->status) { + return false; + } + + if (dump->buffer && !dump->buffer->size) { + ofpbuf_delete(dump->buffer); + dump->buffer = NULL; + } + while (!dump->buffer) { + int retval = nl_dump_recv(dump, &dump->buffer); + if (retval) { + ofpbuf_delete(dump->buffer); + dump->buffer = NULL; + if (retval != EAGAIN) { + dump->status = retval; + return false; + } + } + } + + nlmsghdr = nl_msg_next(dump->buffer, reply); + if (!nlmsghdr) { + VLOG_WARN_RL(&rl, "netlink dump reply contains message fragment"); + dump->status = EPROTO; + return false; + } else if (nlmsghdr->nlmsg_type == NLMSG_DONE) { + dump->status = EOF; + return false; + } + + return true; +} + +/* Completes Netlink dump operation 'dump', which must have been initialized + * with nl_dump_start(). Returns 0 if the dump operation was error-free, + * otherwise a positive errno value describing the problem. */ +int +nl_dump_done(struct nl_dump *dump) +{ + /* Drain any remaining messages that the client didn't read. Otherwise the + * kernel will continue to queue them up and waste buffer space. */ + while (!dump->status) { + struct ofpbuf reply; + if (!nl_dump_next(dump, &reply)) { + assert(dump->status); + } + } + + ofpbuf_delete(dump->buffer); + return dump->status == EOF ? 0 : dump->status; +} + +/* Causes poll_block() to wake up when any of the specified 'events' (which is + * a OR'd combination of POLLIN, POLLOUT, etc.) occur on 'sock'. */ +void +nl_sock_wait(const struct nl_sock *sock, short int events) +{ + poll_fd_wait(sock->fd, events); +} + +/* Miscellaneous. */ + +static const struct nl_policy family_policy[CTRL_ATTR_MAX + 1] = { + [CTRL_ATTR_FAMILY_ID] = {.type = NL_A_U16}, +}; + +static int do_lookup_genl_family(const char *name) +{ + struct nl_sock *sock; + struct ofpbuf request, *reply; + struct nlattr *attrs[ARRAY_SIZE(family_policy)]; + int retval; + + retval = nl_sock_create(NETLINK_GENERIC, 0, 0, 0, &sock); + if (retval) { + return -retval; + } + + ofpbuf_init(&request, 0); + nl_msg_put_genlmsghdr(&request, 0, GENL_ID_CTRL, NLM_F_REQUEST, + CTRL_CMD_GETFAMILY, 1); + nl_msg_put_string(&request, CTRL_ATTR_FAMILY_NAME, name); + retval = nl_sock_transact(sock, &request, &reply); + ofpbuf_uninit(&request); + if (retval) { + nl_sock_destroy(sock); + return -retval; + } + + if (!nl_policy_parse(reply, NLMSG_HDRLEN + GENL_HDRLEN, + family_policy, attrs, ARRAY_SIZE(family_policy))) { + nl_sock_destroy(sock); + ofpbuf_delete(reply); + return -EPROTO; + } + + retval = nl_attr_get_u16(attrs[CTRL_ATTR_FAMILY_ID]); + if (retval == 0) { + retval = -EPROTO; + } + nl_sock_destroy(sock); + ofpbuf_delete(reply); + return retval; +} + +/* If '*number' is 0, translates the given Generic Netlink family 'name' to a + * number and stores it in '*number'. If successful, returns 0 and the caller + * may use '*number' as the family number. On failure, returns a positive + * errno value and '*number' caches the errno value. */ +int +nl_lookup_genl_family(const char *name, int *number) +{ + if (*number == 0) { + *number = do_lookup_genl_family(name); + assert(*number != 0); + } + return *number > 0 ? 0 : -*number; +} + +/* Netlink PID. + * + * Every Netlink socket must be bound to a unique 32-bit PID. By convention, + * programs that have a single Netlink socket use their Unix process ID as PID, + * and programs with multiple Netlink sockets add a unique per-socket + * identifier in the bits above the Unix process ID. + * + * The kernel has Netlink PID 0. + */ + +/* Parameters for how many bits in the PID should come from the Unix process ID + * and how many unique per-socket. */ +#define SOCKET_BITS 10 +#define MAX_SOCKETS (1u << SOCKET_BITS) + +#define PROCESS_BITS (32 - SOCKET_BITS) +#define MAX_PROCESSES (1u << PROCESS_BITS) +#define PROCESS_MASK ((uint32_t) (MAX_PROCESSES - 1)) + +/* Bit vector of unused socket identifiers. */ +static uint32_t avail_sockets[ROUND_UP(MAX_SOCKETS, 32)]; + +/* Allocates and returns a new Netlink PID. */ +static int +alloc_pid(uint32_t *pid) +{ + int i; + + for (i = 0; i < MAX_SOCKETS; i++) { + if ((avail_sockets[i / 32] & (1u << (i % 32))) == 0) { + avail_sockets[i / 32] |= 1u << (i % 32); + *pid = (getpid() & PROCESS_MASK) | (i << PROCESS_BITS); + return 0; + } + } + VLOG_ERR("netlink pid space exhausted"); + return ENOBUFS; +} + +/* Makes the specified 'pid' available for reuse. */ +static void +free_pid(uint32_t pid) +{ + int sock = pid >> PROCESS_BITS; + assert(avail_sockets[sock / 32] & (1u << (sock % 32))); + avail_sockets[sock / 32] &= ~(1u << (sock % 32)); +} + +static void +nlmsghdr_to_string(const struct nlmsghdr *h, struct ds *ds) +{ + struct nlmsg_flag { + unsigned int bits; + const char *name; + }; + static const struct nlmsg_flag flags[] = { + { NLM_F_REQUEST, "REQUEST" }, + { NLM_F_MULTI, "MULTI" }, + { NLM_F_ACK, "ACK" }, + { NLM_F_ECHO, "ECHO" }, + { NLM_F_DUMP, "DUMP" }, + { NLM_F_ROOT, "ROOT" }, + { NLM_F_MATCH, "MATCH" }, + { NLM_F_ATOMIC, "ATOMIC" }, + }; + const struct nlmsg_flag *flag; + uint16_t flags_left; + + ds_put_format(ds, "nl(len:%"PRIu32", type=%"PRIu16, + h->nlmsg_len, h->nlmsg_type); + if (h->nlmsg_type == NLMSG_NOOP) { + ds_put_cstr(ds, "(no-op)"); + } else if (h->nlmsg_type == NLMSG_ERROR) { + ds_put_cstr(ds, "(error)"); + } else if (h->nlmsg_type == NLMSG_DONE) { + ds_put_cstr(ds, "(done)"); + } else if (h->nlmsg_type == NLMSG_OVERRUN) { + ds_put_cstr(ds, "(overrun)"); + } else if (h->nlmsg_type < NLMSG_MIN_TYPE) { + ds_put_cstr(ds, "(reserved)"); + } else { + ds_put_cstr(ds, "(family-defined)"); + } + ds_put_format(ds, ", flags=%"PRIx16, h->nlmsg_flags); + flags_left = h->nlmsg_flags; + for (flag = flags; flag < &flags[ARRAY_SIZE(flags)]; flag++) { + if ((flags_left & flag->bits) == flag->bits) { + ds_put_format(ds, "[%s]", flag->name); + flags_left &= ~flag->bits; + } + } + if (flags_left) { + ds_put_format(ds, "[OTHER:%"PRIx16"]", flags_left); + } + ds_put_format(ds, ", seq=%"PRIx32", pid=%"PRIu32"(%d:%d))", + h->nlmsg_seq, h->nlmsg_pid, + (int) (h->nlmsg_pid & PROCESS_MASK), + (int) (h->nlmsg_pid >> PROCESS_BITS)); +} + +static char * +nlmsg_to_string(const struct ofpbuf *buffer) +{ + struct ds ds = DS_EMPTY_INITIALIZER; + const struct nlmsghdr *h = ofpbuf_at(buffer, 0, NLMSG_HDRLEN); + if (h) { + nlmsghdr_to_string(h, &ds); + if (h->nlmsg_type == NLMSG_ERROR) { + const struct nlmsgerr *e; + e = ofpbuf_at(buffer, NLMSG_HDRLEN, + NLMSG_ALIGN(sizeof(struct nlmsgerr))); + if (e) { + ds_put_format(&ds, " error(%d", e->error); + if (e->error < 0) { + ds_put_format(&ds, "(%s)", strerror(-e->error)); + } + ds_put_cstr(&ds, ", in-reply-to("); + nlmsghdr_to_string(&e->msg, &ds); + ds_put_cstr(&ds, "))"); + } else { + ds_put_cstr(&ds, " error(truncated)"); + } + } else if (h->nlmsg_type == NLMSG_DONE) { + int *error = ofpbuf_at(buffer, NLMSG_HDRLEN, sizeof *error); + if (error) { + ds_put_format(&ds, " done(%d", *error); + if (*error < 0) { + ds_put_format(&ds, "(%s)", strerror(-*error)); + } + ds_put_cstr(&ds, ")"); + } else { + ds_put_cstr(&ds, " done(truncated)"); + } + } + } else { + ds_put_cstr(&ds, "nl(truncated)"); + } + return ds.string; +} + +static void +log_nlmsg(const char *function, int error, + const void *message, size_t size) +{ + struct ofpbuf buffer; + char *nlmsg; + + if (!VLOG_IS_DBG_ENABLED()) { + return; + } + + ofpbuf_use_const(&buffer, message, size); + nlmsg = nlmsg_to_string(&buffer); + VLOG_DBG_RL(&rl, "%s (%s): %s", function, strerror(error), nlmsg); + free(nlmsg); +} + + |