427 lines
9.0 KiB
C
427 lines
9.0 KiB
C
/*
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* Copyright (C) 2014 Martin Willi
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* Copyright (C) 2014 revosec AG
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* Copyright (C) 2008 Tobias Brunner
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* Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#include <sys/socket.h>
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#include <linux/netlink.h>
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#include <linux/rtnetlink.h>
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#include <errno.h>
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#include <unistd.h>
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#include "kernel_netlink_shared.h"
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#include <utils/debug.h>
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#include <threading/mutex.h>
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#include <threading/condvar.h>
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#include <collections/array.h>
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#include <collections/hashtable.h>
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typedef struct private_netlink_socket_t private_netlink_socket_t;
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/**
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* Private variables and functions of netlink_socket_t class.
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*/
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struct private_netlink_socket_t {
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/**
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* public part of the netlink_socket_t object.
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*/
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netlink_socket_t public;
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/**
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* mutex to lock access entries
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*/
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mutex_t *mutex;
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/**
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* Netlink request entries currently active, uintptr_t seq => entry_t
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*/
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hashtable_t *entries;
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/**
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* Current sequence number for Netlink requests
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*/
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refcount_t seq;
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/**
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* netlink socket
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*/
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int socket;
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/**
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* Enum names for Netlink messages
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*/
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enum_name_t *names;
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};
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/**
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* Request entry the answer for a waiting thread is collected in
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*/
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typedef struct {
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/** Condition variable thread is waiting */
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condvar_t *condvar;
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/** Array of hdrs in a multi-message response, as struct nlmsghdr* */
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array_t *hdrs;
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/** All response messages received? */
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bool complete;
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} entry_t;
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/**
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* Clean up a thread waiting entry
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*/
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static void destroy_entry(entry_t *entry)
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{
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entry->condvar->destroy(entry->condvar);
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array_destroy_function(entry->hdrs, (void*)free, NULL);
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free(entry);
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}
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/**
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* Write a Netlink message to socket
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*/
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static bool write_msg(private_netlink_socket_t *this, struct nlmsghdr *msg)
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{
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struct sockaddr_nl addr = {
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.nl_family = AF_NETLINK,
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};
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int len;
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while (TRUE)
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{
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len = sendto(this->socket, msg, msg->nlmsg_len, 0,
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(struct sockaddr*)&addr, sizeof(addr));
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if (len != msg->nlmsg_len)
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{
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if (errno == EINTR)
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{
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continue;
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}
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DBG1(DBG_KNL, "netlink write error: %s", strerror(errno));
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return FALSE;
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}
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return TRUE;
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}
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}
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/**
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* Read a single Netlink message from socket
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*/
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static size_t read_msg(private_netlink_socket_t *this,
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char buf[4096], size_t buflen, bool block)
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{
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ssize_t len;
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len = recv(this->socket, buf, buflen, block ? 0 : MSG_DONTWAIT);
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if (len == buflen)
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{
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DBG1(DBG_KNL, "netlink response exceeds buffer size");
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return 0;
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}
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if (len < 0)
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{
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if (errno != EAGAIN && errno != EWOULDBLOCK && errno != EINTR)
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{
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DBG1(DBG_KNL, "netlink read error: %s", strerror(errno));
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}
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return 0;
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}
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return len;
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}
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/**
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* Queue received response message
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*/
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static bool queue(private_netlink_socket_t *this, struct nlmsghdr *buf)
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{
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struct nlmsghdr *hdr;
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entry_t *entry;
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uintptr_t seq;
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seq = (uintptr_t)buf->nlmsg_seq;
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this->mutex->lock(this->mutex);
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entry = this->entries->get(this->entries, (void*)seq);
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if (entry)
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{
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hdr = malloc(buf->nlmsg_len);
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memcpy(hdr, buf, buf->nlmsg_len);
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array_insert(entry->hdrs, ARRAY_TAIL, hdr);
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if (hdr->nlmsg_type == NLMSG_DONE || !(hdr->nlmsg_flags & NLM_F_MULTI))
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{
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entry->complete = TRUE;
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entry->condvar->signal(entry->condvar);
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}
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}
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else
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{
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DBG1(DBG_KNL, "received unknown netlink seq %u, ignored", seq);
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}
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this->mutex->unlock(this->mutex);
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return entry != NULL;
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}
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/**
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* Read and queue response message, optionally blocking
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*/
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static void read_and_queue(private_netlink_socket_t *this, bool block)
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{
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struct nlmsghdr *hdr;
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union {
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struct nlmsghdr hdr;
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char bytes[4096];
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} buf;
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size_t len;
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len = read_msg(this, buf.bytes, sizeof(buf.bytes), block);
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if (len)
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{
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hdr = &buf.hdr;
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while (NLMSG_OK(hdr, len))
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{
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if (!queue(this, hdr))
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{
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break;
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}
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hdr = NLMSG_NEXT(hdr, len);
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}
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}
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}
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CALLBACK(watch, bool,
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private_netlink_socket_t *this, int fd, watcher_event_t event)
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{
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if (event == WATCHER_READ)
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{
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read_and_queue(this, FALSE);
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}
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return TRUE;
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}
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METHOD(netlink_socket_t, netlink_send, status_t,
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private_netlink_socket_t *this, struct nlmsghdr *in, struct nlmsghdr **out,
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size_t *out_len)
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{
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struct nlmsghdr *hdr;
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chunk_t result = {};
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entry_t *entry;
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uintptr_t seq;
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seq = ref_get(&this->seq);
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in->nlmsg_seq = seq;
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in->nlmsg_pid = getpid();
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if (this->names)
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{
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DBG3(DBG_KNL, "sending %N %u: %b", this->names, in->nlmsg_type,
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(u_int)seq, in, in->nlmsg_len);
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}
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this->mutex->lock(this->mutex);
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if (!write_msg(this, in))
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{
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this->mutex->unlock(this->mutex);
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return FAILED;
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}
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INIT(entry,
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.condvar = condvar_create(CONDVAR_TYPE_DEFAULT),
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.hdrs = array_create(0, 0),
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);
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this->entries->put(this->entries, (void*)seq, entry);
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while (!entry->complete)
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{
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if (lib->watcher->get_state(lib->watcher) == WATCHER_RUNNING)
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{
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entry->condvar->wait(entry->condvar, this->mutex);
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}
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else
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{ /* During (de-)initialization, no watcher thread is active.
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* collect responses ourselves. */
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read_and_queue(this, TRUE);
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}
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}
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this->entries->remove(this->entries, (void*)seq);
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this->mutex->unlock(this->mutex);
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while (array_remove(entry->hdrs, ARRAY_HEAD, &hdr))
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{
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if (this->names)
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{
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DBG3(DBG_KNL, "received %N %u: %b", this->names, hdr->nlmsg_type,
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hdr->nlmsg_seq, hdr, hdr->nlmsg_len);
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}
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result = chunk_cat("mm", result,
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chunk_create((char*)hdr, hdr->nlmsg_len));
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}
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destroy_entry(entry);
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*out_len = result.len;
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*out = (struct nlmsghdr*)result.ptr;
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return SUCCESS;
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}
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METHOD(netlink_socket_t, netlink_send_ack, status_t,
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private_netlink_socket_t *this, struct nlmsghdr *in)
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{
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struct nlmsghdr *out, *hdr;
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size_t len;
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if (netlink_send(this, in, &out, &len) != SUCCESS)
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{
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return FAILED;
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}
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hdr = out;
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while (NLMSG_OK(hdr, len))
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{
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switch (hdr->nlmsg_type)
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{
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case NLMSG_ERROR:
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{
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struct nlmsgerr* err = NLMSG_DATA(hdr);
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if (err->error)
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{
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if (-err->error == EEXIST)
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{ /* do not report existing routes */
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free(out);
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return ALREADY_DONE;
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}
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if (-err->error == ESRCH)
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{ /* do not report missing entries */
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free(out);
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return NOT_FOUND;
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}
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DBG1(DBG_KNL, "received netlink error: %s (%d)",
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strerror(-err->error), -err->error);
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free(out);
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return FAILED;
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}
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free(out);
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return SUCCESS;
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}
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default:
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hdr = NLMSG_NEXT(hdr, len);
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continue;
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case NLMSG_DONE:
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break;
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}
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break;
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}
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DBG1(DBG_KNL, "netlink request not acknowledged");
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free(out);
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return FAILED;
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}
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METHOD(netlink_socket_t, destroy, void,
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private_netlink_socket_t *this)
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{
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if (this->socket != -1)
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{
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lib->watcher->remove(lib->watcher, this->socket);
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close(this->socket);
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}
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this->entries->destroy(this->entries);
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this->mutex->destroy(this->mutex);
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free(this);
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}
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/**
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* Described in header.
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*/
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netlink_socket_t *netlink_socket_create(int protocol, enum_name_t *names)
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{
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private_netlink_socket_t *this;
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struct sockaddr_nl addr = {
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.nl_family = AF_NETLINK,
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};
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INIT(this,
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.public = {
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.send = _netlink_send,
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.send_ack = _netlink_send_ack,
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.destroy = _destroy,
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},
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.seq = 200,
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.mutex = mutex_create(MUTEX_TYPE_RECURSIVE),
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.socket = socket(AF_NETLINK, SOCK_RAW, protocol),
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.entries = hashtable_create(hashtable_hash_ptr, hashtable_equals_ptr, 4),
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.names = names,
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);
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if (this->socket == -1)
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{
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DBG1(DBG_KNL, "unable to create netlink socket");
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destroy(this);
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return NULL;
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}
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if (bind(this->socket, (struct sockaddr*)&addr, sizeof(addr)))
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{
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DBG1(DBG_KNL, "unable to bind netlink socket");
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destroy(this);
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return NULL;
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}
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lib->watcher->add(lib->watcher, this->socket, WATCHER_READ, watch, this);
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return &this->public;
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}
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/**
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* Described in header.
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*/
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void netlink_add_attribute(struct nlmsghdr *hdr, int rta_type, chunk_t data,
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size_t buflen)
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{
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struct rtattr *rta;
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if (NLMSG_ALIGN(hdr->nlmsg_len) + RTA_LENGTH(data.len) > buflen)
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{
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DBG1(DBG_KNL, "unable to add attribute, buffer too small");
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return;
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}
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rta = (struct rtattr*)(((char*)hdr) + NLMSG_ALIGN(hdr->nlmsg_len));
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rta->rta_type = rta_type;
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rta->rta_len = RTA_LENGTH(data.len);
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memcpy(RTA_DATA(rta), data.ptr, data.len);
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hdr->nlmsg_len = NLMSG_ALIGN(hdr->nlmsg_len) + rta->rta_len;
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}
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/**
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* Described in header.
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*/
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void* netlink_reserve(struct nlmsghdr *hdr, int buflen, int type, int len)
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{
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struct rtattr *rta;
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if (NLMSG_ALIGN(hdr->nlmsg_len) + RTA_LENGTH(len) > buflen)
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{
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DBG1(DBG_KNL, "unable to add attribute, buffer too small");
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return NULL;
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}
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rta = ((void*)hdr) + NLMSG_ALIGN(hdr->nlmsg_len);
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rta->rta_type = type;
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rta->rta_len = RTA_LENGTH(len);
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hdr->nlmsg_len = NLMSG_ALIGN(hdr->nlmsg_len) + rta->rta_len;
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return RTA_DATA(rta);
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}
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