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tunsafe-clang15/wireguard.cpp
Ludvig Strigeus cf92ac7a0c Updates for TunSafe 1.4-rc1 
1.Subfolders in the Config/ directory now show up as submenus.
2.Added a way to run TunSafe as a Windows Service.
  Foreground Mode: The service will disconnect when TunSafe closes.
  Background Mode: The service will stay connected in the background.
  No longer required to run the TunSafe client as Admin as long as
  the service is running.
3.New config setting [Interface].ExcludedIPs to configure IPs that
  should not be routed through TunSafe.
4.Can now automatically start TunSafe when Windows starts
5.New UI with tabs and graphs
6.Cache DNS queries to ensure DNS will succeed if connection fails
7.Recreate tray icon when explorer.exe restarts
8.Renamed window title to TunSafe instead of TunSafe VPN Client
9.Main window is now resizable
10.Disallow roaming endpoint when using AllowedIPs=0.0.0.0/0
   Only the original endpoint is added in the routing table so
   this would result in an endless loop of packets.
11.Display approximate Wireguard framing overhead in stats
12.Preparations for protocol handling with multiple threads
13.Delete the routes we made when disconnecting
14.Fix error message about unable to delete a route when connecting
2018-08-12 03:30:06 +02:00

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// SPDX-License-Identifier: AGPL-1.0-only
// Copyright (C) 2018 Ludvig Strigeus <info@tunsafe.com>. All Rights Reserved.
#include "stdafx.h"
#include "wireguard.h"
#include "netapi.h"
#include "wireguard_proto.h"
#include "crypto/chacha20poly1305.h"
#include "crypto/blake2s.h"
#include "crypto/siphash.h"
#include "tunsafe_endian.h"
#include <algorithm>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "ipzip2/ipzip2.h"
#include "wireguard.h"
#include "wireguard_config.h"
uint64 OsGetMilliseconds();
enum {
IPV4_HEADER_SIZE = 20,
IPV6_HEADER_SIZE = 40,
};
WireguardProcessor::WireguardProcessor(UdpInterface *udp, TunInterface *tun, ProcessorDelegate *procdel) {
tun_addr_.size = 0;
tun6_addr_.size = 0;
udp_ = udp;
tun_ = tun;
procdel_ = procdel;
mtu_ = 1420;
memset(&stats_, 0, sizeof(stats_));
listen_port_ = 0;
network_discovery_spoofing_ = false;
add_routes_mode_ = true;
dns_blocking_ = true;
internet_blocking_ = kBlockInternet_Default;
dns6_addr_.sin.sin_family = dns_addr_.sin.sin_family = 0;
stats_last_bytes_in_ = 0;
stats_last_bytes_out_ = 0;
stats_last_ts_ = OsGetMilliseconds();
main_thread_scheduled_ = NULL;
main_thread_scheduled_last_ = &main_thread_scheduled_;
}
WireguardProcessor::~WireguardProcessor() {
}
void WireguardProcessor::SetListenPort(int listen_port) {
listen_port_ = listen_port;
}
bool WireguardProcessor::AddDnsServer(const IpAddr &sin) {
IpAddr *target = (sin.sin.sin_family == AF_INET6) ? &dns6_addr_ : &dns_addr_;
if (target->sin.sin_family != 0)
return false;
*target = sin;
return true;
}
bool WireguardProcessor::SetTunAddress(const WgCidrAddr &addr) {
WgCidrAddr *target = (addr.size == 128) ? &tun6_addr_ : &tun_addr_;
if (target->size != 0)
return false;
*target = addr;
return true;
}
void WireguardProcessor::AddExcludedIp(const WgCidrAddr &cidr_addr) {
excluded_ips_.push_back(cidr_addr);
}
void WireguardProcessor::SetMtu(int mtu) {
if (mtu >= 576 && mtu <= 10000)
mtu_ = mtu;
}
void WireguardProcessor::SetAddRoutesMode(bool mode) {
add_routes_mode_ = mode;
}
void WireguardProcessor::SetDnsBlocking(bool dns_blocking) {
dns_blocking_ = dns_blocking;
}
void WireguardProcessor::SetInternetBlocking(InternetBlockState internet_blocking) {
internet_blocking_ = internet_blocking;
}
void WireguardProcessor::SetHeaderObfuscation(const char *key) {
dev_.SetHeaderObfuscation(key);
}
WgProcessorStats WireguardProcessor::GetStats() {
// todo: only supports one peer but i want this in the ui for now.
stats_.endpoint.sin.sin_family = 0;
WgPeer *peer = dev_.first_peer();
if (peer)
stats_.endpoint = peer->endpoint_;
return stats_;
}
void WireguardProcessor::ResetStats() {
memset(&stats_, 0, sizeof(stats_));
}
void WireguardProcessor::SetupCompressionHeader(WgPacketCompressionVer01 *c) {
memset(c, 0, sizeof(WgPacketCompressionVer01));
// Windows uses a ttl of 128 while other platforms use 64
#if defined(OS_WIN)
c->ttl = 128;
#else // defined(OS_WIN)
c->ttl = 64;
#endif // defined(OS_WIN)
WriteLE16(&c->version, EXT_PACKET_COMPRESSION_VER);
memcpy(c->ipv4_addr, &tun_addr_.addr, 4);
if (tun6_addr_.size == 128)
memcpy(c->ipv6_addr, &tun6_addr_.addr, 16);
c->flags = ((tun_addr_.cidr >> 3) & 3);
}
static inline bool CheckFirstNbitsEquals(const byte *a, const byte *b, size_t n) {
return memcmp(a, b, n >> 3) == 0 && ((n & 7) == 0 || !((a[n >> 3] ^ b[n >> 3]) & (0xff << (8 - (n & 7)))));
}
static bool IsWgCidrAddrSubsetOf(const WgCidrAddr &inner, const WgCidrAddr &outer) {
return inner.size == outer.size && inner.cidr >= outer.cidr &&
CheckFirstNbitsEquals(inner.addr, outer.addr, outer.cidr);
}
bool WireguardProcessor::Start() {
assert(dev_.IsMainThread());
if (!udp_->Initialize(listen_port_))
return false;
if (tun_addr_.size != 32) {
RERROR("No IPv4 address configured");
return false;
}
if (tun_addr_.cidr >= 31) {
RERROR("TAP is not compatible CIDR /31 or /32. Changing to /24");
tun_addr_.cidr = 24;
}
TunInterface::TunConfig config = {0};
config.ip = ReadBE32(tun_addr_.addr);
config.cidr = tun_addr_.cidr;
config.mtu = mtu_;
config.pre_post_commands = pre_post_;
config.excluded_ips = excluded_ips_;
uint32 netmask = tun_addr_.cidr == 32 ? 0xffffffff : 0xffffffff << (32 - tun_addr_.cidr);
uint32 ipv4_broadcast_addr = (netmask == 0xffffffff) ? 0xffffffff : config.ip | ~netmask;
if (tun6_addr_.size == 128) {
if (tun6_addr_.cidr > 126) {
RERROR("IPv6 /127 or /128 not supported. Changing to 120");
tun6_addr_.cidr = 120;
}
config.ipv6_cidr = tun6_addr_.cidr;
memcpy(&config.ipv6_address, tun6_addr_.addr, 16);
}
if (add_routes_mode_) {
WgPeer *peer = (WgPeer *)dev_.ip_to_peer_map().LookupV4DefaultPeer();
if (peer != NULL && peer->endpoint_.sin.sin_family != 0) {
config.default_route_endpoint_v4 = (peer->endpoint_.sin.sin_family == AF_INET) ? ReadBE32(&peer->endpoint_.sin.sin_addr) : 0;
// Set the default route to something
config.use_ipv4_default_route = true;
peer->allow_endpoint_change_ = false;
}
// Also configure ipv6 gw?
if (config.ipv6_cidr != 0) {
peer = (WgPeer*)dev_.ip_to_peer_map().LookupV6DefaultPeer();
if (peer != NULL && peer->endpoint_.sin.sin_family != 0) {
if (peer->endpoint_.sin.sin_family == AF_INET6)
memcpy(&config.default_route_endpoint_v6, &peer->endpoint_.sin6.sin6_addr, 16);
config.use_ipv6_default_route = true;
peer->allow_endpoint_change_ = false;
}
}
// For each peer, add the extra routes to the extra routes table
for (WgPeer *peer = dev_.first_peer(); peer; peer = peer->next_peer_) {
for (auto it = peer->allowed_ips_.begin(); it != peer->allowed_ips_.end(); ++it) {
// Don't add an entry if it's identical to my address or it's a default route
if (IsWgCidrAddrSubsetOf(*it, tun_addr_) || IsWgCidrAddrSubsetOf(*it, tun6_addr_) || it->cidr == 0)
continue;
// Don't add an entry if we have no ipv6 address configured
if (config.ipv6_cidr == 0 && it->size != 32)
continue;
config.extra_routes.push_back(*it);
}
}
}
uint8 dhcp_options[6];
config.block_dns_on_adapters = dns_blocking_ && ((config.use_ipv4_default_route && dns_addr_.sin.sin_family == AF_INET) ||
(config.use_ipv6_default_route && dns6_addr_.sin6.sin6_family == AF_INET6));
config.internet_blocking = internet_blocking_;
if (dns_addr_.sin.sin_family == AF_INET) {
dhcp_options[0] = 6;
dhcp_options[1] = 4;
memcpy(&dhcp_options[2], &dns_addr_.sin.sin_addr, 4);
config.dhcp_options = dhcp_options;
config.dhcp_options_size = sizeof(dhcp_options);
}
if (dns6_addr_.sin6.sin6_family == AF_INET6) {
config.set_ipv6_dns = true;
memcpy(&config.dns_server_v6, &dns6_addr_.sin6.sin6_addr, 16);
}
TunInterface::TunConfigOut config_out;
if (!tun_->Initialize(std::move(config), &config_out))
return false;
SetupCompressionHeader(dev_.compression_header());
network_discovery_spoofing_ = config_out.enable_neighbor_discovery_spoofing;
memcpy(network_discovery_mac_, config_out.neighbor_discovery_spoofing_mac, 6);
for (WgPeer *peer = dev_.first_peer(); peer; peer = peer->next_peer_) {
peer->ipv4_broadcast_addr_ = ipv4_broadcast_addr;
if (peer->endpoint_.sin.sin_family != 0) {
RINFO("Sending handshake...");
SendHandshakeInitiation(peer);
}
}
return true;
}
static uint8 kIcmpv6NeighborMulticastPrefix[] = {0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x01, 0xff};
enum {
kIpProto_ICMPv6 = 0x3A,
kICMPv6_NeighborSolicitation = 135,
};
#pragma pack(push, 1)
struct ICMPv6NaPacket {
uint8 type;
uint8 code;
uint16 checksum;
uint8 rso;
uint8 reserved[3];
uint8 target[16];
uint8 opt_type;
uint8 opt_length;
uint8 target_mac[6];
};
struct ICMPv6NaPacketWithoutTarget {
uint8 type;
uint8 code;
uint16 checksum;
uint8 rso;
uint8 reserved[3];
uint8 target[16];
};
#pragma pack (pop)
static uint16 ComputeIcmpv6Checksum(const uint8 *buf, int buf_size, const uint8 src_addr[16], const uint8 dst_addr[16]) {
uint32 sum = 0;
for (int i = 0; i < buf_size - 1; i += 2)
sum += ReadBE16(&buf[i]);
if (buf_size & 1)
sum += buf[buf_size - 1];
for (int i = 0; i < 16; i += 2)
sum += ReadBE16(&src_addr[i]);
for (int i = 0; i < 16; i += 2)
sum += ReadBE16(&dst_addr[i]);
sum += (uint16)IPPROTO_ICMPV6 + (uint16)buf_size;
while (sum >> 16)
sum = (sum & 0xFFFF) + (sum >> 16);
return ((uint16)~sum);
}
bool WireguardProcessor::HandleIcmpv6NeighborSolicitation(const byte *data, size_t data_size) {
if (data_size < 48 + 16)
return false;
// Filter out neighbor solicitation
if (data[40] != kICMPv6_NeighborSolicitation || data[41] != 0 || !network_discovery_spoofing_)
return false;
bool is_broadcast = true;
if (memcmp(data + 24, kIcmpv6NeighborMulticastPrefix, sizeof(kIcmpv6NeighborMulticastPrefix)) != 0) {
if (memcmp(data + 24, data + 48, 16) != 0)
return false;
is_broadcast = false;
}
// Target address must match a peer's range.
WG_ACQUIRE_RWLOCK_SHARED(dev_.ip_to_peer_map_lock_);
WgPeer *peer = (WgPeer*)dev_.ip_to_peer_map().LookupV6(data + 48);
WG_RELEASE_RWLOCK_SHARED(dev_.ip_to_peer_map_lock_)
if (peer == NULL)
return false;
// Build response packet
Packet *out = AllocPacket();
if (out == NULL)
return false;
byte *odata = out->data;
size_t packet_size = is_broadcast ? sizeof(ICMPv6NaPacket) : sizeof(ICMPv6NaPacketWithoutTarget);
memcpy(odata, data, 4);
WriteBE16(odata + 4, packet_size);
odata[6] = 58; // next = icmp
odata[7] = 255; // HopLimit
memcpy(odata + 8, data + 48, 16); // Source Address
memcpy(odata + 24, data + 8, 16); // Dest addr
((ICMPv6NaPacket*)(odata + 40))->type = 136; // NA
((ICMPv6NaPacket*)(odata + 40))->code = 0;
((ICMPv6NaPacket*)(odata + 40))->checksum = 0;
((ICMPv6NaPacket*)(odata + 40))->rso = 0x60; // solicited
memset(((ICMPv6NaPacket*)(odata + 40))->reserved, 0, 3);
memcpy(((ICMPv6NaPacket*)(odata + 40))->target, odata + 8, 16);
if (is_broadcast) {
((ICMPv6NaPacket*)(odata + 40))->opt_type = 2;
((ICMPv6NaPacket*)(odata + 40))->opt_length = 1;
memcpy(((ICMPv6NaPacket*)(odata + 40))->target_mac, network_discovery_mac_, 6);
// For some reason this is openvpn's 'related mac'
((ICMPv6NaPacket*)(odata + 40))->target_mac[2] += 1;
}
uint16 checksum = ComputeIcmpv6Checksum(odata + 40, (int)packet_size, odata + 8, odata + 24);
WriteBE16(&((ICMPv6NaPacket*)(odata + 40))->checksum, checksum);
out->size = (unsigned)(40 + packet_size);
tun_->WriteTunPacket(out);
return true;
}
static inline bool IsIpv6Multicast(const uint8 dst[16]) {
return dst[0] == 0xff;
}
// On incoming packet to the tun interface.
void WireguardProcessor::HandleTunPacket(Packet *packet) {
uint8 *data = packet->data;
size_t data_size = packet->size;
unsigned ip_version, size_from_header;
WgPeer *peer;
// Sanity check that it looks like a valid ipv4 or ipv6 packet,
// and determine the destination peer from the ip header
if (data_size < IPV4_HEADER_SIZE)
goto getout;
ip_version = *data >> 4;
if (ip_version == 4) {
uint32 ip = ReadBE32(data + 16);
WG_ACQUIRE_RWLOCK_SHARED(dev_.ip_to_peer_map_lock_);
peer = (WgPeer*)dev_.ip_to_peer_map().LookupV4(ip);
WG_RELEASE_RWLOCK_SHARED(dev_.ip_to_peer_map_lock_)
if (peer == NULL)
goto getout;
if ((ip >= (224 << 24) || ip == peer->ipv4_broadcast_addr_) && !peer->allow_multicast_through_peer_)
goto getout;
size_from_header = ReadBE16(data + 2);
if (size_from_header < IPV4_HEADER_SIZE)
goto getout;
} else if (ip_version == 6) {
if (data_size < IPV6_HEADER_SIZE)
goto getout;
// Check if the packet is a Neighbor solicitation ICMP6 packet, in that case fake
// a reply.
if (data[6] == kIpProto_ICMPv6 && HandleIcmpv6NeighborSolicitation(data, data_size))
goto getout;
WG_ACQUIRE_RWLOCK_SHARED(dev_.ip_to_peer_map_lock_);
peer = (WgPeer*)dev_.ip_to_peer_map().LookupV6(data + 24);
WG_RELEASE_RWLOCK_SHARED(dev_.ip_to_peer_map_lock_)
if (peer == NULL)
goto getout;
if (IsIpv6Multicast(data + 24) && !peer->allow_multicast_through_peer_)
goto getout;
size_from_header = IPV6_HEADER_SIZE + ReadBE16(data + 4);
} else {
goto getout;
}
if (size_from_header > data_size)
goto getout;
// WriteAndEncryptPacketToUdp needs a held lock
WG_ACQUIRE_LOCK(peer->mutex_);
WriteAndEncryptPacketToUdp_WillUnlock(peer, packet);
return;
getout:
// send ICMP?
FreePacket(packet);
}
void WgPeer::AddPacketToPeerQueue(Packet *packet) {
assert(IsPeerLocked());
// Keep only the first MAX_QUEUED_PACKETS packets.
while (num_queued_packets_ >= MAX_QUEUED_PACKETS_PER_PEER) {
Packet *packet = first_queued_packet_;
first_queued_packet_ = packet->next;
num_queued_packets_--;
FreePacket(packet);
}
// Add the packet to the out queue that will get sent once handshake completes
*last_queued_packet_ptr_ = packet;
last_queued_packet_ptr_ = &packet->next;
packet->next = NULL;
num_queued_packets_++;
}
// This function must be called with the peer lock held. It will remove the lock
void WireguardProcessor::WriteAndEncryptPacketToUdp_WillUnlock(WgPeer *peer, Packet *packet) {
assert(peer->IsPeerLocked());
uint8 *data = packet->data, *ad;
size_t size = packet->size, ad_len, orig_size = size;
bool want_handshake;
WgKeypair *keypair;
uint64 send_ctr;
// Ensure packet will fit including the biggest padding
if (peer->endpoint_.sin.sin_family == 0 ||
size > kPacketCapacity - 15 - CHACHA20POLY1305_AUTHTAGLEN)
goto getout_discard;
if ((keypair = peer->curr_keypair_) == NULL ||
(send_ctr = keypair->send_ctr) >= REJECT_AFTER_MESSAGES) {
peer->AddPacketToPeerQueue(packet);
WG_RELEASE_LOCK(peer->mutex_);
ScheduleNewHandshake(peer);
return;
}
stats_.tun_bytes_in += size;
stats_.tun_packets_in++;
want_handshake = (send_ctr >= REKEY_AFTER_MESSAGES ||
keypair->send_key_state == WgKeypair::KEY_WANT_REFRESH);
keypair->send_ctr = send_ctr + 1;
packet->addr = peer->endpoint_;
if (size == 0) {
peer->OnKeepaliveSent();
} else {
peer->OnDataSent();
#if WITH_HANDSHAKE_EXT
// Attempt to compress the packet headers using ipzip.
if (keypair->enabled_features[WG_FEATURE_ID_IPZIP]) {
uint32 rv = IpzipCompress(data, (uint32)size, &keypair->ipzip_state_, 0);
if (rv == (uint32)-1)
goto getout_discard;
if (rv == 0)
goto add_padding;
stats_.compression_hdr_saved_out += (int32)(size - rv);
data += (int32)(size - rv);
size = rv;
} else {
add_padding:
#else
{
#endif // WITH_HANDSHAKE_EXT
// Pad packet to a multiple of 16 bytes, but no more than the mtu bytes.
unsigned padding = std::min<unsigned>((0 - size) & 15, (unsigned)mtu_ - (unsigned)size);
memset(data + size, 0, padding);
size += padding;
}
}
#if WITH_SHORT_HEADERS
if (keypair->enabled_features[WG_FEATURE_ID_SHORT_HEADER]) {
size_t header_size;
byte *write = data;
uint8 tag = WG_SHORT_HEADER_BIT, inner_tag;
// For every 16 incoming packets, send out an ack.
if (keypair->incoming_packet_count >= 16) {
keypair->incoming_packet_count = 0;
uint64 next_expected_packet = keypair->replay_detector.expected_seq_nr();
if (next_expected_packet < 0x10000) {
WriteLE16(write -= 2, (uint16)next_expected_packet);
inner_tag = WG_ACK_HEADER_COUNTER_2;
} else if (next_expected_packet < 0x100000000ull) {
WriteLE32(write -= 4, (uint32)next_expected_packet);
inner_tag = WG_ACK_HEADER_COUNTER_4;
} else {
WriteLE32(write -= 4, (uint32)next_expected_packet);
WriteLE16(write -= 2, (uint16)(next_expected_packet>>32));
inner_tag = WG_ACK_HEADER_COUNTER_6;
}
if (keypair->broadcast_short_key != 0) {
inner_tag += keypair->addr_entry_slot;
keypair->broadcast_short_key = 2;
}
*--write = inner_tag;
tag += WG_SHORT_HEADER_ACK;
} else if (keypair->broadcast_short_key == 1) {
keypair->broadcast_short_key = 2;
*--write = keypair->addr_entry_slot;
tag += WG_SHORT_HEADER_ACK;
}
byte *write_after_ack_header = write;
// Determine the distance from the most recently acked packet,
// be conservative when picking a suitable packet length to send.
uint64 distance = send_ctr - keypair->send_ctr_acked;
if (distance < (1 << 6)) {
*(write -= 1) = (uint8)send_ctr;
tag += WG_SHORT_HEADER_CTR1;
} else if (distance < (1 << 14)) {
WriteLE16(write -= 2, (uint16)send_ctr);
tag += WG_SHORT_HEADER_CTR2;
} else if (distance < (1 << 30)) {
WriteLE32(write -= 4, (uint32)send_ctr);
tag += WG_SHORT_HEADER_CTR4;
} else {
// Too far ahead. Can't use short packets.
goto need_big_packet;
}
tag += keypair->can_use_short_key_for_outgoing;
if (!keypair->can_use_short_key_for_outgoing)
WriteLE32(write -= 4, keypair->remote_key_id);
*--write = tag;
// Not using any fields from now on
WG_RELEASE_LOCK(peer->mutex_);
header_size = data - write;
stats_.compression_wg_saved_out += (int64)16 - header_size;
packet->data = data - header_size;
packet->size = (int)(size + header_size + keypair->auth_tag_length);
// todo: figure out what to actually use as ad.
ad = write_after_ack_header;
ad_len = data - write_after_ack_header;
} else {
need_big_packet:
#else
{
#endif // #if WITH_SHORT_HEADERS
// Not using any fields from now on
WG_RELEASE_LOCK(peer->mutex_);
((MessageData*)data)[-1].type = ToLE32(MESSAGE_DATA);
((MessageData*)data)[-1].receiver_id = keypair->remote_key_id;
((MessageData*)data)[-1].counter = ToLE64(send_ctr);
packet->data = data - sizeof(MessageData);
packet->size = (int)(size + sizeof(MessageData) + keypair->auth_tag_length);
ad = NULL;
ad_len = 0;
}
WgKeypairEncryptPayload(data, size, ad, ad_len, send_ctr, keypair);
DoWriteUdpPacket(packet);
if (want_handshake)
ScheduleNewHandshake(peer);
return;
getout_discard:
WG_RELEASE_LOCK(peer->mutex_);
FreePacket(packet);
return;
}
// This scrambles the initial 16 bytes of the packet with the
// next 8 bytes of the packet as a seed.
static void ScrambleUnscramblePacket(Packet *packet, ScramblerSiphashKeys *keys) {
uint8 *data = packet->data;
size_t data_size = packet->size;
if (data_size <= 8)
return;
uint64 last_uint64 = ReadLE64(data_size >= 24 ? data + 16 : data + data_size - 8);
uint64 a = siphash_u64_u32(last_uint64, (uint32)data_size, (siphash_key_t*)&keys->keys[0]);
uint64 b = siphash_u64_u32(last_uint64, (uint32)data_size, (siphash_key_t*)&keys->keys[2]);
a = ToLE64(a);
b = ToLE64(b);
if (data_size >= 24) {
((uint64*)data)[0] ^= a;
((uint64*)data)[1] ^= b;
} else {
union {
uint64 d[2];
uint8 s[16];
} scrambler = {{a,b}};
for (size_t i = 0; i < data_size - 8; i++)
data[i] ^= scrambler.s[i];
}
}
static NOINLINE void ScrambleUnscrambleAndWrite(Packet *packet, ScramblerSiphashKeys *keys, UdpInterface *udp) {
#if WITH_HEADER_OBFUSCATION
ScrambleUnscramblePacket(packet, keys);
udp->WriteUdpPacket(packet);
#endif // WITH_HEADER_OBFUSCATION
}
void WireguardProcessor::DoWriteUdpPacket(Packet *packet) {
stats_.udp_packets_out++;
stats_.udp_bytes_out += packet->size;
if (!dev_.header_obfuscation_)
udp_->WriteUdpPacket(packet);
else
ScrambleUnscrambleAndWrite(packet, &dev_.header_obfuscation_key_, udp_);
}
void WireguardProcessor::ScheduleNewHandshake(WgPeer *peer) {
if (peer->main_thread_scheduled_.fetch_or(WgPeer::kMainThreadScheduled_ScheduleHandshake) == 0) {
peer->main_thread_scheduled_next_ = NULL;
WG_ACQUIRE_LOCK(main_thread_scheduled_lock_);
*main_thread_scheduled_last_ = peer;
main_thread_scheduled_last_ = &peer->main_thread_scheduled_next_;
WG_RELEASE_LOCK(main_thread_scheduled_lock_);
// todo: in multithreaded impl need to trigger |RunAllMainThreadScheduled| to get called
}
}
void WireguardProcessor::RunAllMainThreadScheduled() {
assert(dev_.IsMainThread());
if (main_thread_scheduled_ == NULL)
return;
WG_ACQUIRE_LOCK(main_thread_scheduled_lock_);
WgPeer *peer = main_thread_scheduled_;
main_thread_scheduled_ = NULL;
main_thread_scheduled_last_ = &main_thread_scheduled_;
WG_RELEASE_LOCK(main_thread_scheduled_lock_);
while (peer) {
// todo: for the multithreaded use case figure out whether to use atomic_thread_fence here.
WgPeer *next = peer->main_thread_scheduled_next_;
uint32 ev = peer->main_thread_scheduled_.exchange(0);
if (ev & WgPeer::kMainThreadScheduled_ScheduleHandshake) {
peer->handshake_attempts_ = 0;
SendHandshakeInitiation(peer);
}
peer = next;
}
}
void WireguardProcessor::SendHandshakeInitiation(WgPeer *peer) {
assert(dev_.IsMainThread());
if (!peer->CheckHandshakeRateLimit())
return;
stats_.handshakes_out++;
Packet *packet = AllocPacket();
if (packet) {
peer->CreateMessageHandshakeInitiation(packet);
WG_ACQUIRE_LOCK(peer->mutex_);
int attempts = ++peer->total_handshake_attempts_;
if (procdel_)
procdel_->OnConnectionRetry(attempts);
peer->OnHandshakeInitSent();
packet->addr = peer->endpoint_;
WG_RELEASE_LOCK(peer->mutex_);
DoWriteUdpPacket(packet);
if (attempts > 1 && attempts <= 20)
RINFO("Retrying handshake, attempt %d...%s", attempts, (attempts == 20) ? " (last notice)" : "");
}
}
bool WireguardProcessor::IsMainThreadPacket(Packet *packet) {
// TODO(ludde): Support header obfuscation
return packet->size == 0 || (packet->data[0] != MESSAGE_DATA && !(packet->data[0] & WG_SHORT_HEADER_BIT));
}
// Handles an incoming WireGuard packet from the UDP side, decrypt etc.
void WireguardProcessor::HandleUdpPacket(Packet *packet, bool overload) {
uint32 type;
// Unscramble incoming packets
#if WITH_HEADER_OBFUSCATION
if (dev_.header_obfuscation_)
ScrambleUnscramblePacket(packet, &dev_.header_obfuscation_key_);
#endif // WITH_HEADER_OBFUSCATION
stats_.udp_bytes_in += packet->size;
stats_.udp_packets_in++;
if (packet->size < sizeof(uint32))
goto invalid_size;
type = ReadLE32((uint32*)packet->data);
if (type == MESSAGE_DATA) {
if (packet->size < sizeof(MessageData))
goto invalid_size;
HandleDataPacket(packet);
#if WITH_SHORT_HEADERS
} else if (type & WG_SHORT_HEADER_BIT) {
HandleShortHeaderFormatPacket(type, packet);
#endif // WITH_SHORT_HEADERS
} else if (type == MESSAGE_HANDSHAKE_COOKIE) {
assert(dev_.IsMainThread());
if (packet->size != sizeof(MessageHandshakeCookie))
goto invalid_size;
HandleHandshakeCookiePacket(packet);
} else if (type == MESSAGE_HANDSHAKE_INITIATION) {
assert(dev_.IsMainThread());
if (WITH_HANDSHAKE_EXT ? (packet->size < sizeof(MessageHandshakeInitiation)) : (packet->size != sizeof(MessageHandshakeInitiation)))
goto invalid_size;
stats_.handshakes_in++;
if (CheckIncomingHandshakeRateLimit(packet, overload))
HandleHandshakeInitiationPacket(packet);
} else if (type == MESSAGE_HANDSHAKE_RESPONSE) {
assert(dev_.IsMainThread());
if (WITH_HANDSHAKE_EXT ? (packet->size < sizeof(MessageHandshakeResponse)) : (packet->size != sizeof(MessageHandshakeResponse)))
goto invalid_size;
if (CheckIncomingHandshakeRateLimit(packet, overload))
HandleHandshakeResponsePacket(packet);
} else {
// unknown packet
invalid_size:
FreePacket(packet);
}
}
// Returns nonzero if two endpoints are different.
static uint32 CompareIpAddr(const IpAddr *a, const IpAddr *b) {
uint32 rv = b->sin.sin_family ^ a->sin.sin_family;
if (b->sin.sin_family != AF_INET6) {
rv |= b->sin.sin_addr.s_addr ^ a->sin.sin_addr.s_addr;
rv |= b->sin.sin_port ^ a->sin.sin_port;
} else {
uint64 rx = ((uint64*)&b->sin6.sin6_addr)[0] ^ ((uint64*)&a->sin6.sin6_addr)[0];
rx |= ((uint64*)&b->sin6.sin6_addr)[1] ^ ((uint64*)&a->sin6.sin6_addr)[1];
rv |= rx | (rx >> 32);
rv |= b->sin6.sin6_port ^ a->sin6.sin6_port;
}
return rv;
}
void WgPeer::CopyEndpointToPeer_Locked(WgKeypair *keypair, const IpAddr *addr) {
// Remember how to send packets to this peer
if (keypair->peer->allow_endpoint_change_ &&
CompareIpAddr(&keypair->peer->endpoint_, addr)) {
#if WITH_SHORT_HEADERS
// When the endpoint changes, forget about using the short key.
keypair->broadcast_short_key = 0;
keypair->can_use_short_key_for_outgoing = false;
#endif // WITH_SHORT_HEADERS
keypair->peer->endpoint_ = *addr;
}
}
#if WITH_SHORT_HEADERS
void WireguardProcessor::HandleShortHeaderFormatPacket(uint32 tag, Packet *packet) {
uint8 *data = packet->data + 1;
size_t bytes_left = packet->size - 1;
WgKeypair *keypair;
uint64 counter, acked_counter;
uint8 ack_tag, *ack_start;
if ((tag & WG_SHORT_HEADER_KEY_ID_MASK) == 0x00) {
// The key_id is explicitly included in the packet.
if (bytes_left < 4) goto getout;
uint32 key_id = ReadLE32(data);
data += 4, bytes_left -= 4;
keypair = dev_.LookupKeypairByKeyId(key_id);
} else {
// Lookup the packet source ip and port in the address mapping
uint64 addr_id = packet->addr.sin.sin_addr.s_addr | ((uint64)packet->addr.sin.sin_port << 32);
keypair = dev_.LookupKeypairInAddrEntryMap(addr_id, ((tag / WG_SHORT_HEADER_KEY_ID) & 3) - 1);
}
if (!keypair || !keypair->enabled_features[WG_FEATURE_ID_SHORT_HEADER])
goto getout;
// Pick the closest possible counter value with the same low bits.
counter = keypair->replay_detector.expected_seq_nr();
switch (tag & WG_SHORT_HEADER_TYPE_MASK) {
case WG_SHORT_HEADER_CTR1:
if (bytes_left < 1) goto getout;
counter += (int8)(*data - counter);
data += 1, bytes_left -= 1;
break;
case WG_SHORT_HEADER_CTR2:
if (bytes_left < 2) goto getout;
counter += (int16)(ReadLE16(data) - counter);
data += 2, bytes_left -= 2;
break;
case WG_SHORT_HEADER_CTR4:
if (bytes_left < 4) goto getout;
counter += (int32)(ReadLE32(data) - counter);
data += 4, bytes_left -= 4;
break;
default:
goto getout; // invalid packet
}
acked_counter = 0;
ack_tag = 0;
ack_start = data;
// If the acknowledge header is present, then parse it so we may
// get an ack for the highest seen packet.
if (tag & WG_SHORT_HEADER_ACK) {
if (bytes_left == 0) goto getout;
ack_tag = *data;
if (ack_tag & 0xF0) goto getout; // undefined bits
data += 1, bytes_left -= 1;
switch (ack_tag & WG_ACK_HEADER_COUNTER_MASK) {
case WG_ACK_HEADER_COUNTER_2:
if (bytes_left < 2) goto getout;
acked_counter = ReadLE16(data);
data += 2, bytes_left -= 2;
break;
case WG_ACK_HEADER_COUNTER_4:
if (bytes_left < 4) goto getout;
acked_counter = ReadLE32(data);
data += 4, bytes_left -= 4;
break;
case WG_ACK_HEADER_COUNTER_6:
if (bytes_left < 6) goto getout;
acked_counter = ReadLE32(data) | ((uint64)ReadLE16(data + 4) << 32);
data += 6, bytes_left -= 6;
break;
default:
goto getout;
}
}
if (counter >= REJECT_AFTER_MESSAGES)
goto getout;
// Authenticate the packet before we can apply the state changes.
if (!WgKeypairDecryptPayload(data, bytes_left, ack_start, data - ack_start, counter, keypair))
goto getout;
WG_ACQUIRE_LOCK(keypair->peer->mutex_);
if (keypair->recv_key_state == WgKeypair::KEY_INVALID)
goto getout_unlock;
if (!keypair->replay_detector.CheckReplay(counter))
goto getout_unlock;
stats_.compression_wg_saved_in += 16 - (data - packet->data);
keypair->send_ctr_acked = std::max<uint64>(keypair->send_ctr_acked, acked_counter);
keypair->incoming_packet_count++;
WgPeer::CopyEndpointToPeer_Locked(keypair, &packet->addr);
// Periodically broadcast out the short key
if ((tag & WG_SHORT_HEADER_KEY_ID_MASK) == 0x00 && !keypair->did_attempt_remember_ip_port) {
keypair->did_attempt_remember_ip_port = true;
if (keypair->enabled_features[WG_FEATURE_ID_SKIP_KEYID_IN]) {
uint64 addr_id = packet->addr.sin.sin_addr.s_addr | ((uint64)packet->addr.sin.sin_port << 32);
dev_.UpdateKeypairAddrEntry_Locked(addr_id, keypair);
}
}
// Ack header may also signal that we can omit the key id in packets from now on.
if (tag & WG_SHORT_HEADER_ACK)
keypair->can_use_short_key_for_outgoing = (ack_tag & WG_ACK_HEADER_KEY_MASK) * WG_SHORT_HEADER_KEY_ID;
HandleAuthenticatedDataPacket_WillUnlock(keypair, packet, data, bytes_left - keypair->auth_tag_length);
return;
getout_unlock:
WG_RELEASE_LOCK(keypair->peer->mutex_);
getout:
FreePacket(packet);
return;
}
#endif // WITH_SHORT_HEADERS
void WireguardProcessor::NotifyHandshakeComplete() {
uint64 now = OsGetMilliseconds();
// todo: should lock something
stats_.last_complete_handshake_timestamp = now;
if (stats_.first_complete_handshake_timestamp == 0)
stats_.first_complete_handshake_timestamp = now;
if (procdel_)
procdel_->OnConnected();
}
void WireguardProcessor::HandleAuthenticatedDataPacket_WillUnlock(WgKeypair *keypair, Packet *packet, uint8 *data, size_t data_size) {
WgPeer *peer = keypair->peer;
assert(peer->IsPeerLocked());
// Promote the next key to the current key when we receive a data packet,
// the handshake is now complete.
if (peer->CheckSwitchToNextKey_Locked(keypair)) {
stats_.handshakes_in_success++;
peer->OnHandshakeFullyComplete();
NotifyHandshakeComplete();
SendQueuedPackets_Locked(peer);
}
// Refresh when current key gets too old
WgKeypair *curr_keypair = peer->curr_keypair_;
if (curr_keypair && curr_keypair->recv_key_state == WgKeypair::KEY_WANT_REFRESH) {
curr_keypair->recv_key_state = WgKeypair::KEY_DID_REFRESH;
ScheduleNewHandshake(peer);
}
if (data_size == 0) {
peer->OnKeepaliveReceived();
WG_RELEASE_LOCK(peer->mutex_);
goto getout;
}
peer->OnDataReceived();
WG_RELEASE_LOCK(peer->mutex_);
#if WITH_HANDSHAKE_EXT
// Unpack the packet headers using ipzip
if (keypair->enabled_features[WG_FEATURE_ID_IPZIP]) {
uint32 rv = IpzipDecompress(data, (uint32)data_size, &keypair->ipzip_state_, IPZIP_RECV_BY_CLIENT);
if (rv == (uint32)-1)
goto getout;
stats_.compression_hdr_saved_in += (int64)rv - data_size;
data -= (int64)rv - data_size, data_size = rv;
}
#endif // WITH_HANDSHAKE_EXT
// Verify that the packet is a valid ipv4 or ipv6 packet of proper length,
// with a source address that belongs to the peer.
WgPeer *peer_from_header;
unsigned int ip_version, size_from_header;
ip_version = *data >> 4;
if (ip_version == 4) {
if (data_size < IPV4_HEADER_SIZE)
goto getout_error_header;
WG_ACQUIRE_RWLOCK_SHARED(dev_.ip_to_peer_map_lock_);
peer_from_header = (WgPeer*)dev_.ip_to_peer_map().LookupV4(ReadBE32(data + 12));
WG_RELEASE_RWLOCK_SHARED(dev_.ip_to_peer_map_lock_)
size_from_header = ReadBE16(data + 2);
if (size_from_header < IPV4_HEADER_SIZE) {
// too small packet?
goto getout_error_header;
}
} else if (ip_version == 6) {
if (data_size < IPV6_HEADER_SIZE)
goto getout_error_header;
WG_ACQUIRE_RWLOCK_SHARED(dev_.ip_to_peer_map_lock_);
peer_from_header = (WgPeer*)dev_.ip_to_peer_map().LookupV6(data + 8);
WG_RELEASE_RWLOCK_SHARED(dev_.ip_to_peer_map_lock_)
size_from_header = IPV6_HEADER_SIZE + ReadBE16(data + 4);
} else {
// invalid ip version
goto getout_error_header;
}
if (peer_from_header != peer || size_from_header > data_size)
goto getout_error_header;
packet->data = data;
packet->size = size_from_header;
stats_.tun_bytes_out += packet->size;
stats_.tun_packets_out++;
tun_->WriteTunPacket(packet);
return;
getout_error_header:
stats_.error_header++;
getout:
FreePacket(packet);
}
void WireguardProcessor::HandleDataPacket(Packet *packet) {
uint8 *data = packet->data;
size_t data_size = packet->size;
uint32 key_id = ((MessageData*)data)->receiver_id;
uint64 counter = ToLE64((((MessageData*)data)->counter));
WgKeypair *keypair = dev_.LookupKeypairByKeyId(key_id);
if (keypair == NULL || counter >= REJECT_AFTER_MESSAGES) {
stats_.error_key_id++;
getout:
FreePacket(packet);
return;
}
if (!WgKeypairDecryptPayload(data + sizeof(MessageData), data_size - sizeof(MessageData),
NULL, 0, counter, keypair)) {
stats_.error_mac++;
goto getout;
}
WG_ACQUIRE_LOCK(keypair->peer->mutex_);
if (keypair->recv_key_state == WgKeypair::KEY_INVALID) {
stats_.error_key_id++;
WG_RELEASE_LOCK(keypair->peer->mutex_);
goto getout;
} else if (!keypair->replay_detector.CheckReplay(counter)) {
stats_.error_duplicate++;
WG_RELEASE_LOCK(keypair->peer->mutex_);
goto getout;
} else {
WgPeer::CopyEndpointToPeer_Locked(keypair, &packet->addr);
HandleAuthenticatedDataPacket_WillUnlock(keypair, packet, data + sizeof(MessageData), data_size - sizeof(MessageData) - keypair->auth_tag_length);
}
}
static uint64 GetIpForRateLimit(Packet *packet) {
if (packet->addr.sin.sin_family == AF_INET) {
return ReadLE32(&packet->addr.sin.sin_addr);
} else {
return ReadLE64(&packet->addr.sin6.sin6_addr);
}
}
bool WireguardProcessor::CheckIncomingHandshakeRateLimit(Packet *packet, bool overload) {
assert(dev_.IsMainThread());
WgRateLimit::RateLimitResult rr = dev_.rate_limiter()->CheckRateLimit(GetIpForRateLimit(packet));
if ((overload && rr.is_rate_limited()) || !dev_.CheckCookieMac1(packet)) {
FreePacket(packet);
return false;
}
dev_.rate_limiter()->CommitResult(rr);
if (overload && !rr.is_first_ip() && !dev_.CheckCookieMac2(packet)) {
dev_.CreateCookieMessage((MessageHandshakeCookie*)packet->data, packet, ((MessageHandshakeInitiation*)packet->data)->sender_key_id);
packet->size = sizeof(MessageHandshakeCookie);
DoWriteUdpPacket(packet);
return false;
}
return true;
}
// server receives this when client wants to setup a session
void WireguardProcessor::HandleHandshakeInitiationPacket(Packet *packet) {
assert(dev_.IsMainThread());
WgPeer *peer = WgPeer::ParseMessageHandshakeInitiation(&dev_, packet);
if (peer) {
DoWriteUdpPacket(packet);
} else {
FreePacket(packet);
}
}
// client receives this after session is established
void WireguardProcessor::HandleHandshakeResponsePacket(Packet *packet) {
assert(dev_.IsMainThread());
WgPeer *peer = WgPeer::ParseMessageHandshakeResponse(&dev_, packet);
if (peer) {
stats_.handshakes_out_success++;
WG_SCOPED_LOCK(peer->mutex_);
if (peer->allow_endpoint_change_)
peer->endpoint_ = packet->addr;
peer->OnHandshakeAuthComplete();
peer->OnHandshakeFullyComplete();
NotifyHandshakeComplete();
SendKeepalive_Locked(peer);
}
FreePacket(packet);
}
void WireguardProcessor::SendKeepalive_Locked(WgPeer *peer) {
assert(dev_.IsMainThread() && peer->IsPeerLocked());
// can't send keepalive if no endpoint is configured
if (peer->endpoint_.sin.sin_family == 0)
return;
// If nothing is queued, insert a keepalive packet
if (peer->first_queued_packet_ == NULL) {
Packet *packet = AllocPacket();
if (!packet)
return;
packet->size = 0;
packet->next = NULL;
peer->first_queued_packet_ = packet;
}
SendQueuedPackets_Locked(peer);
}
void WireguardProcessor::SendQueuedPackets_Locked(WgPeer *peer) {
assert(peer->IsPeerLocked());
// Steal the queue of all packets and send them all.
Packet *packet = peer->first_queued_packet_;
peer->first_queued_packet_ = NULL;
peer->last_queued_packet_ptr_ = &peer->first_queued_packet_;
peer->num_queued_packets_ = 0;
while (packet != NULL) {
Packet *next = packet->next;
WriteAndEncryptPacketToUdp_WillUnlock(peer, packet);
packet = next;
WG_ACQUIRE_LOCK(peer->mutex_); // WriteAndEncryptPacketToUdp_WillUnlock releases the lock
}
}
void WireguardProcessor::HandleHandshakeCookiePacket(Packet *packet) {
assert(dev_.IsMainThread());
WgPeer::ParseMessageHandshakeCookie(&dev_, (MessageHandshakeCookie *)packet->data);
}
// Only one thread may run the second loop
void WireguardProcessor::SecondLoop() {
assert(dev_.IsMainThread());
uint64 now = OsGetMilliseconds();
uint64 bytes_in = stats_.tun_bytes_in - stats_last_bytes_in_;
uint64 bytes_out = stats_.tun_bytes_out - stats_last_bytes_out_;
stats_last_bytes_in_ = stats_.tun_bytes_in;
stats_last_bytes_out_ = stats_.tun_bytes_out;
uint64 millis = now - stats_last_ts_;
stats_last_ts_ = now;
double f = 1000.0 / std::max<uint32>((uint32)millis, 500);
stats_.tun_bytes_in_per_second = (float)(bytes_in * f);
stats_.tun_bytes_out_per_second = (float)(bytes_out * f);
for (WgPeer *peer = dev_.first_peer(); peer; peer = peer->next_peer_) {
WgKeypair *keypair = peer->curr_keypair_;
// Allow ip/port to be remembered again for this keypair
if (keypair)
keypair->did_attempt_remember_ip_port = false;
// Avoid taking the lock if it seems unneccessary
if (now >= peer->time_of_next_key_event_ || peer->timers_ != 0) {
uint32 mask;
{
WG_SCOPED_LOCK(peer->mutex_);
mask = peer->CheckTimeouts(now);
if (mask == 0)
continue;
if (mask & WgPeer::ACTION_SEND_KEEPALIVE)
SendKeepalive_Locked(peer);
}
if (mask & WgPeer::ACTION_SEND_HANDSHAKE)
SendHandshakeInitiation(peer);
}
}
dev_.SecondLoop(now);
}
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