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net: recognize TORv3/I2P/CJDNS networks
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Recognizing addresses from those networks allows us to accept and gossip
them, even though we don't know how to connect to them (yet).

Co-authored-by: eriknylund <erik@daychanged.com>
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@vasild @eriknylund @furszy
2 people authored and furszy committed Aug 10, 2021
1 parent 8e50853 commit a237ba4
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Showing 7 changed files with 367 additions and 58 deletions.
7 changes: 7 additions & 0 deletions src/crypto/common.h
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Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,13 @@ void static inline WriteLE64(unsigned char* ptr, uint64_t x)
memcpy(ptr, (char*)&v, 8);
}

uint16_t static inline ReadBE16(const unsigned char* ptr)
{
uint16_t x;
memcpy((char*)&x, ptr, 2);
return be16toh(x);
}

uint32_t static inline ReadBE32(const unsigned char* ptr)
{
uint32_t x;
Expand Down
243 changes: 198 additions & 45 deletions src/netaddress.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,11 @@
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include "crypto/common.h"
#include "crypto/sha3.h"
#include "netaddress.h"
#include "hash.h"
#include "prevector.h"
#include "tinyformat.h"
#include "util/asmap.h"
#include "util/string.h"
Expand All @@ -29,7 +32,18 @@ CNetAddr::BIP155Network CNetAddr::GetBIP155Network() const
case NET_IPV6:
return BIP155Network::IPV6;
case NET_ONION:
return BIP155Network::TORV2;
switch (m_addr.size()) {
case ADDR_TORV2_SIZE:
return BIP155Network::TORV2;
case ADDR_TORV3_SIZE:
return BIP155Network::TORV3;
default:
assert(false);
}
case NET_I2P:
return BIP155Network::I2P;
case NET_CJDNS:
return BIP155Network::CJDNS;
case NET_INTERNAL: // should have been handled before calling this function
case NET_UNROUTABLE: // m_net is never and should not be set to NET_UNROUTABLE
case NET_MAX: // m_net is never and should not be set to NET_MAX
Expand Down Expand Up @@ -66,6 +80,30 @@ bool CNetAddr::SetNetFromBIP155Network(uint8_t possible_bip155_net, size_t addre
throw std::ios_base::failure(
strprintf("BIP155 TORv2 address with length %u (should be %u)", address_size,
ADDR_TORV2_SIZE));
case BIP155Network::TORV3:
if (address_size == ADDR_TORV3_SIZE) {
m_net = NET_ONION;
return true;
}
throw std::ios_base::failure(
strprintf("BIP155 TORv3 address with length %u (should be %u)", address_size,
ADDR_TORV3_SIZE));
case BIP155Network::I2P:
if (address_size == ADDR_I2P_SIZE) {
m_net = NET_I2P;
return true;
}
throw std::ios_base::failure(
strprintf("BIP155 I2P address with length %u (should be %u)", address_size,
ADDR_I2P_SIZE));
case BIP155Network::CJDNS:
if (address_size == ADDR_CJDNS_SIZE) {
m_net = NET_CJDNS;
return true;
}
throw std::ios_base::failure(
strprintf("BIP155 CJDNS address with length %u (should be %u)", address_size,
ADDR_CJDNS_SIZE));
}

// Don't throw on addresses with unknown network ids (maybe from the future).
Expand All @@ -92,7 +130,13 @@ void CNetAddr::SetIP(const CNetAddr& ipIn)
assert(ipIn.m_addr.size() == ADDR_IPV6_SIZE);
break;
case NET_ONION:
assert(ipIn.m_addr.size() == ADDR_TORV2_SIZE);
assert(ipIn.m_addr.size() == ADDR_TORV2_SIZE || ipIn.m_addr.size() == ADDR_TORV3_SIZE);
break;
case NET_I2P:
assert(ipIn.m_addr.size() == ADDR_I2P_SIZE);
break;
case NET_CJDNS:
assert(ipIn.m_addr.size() == ADDR_CJDNS_SIZE);
break;
case NET_INTERNAL:
assert(ipIn.m_addr.size() == ADDR_INTERNAL_SIZE);
Expand Down Expand Up @@ -150,24 +194,80 @@ bool CNetAddr::SetInternal(const std::string &name)
return true;
}

namespace torv3 {
// https://gitweb.torproject.org/torspec.git/tree/rend-spec-v3.txt#n2135
static constexpr size_t CHECKSUM_LEN = 2;
static const unsigned char VERSION[] = {3};
static constexpr size_t TOTAL_LEN = ADDR_TORV3_SIZE + CHECKSUM_LEN + sizeof(VERSION);

static void Checksum(Span<const uint8_t> addr_pubkey, uint8_t (&checksum)[CHECKSUM_LEN])
{
// TORv3 CHECKSUM = H(".onion checksum" | PUBKEY | VERSION)[:2]
static const unsigned char prefix[] = ".onion checksum";
static constexpr size_t prefix_len = 15;

SHA3_256 hasher;

hasher.Write(MakeSpan(prefix).first(prefix_len));
hasher.Write(addr_pubkey);
hasher.Write(VERSION);

uint8_t checksum_full[SHA3_256::OUTPUT_SIZE];

hasher.Finalize(checksum_full);

memcpy(checksum, checksum_full, sizeof(checksum));
}

}; // namespace torv3

/**
* Parse a TORv2 address and set this object to it.
* Parse a TOR address and set this object to it.
*
* @returns Whether or not the operation was successful.
*
* @see CNetAddr::IsTor()
*/
bool CNetAddr::SetSpecial(const std::string& strName)
bool CNetAddr::SetSpecial(const std::string& str)
{
if (strName.size()>6 && strName.substr(strName.size() - 6, 6) == ".onion") {
std::vector<unsigned char> vchAddr = DecodeBase32(strName.substr(0, strName.size() - 6).c_str());
if (vchAddr.size() != ADDR_TORV2_SIZE) {
static const char* suffix{".onion"};
static constexpr size_t suffix_len{6};

if (!ValidAsCString(str) || str.size() <= suffix_len ||
str.substr(str.size() - suffix_len) != suffix) {
return false;
}

bool invalid;
const auto& input = DecodeBase32(str.substr(0, str.size() - suffix_len).c_str(), &invalid);

if (invalid) {
return false;
}

switch (input.size()) {
case ADDR_TORV2_SIZE:
m_net = NET_ONION;
m_addr.assign(input.begin(), input.end());
return true;
case torv3::TOTAL_LEN: {
Span<const uint8_t> input_pubkey{input.data(), ADDR_TORV3_SIZE};
Span<const uint8_t> input_checksum{input.data() + ADDR_TORV3_SIZE, torv3::CHECKSUM_LEN};
Span<const uint8_t> input_version{input.data() + ADDR_TORV3_SIZE + torv3::CHECKSUM_LEN, sizeof(torv3::VERSION)};

uint8_t calculated_checksum[torv3::CHECKSUM_LEN];
torv3::Checksum(input_pubkey, calculated_checksum);

if (input_checksum != calculated_checksum || input_version != torv3::VERSION) {
return false;
}

m_net = NET_ONION;
m_addr.assign(vchAddr.begin(), vchAddr.end());
m_addr.assign(input_pubkey.begin(), input_pubkey.end());
return true;
}
}

return false;
}

Expand Down Expand Up @@ -284,13 +384,21 @@ bool CNetAddr::IsHeNet() const
}

/**
* @returns Whether or not this is a dummy address that maps an onion address
* into IPv6.
*
* Check whether this object represents a TOR address.
* @see CNetAddr::SetSpecial(const std::string &)
*/
bool CNetAddr::IsTor() const { return m_net == NET_ONION; }

/**
* Check whether this object represents an I2P address.
*/
bool CNetAddr::IsI2P() const { return m_net == NET_I2P; }

/**
* Check whether this object represents a CJDNS address.
*/
bool CNetAddr::IsCJDNS() const { return m_net == NET_CJDNS; }

bool CNetAddr::IsLocal() const
{
// IPv4 loopback (127.0.0.0/8 or 0.0.0.0/8)
Expand Down Expand Up @@ -369,28 +477,72 @@ enum Network CNetAddr::GetNetwork() const
return m_net;
}

static std::string IPv6ToString(Span<const uint8_t> a)
{
assert(a.size() == ADDR_IPV6_SIZE);
// clang-format off
return strprintf("%x:%x:%x:%x:%x:%x:%x:%x",
ReadBE16(&a[0]),
ReadBE16(&a[2]),
ReadBE16(&a[4]),
ReadBE16(&a[6]),
ReadBE16(&a[8]),
ReadBE16(&a[10]),
ReadBE16(&a[12]),
ReadBE16(&a[14]));
// clang-format on
}

std::string CNetAddr::ToStringIP() const
{
if (IsTor())
return EncodeBase32(m_addr) + ".onion";
if (IsInternal())
switch (m_net) {
case NET_IPV4:
case NET_IPV6: {
CService serv(*this, 0);
struct sockaddr_storage sockaddr;
socklen_t socklen = sizeof(sockaddr);
if (serv.GetSockAddr((struct sockaddr*)&sockaddr, &socklen)) {
char name[1025] = "";
if (!getnameinfo((const struct sockaddr*)&sockaddr, socklen, name,
sizeof(name), nullptr, 0, NI_NUMERICHOST))
return std::string(name);
}
if (m_net == NET_IPV4) {
return strprintf("%u.%u.%u.%u", m_addr[0], m_addr[1], m_addr[2], m_addr[3]);
}
return IPv6ToString(m_addr);
}
case NET_ONION:
switch (m_addr.size()) {
case ADDR_TORV2_SIZE:
return EncodeBase32(m_addr) + ".onion";
case ADDR_TORV3_SIZE: {

uint8_t checksum[torv3::CHECKSUM_LEN];
torv3::Checksum(m_addr, checksum);

// TORv3 onion_address = base32(PUBKEY | CHECKSUM | VERSION) + ".onion"
prevector<torv3::TOTAL_LEN, uint8_t> address{m_addr.begin(), m_addr.end()};
address.insert(address.end(), checksum, checksum + torv3::CHECKSUM_LEN);
address.insert(address.end(), torv3::VERSION, torv3::VERSION + sizeof(torv3::VERSION));

return EncodeBase32(address) + ".onion";
}
default:
assert(false);
}
case NET_I2P:
return EncodeBase32(m_addr, false /* don't pad with = */) + ".b32.i2p";
case NET_CJDNS:
return IPv6ToString(m_addr);
case NET_INTERNAL:
return EncodeBase32(m_addr) + ".internal";
CService serv(*this, 0);
struct sockaddr_storage sockaddr;
socklen_t socklen = sizeof(sockaddr);
if (serv.GetSockAddr((struct sockaddr*)&sockaddr, &socklen)) {
char name[1025] = "";
if (!getnameinfo((const struct sockaddr*)&sockaddr, socklen, name, sizeof(name), nullptr, 0, NI_NUMERICHOST))
return std::string(name);
}
if (IsIPv4())
return strprintf("%u.%u.%u.%u", m_addr[0], m_addr[1], m_addr[2], m_addr[3]);
assert(IsIPv6());
return strprintf("%x:%x:%x:%x:%x:%x:%x:%x",
m_addr[0] << 8 | m_addr[1], m_addr[2] << 8 | m_addr[3],
m_addr[4] << 8 | m_addr[5], m_addr[6] << 8 | m_addr[7],
m_addr[8] << 8 | m_addr[9], m_addr[10] << 8 | m_addr[11],
m_addr[12] << 8 | m_addr[13], m_addr[14] << 8 | m_addr[15]);
case NET_UNROUTABLE: // m_net is never and should not be set to NET_UNROUTABLE
case NET_MAX: // m_net is never and should not be set to NET_MAX
assert(false);
} // no default case, so the compiler can warn about missing cases

assert(false);
}

std::string CNetAddr::ToString() const
Expand Down Expand Up @@ -464,21 +616,22 @@ uint32_t CNetAddr::GetLinkedIPv4() const
assert(false);
}

uint32_t CNetAddr::GetNetClass() const {
uint32_t net_class = NET_IPV6;
if (IsLocal()) {
net_class = 255;
}
uint32_t CNetAddr::GetNetClass() const
{
// Make sure that if we return NET_IPV6, then IsIPv6() is true. The callers expect that.

// Check for "internal" first because such addresses are also !IsRoutable()
// and we don't want to return NET_UNROUTABLE in that case.
if (IsInternal()) {
net_class = NET_INTERNAL;
} else if (!IsRoutable()) {
net_class = NET_UNROUTABLE;
} else if (HasLinkedIPv4()) {
net_class = NET_IPV4;
} else if (IsTor()) {
net_class = NET_ONION;
return NET_INTERNAL;
}
return net_class;
if (!IsRoutable()) {
return NET_UNROUTABLE;
}
if (HasLinkedIPv4()) {
return NET_IPV4;
}
return m_net;
}

uint32_t CNetAddr::GetMappedAS(const std::vector<bool> &asmap) const {
Expand Down Expand Up @@ -553,7 +706,7 @@ std::vector<unsigned char> CNetAddr::GetGroup(const std::vector<bool> &asmap) co
vchRet.push_back((ipv4 >> 24) & 0xFF);
vchRet.push_back((ipv4 >> 16) & 0xFF);
return vchRet;
} else if (IsTor()) {
} else if (IsTor() || IsI2P() || IsCJDNS()) {
nBits = 4;
} else if (IsHeNet()) {
// for he.net, use /36 groups
Expand Down Expand Up @@ -768,7 +921,7 @@ std::string CService::ToStringPort() const

std::string CService::ToStringIPPort() const
{
if (IsIPv4() || IsTor() || IsInternal()) {
if (IsIPv4() || IsTor() || IsI2P() || IsInternal()) {
return ToStringIP() + ":" + ToStringPort();
} else {
return "[" + ToStringIP() + "]:" + ToStringPort();
Expand Down
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