From 7f31762cb6261806542cc6d1188ca07db98a6950 Mon Sep 17 00:00:00 2001 From: Cory Fields Date: Tue, 23 May 2017 20:04:38 -0400 Subject: [PATCH] net: add an internal subnet for representing unresolved hostnames We currently do two resolves for dns seeds: one for the results, and one to serve in addrman as the source for those addresses. There's no requirement that the source hostname resolves to the stored identifier, only that the mapping is unique. So rather than incurring the second lookup, combine a private subnet with a hash of the hostname. The resulting v6 ip is guaranteed not to be publicy routable, and has only a negligible chance of colliding with a user's internal network (which would be of no consequence anyway). --- src/net.cpp | 2 +- src/netaddress.cpp | 48 ++++++++++++++++++++++++++++++++------ src/netaddress.h | 8 +++++++ src/rpc/net.cpp | 2 +- src/test/netbase_tests.cpp | 13 +++++++++++ 5 files changed, 64 insertions(+), 9 deletions(-) diff --git a/src/net.cpp b/src/net.cpp index 75d1719e8..e10016d98 100644 --- a/src/net.cpp +++ b/src/net.cpp @@ -240,7 +240,7 @@ bool RemoveLocal(const CService& addr) /** Make a particular network entirely off-limits (no automatic connects to it) */ void SetLimited(enum Network net, bool fLimited) { - if (net == NET_UNROUTABLE) + if (net == NET_UNROUTABLE || net == NET_INTERNAL) return; LOCK(cs_mapLocalHost); vfLimited[net] = fLimited; diff --git a/src/netaddress.cpp b/src/netaddress.cpp index 34a702986..89f257c64 100644 --- a/src/netaddress.cpp +++ b/src/netaddress.cpp @@ -15,6 +15,9 @@ static const unsigned char pchIPv4[12] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff }; static const unsigned char pchOnionCat[] = {0xFD,0x87,0xD8,0x7E,0xEB,0x43}; +// 0xFD + sha256("bitcoin")[0:5] +static const unsigned char g_internal_prefix[] = { 0xFD, 0x6B, 0x88, 0xC0, 0x87, 0x24 }; + void CNetAddr::Init() { memset(ip, 0, sizeof(ip)); @@ -42,6 +45,18 @@ void CNetAddr::SetRaw(Network network, const uint8_t *ip_in) } } +bool CNetAddr::SetInternal(const std::string &name) +{ + if (name.empty()) { + return false; + } + unsigned char hash[32] = {}; + CSHA256().Write((const unsigned char*)name.data(), name.size()).Finalize(hash); + memcpy(ip, g_internal_prefix, sizeof(g_internal_prefix)); + memcpy(ip + sizeof(g_internal_prefix), hash, sizeof(ip) - sizeof(g_internal_prefix)); + return true; +} + bool CNetAddr::SetSpecial(const std::string &strName) { if (strName.size()>6 && strName.substr(strName.size() - 6, 6) == ".onion") { @@ -84,7 +99,7 @@ bool CNetAddr::IsIPv4() const bool CNetAddr::IsIPv6() const { - return (!IsIPv4() && !IsTor()); + return (!IsIPv4() && !IsTor() && !IsInternal()); } bool CNetAddr::IsRFC1918() const @@ -199,6 +214,9 @@ bool CNetAddr::IsValid() const if (IsRFC3849()) return false; + if (IsInternal()) + return false; + if (IsIPv4()) { // INADDR_NONE @@ -217,11 +235,19 @@ bool CNetAddr::IsValid() const bool CNetAddr::IsRoutable() const { - return IsValid() && !(IsRFC1918() || IsRFC2544() || IsRFC3927() || IsRFC4862() || IsRFC6598() || IsRFC5737() || (IsRFC4193() && !IsTor()) || IsRFC4843() || IsLocal()); + return IsValid() && !(IsRFC1918() || IsRFC2544() || IsRFC3927() || IsRFC4862() || IsRFC6598() || IsRFC5737() || (IsRFC4193() && !IsTor()) || IsRFC4843() || IsLocal() || IsInternal()); +} + +bool CNetAddr::IsInternal() const +{ + return memcmp(ip, g_internal_prefix, sizeof(g_internal_prefix)) == 0; } enum Network CNetAddr::GetNetwork() const { + if (IsInternal()) + return NET_INTERNAL; + if (!IsRoutable()) return NET_UNROUTABLE; @@ -238,6 +264,8 @@ std::string CNetAddr::ToStringIP() const { if (IsTor()) return EncodeBase32(&ip[6], 10) + ".onion"; + if (IsInternal()) + return EncodeBase32(ip + sizeof(g_internal_prefix), sizeof(ip) - sizeof(g_internal_prefix)) + ".internal"; CService serv(*this, 0); struct sockaddr_storage sockaddr; socklen_t socklen = sizeof(sockaddr); @@ -305,9 +333,15 @@ std::vector CNetAddr::GetGroup() const nClass = 255; nBits = 0; } - - // all unroutable addresses belong to the same group - if (!IsRoutable()) + // all internal-usage addresses get their own group + if (IsInternal()) + { + nClass = NET_INTERNAL; + nStartByte = sizeof(g_internal_prefix); + nBits = (sizeof(ip) - sizeof(g_internal_prefix)) * 8; + } + // all other unroutable addresses belong to the same group + else if (!IsRoutable()) { nClass = NET_UNROUTABLE; nBits = 0; @@ -393,7 +427,7 @@ int CNetAddr::GetReachabilityFrom(const CNetAddr *paddrPartner) const REACH_PRIVATE }; - if (!IsRoutable()) + if (!IsRoutable() || IsInternal()) return REACH_UNREACHABLE; int ourNet = GetExtNetwork(this); @@ -552,7 +586,7 @@ std::string CService::ToStringPort() const std::string CService::ToStringIPPort() const { - if (IsIPv4() || IsTor()) { + if (IsIPv4() || IsTor() || IsInternal()) { return ToStringIP() + ":" + ToStringPort(); } else { return "[" + ToStringIP() + "]:" + ToStringPort(); diff --git a/src/netaddress.h b/src/netaddress.h index fbc4d1a65..80716600d 100644 --- a/src/netaddress.h +++ b/src/netaddress.h @@ -22,6 +22,7 @@ enum Network NET_IPV4, NET_IPV6, NET_TOR, + NET_INTERNAL, NET_MAX, }; @@ -45,6 +46,12 @@ class CNetAddr */ void SetRaw(Network network, const uint8_t *data); + /** + * Transform an arbitrary string into a non-routable ipv6 address. + * Useful for mapping resolved addresses back to their source. + */ + bool SetInternal(const std::string& name); + bool SetSpecial(const std::string &strName); // for Tor addresses bool IsIPv4() const; // IPv4 mapped address (::FFFF:0:0/96, 0.0.0.0/0) bool IsIPv6() const; // IPv6 address (not mapped IPv4, not Tor) @@ -64,6 +71,7 @@ class CNetAddr bool IsTor() const; bool IsLocal() const; bool IsRoutable() const; + bool IsInternal() const; bool IsValid() const; enum Network GetNetwork() const; std::string ToString() const; diff --git a/src/rpc/net.cpp b/src/rpc/net.cpp index 10bf99eb3..ab4ecbcf1 100644 --- a/src/rpc/net.cpp +++ b/src/rpc/net.cpp @@ -397,7 +397,7 @@ static UniValue GetNetworksInfo() for(int n=0; n(n); - if(network == NET_UNROUTABLE) + if(network == NET_UNROUTABLE || network == NET_INTERNAL) continue; proxyType proxy; UniValue obj(UniValue::VOBJ); diff --git a/src/test/netbase_tests.cpp b/src/test/netbase_tests.cpp index e4b4b8572..94a3dac4b 100644 --- a/src/test/netbase_tests.cpp +++ b/src/test/netbase_tests.cpp @@ -25,6 +25,13 @@ static CSubNet ResolveSubNet(const char* subnet) return ret; } +static CNetAddr CreateInternal(const char* host) +{ + CNetAddr addr; + addr.SetInternal(host); + return addr; +} + BOOST_AUTO_TEST_CASE(netbase_networks) { BOOST_CHECK(ResolveIP("127.0.0.1").GetNetwork() == NET_UNROUTABLE); @@ -32,6 +39,7 @@ BOOST_AUTO_TEST_CASE(netbase_networks) BOOST_CHECK(ResolveIP("8.8.8.8").GetNetwork() == NET_IPV4); BOOST_CHECK(ResolveIP("2001::8888").GetNetwork() == NET_IPV6); BOOST_CHECK(ResolveIP("FD87:D87E:EB43:edb1:8e4:3588:e546:35ca").GetNetwork() == NET_TOR); + BOOST_CHECK(CreateInternal("foo.com").GetNetwork() == NET_INTERNAL); } @@ -58,6 +66,8 @@ BOOST_AUTO_TEST_CASE(netbase_properties) BOOST_CHECK(ResolveIP("8.8.8.8").IsRoutable()); BOOST_CHECK(ResolveIP("2001::1").IsRoutable()); BOOST_CHECK(ResolveIP("127.0.0.1").IsValid()); + BOOST_CHECK(CreateInternal("FD6B:88C0:8724:edb1:8e4:3588:e546:35ca").IsInternal()); + BOOST_CHECK(CreateInternal("bar.com").IsInternal()); } @@ -281,6 +291,9 @@ BOOST_AUTO_TEST_CASE(netbase_getgroup) BOOST_CHECK(ResolveIP("2001:470:abcd:9999:9999:9999:9999:9999").GetGroup() == std::vector({(unsigned char)NET_IPV6, 32, 1, 4, 112, 175})); //he.net BOOST_CHECK(ResolveIP("2001:2001:9999:9999:9999:9999:9999:9999").GetGroup() == std::vector({(unsigned char)NET_IPV6, 32, 1, 32, 1})); //IPv6 + // baz.net sha256 hash: 12929400eb4607c4ac075f087167e75286b179c693eb059a01774b864e8fe505 + std::vector internal_group = {NET_INTERNAL, 0x12, 0x92, 0x94, 0x00, 0xeb, 0x46, 0x07, 0xc4, 0xac, 0x07}; + BOOST_CHECK(CreateInternal("baz.net").GetGroup() == internal_group); } BOOST_AUTO_TEST_SUITE_END()