From 407a7605dc49a4a4fd249cbac2a8d305bb1fdd51 Mon Sep 17 00:00:00 2001
From: "Wladimir J. van der Laan" <laanwj@gmail.com>
Date: Mon, 28 Apr 2014 11:08:57 +0200
Subject: [PATCH] net: Add CSubNet class for subnet matching

---
 src/netbase.cpp            | 123 ++++++++++++++++++++++++++++++++++++-
 src/netbase.h              |  30 +++++++++
 src/test/netbase_tests.cpp |  37 +++++++++++
 3 files changed, 187 insertions(+), 3 deletions(-)

diff --git a/src/netbase.cpp b/src/netbase.cpp
index 4f7e3f6b7..82a681281 100644
--- a/src/netbase.cpp
+++ b/src/netbase.cpp
@@ -546,6 +546,22 @@ void CNetAddr::SetIP(const CNetAddr& ipIn)
     memcpy(ip, ipIn.ip, sizeof(ip));
 }
 
+void CNetAddr::SetRaw(Network network, const uint8_t *ip_in)
+{
+    switch(network)
+    {
+        case NET_IPV4:
+            memcpy(ip, pchIPv4, 12);
+            memcpy(ip+12, ip_in, 4);
+            break;
+        case NET_IPV6:
+            memcpy(ip, ip_in, 16);
+            break;
+        default:
+            assert(!"invalid network");
+    }
+}
+
 static const unsigned char pchOnionCat[] = {0xFD,0x87,0xD8,0x7E,0xEB,0x43};
 
 bool CNetAddr::SetSpecial(const std::string &strName)
@@ -569,13 +585,12 @@ CNetAddr::CNetAddr()
 
 CNetAddr::CNetAddr(const struct in_addr& ipv4Addr)
 {
-    memcpy(ip,    pchIPv4, 12);
-    memcpy(ip+12, &ipv4Addr, 4);
+    SetRaw(NET_IPV4, (const uint8_t*)&ipv4Addr);
 }
 
 CNetAddr::CNetAddr(const struct in6_addr& ipv6Addr)
 {
-    memcpy(ip, &ipv6Addr, 16);
+    SetRaw(NET_IPV6, (const uint8_t*)&ipv6Addr);
 }
 
 CNetAddr::CNetAddr(const char *pszIp, bool fAllowLookup)
@@ -1120,3 +1135,105 @@ void CService::SetPort(unsigned short portIn)
 {
     port = portIn;
 }
+
+CSubNet::CSubNet():
+    valid(false)
+{
+    memset(netmask, 0, sizeof(netmask));
+}
+
+CSubNet::CSubNet(const std::string &strSubnet, bool fAllowLookup)
+{
+    size_t slash = strSubnet.find_last_of('/');
+    std::vector<CNetAddr> vIP;
+
+    valid = true;
+    // Default to /32 (IPv4) or /128 (IPv6), i.e. match single address
+    memset(netmask, 255, sizeof(netmask));
+
+    std::string strAddress = strSubnet.substr(0, slash);
+    if (LookupHost(strAddress.c_str(), vIP, 1, fAllowLookup))
+    {
+        network = vIP[0];
+        if (slash != strSubnet.npos)
+        {
+            std::string strNetmask = strSubnet.substr(slash + 1);
+            int32_t n;
+            // IPv4 addresses start at offset 12, and first 12 bytes must match, so just offset n
+            int noffset = network.IsIPv4() ? (12 * 8) : 0;
+            if (ParseInt32(strNetmask, &n)) // If valid number, assume /24 symtex
+            {
+                if(n >= 0 && n <= (128 - noffset)) // Only valid if in range of bits of address
+                {
+                    n += noffset;
+                    // Clear bits [n..127]
+                    for (; n < 128; ++n)
+                        netmask[n>>3] &= ~(1<<(n&7));
+                }
+                else
+                {
+                    valid = false;
+                }
+            }
+            else // If not a valid number, try full netmask syntax
+            {
+                if (LookupHost(strNetmask.c_str(), vIP, 1, false)) // Never allow lookup for netmask
+                {
+                    // Remember: GetByte returns bytes in reversed order
+                    // Copy only the *last* four bytes in case of IPv4, the rest of the mask should stay 1's as
+                    // we don't want pchIPv4 to be part of the mask.
+                    int asize = network.IsIPv4() ? 4 : 16;
+                    for(int x=0; x<asize; ++x)
+                        netmask[15-x] = vIP[0].GetByte(x);
+                }
+                else
+                {
+                    valid = false;
+                }
+            }
+        }
+    }
+    else
+    {
+        valid = false;
+    }
+}
+
+bool CSubNet::Match(const CNetAddr &addr) const
+{
+    if (!valid || !addr.IsValid())
+        return false;
+    for(int x=0; x<16; ++x)
+        if ((addr.GetByte(x) & netmask[15-x]) != network.GetByte(x))
+            return false;
+    return true;
+}
+
+std::string CSubNet::ToString() const
+{
+    std::string strNetmask;
+    if (network.IsIPv4())
+        strNetmask = strprintf("%u.%u.%u.%u", netmask[12], netmask[13], netmask[14], netmask[15]);
+    else
+        strNetmask = strprintf("%x:%x:%x:%x:%x:%x:%x:%x",
+                         netmask[0] << 8 | netmask[1], netmask[2] << 8 | netmask[3],
+                         netmask[4] << 8 | netmask[5], netmask[6] << 8 | netmask[7],
+                         netmask[8] << 8 | netmask[9], netmask[10] << 8 | netmask[11],
+                         netmask[12] << 8 | netmask[13], netmask[14] << 8 | netmask[15]);
+    return network.ToString() + "/" + strNetmask;
+}
+
+bool CSubNet::IsValid() const
+{
+    return valid;
+}
+
+bool operator==(const CSubNet& a, const CSubNet& b)
+{
+    return a.valid == b.valid && a.network == b.network && !memcmp(a.netmask, b.netmask, 16);
+}
+
+bool operator!=(const CSubNet& a, const CSubNet& b)
+{
+    return !(a==b);
+}
diff --git a/src/netbase.h b/src/netbase.h
index 95b179576..118f866d6 100644
--- a/src/netbase.h
+++ b/src/netbase.h
@@ -49,6 +49,13 @@ class CNetAddr
         explicit CNetAddr(const std::string &strIp, bool fAllowLookup = false);
         void Init();
         void SetIP(const CNetAddr& ip);
+
+        /**
+         * Set raw IPv4 or IPv6 address (in network byte order)
+         * @note Only NET_IPV4 and NET_IPV6 are allowed for network.
+         */
+        void SetRaw(Network network, const uint8_t *data);
+
         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)
@@ -90,6 +97,29 @@ class CNetAddr
             )
 };
 
+class CSubNet
+{
+    protected:
+        /// Network (base) address
+        CNetAddr network;
+        /// Netmask, in network byte order
+        uint8_t netmask[16];
+        /// Is this value valid? (only used to signal parse errors)
+        bool valid;
+
+    public:
+        CSubNet();
+        explicit CSubNet(const std::string &strSubnet, bool fAllowLookup = false);
+
+        bool Match(const CNetAddr &addr) const;
+
+        std::string ToString() const;
+        bool IsValid() const;
+
+        friend bool operator==(const CSubNet& a, const CSubNet& b);
+        friend bool operator!=(const CSubNet& a, const CSubNet& b);
+};
+
 /** A combination of a network address (CNetAddr) and a (TCP) port */
 class CService : public CNetAddr
 {
diff --git a/src/test/netbase_tests.cpp b/src/test/netbase_tests.cpp
index 4321852d1..c26e73838 100644
--- a/src/test/netbase_tests.cpp
+++ b/src/test/netbase_tests.cpp
@@ -102,4 +102,41 @@ BOOST_AUTO_TEST_CASE(onioncat_test)
     BOOST_CHECK(addr1.IsRoutable());
 }
 
+BOOST_AUTO_TEST_CASE(subnet_test)
+{
+    BOOST_CHECK(CSubNet("1.2.3.0/24") == CSubNet("1.2.3.0/255.255.255.0"));
+    BOOST_CHECK(CSubNet("1.2.3.0/24") != CSubNet("1.2.4.0/255.255.255.0"));
+    BOOST_CHECK(CSubNet("1.2.3.0/24").Match(CNetAddr("1.2.3.4")));
+    BOOST_CHECK(!CSubNet("1.2.2.0/24").Match(CNetAddr("1.2.3.4")));
+    BOOST_CHECK(CSubNet("1.2.3.4").Match(CNetAddr("1.2.3.4")));
+    BOOST_CHECK(CSubNet("1.2.3.4/32").Match(CNetAddr("1.2.3.4")));
+    BOOST_CHECK(!CSubNet("1.2.3.4").Match(CNetAddr("5.6.7.8")));
+    BOOST_CHECK(!CSubNet("1.2.3.4/32").Match(CNetAddr("5.6.7.8")));
+    BOOST_CHECK(CSubNet("::ffff:127.0.0.1").Match(CNetAddr("127.0.0.1")));
+    BOOST_CHECK(CSubNet("1:2:3:4:5:6:7:8").Match(CNetAddr("1:2:3:4:5:6:7:8")));
+    BOOST_CHECK(!CSubNet("1:2:3:4:5:6:7:8").Match(CNetAddr("1:2:3:4:5:6:7:9")));
+    BOOST_CHECK(CSubNet("1:2:3:4:5:6:7:0/112").Match(CNetAddr("1:2:3:4:5:6:7:1234")));
+    // All-Matching IPv6 Matches arbitrary IPv4 and IPv6
+    BOOST_CHECK(CSubNet("::/0").Match(CNetAddr("1:2:3:4:5:6:7:1234")));
+    BOOST_CHECK(CSubNet("::/0").Match(CNetAddr("1.2.3.4")));
+    // All-Matching IPv4 does not Match IPv6
+    BOOST_CHECK(!CSubNet("0.0.0.0/0").Match(CNetAddr("1:2:3:4:5:6:7:1234")));
+    // Invalid subnets Match nothing (not even invalid addresses)
+    BOOST_CHECK(!CSubNet().Match(CNetAddr("1.2.3.4")));
+    BOOST_CHECK(!CSubNet("").Match(CNetAddr("4.5.6.7")));
+    BOOST_CHECK(!CSubNet("bloop").Match(CNetAddr("0.0.0.0")));
+    BOOST_CHECK(!CSubNet("bloop").Match(CNetAddr("hab")));
+    // Check valid/invalid
+    BOOST_CHECK(CSubNet("1.2.3.0/0").IsValid());
+    BOOST_CHECK(!CSubNet("1.2.3.0/-1").IsValid());
+    BOOST_CHECK(CSubNet("1.2.3.0/32").IsValid());
+    BOOST_CHECK(!CSubNet("1.2.3.0/33").IsValid());
+    BOOST_CHECK(CSubNet("1:2:3:4:5:6:7:8/0").IsValid());
+    BOOST_CHECK(CSubNet("1:2:3:4:5:6:7:8/33").IsValid());
+    BOOST_CHECK(!CSubNet("1:2:3:4:5:6:7:8/-1").IsValid());
+    BOOST_CHECK(CSubNet("1:2:3:4:5:6:7:8/128").IsValid());
+    BOOST_CHECK(!CSubNet("1:2:3:4:5:6:7:8/129").IsValid());
+    BOOST_CHECK(!CSubNet("fuzzy").IsValid());
+}
+
 BOOST_AUTO_TEST_SUITE_END()