From c92f8ebd92337a009410cc263d4a1392136629d2 Mon Sep 17 00:00:00 2001
From: w00t <w00t@e03df62e-2008-0410-955e-edbf42e46eb7>
Date: Sat, 12 Jul 2008 08:57:44 +0000
Subject: Add User::GetCIDRMask(int range), will be used for CIDR throttling,
 etc. Also probably opens up the way for /gline nickname to place CIDR bans
 instead of regular bans, which could be helpful. Much thanks to Om for his
 help.

git-svn-id: http://svn.inspircd.org/repository/trunk/inspircd@9959 e03df62e-2008-0410-955e-edbf42e46eb7
---
 include/users.h |   9 +++++
 src/users.cpp   | 113 +++++++++++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 117 insertions(+), 5 deletions(-)

diff --git a/include/users.h b/include/users.h
index f098500e3..3edb9a99e 100644
--- a/include/users.h
+++ b/include/users.h
@@ -661,6 +661,15 @@ class CoreExport User : public connection
 	 */
 	const char* GetIPString(bool translate4in6 = true);
 
+	/** Get a CIDR mask from the IP of this user, using a static internal buffer.
+	 * e.g., GetCIDRMask(16) for 223.254.214.52 returns 223.254.0.0/16
+	 * This may be used for CIDR clone detection, etc.
+	 *
+	 * (XXX, brief note: when we do the sockets rewrite, this should move down a
+	 * level so it may be used on more derived objects. -- w00t)
+	 */
+	const char *GetCIDRMask(int range);
+
 	/* Write error string
 	 */
 	std::string WriteError;
diff --git a/src/users.cpp b/src/users.cpp
index f532b60d1..c82c351ab 100644
--- a/src/users.cpp
+++ b/src/users.cpp
@@ -1098,13 +1098,116 @@ int User::GetProtocolFamily()
 	return sin->sin_family;
 }
 
-/*
- * XXX the duplication here is horrid..
- * do we really need two methods doing essentially the same thing?
- */
+const char* User::GetCIDRMask(int range)
+{
+	static char buf[40];
+
+	if (this->ip == NULL)
+		return "";
+
+	if (range < 0)
+		throw "Negative range, sorry, no.";
+
+	/*
+	 * Original code written by Oliver Lupton (Om).
+	 * Integrated by me. Thanks. :) -- w00t
+	 */
+	switch (this->GetProtocolFamily())
+	{
+#ifdef SUPPORT_IP6LINKS
+		case AF_INET6:
+		{
+			struct in6_addr v6;
+	 
+			if(range > 128)
+			{
+				printf("Error, range given (%d) larger than address length (128)\n", range);
+				return 0;
+			}
+	 
+			if(inet_pton(AF_INET6, this->GetIPString(), &v6))
+			{
+				/* unsigned char s6_addr[16]; */
+				int i;
+				int bytestoblank;
+				int extrabits;
+				char buffer[64];
+
+				if(range > 0)
+				{
+					/* (128 - range) bits must be blanked, so ((128 - range) / 8) of the bytes, working backwards, must be blanked. */
+					bytestoblank = (128 - range) / 8;
+	 
+					/* ((128 - range) % 8) bits of the next byte must also be blanked. */
+					extrabits = (128 - range) % 8;
+					v6.s6_addr[15 - bytestoblank] = (v6.s6_addr[15 - bytestoblank] >> extrabits) << extrabits;
+
+					for(i = 0; i < bytestoblank; i++)
+					{
+						v6.s6_addr[15 - i] = 0;
+					}
+				}
+				else
+				{
+					for(i = 0; i < 15; i++)
+					{
+						v6.s6_addr[i] = 0;
+					}
+				}
+
+				sprintf(buf, "%s/%d\n", inet_ntop(AF_INET6, &v6, buffer, 64), range);
+				return buf;
+			}
+			else
+			{
+				throw "CIDR mask for v6 failed";
+			}
+
+		}
+		break;
+#endif
+		case AF_INET:
+		{
+			struct in_addr v4;
+
+			if (range > 32)
+				throw "more than 32 bits on an ipv4 connection, can't do that..";
+
+			if(inet_pton(AF_INET, this->GetIPString(), &v4))
+			{
+				char buffer[16];
+				uint32_t temp;
+
+				/* (32 - range) is the number of bits we are *ignoring*. We shift this left and then right to wipe off these bits. */
+
+				if(range > 0)
+				{
+					temp = ntohl(v4.s_addr);
+					temp = (temp >> (32 - range)) << (32 - range);
+					v4.s_addr = htonl(temp);
+				}
+				else
+				{
+					v4.s_addr = 0;
+				}
+
+				sprintf(buf, "%s/%d\n", inet_ntop(AF_INET, &v4, buffer, 16), range);
+				return buf;
+			}
+			else
+			{
+				throw "CIDR mask for v4 failed";
+			}
+		}
+		break;
+	}
+
+	return ""; // unused, but oh well
+}
+
 const char* User::GetIPString(bool translate4in6)
 {
-	static char buf[1024];
+	static char buf[40];
 
 	if (this->ip == NULL)
 		return "";
-- 
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