From 216e9a4456207f5ae9cd85926521851e11a26d92 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Thu, 7 Aug 2014 23:00:01 +0200
Subject: [PATCH] Add a way to limit deserialized string lengths

and use it for most strings being serialized.
---
 src/alert.h     |  6 +++---
 src/main.cpp    |  9 +++------
 src/serialize.h | 39 +++++++++++++++++++++++++++++++++++++--
 src/wallet.h    |  6 +++---
 4 files changed, 46 insertions(+), 14 deletions(-)

diff --git a/src/alert.h b/src/alert.h
index da140be5e..296d48891 100644
--- a/src/alert.h
+++ b/src/alert.h
@@ -60,9 +60,9 @@ public:
         READWRITE(setSubVer);
         READWRITE(nPriority);
 
-        READWRITE(strComment);
-        READWRITE(strStatusBar);
-        READWRITE(strReserved);
+        READWRITE(LIMITED_STRING(strComment, 65536));
+        READWRITE(LIMITED_STRING(strStatusBar, 256));
+        READWRITE(LIMITED_STRING(strReserved, 256));
     )
 
     void SetNull();
diff --git a/src/main.cpp b/src/main.cpp
index ba521b6b1..dec5bb652 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -3559,7 +3559,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         if (!vRecv.empty())
             vRecv >> addrFrom >> nNonce;
         if (!vRecv.empty()) {
-            vRecv >> pfrom->strSubVer;
+            vRecv >> LIMITED_STRING(pfrom->strSubVer, 256);
             pfrom->cleanSubVer = SanitizeString(pfrom->strSubVer);
         }
         if (!vRecv.empty())
@@ -4183,7 +4183,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         if (fDebug)
         {
             string strMsg; unsigned char ccode; string strReason;
-            vRecv >> strMsg >> ccode >> strReason;
+            vRecv >> LIMITED_STRING(strMsg, CMessageHeader::COMMAND_SIZE) >> ccode >> LIMITED_STRING(strReason, 111);
 
             ostringstream ss;
             ss << strMsg << " code " << itostr(ccode) << ": " << strReason;
@@ -4194,10 +4194,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
                 vRecv >> hash;
                 ss << ": hash " << hash.ToString();
             }
-            // Truncate to reasonable length and sanitize before printing:
-            string s = ss.str();
-            if (s.size() > 111) s.erase(111, string::npos);
-            LogPrint("net", "Reject %s\n", SanitizeString(s));
+            LogPrint("net", "Reject %s\n", SanitizeString(ss.str()));
         }
     }
 
diff --git a/src/serialize.h b/src/serialize.h
index f876efd9b..2eb69b3ec 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -334,8 +334,9 @@ I ReadVarInt(Stream& is)
     }
 }
 
-#define FLATDATA(obj)  REF(CFlatData((char*)&(obj), (char*)&(obj) + sizeof(obj)))
-#define VARINT(obj)    REF(WrapVarInt(REF(obj)))
+#define FLATDATA(obj) REF(CFlatData((char*)&(obj), (char*)&(obj) + sizeof(obj)))
+#define VARINT(obj) REF(WrapVarInt(REF(obj)))
+#define LIMITED_STRING(obj,n) REF(LimitedString< n >(REF(obj)))
 
 /** Wrapper for serializing arrays and POD.
  */
@@ -398,6 +399,40 @@ public:
     }
 };
 
+template<size_t Limit>
+class LimitedString
+{
+protected:
+    std::string& string;
+public:
+    LimitedString(std::string& string) : string(string) {}
+
+    template<typename Stream>
+    void Unserialize(Stream& s, int, int=0)
+    {
+        size_t size = ReadCompactSize(s);
+        if (size > Limit) {
+            throw std::ios_base::failure("String length limit exceeded");
+        }
+        string.resize(size);
+        if (size != 0)
+            s.read((char*)&string[0], size);
+    }
+
+    template<typename Stream>
+    void Serialize(Stream& s, int, int=0) const
+    {
+        WriteCompactSize(s, string.size());
+        if (!string.empty())
+            s.write((char*)&string[0], string.size());
+    }
+
+    unsigned int GetSerializeSize(int, int=0) const
+    {
+        return GetSizeOfCompactSize(string.size()) + string.size();
+    }
+};
+
 template<typename I>
 CVarInt<I> WrapVarInt(I& n) { return CVarInt<I>(n); }
 
diff --git a/src/wallet.h b/src/wallet.h
index 73fcfa24e..864a635ec 100644
--- a/src/wallet.h
+++ b/src/wallet.h
@@ -858,7 +858,7 @@ public:
         READWRITE(vchPrivKey);
         READWRITE(nTimeCreated);
         READWRITE(nTimeExpires);
-        READWRITE(strComment);
+        READWRITE(LIMITED_STRING(strComment, 65536));
     )
 };
 
@@ -933,7 +933,7 @@ public:
         // Note: strAccount is serialized as part of the key, not here.
         READWRITE(nCreditDebit);
         READWRITE(nTime);
-        READWRITE(strOtherAccount);
+        READWRITE(LIMITED_STRING(strOtherAccount, 65536));
 
         if (!fRead)
         {
@@ -949,7 +949,7 @@ public:
             }
         }
 
-        READWRITE(strComment);
+        READWRITE(LIMITED_STRING(strComment, 65536));
 
         size_t nSepPos = strComment.find("\0", 0, 1);
         if (fRead)