1 files changed, 7 insertions, 3 deletions
diff --git a/Swiften/IDN/LibIDNConverter.cpp b/Swiften/IDN/LibIDNConverter.cpp
index 0c01352..e2a87be 100644
--- a/Swiften/IDN/LibIDNConverter.cpp
+++ b/Swiften/IDN/LibIDNConverter.cpp
@@ -1,11 +1,11 @@
 /*
- * Copyright (c) 2012-2016 Isode Limited.
+ * Copyright (c) 2012-2018 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
 
 #include <Swiften/IDN/LibIDNConverter.h>
 
 extern "C" {
     #include <stringprep.h>
     #include <idna.h>
@@ -18,19 +18,19 @@ extern "C" {
 #include <memory>
 
 #include <Swiften/Base/ByteArray.h>
 #include <Swiften/Base/SafeAllocator.h>
 #include <Swiften/IDN/UTF8Validator.h>
 
 using namespace Swift;
 
 namespace {
-    static const int MAX_STRINGPREP_SIZE = 1024;
+    static const size_t MAX_STRINGPREP_SIZE = 1024;
 
     const Stringprep_profile* getLibIDNProfile(IDNConverter::StringPrepProfile profile) {
         switch(profile) {
             case IDNConverter::NamePrep: return stringprep_nameprep;
             case IDNConverter::XMPPNodePrep: return stringprep_xmpp_nodeprep;
             case IDNConverter::XMPPResourcePrep: return stringprep_xmpp_resourceprep;
             case IDNConverter::SASLPrep: return stringprep_saslprep;
         }
         assert(false);
@@ -38,19 +38,20 @@ namespace {
     }
 
     template<typename StringType, typename ContainerType>
     ContainerType getStringPreparedInternal(const StringType& s, IDNConverter::StringPrepProfile profile) {
         ContainerType input(s.begin(), s.end());
         if (!UTF8IsValid(s.data(), s.size())) {
             return ContainerType();
         }
 
-        input.resize(MAX_STRINGPREP_SIZE);
+        // Ensure we have enough space for stringprepping, and that input is always NUL terminated
+        input.resize(std::max(MAX_STRINGPREP_SIZE, input.size() + 1));
         if (stringprep(&input[0], MAX_STRINGPREP_SIZE, static_cast<Stringprep_profile_flags>(0), getLibIDNProfile(profile)) == 0) {
             return input;
         }
         else {
             return ContainerType();
         }
     }
 }
 
@@ -71,17 +72,20 @@ SafeByteArray LibIDNConverter::getStringPrepared(const SafeByteArray& s, StringP
     }
     return createSafeByteArray(reinterpret_cast<const char*>(vecptr(preparedData)));
 }
 
 boost::optional<std::string> LibIDNConverter::getIDNAEncoded(const std::string& domain) {
     char* output;
     if (idna_to_ascii_8z(domain.c_str(), &output, IDNA_USE_STD3_ASCII_RULES) == IDNA_SUCCESS) {
         std::string result(output);
         free(output);
+        if (result.size() > 255) {
+            return boost::optional<std::string>();
+        }
         return result;
     }
     else {
         return boost::optional<std::string>();
     }
 }
 
 }