Issue 5146 - Part 2: Process http response in C++

compiled/subscription/DownloadableSubscription.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 68 matching lines @@
         param.first.toLower();
         param.second = DependentString(
           text, beginValue, text.length() - beginValue);
       }
     }
     return param;
   }
 }
 
 DownloadableSubscription_Parser::DownloadableSubscription_Parser()
-  : mFirstLine(true)
 {
   annotate_address(this, "DownloadableSubscription_Parser");
 }
 
 namespace {
   const DependentString ADBLOCK_HEADER(u"[Adblock"_str);
+  const DependentString ADBLOCK_PLUS_EXTRA_HEADER(u"Plus"_str);
+
+  const DependentString ERROR_INVALID_DATA(u"synchronize_invalid_data"_str);
 
   // Only check for trailing base64 padding. There should be at most 2 '='.
   // In that case return a truncated string.
   DependentString CleanUpChecksum(const String& checksum)
   {
     const auto len = checksum.length();
     if ((len > 22 && len <= 24) &&
         (checksum[22] == u'=' && (len == 23 || checksum[23] == u'=')))
       return DependentString(checksum, 0, 22);
     return DependentString(checksum);
   }
 }
 
-void DownloadableSubscription_Parser::Process(const String& line)
+/// Return true if more line expected.
+bool DownloadableSubscription_Parser::GetNextLine(DependentString& buffer, DependentString& line)
 {
-  bool isHeader = false;
-  isHeader = line.find(ADBLOCK_HEADER) != String::npos;
-  if (!isHeader)
+  StringScanner scanner(buffer);
+  String::value_type ch = 0;
+  while (ch != u'\r' && ch != u'\n')
   {
-    auto param = ParseParam(line);
-    if (param.first.is_invalid())
-      mFiltersText.emplace_back(line);
-    else if (param.first == u"checksum"_str)
+    ch = scanner.next();
+    if (ch == 0)
+      break;
+  }
+
+  auto eol = scanner.position();
+  line.reset(buffer, 0, eol);
+  if (eol == 0 || ch == 0)
+    return false;
+  while (scanner.skipOne(u'\r') || scanner.skipOne(u'\n'))
+    ;
+  buffer.reset(buffer, scanner.position() + 1);
+  return true;
+}
+
+bool DownloadableSubscription_Parser::Process(const String& buffer)
+{
+  DependentString currentBuffer(buffer);
+  bool firstLine = true;
+
+  DependentString line;
+  while (true)
+  {
+    bool more = GetNextLine(currentBuffer, line);
+    if (firstLine)
     {
-      mParams[param.first] = CleanUpChecksum(param.second);
-      return;
+      if (!ProcessFirstLine(line))
+      {
+        mError = ERROR_INVALID_DATA;
+        return false;
+      }
+      firstLine = false;
     }
     else
-      mParams[param.first] = param.second;
+      ProcessLine(line);
+    if (!more)
+      break;
   }
+  return true;
+}
+
+bool DownloadableSubscription_Parser::ProcessFirstLine(const String& line)
+{
+  auto index = line.find(ADBLOCK_HEADER);
+  if (index == String::npos)
+    return false;
+
+  DependentString minVersion;
+  DependentString current(line, index + ADBLOCK_HEADER.length());
+  StringScanner scanner(current);
+  if (scanner.skipWhiteSpace() && scanner.skipString(ADBLOCK_PLUS_EXTRA_HEADER))
+    scanner.skipWhiteSpace();
+  index = scanner.position() + 1;
+  String::value_type ch = u'\0';
+  while((ch = scanner.next()) && (ch == u'.' || std::iswdigit(ch)))
+    ;
+  if (ch)
+    scanner.back();
+  if (scanner.position() + 1 > index)
+    minVersion.reset(current, index, scanner.position() + 1 - index);
+
+  if (ch != u']')
+    return false;
+
+  mRequiredVersion = minVersion;
+  mChecksum.Update(line);
+  return true;
+}
+
+void DownloadableSubscription_Parser::ProcessLine(const String& line)
+{
+  auto param = ParseParam(line);
+  if (param.first.is_invalid())
+  {
+    if (!line.empty())
+      mFiltersText.emplace_back(line);
+  }
+  else if (param.first == u"checksum"_str)
+  {
+    mParams[param.first] = CleanUpChecksum(param.second);
+    return;
+  }
+  else
+    mParams[param.first] = param.second;
+
   // Checksum is an MD5 checksum (base64-encoded without the trailing "=") of
   // all lines in UTF-8 without the checksum line, joined with "\n".
-  if (!mFirstLine)
-    mChecksum.Update((const uint8_t*)"\n", 1);
-  else
-    mFirstLine = false;
+  mChecksum.Update((const uint8_t*)"\n", 1);
   mChecksum.Update(line);
 }
 
 int64_t DownloadableSubscription_Parser::ParseExpires(const String& expires)
 {
   bool isHour = false;
   StringScanner scanner(expires);
   String::size_type numStart = 0;
   String::size_type numLen = 0;
   while(!scanner.done())
@@ skipping 55 matching lines @@
     mB64Checksum = ToBase64(checksum, MD5::CHECKSUM_LENGTH);
   }
   return (mParams[u"checksum"_str] == mB64Checksum);
 }
 
 int64_t DownloadableSubscription_Parser::Finalize(DownloadableSubscription& subscription)
 {
   if (mB64Checksum.is_invalid())
     VerifyChecksum(); // here we ignore the checksum, but we calculate it.
 
+  FilterNotifier::SubscriptionChange(
+    FilterNotifier::Topic::SUBSCRIPTION_BEFORE_FILTERS_REPLACED,
+    subscription);
+
+  if (!mRequiredVersion.empty())
+    subscription.SetRequiredVersion(mRequiredVersion);
+
   auto entry = mParams.find(u"title"_str);
   if (entry)
   {
     subscription.SetTitle(entry->second);
     subscription.SetFixedTitle(true);
   }
   else
     subscription.SetFixedTitle(false);
 
   int32_t version = 0;
   entry = mParams.find(u"version"_str);
   if (entry)
     version = entry->second.toInt<int32_t>();
   subscription.SetDataRevision(version);
 
   int64_t expires = 0;
   entry = mParams.find(u"expires"_str);
   if (entry)
     expires = ParseExpires(entry->second);
 
-  FilterNotifier::SubscriptionChange(
-    FilterNotifier::Topic::SUBSCRIPTION_BEFORE_FILTERS_REPLACED,
-    subscription);
-
   Subscription::Filters filters;
   filters.reserve(mFiltersText.size());
   for (auto text : mFiltersText)
   {
     DependentString dependent(text);
     filters.emplace_back(Filter::FromText(dependent), false);
   }
 
   subscription.SetFilters(std::move(filters));
   FilterNotifier::SubscriptionChange(
@@ skipping 101 matching lines @@
     result.append(u'\n');
   }
   if (mDownloadCount)
   {
     result.append(u"downloadCount="_str);
     result.append(mDownloadCount);
     result.append(u'\n');
   }
   return result;
 }