Support replacement of IP address resolutions via command line flag

net/base/ip_mapping_rules.cc

Index: net/base/ip_mapping_rules.cc
diff --git a/net/base/ip_mapping_rules.cc b/net/base/ip_mapping_rules.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1f16bc39eeefa53d594ac607105e263563bbd4aa
--- /dev/null
+++ b/net/base/ip_mapping_rules.cc
@@ -0,0 +1,127 @@
+// Copyright (c) 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "net/base/ip_mapping_rules.h"
+
+#include <vector>
+
+#include "base/logging.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_split.h"
+#include "base/strings/string_tokenizer.h"
+#include "base/strings/string_util.h"
+#include "net/base/ip_pattern.h"
+
+namespace net {
+
+class IPMappingRules::MapRule {
+ public:
+  MapRule(const IPAddressNumber& address,
+          IPPattern* pattern,
+          MapRule* next)
+      : next_(next),
+        pattern_(pattern),
+        address_(address) {
+  }
+
+  bool Match(const IPAddressNumber& address) const {
+    return pattern_->Match(address);
+  }
+
+  const IPAddressNumber& Address() const { return address_; }

[wtc, 2014/02/11 23:52:30]

Nit: this getter method should be lowercase "address()".

[jar (doing other things), 2014/02/15 21:14:56]

Done.

+  MapRule* next() const { return next_; }
+
+ private:
+  MapRule* next_;                  // Linked list of other rules.
+  scoped_ptr<IPPattern> pattern_;  // The pattern we can match.

[wtc, 2014/02/11 23:52:30]

You should be able to declare this member as
  IPPattern pattern_;

This eliminates one heap allocation. It will require you to provide a getter
method for the pattern_ member. I think you can just declare this class as a
struct and make all data members public.

[jar (doing other things), 2014/02/15 21:14:56]

Done.

+  IPAddressNumber address_;        // The replacement address we provide.

[wtc, 2014/02/11 23:52:30]

Nit: I suggest renaming this member "replacement_address_".

[jar (doing other things), 2014/02/15 21:14:56]

Done.

+  DISALLOW_COPY_AND_ASSIGN(MapRule);
+};
+
+IPMappingRules::IPMappingRules() : first_rule_(NULL) {}
+
+IPMappingRules::~IPMappingRules() {
+  DeleteRules();
+}
+
+bool IPMappingRules::RewriteAddresses(AddressList* addresses) const {
+  for (MapRule* next_rule = first_rule_;

[wtc, 2014/02/11 23:52:30]

Nit: I suggest "next_rule" be renamed "rule".

[jar (doing other things), 2014/02/15 21:14:56]

Done (plus new container refector)

+       next_rule != NULL; next_rule = next_rule->next()) {
+    for (AddressList::iterator address_it = addresses->begin();
+        address_it != addresses->end(); ++address_it) {
+      if (!next_rule->Match(address_it->address())) {
+        continue;
+      }

[wtc, 2014/02/11 23:52:30]

Nit: omit curly braces.

[jar (doing other things), 2014/02/15 21:14:56]

I thought net/* style was to *always* use curlies.  I'm assuming this is an
exception....  I like it better.. and will do so consistently.

Done.

+      // We have a match.
+      int port = address_it->port();
+      addresses->insert(addresses->begin(),
+                        IPEndPoint(next_rule->Address(), port));
+      return true;
+    }
+  }
+  return false;
+}
+
+bool IPMappingRules::AddRuleFromString(const std::string& rule_string) {
+  std::string trimmed;
+  TrimWhitespaceASCII(rule_string, TRIM_ALL, &trimmed);
+  if (trimmed == "")

[wtc, 2014/02/11 23:52:30]

Nit: test trimmed.empty().

[jar (doing other things), 2014/02/15 21:14:56]

Done.

+    return true;  // Allow empty rules.
+
+  std::vector<std::string> parts;
+  base::SplitString(trimmed, ' ', &parts);
+
+  if (parts.size() != 3) {
+    DVLOG(1) << "Rule has wrong number of parts: " << rule_string;
+    return false;
+  }
+
+  if (!LowerCaseEqualsASCII(parts[0], "preface")) {
+    DVLOG(1) << "Rule missing directive: " << rule_string;

[wtc, 2014/02/11 23:52:30]

The error message should be "Unknown directive".

[jar (doing other things), 2014/02/15 21:14:56]

Done.

+    return false;
+  }
+
+  scoped_ptr<IPPattern> pattern(new IPPattern);
+  if (!pattern->ParsePattern(parts[1])) {
+    DVLOG(1) << "Unacceptable pattern: " << rule_string;
+    return false;
+  }
+
+  IPAddressNumber address;
+  if (!ParseIPLiteralToNumber(parts[2], &address)) {
+    DVLOG(1) << "Invalid replacement address: " << rule_string;
+    return false;
+  }
+
+  if (pattern->is_ipv4() != (address.size() == kIPv4AddressSize)) {
+    DVLOG(1) << "Mixture of IPv4 and IPv6: " << rule_string;
+    return false;
+  }
+  // Push a new MapRule, linking it to point at our previous list.
+  first_rule_  = new MapRule(address, pattern.release(), first_rule_);
+  return true;
+}
+
+bool IPMappingRules::SetRulesFromString(const std::string& rules_string) {
+  DeleteRules();
+
+  base::StringTokenizer rules(rules_string, ";");
+  while (rules.GetNext()) {
+    if (!AddRuleFromString(rules.token())) {
+      DVLOG(1) << "Failed parsing rule: " << rules.token();
+      DeleteRules();
+      return false;
+    }
+  }
+  return true;
+}
+
+void IPMappingRules::DeleteRules() {
+  while (first_rule_ != NULL) {
+    MapRule* rule = first_rule_;
+    first_rule_ = first_rule_->next();
+    delete rule;
+  }
+}
+}  // namespace net