Support replacement of IP address resolutions via command line flag

net/base/ip_pattern.cc

Index: net/base/ip_pattern.cc
diff --git a/net/base/ip_pattern.cc b/net/base/ip_pattern.cc
new file mode 100644
index 0000000000000000000000000000000000000000..780be8db909956c225d862aa1520ee183229f2ab
--- /dev/null
+++ b/net/base/ip_pattern.cc
@@ -0,0 +1,188 @@
+// 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_pattern.h"
+
+#include <string>
+
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/stl_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_split.h"
+#include "base/strings/string_tokenizer.h"
+
+namespace net {
+
+class IPPattern::ComponentPattern {
+ public:
+  ComponentPattern();
+  void AppendRange(uint32 min, uint32 max);
+  bool Match(uint32 value) const;
+
+ private:
+  struct Range {
+   public:
+    Range(uint32 min, uint32 max) : minimum(min), maximum(max) {}
+    uint32 minimum;
+    uint32 maximum;
+  };
+  typedef std::vector<Range> RangeVector;
+
+  RangeVector ranges_;
+
+  DISALLOW_COPY_AND_ASSIGN(ComponentPattern);
+};
+
+IPPattern::ComponentPattern::ComponentPattern() {}
+
+void IPPattern::ComponentPattern::AppendRange(uint32 min, uint32 max) {
+  ranges_.push_back(Range(min, max));
+}
+
+bool IPPattern::ComponentPattern::Match(uint32 value) const {
+  // Simple linear search should be fine, as we usually only have very few
+  // distinct ranges to test.
+  for (RangeVector::const_iterator range_it = ranges_.begin();
+       range_it != ranges_.end(); ++range_it) {
+    if (range_it->maximum >= value && range_it->minimum <= value)
+      return true;
+  }
+  return false;
+}
+
+IPPattern::IPPattern() : is_ipv4_(true) {}
+
+IPPattern::~IPPattern() {
+  STLDeleteElements(&component_patterns_);
+}
+
+bool IPPattern::Match(const IPAddressNumber& address) const {
+  if (ip_mask_.empty())
+    return false;
+  bool address_is_ipv4 = address.size() == kIPv4AddressSize;
+  if (address_is_ipv4 != is_ipv4_)
+    return false;
+
+  ComponentPatternList::const_iterator pattern_it(component_patterns_.begin());
+  int fixed_value_index = 0;
+  // IPv6 |address| vectors have 16 pieces, while our  |ip_mask_| has only
+  // 8, so it is easier to count separately.
+  int address_index = 0;
+  for (size_t i = 0; i < ip_mask_.size(); ++i) {
+    uint32 value_to_test = address[address_index++];
+    if (!is_ipv4_) {
+      value_to_test = (value_to_test << 8) + address[address_index++];
+    }
+    if (ip_mask_[i]) {
+      if (component_values_[fixed_value_index++] != value_to_test)
+        return false;
+      continue;
+    }
+    if (!(*pattern_it)->Match(value_to_test))
+      return false;
+    ++pattern_it;
+  }
+  return true;
+}
+
+bool IPPattern::ParsePattern(const std::string& ip_pattern) {
+  DCHECK(ip_mask_.empty());
+  if (ip_pattern.find(':') != std::string::npos) {
+    is_ipv4_ = false;
+  }
+  Strings components;
+  base::SplitString(ip_pattern, is_ipv4_ ? '.' : ':', &components);
+  if (components.size() != (is_ipv4_ ? 4u : 8u)) {
+    DVLOG(1) << "Invalid component count: " << ip_pattern;
+    return false;
+  }
+  for (Strings::iterator component_it = components.begin();
+       component_it != components.end(); ++component_it) {
+    if (component_it->empty()) {
+      DVLOG(1) << "Empty component: " << ip_pattern;
+      return false;
+    }
+    if (*component_it == "*") {
+      // Let standard code handle this below.
+      *component_it = is_ipv4_ ? "[0-255]" : "[0-FFFF]";
+    } else if ((*component_it)[0] != '[') {
+      // This value will just have a specific integer to match.
+      uint32 value;
+      if (!ValueTextToInt(*component_it, &value))
+        return false;
+      ip_mask_.push_back(true);
+      component_values_.push_back(value);
+      continue;
+    }
+    if ((*component_it)[component_it->size() - 1] != ']') {
+      DVLOG(1) << "Missing close bracket: " << ip_pattern;
+      return false;
+    }
+    // Now we know the size() is at least 2.
+    if (component_it->size() == 2) {
+      DVLOG(1) << "Empty bracket: " << ip_pattern;
+      return false;
+    }
+    // We'll need a pattern to match this bracketed component.
+    scoped_ptr<ComponentPattern> component_pattern(new ComponentPattern);
+    // Trim leading and trailing bracket before calling for parsing.
+    if (!ParseComponentPattern(base::StringPiece(component_it->data() + 1,
+        component_it->size() - 2), component_pattern.get())) {
+      return false;
+    }
+    ip_mask_.push_back(false);
+    component_patterns_.push_back(component_pattern.release());
+  }
+  return true;
+}
+
+bool IPPattern::ParseComponentPattern(const base::StringPiece& text,
+                                      ComponentPattern* pattern) const {
+  // We're given a comma separated set of ranges, some of which may be simple
+  // constants.
+  Strings ranges;
+  base::SplitString(text.as_string(), ',', &ranges);
+  for (Strings::iterator range_it = ranges.begin();
+        range_it != ranges.end(); ++range_it) {
+    base::StringTokenizer range_pair(*range_it, "-");
+    uint32 min = 0;
+    range_pair.GetNext();
+    if (!ValueTextToInt(range_pair.token(), &min))
+      return false;
+    uint32 max = min;  // Sometimes we have no distinct max.
+    if (range_pair.GetNext()) {
+      if (!ValueTextToInt(range_pair.token(), &max))
+        return false;
+    }
+    if (range_pair.GetNext()) {
+      // Too many "-" in this range specifier.
+      DVLOG(1) << "Too many hyphens in range: ";
+      return false;
+    }
+    pattern->AppendRange(min, max);
+  }
+  return true;
+}
+
+bool IPPattern::ValueTextToInt(const base::StringPiece& input,
+                               uint32* output) const {
+  bool ok = is_ipv4_ ? base::StringToUint(input, output) :
+                       base::HexStringToUInt(input, output);
+  if (!ok) {
+    DVLOG(1) << "Could not convert value to number: " << input;
+    return false;
+  }
+  if (is_ipv4_ && *output > 255u) {
+    DVLOG(1) << "IPv4 component greater than 255";
+    return false;
+  }
+  if (!is_ipv4_ && *output > 0xFFFFu) {
+    DVLOG(1) << "IPv6 component greater than 0xFFFF";
+    return false;
+  }
+  return ok;
+}
+
+}  // namespace net