Add read-only access to POST data for webRequest's onBeforeRequest

chrome/browser/extensions/api/web_request/post_data_parser.h

+// Copyright (c) 2012 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.
+
+#ifndef CHROME_BROWSER_EXTENSIONS_API_WEB_REQUEST_POST_DATA_PARSER_H_
+#define CHROME_BROWSER_EXTENSIONS_API_WEB_REQUEST_POST_DATA_PARSER_H_
+
+#include <string>
+#include <vector>
+
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/string_piece.h"
+
+namespace base {
+class DictionaryValue;
+}
+
+namespace net {
+class URLRequest;
+}
+
+namespace extensions {
+
+// Interface for parsers for the POST data.
+class PostDataParser {
+ public:
+  class Result {
+   public:
+    Result();
+    ~Result();
+    const std::string& get_key() const {

[Matt Perry, 2012/07/30 16:14:15]

just key() and val() for accessors

[vabr (Chromium), 2012/07/31 09:03:18]

Done.

+      return key_;
+    }
+    const std::string& get_val() const {
+      return val_;
+    }
+    void Reset();
+    void SetKey(const char* s, size_t n);

[Matt Perry, 2012/07/30 16:14:15]

do you know about StringPiece? That's generally preferred when you need
raw_string+size. I think it would also serve for the std::string version too.

[vabr (Chromium), 2012/07/31 09:03:18]

I changed the char*+size_t to StringPiece because it certainly increases the
readability, and does the same thing behind scenes. However, I would like to
retain the std::string version, it spares one copying of the string, compared to
going through StringPiece, and I don't think the code is obfuscated by this.

+    void SetKey(const std::string& str);
+    void SetVal(const char* s, size_t n);
+    void SetVal(const std::string& str);
+
+   private:
+    std::string key_;
+    std::string val_;
+  };
+  // Creates a correct parser instance based on the |request|. Returns NULL

[Matt Perry, 2012/07/30 16:14:15]

This class could use some vertical whitespace. Put a newline before each of
these comment blocks.

[vabr (Chromium), 2012/07/31 09:03:18]

Done.

+  // on failure.
+  static scoped_ptr<PostDataParser> CreatePostDataParser(
+      const net::URLRequest* request);
+  // Creates a correct parser instance based on the |content_type| of
+  // "Content-Type" URLRequest headers. If |content_type| is NULL, it defaults
+  // to "application/x-www-form-urlencoded". Returns NULL on failure.
+  static scoped_ptr<PostDataParser> CreatePostDataParser(
+      const std::string* content_type);
+  // Tries to parse the POST data of |request| to extract encoded forms.
+  // On success returns the parsed data, otherwise NULL.
+  static scoped_ptr<base::DictionaryValue> ParseURLRequestData(
+      const net::URLRequest* request);
+  // No member variables, so the destructor can be safely inlined.
+  virtual ~PostDataParser();
+  // Returns true if there was some data, it was well formed and all was read.
+  virtual bool AllDataReadOK() = 0;
+  // Returns the next key-value pair as |result|. After SetSource has succeeded,
+  // this allows to iterate over all pairs in the source.
+  // Returns true as long as a new pair was successfully found.
+  virtual bool GetNextPair(Result* result) = 0;
+  // Sets the |source| of the data to be parsed. The ownership is let with the
+  // caller and the source should live until |this| dies or |this->SetSource()|
+  // is called again, whatever comes sooner. Returns true on success.
+  virtual bool SetSource(const std::vector<char>* source) = 0;
+
+ protected:
+  PostDataParser() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(PostDataParser);
+};
+
+// Parses URLencoded forms, see
+// http://www.w3.org/TR/REC-html40-971218/interact/forms.html#h-17.13.4.1 .
+class PostDataParserUrlEncoded : public PostDataParser {
+ public:
+  PostDataParserUrlEncoded();
+  virtual ~PostDataParserUrlEncoded();
+  // Implementation of PostDataParser.
+  virtual bool AllDataReadOK() OVERRIDE;
+  virtual bool GetNextPair(Result* result) OVERRIDE;
+  virtual bool SetSource(const std::vector<char>* source) OVERRIDE;
+
+ private:
+  const std::vector<char>* source_;
+  std::vector<char>::const_iterator offset_;
+  DISALLOW_COPY_AND_ASSIGN(PostDataParserUrlEncoded);
+};
+
+// Parses forms encoded as multipart, see RFC2388.
+class PostDataParserMultipart : public PostDataParser {
+ public:
+  explicit PostDataParserMultipart(const std::string& boundary_separator);
+  virtual ~PostDataParserMultipart();
+  // Implementation of PostDataParser.
+  virtual bool AllDataReadOK() OVERRIDE;
+  virtual bool GetNextPair(Result* result) OVERRIDE;
+  virtual bool SetSource(const std::vector<char>* source) OVERRIDE;
+
+ private:
+  // Note on implementation:
+  // This parser reads the source line by line. There are four types of lines:
+  // - "Boundary" line, separating entries.
+  // - "End boundary" line, ends the data.
+  // - "Content-Disposition" line, containing the "key" for |result|.
+  // - Empty lines.
+  // - Other non-empty lines.
+  enum LineType {kBoundary, kEndBoundary, kDisposition, kEmpty, kOther};
+  // The parser uses the following 7-state automaton to check for structure:
+  // kInit --Boundary--> kHeadStart, kInit --not(Boundary)--> kError
+  // kHeadStart --Disposition--> kHeadRead,
+  //     kHeadStart --not(Disposition)--> kHead
+  // kHead --Disposition--> kHeadRead, kHead --not(Disposition)-->kHead
+  // kHeadRead --Empty-->kBody, kHeadRead --not(Empty)--> kHeadRead
+  // kBody --Boundary--> kHeadStart, kBody --EndBoundary--> kFinal,
+  //     kBody --not(Boundary OR EndBoundary)--> kBody
+  enum State {kInit, kHeadStart, kHead, kHeadRead, kBody, kFinal, kError};
+  // One-step of the automaton, based on |state_| and |line_type_|.
+  // This calls SeekNextLine() and returns it return value.
+  bool DoStep();
+  // Determine the |line_type_| of the current line_start_.
+  LineType GetLineType();
+  // Read one more line from |source_|, update line pointers.
+  bool SeekNextLine();
+  // Extracts "key" and possibly "val" from a DISP line. Returns success.
+  bool ParseHead(Result* result, bool* val_extracted);
+  // We parse the first |length_| bytes from |source_|.
+  const char* source_;
+  size_t length_;
+  // Offset of the current and next line from |source_|:
+  // [line_start_]...line... [line_end_]EOL [next_line_]...line...
+  size_t line_start_;  // Points at the first character of the current line.
+  size_t line_end_;  // Points right beyond the last character of the line.
+  size_t next_line_;  // First char. of the next line, or beyond source length.
+  const std::string boundary_;
+  const std::string final_boundary_;
+  State state_;
+  LineType line_type_;
+  DISALLOW_COPY_AND_ASSIGN(PostDataParserMultipart);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_WEB_REQUEST_POST_DATA_PARSER_H_