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- // Copyright 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.
- // The GZipHeader class allows you to parse a gzip header, such as you
- // might find at the beginning of a file compressed by gzip (ie, a .gz
- // file), or at the beginning of an HTTP response that uses a gzip
- // Content-Encoding. See RFC 1952 for the specification for the gzip
- // header.
- //
- // The model is that you call ReadMore() for each chunk of bytes
- // you've read from a file or socket.
- //
- #ifndef NET_FILTER_GZIP_HEADER_H_
- #define NET_FILTER_GZIP_HEADER_H_
- #include <stddef.h>
- #include <stdint.h>
- #include "net/base/net_export.h"
- namespace net {
- class NET_EXPORT GZipHeader {
- public:
- enum Status {
- INCOMPLETE_HEADER, // don't have all the bits yet...
- COMPLETE_HEADER, // complete, valid header
- INVALID_HEADER, // found something invalid in the header
- };
- GZipHeader();
- GZipHeader(const GZipHeader&) = delete;
- GZipHeader& operator=(const GZipHeader&) = delete;
- ~GZipHeader();
- // Wipe the slate clean and start from scratch.
- void Reset();
- // Attempt to parse the given buffer as the next installment of
- // bytes from a gzip header. If the bytes we've seen so far do not
- // yet constitute a complete gzip header, return
- // INCOMPLETE_HEADER. If these bytes do not constitute a *valid*
- // gzip header, return INVALID_HEADER. When we've seen a complete
- // gzip header, return COMPLETE_HEADER and set the pointer pointed
- // to by header_end to the first byte beyond the gzip header.
- Status ReadMore(const char* inbuf, size_t inbuf_len, const char** header_end);
- private:
- enum { // flags (see RFC)
- FLAG_FTEXT = 0x01, // bit 0 set: file probably ascii text
- FLAG_FHCRC = 0x02, // bit 1 set: header CRC present
- FLAG_FEXTRA = 0x04, // bit 2 set: extra field present
- FLAG_FNAME = 0x08, // bit 3 set: original file name present
- FLAG_FCOMMENT = 0x10, // bit 4 set: file comment present
- FLAG_RESERVED = 0xE0, // bits 5..7: reserved
- };
- enum State {
- // The first 10 bytes are the fixed-size header:
- IN_HEADER_ID1,
- IN_HEADER_ID2,
- IN_HEADER_CM,
- IN_HEADER_FLG,
- IN_HEADER_MTIME_BYTE_0,
- IN_HEADER_MTIME_BYTE_1,
- IN_HEADER_MTIME_BYTE_2,
- IN_HEADER_MTIME_BYTE_3,
- IN_HEADER_XFL,
- IN_HEADER_OS,
- IN_XLEN_BYTE_0,
- IN_XLEN_BYTE_1,
- IN_FEXTRA,
- IN_FNAME,
- IN_FCOMMENT,
- IN_FHCRC_BYTE_0,
- IN_FHCRC_BYTE_1,
- IN_DONE,
- };
- static const uint8_t magic[]; // gzip magic header
- int state_; // our current State in the parsing FSM: an int so we can ++
- uint8_t flags_; // the flags byte of the header ("FLG" in the RFC)
- uint16_t extra_length_; // how much of the "extra field" we have yet to read
- };
- } // namespace net
- #endif // NET_FILTER_GZIP_HEADER_H_
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