Eric Lee / smarc-fsl-linux-kernel

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  #ifndef __NET_GUE_H
  #define __NET_GUE_H
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  /* Definitions for the GUE header, standard and private flags, lengths
   * of optional fields are below.
   *
   * Diagram of GUE header:
   *
   * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   * |Ver|C|  Hlen   | Proto/ctype   |        Standard flags       |P|
   * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   * |                                                               |
   * ~                      Fields (optional)                        ~
   * |                                                               |
   * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   * |            Private flags (optional, P bit is set)             |
   * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   * |                                                               |
   * ~                   Private fields (optional)                   ~
   * |                                                               |
   * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   *
   * C bit indicates contol message when set, data message when unset.
   * For a control message, proto/ctype is interpreted as a type of
   * control message. For data messages, proto/ctype is the IP protocol
   * of the next header.
   *
   * P bit indicates private flags field is present. The private flags
   * may refer to options placed after this field.
   */
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  struct guehdr {
  	union {
  		struct {
  #if defined(__LITTLE_ENDIAN_BITFIELD)
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  			__u8	hlen:5,
  				control:1,
  				version:2;
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  #elif defined (__BIG_ENDIAN_BITFIELD)
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  			__u8	version:2,
  				control:1,
  				hlen:5;
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  #else
  #error  "Please fix <asm/byteorder.h>"
  #endif
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  			__u8    proto_ctype;
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  			__u16   flags;
  		};
  		__u32 word;
  	};
  };
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  /* Standard flags in GUE header */
  
  #define GUE_FLAG_PRIV	htons(1<<0)	/* Private flags are in options */
  #define GUE_LEN_PRIV	4
  
  #define GUE_FLAGS_ALL	(GUE_FLAG_PRIV)
  
  /* Private flags in the private option extension */
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  #define GUE_PFLAG_REMCSUM	htonl(1 << 31)
  #define GUE_PLEN_REMCSUM	4
  
  #define GUE_PFLAGS_ALL	(GUE_PFLAG_REMCSUM)
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  /* Functions to compute options length corresponding to flags.
   * If we ever have a lot of flags this can be potentially be
   * converted to a more optimized algorithm (table lookup
   * for instance).
   */
  static inline size_t guehdr_flags_len(__be16 flags)
  {
  	return ((flags & GUE_FLAG_PRIV) ? GUE_LEN_PRIV : 0);
  }
  
  static inline size_t guehdr_priv_flags_len(__be32 flags)
  {
  	return 0;
  }
  
  /* Validate standard and private flags. Returns non-zero (meaning invalid)
   * if there is an unknown standard or private flags, or the options length for
   * the flags exceeds the options length specific in hlen of the GUE header.
   */
  static inline int validate_gue_flags(struct guehdr *guehdr,
  				     size_t optlen)
  {
  	size_t len;
  	__be32 flags = guehdr->flags;
  
  	if (flags & ~GUE_FLAGS_ALL)
  		return 1;
  
  	len = guehdr_flags_len(flags);
  	if (len > optlen)
  		return 1;
  
  	if (flags & GUE_FLAG_PRIV) {
  		/* Private flags are last four bytes accounted in
  		 * guehdr_flags_len
  		 */
  		flags = *(__be32 *)((void *)&guehdr[1] + len - GUE_LEN_PRIV);
  
  		if (flags & ~GUE_PFLAGS_ALL)
  			return 1;
  
  		len += guehdr_priv_flags_len(flags);
  		if (len > optlen)
  			return 1;
  	}
  
  	return 0;
  }
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  #endif