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