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Reading and writing addresses in network byte order in netlink is traditional and I see no reason to change that. MPLS is interesting as effectively it has variabely length addresses (the MPLS label stack). To represent these variable length addresses in netlink I use a valid MPLS label stack (complete with stop bit). This achieves two things: a well defined existing format is used, and the data can be interpreted without looking at it's length. Not needed to look at the length to decode the variable length network representation allows existing userspace functions such as inet_ntop to be used without needed to change their prototype. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: David S. Miller <davem@davemloft.net>
60 lines
1.6 KiB
C
60 lines
1.6 KiB
C
#ifndef MPLS_INTERNAL_H
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#define MPLS_INTERNAL_H
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#define LABEL_IPV4_EXPLICIT_NULL 0 /* RFC3032 */
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#define LABEL_ROUTER_ALERT_LABEL 1 /* RFC3032 */
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#define LABEL_IPV6_EXPLICIT_NULL 2 /* RFC3032 */
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#define LABEL_IMPLICIT_NULL 3 /* RFC3032 */
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#define LABEL_ENTROPY_INDICATOR 7 /* RFC6790 */
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#define LABEL_GAL 13 /* RFC5586 */
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#define LABEL_OAM_ALERT 14 /* RFC3429 */
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#define LABEL_EXTENSION 15 /* RFC7274 */
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struct mpls_shim_hdr {
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__be32 label_stack_entry;
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};
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struct mpls_entry_decoded {
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u32 label;
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u8 ttl;
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u8 tc;
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u8 bos;
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};
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struct sk_buff;
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static inline struct mpls_shim_hdr *mpls_hdr(const struct sk_buff *skb)
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{
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return (struct mpls_shim_hdr *)skb_network_header(skb);
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}
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static inline struct mpls_shim_hdr mpls_entry_encode(u32 label, unsigned ttl, unsigned tc, bool bos)
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{
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struct mpls_shim_hdr result;
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result.label_stack_entry =
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cpu_to_be32((label << MPLS_LS_LABEL_SHIFT) |
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(tc << MPLS_LS_TC_SHIFT) |
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(bos ? (1 << MPLS_LS_S_SHIFT) : 0) |
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(ttl << MPLS_LS_TTL_SHIFT));
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return result;
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}
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static inline struct mpls_entry_decoded mpls_entry_decode(struct mpls_shim_hdr *hdr)
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{
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struct mpls_entry_decoded result;
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unsigned entry = be32_to_cpu(hdr->label_stack_entry);
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result.label = (entry & MPLS_LS_LABEL_MASK) >> MPLS_LS_LABEL_SHIFT;
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result.ttl = (entry & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
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result.tc = (entry & MPLS_LS_TC_MASK) >> MPLS_LS_TC_SHIFT;
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result.bos = (entry & MPLS_LS_S_MASK) >> MPLS_LS_S_SHIFT;
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return result;
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}
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int nla_put_labels(struct sk_buff *skb, int attrtype, u8 labels, const u32 label[]);
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int nla_get_labels(const struct nlattr *nla, u32 max_labels, u32 *labels, u32 label[]);
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#endif /* MPLS_INTERNAL_H */
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