690e36e726
Drivers, and perhaps other entities we have not yet considered, sometimes want to know how deep the protocol headers go before deciding how large of an SKB to allocate and how much of the packet to place into the linear SKB area. For example, consider a driver which has a device which DMAs into pools of pages and then tells the driver where the data went in the DMA descriptor(s). The driver can then build an SKB and reference most of the data via SKB fragments (which are page/offset/length triplets). However at least some of the front of the packet should be placed into the linear SKB area, which comes before the fragments, so that packet processing can get at the headers efficiently. The first thing each protocol layer is going to do is a "pskb_may_pull()" so we might as well aggregate as much of this as possible while we're building the SKB in the driver. Part of supporting this is that we don't have an SKB yet, so we want to be able to let the flow dissector operate on a raw buffer in order to compute the offset of the end of the headers. So now we have a __skb_flow_dissect() which takes an explicit data pointer and length. Signed-off-by: David S. Miller <davem@davemloft.net>
43 lines
1.3 KiB
C
43 lines
1.3 KiB
C
#ifndef _NET_FLOW_KEYS_H
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#define _NET_FLOW_KEYS_H
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/* struct flow_keys:
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* @src: source ip address in case of IPv4
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* For IPv6 it contains 32bit hash of src address
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* @dst: destination ip address in case of IPv4
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* For IPv6 it contains 32bit hash of dst address
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* @ports: port numbers of Transport header
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* port16[0]: src port number
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* port16[1]: dst port number
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* @thoff: Transport header offset
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* @n_proto: Network header protocol (eg. IPv4/IPv6)
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* @ip_proto: Transport header protocol (eg. TCP/UDP)
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* All the members, except thoff, are in network byte order.
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*/
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struct flow_keys {
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/* (src,dst) must be grouped, in the same way than in IP header */
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__be32 src;
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__be32 dst;
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union {
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__be32 ports;
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__be16 port16[2];
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};
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u16 thoff;
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u16 n_proto;
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u8 ip_proto;
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};
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bool __skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow,
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void *data, int hlen);
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static inline bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow)
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{
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return __skb_flow_dissect(skb, flow, NULL, 0);
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}
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__be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
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void *data, int hlen_proto);
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static inline __be32 skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto)
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{
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return __skb_flow_get_ports(skb, thoff, ip_proto, NULL, 0);
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}
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u32 flow_hash_from_keys(struct flow_keys *keys);
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#endif
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