include/linux/ip.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              Definitions for the IP protocol.
   8  *
   9  * Version:     @(#)ip.h        1.0.2   04/28/93
  10  *
  11  * Authors:     Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  */
  13 #ifndef _LINUX_IP_H
  14 #define _LINUX_IP_H
  15
  16 #include <linux/skbuff.h>
  17 #include <uapi/linux/ip.h>
  18
  19 static inline struct iphdr *ip_hdr(const struct sk_buff *skb)
  20 {
  21         return (struct iphdr *)skb_network_header(skb);
  22 }
  23
  24 static inline struct iphdr *inner_ip_hdr(const struct sk_buff *skb)
  25 {
  26         return (struct iphdr *)skb_inner_network_header(skb);
  27 }
  28
  29 static inline struct iphdr *ipip_hdr(const struct sk_buff *skb)
  30 {
  31         return (struct iphdr *)skb_transport_header(skb);
  32 }
  33
  34 static inline unsigned int ip_transport_len(const struct sk_buff *skb)
  35 {
  36         return ntohs(ip_hdr(skb)->tot_len) - skb_network_header_len(skb);
  37 }
  38
  39 static inline unsigned int iph_totlen(const struct sk_buff *skb, const struct iphdr *iph)
  40 {
  41         u32 len = ntohs(iph->tot_len);
  42
  43         return (len || !skb_is_gso(skb) || !skb_is_gso_tcp(skb)) ?
  44                len : skb->len - skb_network_offset(skb);
  45 }
  46
  47 static inline unsigned int skb_ip_totlen(const struct sk_buff *skb)
  48 {
  49         return iph_totlen(skb, ip_hdr(skb));
  50 }
  51
  52 /* IPv4 datagram length is stored into 16bit field (tot_len) */
  53 #define IP_MAX_MTU      0xFFFFU
  54
  55 static inline void iph_set_totlen(struct iphdr *iph, unsigned int len)
  56 {
  57         iph->tot_len = len <= IP_MAX_MTU ? htons(len) : 0;
  58 }
  59 #endif  /* _LINUX_IP_H */