diff options
Diffstat (limited to 'sys/net/if_tun.h')
| -rw-r--r-- | sys/net/if_tun.h | 53 |
1 files changed, 52 insertions, 1 deletions
diff --git a/sys/net/if_tun.h b/sys/net/if_tun.h index 3e17f0d10b1..fb40345744e 100644 --- a/sys/net/if_tun.h +++ b/sys/net/if_tun.h @@ -1,4 +1,4 @@ -/* $OpenBSD: if_tun.h,v 1.17 2024/11/14 13:47:38 sthen Exp $ */ +/* $OpenBSD: if_tun.h,v 1.18 2024/11/17 00:25:07 dlg Exp $ */ /* * Copyright (c) 1988, Julian Onions <Julian.Onions@nexor.co.uk> @@ -31,6 +31,49 @@ #include <sys/ioccom.h> +/* + * tun_hdr is a multiple of 4 bytes, but is built out of uint16_t + * fields. This allows it to sit on a 2 byte boundary in front of + * either IP (and MPLS) or Ethernet packets for tun(4) and tap(4) + * interfaces respectively while maintaining the alignment of their + * payloads. + * + * Userland can request the use of the tun_hdr using the TUNSCAP + * ioctl. This ioctl also allows userland to specify which "offload" + * capabilities it is able to accept in packets it will read from the + * kernel. It is acceptable to enable tun_hdr without enabling any + * interface offload capabilities. + * + * Once the tap_hdr is enabled, userland can write packets into the + * kernel with any of the supported features. tun(4)/tap(4) reads + * will unconditionally handle any features specified on the packet, + * regardless of what capabilities were specified by the TUNSCAP + * ioctl. + * + * The tun_hdr can be read from one interface and written directly + * to another without interpretation or modification. + * + * Use of tun_hdr and the associated capabilities are reset when a + * tun(4)/tap(4) device is closed. + */ + +struct tun_hdr { + uint16_t th_flags; +#define TUN_H_PRIO_MASK 0x7 +#define TUN_H_VTAG (1 << 4) /* th_vtag is set */ +#define TUN_H_TCP_MSS (1 << 5) /* Cut TCP frame up by th_mss */ + +#define TUN_H_IPV4_CSUM (1 << 8) +#define TUN_H_TCP_CSUM (1 << 9) +#define TUN_H_UDP_CSUM (1 << 10) +#define TUN_H_ICMP_CSUM (1 << 11) + + uint16_t th_pad; + + uint16_t th_vtag; + uint16_t th_mss; +}; + #define TUN_OPEN 0x0001 #define TUN_INITED 0x0002 #define TUN_RCOLL 0x0004 /* unused */ @@ -68,4 +111,12 @@ struct tuninfo { #define TUNSDEBUG _IOW('t', 94, int) #define TUNGDEBUG _IOR('t', 95, int) +struct tun_capabilities { + uint32_t tun_if_capabilities; /* IFCAP_* from net/if.h */ +}; + +#define TUNSCAP _IOW('t', 196, struct tun_capabilities) +#define TUNGCAP _IOR('t', 196, struct tun_capabilities) +#define TUNDCAP _IO('t', 196) + #endif /* _NET_IF_TUN_H_ */ |