// SPDX-License-Identifier: GPL-2.0-only /****************************************************************************** Copyright(c) 2003 - 2005 Intel Corporation. All rights reserved. Contact Information: Intel Linux Wireless <[email protected]> Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497 ******************************************************************************/ #include <linux/compiler.h> #include <linux/errno.h> #include <linux/if_arp.h> #include <linux/in6.h> #include <linux/in.h> #include <linux/ip.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/netdevice.h> #include <linux/proc_fs.h> #include <linux/skbuff.h> #include <linux/slab.h> #include <linux/tcp.h> #include <linux/types.h> #include <linux/wireless.h> #include <linux/etherdevice.h> #include <linux/uaccess.h> #include "libipw.h" /* 802.11 Data Frame ,-------------------------------------------------------------------. Bytes | 2 | 2 | 6 | 6 | 6 | 2 | 0..2312 | 4 | |------|------|---------|---------|---------|------|---------|------| Desc. | ctrl | dura | DA/RA | TA | SA | Sequ | Frame | fcs | | | tion | (BSSID) | | | ence | data | | `--------------------------------------------------| |------' Total: 28 non-data bytes `----.----' | .- 'Frame data' expands, if WEP enabled, to <----------' | V ,-----------------------. Bytes | 4 | 0-2296 | 4 | |-----|-----------|-----| Desc. | IV | Encrypted | ICV | | | Packet | | `-----| |-----' `-----.-----' | .- 'Encrypted Packet' expands to | V ,---------------------------------------------------. Bytes | 1 | 1 | 1 | 3 | 2 | 0-2304 | |------|------|---------|----------|------|---------| Desc. | SNAP | SNAP | Control |Eth Tunnel| Type | IP | | DSAP | SSAP | | | | Packet | | 0xAA | 0xAA |0x03 (UI)|0x00-00-F8| | | `---------------------------------------------------- Total: 8 non-data bytes 802.3 Ethernet Data Frame ,-----------------------------------------. Bytes | 6 | 6 | 2 | Variable | 4 | |-------|-------|------|-----------|------| Desc. | Dest. | Source| Type | IP Packet | fcs | | MAC | MAC | | | | `-----------------------------------------' Total: 18 non-data bytes In the event that fragmentation is required, the incoming payload is split into N parts of size ieee->fts. The first fragment contains the SNAP header and the remaining packets are just data. If encryption is enabled, each fragment payload size is reduced by enough space to add the prefix and postfix (IV and ICV totalling 8 bytes in the case of WEP) So if you have 1500 bytes of payload with ieee->fts set to 500 without encryption it will take 3 frames. With WEP it will take 4 frames as the payload of each frame is reduced to 492 bytes. * SKB visualization * * ,- skb->data * | * | ETHERNET HEADER ,-<-- PAYLOAD * | | 14 bytes from skb->data * | 2 bytes for Type --> ,T. | (sizeof ethhdr) * | | | | * |,-Dest.--. ,--Src.---. | | | * | 6 bytes| | 6 bytes | | | | * v | | | | | | * 0 | v 1 | v | v 2 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 * ^ | ^ | ^ | * | | | | | | * | | | | `T' <---- 2 bytes for Type * | | | | * | | '---SNAP--' <-------- 6 bytes for SNAP * | | * `-IV--' <-------------------- 4 bytes for IV (WEP) * * SNAP HEADER * */ static u8 P802_1H_OUI[P80211_OUI_LEN] = …; static u8 RFC1042_OUI[P80211_OUI_LEN] = …; static int libipw_copy_snap(u8 * data, __be16 h_proto) { … } static int libipw_encrypt_fragment(struct libipw_device *ieee, struct sk_buff *frag, int hdr_len) { … } void libipw_txb_free(struct libipw_txb *txb) { … } static struct libipw_txb *libipw_alloc_txb(int nr_frags, int txb_size, int headroom, gfp_t gfp_mask) { … } static int libipw_classify(struct sk_buff *skb) { … } /* Incoming skb is converted to a txb which consists of * a block of 802.11 fragment packets (stored as skbs) */ netdev_tx_t libipw_xmit(struct sk_buff *skb, struct net_device *dev) { … } EXPORT_SYMBOL(…); EXPORT_SYMBOL(…);
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