Hesham/wintun
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Decrease alignment requirements to 4

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Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2019-07-04 21:06:17 +00:00
parent a0f031c692
commit 7437155446
3 changed files with 11 additions and 14 deletions
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1
.clang-format
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@ -98,6 +98,7 @@ StatementMacros: [
'__drv_preferredFunction', '__drv_preferredFunction',
'__drv_allocatesMem', '__drv_allocatesMem',
'__drv_freesMem', '__drv_freesMem',
'_Field_size_bytes_',
] ]
TabWidth: '4' TabWidth: '4'
UseTab: Never UseTab: Never

19
README.md
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@ -89,11 +89,6 @@ After loading the driver and creating a network interface the typical way using
| 4 bytes, native endian | | 4 bytes, native endian |
+------------------------------+ +------------------------------+
| | | |
| padding |
| 12 bytes, all zero |
| |
+------------------------------+
| |
| packet_0 | | packet_0 |
| size_0 bytes | | size_0 bytes |
| | | |
@ -101,22 +96,22 @@ After loading the driver and creating a network interface the typical way using
| | | |
+------------------------------+ +------------------------------+
| padding | | padding |
| 16-(size_0&15) bytes, | | 4-(size_0&3) bytes |
| all zero |
+------------------------------+ +------------------------------+
| size_1 | | size_1 |
| 4 bytes, native endian | | 4 bytes, native endian |
+------------------------------+ +------------------------------+
| | | |
| padding |
| 12 bytes, all zero |
| |
+------------------------------+
| |
| packet_1 | | packet_1 |
| size_1 bytes | | size_1 bytes |
| | | |
~ ~ ~ ~
| |
+------------------------------+
| padding |
| 4-(size_1&3) bytes |
+------------------------------+
~ ~
``` ```
Each packet segment should contain a layer 3 IPv4 or IPv6 packet. Up to 15728640 bytes may be read or written during each call to `ReadFile` or `WriteFile`. All calls to `ReadFile` must be called with the same virtual address, for a given handle. This virtual address must reference pages that are writable for the same length as passed to the first call of `ReadFile`. Each packet segment should contain a layer 3 IPv4 or IPv6 packet. Up to 15728640 bytes may be read or written during each call to `ReadFile` or `WriteFile`. All calls to `ReadFile` must be called with the same virtual address, for a given handle. This virtual address must reference pages that are writable for the same length as passed to the first call of `ReadFile`.

5
wintun.c
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@ -32,7 +32,7 @@
#define TUN_EXCH_MAX_PACKETS 256 #define TUN_EXCH_MAX_PACKETS 256
/* Maximum exchange packet size - empirically determined by net buffer list (pool) limitations */ /* Maximum exchange packet size - empirically determined by net buffer list (pool) limitations */
#define TUN_EXCH_MAX_PACKET_SIZE 0xF000 #define TUN_EXCH_MAX_PACKET_SIZE 0xF000
#define TUN_EXCH_ALIGNMENT 16 /* Memory alignment in exchange buffers */ #define TUN_EXCH_ALIGNMENT sizeof(ULONG) /* Memory alignment in exchange buffers */
/* Maximum IP packet size (headers + payload) */ /* Maximum IP packet size (headers + payload) */
#define TUN_EXCH_MAX_IP_PACKET_SIZE (TUN_EXCH_MAX_PACKET_SIZE - sizeof(TUN_PACKET)) #define TUN_EXCH_MAX_IP_PACKET_SIZE (TUN_EXCH_MAX_PACKET_SIZE - sizeof(TUN_PACKET))
/* Maximum size of read/write exchange buffer */ /* Maximum size of read/write exchange buffer */
@ -60,7 +60,8 @@
typedef struct _TUN_PACKET typedef struct _TUN_PACKET
{ {
ULONG Size; /* Size of packet data (TUN_EXCH_MAX_IP_PACKET_SIZE max) */ ULONG Size; /* Size of packet data (TUN_EXCH_MAX_IP_PACKET_SIZE max) */
_Field_size_bytes_(Size) __declspec(align(TUN_EXCH_ALIGNMENT)) UCHAR Data[]; /* Packet data */ _Field_size_bytes_(Size)
UCHAR Data[]; /* Packet data */
} TUN_PACKET; } TUN_PACKET;
typedef enum _TUN_FLAGS typedef enum _TUN_FLAGS