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| author |   Jason A. Donenfeld <Jason@zx2c4.com> | 2019-07-04 21:06:17 +0000 |
|---|---|---|
| committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2019-07-05 06:15:46 +0000 |
| commit | 74371554461a5f8cc42e4828d6123febc88c1dec (patch) | |
| tree | 5f983d40f854164c5e27aefb7f54c5e5455193db | |
| parent | Do not use _RESOURCES but rather allocate our own copy (diff) | |
| download | wintun-74371554461a5f8cc42e4828d6123febc88c1dec.tar.xz wintun-74371554461a5f8cc42e4828d6123febc88c1dec.zip | |
Decrease alignment requirements to 4
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
| -rw-r--r-- | .clang-format | 1 | ||||
| -rw-r--r-- | README.md | 19 | ||||
| -rw-r--r-- | wintun.c | 5 |
3 files changed, 11 insertions, 14 deletions
diff --git a/.clang-format b/.clang-format index 9bbe60a..0b702a7 100644 --- a/.clang-format +++ b/.clang-format @@ -98,6 +98,7 @@ StatementMacros: [ '__drv_preferredFunction', '__drv_allocatesMem', '__drv_freesMem', + '_Field_size_bytes_', ] TabWidth: '4' UseTab: Never @@ -89,11 +89,6 @@ After loading the driver and creating a network interface the typical way using | 4 bytes, native endian | +------------------------------+ | | -| padding | -| 12 bytes, all zero | -| | -+------------------------------+ -| | | packet_0 | | size_0 bytes | | | @@ -101,22 +96,22 @@ After loading the driver and creating a network interface the typical way using | | +------------------------------+ | padding | -| 16-(size_0&15) bytes, | -| all zero | +| 4-(size_0&3) bytes | +------------------------------+ | size_1 | | 4 bytes, native endian | +------------------------------+ | | -| padding | -| 12 bytes, all zero | -| | -+------------------------------+ -| | | packet_1 | | 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`. @@ -32,7 +32,7 @@ #define TUN_EXCH_MAX_PACKETS 256 /* Maximum exchange packet size - empirically determined by net buffer list (pool) limitations */ #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) */ #define TUN_EXCH_MAX_IP_PACKET_SIZE (TUN_EXCH_MAX_PACKET_SIZE - sizeof(TUN_PACKET)) /* Maximum size of read/write exchange buffer */ @@ -60,7 +60,8 @@ typedef struct _TUN_PACKET { 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; typedef enum _TUN_FLAGS |