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tun-device: Read from tun to buffer on stack to avoid over-allocation of packets

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Instead of allocating MTU-sized buffers for each packet, read to a stack buffer
and copy to an allocation of the actual packet size. While it requires an
additional copy on non-Apple platforms, this should make allocation more
efficient for small packets.
This commit is contained in:
Martin Willi 2014-11-21 11:23:08 +01:00
parent eaca7f2143
commit 946cf367d4
1 changed files with 6 additions and 8 deletions
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14
src/libstrongswan/networking/tun_device.c
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@ -346,29 +346,27 @@ METHOD(tun_device_t, write_packet, bool,
METHOD(tun_device_t, read_packet, bool,
private_tun_device_t *this, chunk_t *packet)
{
chunk_t data;
ssize_t len;
bool old;
*packet = chunk_alloc(get_mtu(this));
data = chunk_alloca(get_mtu(this));
thread_cleanup_push(free, packet->ptr);
old = thread_cancelability(TRUE);
len = read(this->tunfd, packet->ptr, packet->len);
len = read(this->tunfd, data.ptr, data.len);
thread_cancelability(old);
thread_cleanup_pop(FALSE);
if (len < 0)
{
DBG1(DBG_LIB, "reading from TUN device %s failed: %s", this->if_name,
strerror(errno));
free(packet->ptr);
return FALSE;
}
packet->len = len;
data.len = len;
#ifdef __APPLE__
/* UTUN's prepend packets with a 32-bit protocol number */
packet->len -= sizeof(u_int32_t);
memmove(packet->ptr, packet->ptr + sizeof(u_int32_t), packet->len);
data = chunk_skip(data, sizeof(u_int32_t));
#endif
*packet = chunk_clone(data);
return TRUE;
}