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KernelTun: Use IFF_NO_PI on Linux, remove LINUX_ETHERTAP mode #397

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KernelTun: Use IFF_NO_PI on Linux, remove LINUX_ETHERTAP mode #397

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100 changes: 17 additions & 83 deletions elements/userlevel/kerneltun.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -134,7 +134,7 @@ KernelTun::try_linux_universal()

struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = (_tap ? IFF_TAP : IFF_TUN);
ifr.ifr_flags = (_tap ? IFF_TAP : IFF_TUN) | IFF_NO_PI;
if (_dev_name)
// Setting ifr_name allows us to select an arbitrary interface name.
strncpy(ifr.ifr_name, _dev_name.c_str(), sizeof(ifr.ifr_name));
Expand Down Expand Up @@ -189,24 +189,20 @@ KernelTun::alloc_tun(ErrorHandler *errh)
saved_message = "\n(Perhaps you need to enable tun in your kernel or load the 'tun' module.)";
}
tried << "/dev/net/tun, ";
#endif

#else
String dev_prefix;
#ifdef __linux__
_type = LINUX_ETHERTAP;
dev_prefix = "tap";
#elif defined(KERNELTUN_OSX)
# if defined(KERNELTUN_OSX)
_type = OSX_TUN;
dev_prefix = "tun";
#elif defined(__NetBSD__) && !defined(TUNSIFHEAD)
# elif defined(__NetBSD__) && !defined(TUNSIFHEAD)
_type = (_tap ? NETBSD_TAP : NETBSD_TUN);
dev_prefix = (_tap ? "tap" : "tun");
#else
# else
_type = (_tap ? BSD_TAP : BSD_TUN);
dev_prefix = (_tap ? "tap" : "tun");
#endif
# endif

#if defined(__NetBSD__) && !defined(TUNSIFHEAD)
# if defined(__NetBSD__) && !defined(TUNSIFHEAD)
if (_type == NETBSD_TAP) {
// In NetBSD, two ways to create a tap:
// 1. open /dev/tap cloning interface.
Expand All @@ -224,7 +220,7 @@ KernelTun::alloc_tun(ErrorHandler *errh)
tried << "/dev/" << dev_prefix;
goto error_out;
}
#endif
# endif

for (int i = 0; i < 6; i++) {
if ((error = try_tun(dev_prefix + String(i), errh)) >= 0)
Expand All @@ -234,8 +230,10 @@ KernelTun::alloc_tun(ErrorHandler *errh)
tried << "/dev/" << dev_prefix << i << ", ";
}

#if defined(__NetBSD__) && !defined(TUNSIFHEAD)
# if defined(__NetBSD__) && !defined(TUNSIFHEAD)
error_out:
# endif

#endif
if (saved_error == -ENOENT) {
tried.pop_back(2);
Expand Down Expand Up @@ -438,22 +436,11 @@ KernelTun::setup_tun(ErrorHandler *errh)
// calculate maximum packet size needed to receive data from
// tun/tap.
if (_tap) {
if (_type == LINUX_UNIVERSAL)
_mtu_in = _mtu_out + 18;
else if (_type == LINUX_ETHERTAP)
_mtu_in = _mtu_out + 16;
else
_mtu_in = _mtu_out + 14;
} else if (_type == LINUX_UNIVERSAL)
_mtu_in = _mtu_out + 4;
else if (_type == BSD_TUN)
_mtu_in = _mtu_out + 14;
} else if (_type == BSD_TUN)
_mtu_in = _mtu_out + 4;
else if (_type == BSD_TAP || _type == NETBSD_TAP || _type == NETBSD_TUN)
else
_mtu_in = _mtu_out;
else if (_type == OSX_TUN)
_mtu_in = _mtu_out + 4; // + 0?
else /* _type == LINUX_ETHERTAP */
_mtu_in = _mtu_out + 16;

return 0;
}
Expand All @@ -470,10 +457,7 @@ KernelTun::initialize(ErrorHandler *errh)
_signal = Notifier::upstream_empty_signal(this, 0, &_task);
}
if (_adjust_headroom) {
if (_tap && _type == LINUX_UNIVERSAL)
_headroom += (4 - (_headroom + 2) % 4) % 4; // default 4/2 alignment
else
_headroom += (4 - _headroom % 4) % 4; // default 4/0 alignment
_headroom += (4 - _headroom % 4) % 4; // default 4/0 alignment
}
add_select(_fd, SELECT_READ);
return 0;
Expand Down Expand Up @@ -518,21 +502,7 @@ KernelTun::one_selected(const Timestamp &now)
bool ok = false;

if (_tap) {
if (_type == LINUX_UNIVERSAL)
// 2-byte padding, 2-byte Ethernet type, then Ethernet header
p->pull(4);
else if (_type == LINUX_ETHERTAP)
// 2-byte padding, then Ethernet header
p->pull(2);
ok = true;
} else if (_type == LINUX_UNIVERSAL) {
// 2-byte padding followed by an Ethernet type
uint16_t etype = *(uint16_t *)(p->data() + 2);
p->pull(4);
if (etype != htons(ETHERTYPE_IP) && etype != htons(ETHERTYPE_IP6))
checked_output_push(1, p->clone());
else
ok = fake_pcap_force_ip(p, FAKE_DLT_RAW);
} else if (_type == BSD_TUN) {
// 4-byte address family followed by IP header
int af = ntohl(*(unsigned *)p->data());
Expand All @@ -542,16 +512,8 @@ KernelTun::one_selected(const Timestamp &now)
checked_output_push(1, p->clone());
} else
ok = fake_pcap_force_ip(p, FAKE_DLT_RAW);
} else if (_type == OSX_TUN || _type == NETBSD_TUN) {
} else {
ok = fake_pcap_force_ip(p, FAKE_DLT_RAW);
} else { /* _type == LINUX_ETHERTAP */
// 2-byte padding followed by a mostly-useless Ethernet header
uint16_t etype = *(uint16_t *)(p->data() + 14);
p->pull(16);
if (etype != htons(ETHERTYPE_IP) && etype != htons(ETHERTYPE_IP6))
checked_output_push(1, p->clone());
else
ok = fake_pcap_force_ip(p, FAKE_DLT_RAW);
}

if (ok) {
Expand Down Expand Up @@ -624,40 +586,12 @@ KernelTun::push(int, Packet *p)

WritablePacket *q;
if (_tap) {
if (_type == LINUX_UNIVERSAL) {
// 2-byte padding, 2-byte Ethernet type, then Ethernet header
uint16_t ethertype = ((const click_ether *) p->data())->ether_type;
if ((q = p->push(4)))
((uint16_t *) q->data())[1] = ethertype;
p = q;
} else if (_type == LINUX_ETHERTAP) {
// 2-byte padding, then Ethernet header
p = p->push(2);
} else {
/* existing packet is OK */;
}
} else if (_type == LINUX_UNIVERSAL) {
// 2-byte padding followed by an Ethernet type
uint32_t ethertype = (iph->ip_v == 4 ? htonl(ETHERTYPE_IP) : htonl(ETHERTYPE_IP6));
if ((q = p->push(4)))
*(uint32_t *)(q->data()) = ethertype;
p = q;
/* existing packet is OK */;
} else if (_type == BSD_TUN) {
uint32_t af = (iph->ip_v == 4 ? htonl(AF_INET) : htonl(AF_INET6));
if ((q = p->push(4)))
*(uint32_t *)(q->data()) = af;
p = q;
} else if (_type == LINUX_ETHERTAP) {
uint16_t ethertype = (iph->ip_v == 4 ? htons(ETHERTYPE_IP) : htons(ETHERTYPE_IP6));
if ((q = p->push(16))) {
/* ethertap driver is very picky about what address we use
* here. e.g. if we have the wrong address, linux might ignore
* all the packets, or accept udp or icmp, but ignore tcp.
* aaarrrgh, well this works. -ddc */
memcpy(q->data(), "\x00\x00\xFE\xFD\x00\x00\x00\x00\xFE\xFD\x00\x00\x00\x00", 14);
*(uint16_t *)(q->data() + 14) = ethertype;
}
p = q;
} else {
/* existing packet is OK */;
}
Expand Down