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Applied patch from #88, thanks a lot!

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J. A. Bezemer 2009-12-29 20:00:57 +00:00 committed by Erik Ekman
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README
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@ -11,12 +11,12 @@ firewalled, but DNS queries are allowed.
QUICKSTART:
Try it out within your own LAN! Follow these simple steps:
- On your server, run: ./iodined -f 10.0.0.1 test.asdf
- On your server, run: ./iodined -f 10.0.0.1 test.com
(If you already use the 10.0.0.0 network, use another internal net like
172.16.0.0)
- Enter a password
- On the client, run: ./iodine -f 192.168.0.1 test.asdf
(Replace 192.168.0.1 with the server's ip address)
- On the client, run: ./iodine -f -r 192.168.0.1 test.com
(Replace 192.168.0.1 with your server's ip address)
- Enter the same password
- Now the client has the tunnel ip 10.0.0.2 and the server has 10.0.0.1
- Try pinging each other through the tunnel
@ -26,113 +26,196 @@ To actually use it through a relaying nameserver, see below.
HOW TO USE:
Note: server and client are required to speak the exact same protocol. In most
cases, this means running the same iodine version. Unfortunately, implementing
backward and forward protocol compatibility is usually not feasible.
Server side:
To use this tunnel, you need control over a real domain (like mytunnel.com),
and a server with a public IP number. If the server already runs a DNS
server, change the listening port and then use the -b option to let
iodined forward the DNS requests. Then, delegate a subdomain
(say, tunnel1.mytunnel.com) to the server. If you use BIND for the domain,
add these lines to the zone file:
To use this tunnel, you need control over a real domain (like mydomain.com),
and a server with a public IP address to run iodined on. If this server
already runs a DNS program, change its listening port and then use iodined's
-b option to let iodined forward the DNS requests. (Note that this procedure
is not advised in production environments, because iodined's DNS forwarding
is not completely transparent.)
tunnel1host IN A 10.15.213.99
tunnel1 IN NS tunnel1host.mytunnel.com.
Then, delegate a subdomain (say, t1.mydomain.com) to the iodined server.
If you use BIND for your domain, add two lines like these to the zone file:
Do not use CNAME instead of A above.
If your server has a dynamic IP, use a dynamic dns provider:
t1 IN NS t1ns.mydomain.com. ; note the dot!
t1ns IN A 10.15.213.99
tunnel1 IN NS tunnel1host.mydyndnsprovider.com
The "NS" line is all that's needed to route queries for the "t1" subdomain
to the "t1ns" server. We use a short name for the subdomain, to keep as much
space as possible available for the data traffic. At the end of the "NS" line
is the name of your iodined server. This can be any name, pointing anywhere,
but in this case it's easily kept in the same zone file. It must be a name
(not an IP address), and that name itself must have an A record (not a CNAME).
Now any DNS querys for domains ending with tunnel1.mytunnnel.com will be sent
to your server. Start iodined on the server. The first argument is the tunnel
IP address (like 192.168.99.1) and the second is the assigned domain (in this
case tunnel1.mytunnel.com). The -f argument will keep iodined running in the
foreground, which helps when testing. iodined will start a virtual interface,
and also start listening for DNS queries on UDP port 53. Either enter a
password on the commandline (-P pass) or after the server has started. Now
everything is ready for the client.
If your iodined server has a dynamic IP, use a dynamic dns provider. Simply
point the "NS" line to it, and leave the "A" line out:
t1 IN NS myname.mydyndnsprovider.com. ; note the dot!
Then reload or restart your nameserver program. Now any DNS queries for
domains ending in t1.mydomain.com will be sent to your iodined server.
Finally start iodined on your server. The first argument is the IP address
inside the tunnel, which can be from any range that you don't use yet (for
example 192.168.99.1), and the second argument is the assigned domain (in this
case t1.mydomain.com). Using the -f option will keep iodined running in the
foreground, which helps when testing. iodined will open a virtual interface
("tun device"), and will also start listening for DNS queries on UDP port 53.
Either enter a password on the commandline (-P pass) or after the server has
started. Now everything is ready for the client.
If there is a chance you'll be using an iodine tunnel from unexpected
environments, start iodined with a -c option.
Resulting commandline in this example situation:
./iodined -f -c -P secretpassword 192.168.99.1 t1.mydomain.com
Client side:
All the setup is done, just start iodine. It takes up to two arguments, the
All the setup is done, just start iodine. It takes one or two arguments, the
first is the local relaying DNS server (optional) and the second is the domain
used (tunnel1.mytunnnel.com). If DNS queries are allowed to any computer, you
can use the tunnel endpoint (example: 10.15.213.99 or tunnel1host.mytunnel.com)
as the first argument. The tunnel interface will get an IP close to the servers
(in this case 192.168.99.2) and a suitable MTU. Enter the same password as on
the server either by argument or after the client has started. Now you should
be able to ping the other end of the tunnel from either side.
you used (t1.mydomain.com). If you don't specify the first argument, the
system's current DNS setting will be consulted.
If DNS queries are allowed to any computer, you can directly give the iodined
server's address as first argument (in the example: t1ns.mydomain.com or
10.15.213.99). In that case, it may also happen that _any_ traffic is allowed
to the DNS port (53 UDP) of any computer. Iodine will detect this, and switch
to raw UDP tunneling if possible. To force DNS tunneling in any case, use the
-r option (especially useful when testing within your own network).
The client's tunnel interface will get an IP close to the server's (in this
case 192.168.99.2 or .3 etc.) and a suitable MTU. Enter the same password as
on the server either as commandline option or after the client has started.
Using the -f option will keep the iodine client running in the foreground.
Resulting commandline in this example situation:
./iodine -f -P secretpassword t1.mydomain.com
(add -r to force DNS tunneling even if raw UDP tunneling would be possible)
From either side, you should now be able to ping the IP address on the other
end of the tunnel. In this case, ping 192.168.99.1 from the iodine client, and
192.168.99.2 or .3 etc. from the iodine server.
MISC. INFO:
Routing:
The normal case is to route all traffic through the DNS tunnel. To do this, first
add a route to the nameserver you use with the default gateway as gateway. Then
replace the default gateway with the servers IP address within the DNS tunnel,
and configure the server to do NAT.
It is possible to route all traffic through the DNS tunnel. To do this, first
add a host route to the nameserver used by iodine over the wired/wireless
interface with the default gateway as gateway. Then replace the default
gateway with the iodined server's IP address inside the DNS tunnel, and
configure the server to do NAT.
However, note that the tunneled data traffic is not encrypted at all, and can
be read and changed by external parties relatively easily. For maximum
security, run a VPN through the DNS tunnel (=double tunneling), or use secure
shell (SSH) access, possibly with port forwarding. The latter can also be used
for web browsing, when you run a web proxy (for example Privoxy) on your
server.
Testing:
The iodined server replies to NS requests sent for subdomains of the tunnel
domain. If your iodined subdomain is t1.mydomain.com, send a NS request for
foo123.t1.mydomain.com to see if the delegation works. dig is a good tool
for this:
dig -t NS foo123.t1.mydomain.com
Also, the iodined server will answer requests starting with 'z' for any of the
supported request types, for example:
dig -t TXT z456.t1.mydomain.com
dig -t SRV z456.t1.mydomain.com
dig -t CNAME z456.t1.mydomain.com
The reply should look like garbled text in all these cases.
Operational info:
The DNS-response fragment size is normally autoprobed to get maximum bandwidth.
To force a specific value (and speed things up), use the -m option.
The iodined server replies to NS requests sent for subdomains of the tunnel
domain. If your domain is tunnel.com, send a NS request for foo.tunnel.com
to see if the delegation works. dig is a good tool for this:
dig -t NS foo123.tunnel.com
The DNS hostnames are normally used up to their maximum length, 255 characters.
Some DNS relays have been found that answer full-length queries rather
unreliably, giving widely varying (and mostly very bad) results of the
fragment size autoprobe on repeated tries. In these cases, use the -M switch
to reduce the DNS hostname length to for example 200 characters, which makes
these DNS relays much more stable. This is also useful on some "de-optimizing"
DNS relays that stuff the response with two full copies of the query, leaving
very little space for downstream data (also not capable of EDNS0). The -M
switch can trade some upstream bandwidth for downstream bandwidth. Note that
the minimum -M value is about 100, since the protocol can split packets (1200
bytes max) in only 16 fragments, requiring at least 75 real data bytes per
fragment.
The upstream data is sent gzipped encoded with Base32, or Base64 if the relay
server support '+' in domain names. DNS protocol allows one query per packet,
and one query can be max 256 chars. Each domain name part can be max 63 chars.
So your domain name and subdomain should be as short as possible to allow
maximum upstream throughput.
The upstream data is sent gzipped encoded with Base32; or Base64 if the relay
server supports mixed case and '+' in domain names; or Base64u if '_' is
supported instead; or Base128 if high-byte-value characters are supported.
This upstream encoding is autodetected. The DNS protocol allows one query per
packet, and one query can be max 256 chars. Each domain name part can be max
63 chars. So your domain name and subdomain should be as short as possible to
allow maximum upstream throughput.
The default is to use DNS NULL-type queries, as this provides the largest
downstream bandwidth. If your DNS server blocks NULL requests, try TXT or
CNAME queries via the -T option. Also supported are A (returning CNAME) and
MX requests, but these may/will cause additional lookups by "smart" caching
nameservers to get an actual IP address, which may either slow down or fail
completely. DNS responses for non-NULL are Base32 encoded by default, which
should always work. For more bandwidth, try Base64 or Raw (TXT only) via the
-O option. If Base64/Raw doesn't work, you'll see many failures in the
fragment size autoprobe.
Several DNS request types are supported, with the NULL type expected to provide
the largest downstream bandwidth. Other available types are TXT, SRV, MX,
CNAME and A (returning CNAME), in decreasing bandwidth order. Normally the
"best" request type is autodetected and used. However, DNS relays may impose
limits on for example NULL and TXT, making SRV or MX actually the best choice.
This is not autodetected, but can be forced using the -T option. It is
advisable to try various alternatives especially when the autodetected request
type provides a downstream fragment size of less than 200 bytes.
Note that SRV, MX and A (returning CNAME) queries may/will cause additional
lookups by "smart" caching nameservers to get an actual IP address, which may
either slow down or fail completely.
DNS responses for non-NULL queries can be encoded with the same set of codecs
as upstream data. This is normally also autodetected, but no fully exhaustive
tests are done, so some problems may not be noticed when selecting more
advanced codecs. In that case, you'll see failures/corruption in the fragment
size autoprobe. In particular, several DNS relays have been found that change
replies returning hostnames (SRV, MX, CNAME, A) to lowercase only when that
hostname exceeds ca. 180 characters. In these and similar cases, use the -O
option to try other downstream codecs; Base32 should always work.
Normal operation now is for the server to _not_ answer a DNS request until
the next DNS request has come in, a.k.a. being "lazy". This way, the server
will always have a DNS request handy when new downstream data has to be sent.
This greatly improves (interactive) performance and latency, and allows to
slow down the quiescent ping requests to 4 second intervals by default.
In fact, the main purpose of the pings now is to force a reply to the previous
ping, and prevent DNS server timeouts (usually 5-10 seconds per RFC1035).
In the unlikely case that you do experience DNS server timeouts (SERVFAIL),
decrease the -I option to 1. If you are running on a local network without
any DNS server in-between, try -I 50 (iodine and iodined time out after 60
seconds). The only time you'll notice a slowdown, is when DNS reply packets
go missing; the iodined server then has to wait for a new ping to re-send the
data. You can speed this up by generating some upstream traffic (keypress,
ping). If this happens often, check your network for bottlenecks and/or run
with -I1 .
slow down the quiescent ping requests to 4 second intervals by default, and
possibly much slower. In fact, the main purpose of the pings now is to force
a reply to the previous ping, and prevent DNS server timeouts (usually at
least 5-10 seconds per RFC1035). Some DNS servers are more impatient and will
give SERVFAIL errors (timeouts) in periods without tunneled data traffic. All
data should still get through in these cases, but iodine will reduce the ping
interval to 1 second anyway (-I1) to reduce the number of error messages. This
may not help for very impatient DNS relays like dnsadvantage.com (ultradns),
which time out in 1 second or even less. Yet data will still get trough, and
you can ignore the SERVFAIL errors.
Some DNS servers appear to be quite impatient and start retrying DNS requests
(with _different_ DNS ids!) when an answer does not appear within a few
milliseconds. Usually they scale back retries when iodined's lazy mode
repeatedly takes several seconds to answer; and they scale up retries again
when iodined answers fast during heavy data transfer. Some commercial DNS
servers advertise this as "carrier-grade adaptive retransmission techniques".
The effect will only be visible in the network traffic at the iodined server,
and will not affect the client's connection. Iodined has rather elaborate
logic to deal with (i.e., ignore) these unwanted duplicates.
If you are running on a local network without any DNS server in-between, try
-I 50 (iodine and iodined close the connection after 60 seconds of silence).
The only time you'll notice a slowdown, is when DNS reply packets go missing;
the iodined server then has to wait for a new ping to re-send the data. You can
speed this up by generating some upstream traffic (keypress, ping). If this
happens often, check your network for bottlenecks and/or run with -I1.
Other DNS servers, notably the opendns.com network, seem to regard iodined's
lazyness as incompetency, and will start shuffling requests around, possibly
in an attempt to reduce iodined's workload. The resulting out-of-sequence DNS
traffic works quite badly for lazy mode. The iodine client will detect this,
and switch back to legacy mode ("immediate ping-pong") automatically. In these
cases, start the iodine client with -L0 to prevent it from operating in lazy
mode altogether. Note that this will negatively affect interactive performance
and latency, especially in the downstream direction.
The delayed answering in lazy mode will cause some "carrier grade" commercial
DNS relays to repeatedly re-send the same DNS query to the iodined server.
If the DNS relay is actually implemented as a pool of parallel servers,
duplicate requests may even arrive from multiple sources. This effect will
only be visible in the network traffic at the iodined server, and will not
affect the client's connection. Iodined will notice these duplicates, and send
the same answer (when its time has come) to both the original query and the
latest duplicate. After that, the full answer is cached for a short while.
Delayed duplicates that arrive at the server even later, get a reply that the
iodine client will ignore (if it ever arrives there).
If you have problems, try inspecting the traffic with network monitoring tools
and make sure that the relaying DNS server has not cached the response. A
cached error message could mean that you started the client before the server.
The -D (and -DD) option on the server can also show received and sent queries.
like tcpdump or ethereal/wireshark, and make sure that the relaying DNS server
has not cached the response. A cached error message could mean that you
started the client before the server. The -D (and -DD) option on the server
can also show received and sent queries.
TIPS & TRICKS:
@ -165,13 +248,16 @@ PERFORMANCE:
This section tabulates some performance measurements. To view properly, use
a fixed-width font like Courier.
Measurements were done in protocol 00000500 with lazy mode unless indicated
otherwise. Upstream encoding always Base64.
Measurements were done in protocol 00000502 in lazy mode; upstream encoding
always Base128; iodine -M255; iodined -m1130. Network conditions were not
extremely favorable; results are not benchmarks but a realistic indication of
real-world performance that can be expected in similar situations.
Upstream/downstream throughput was measured by scp'ing a file previously
read from /dev/urandom (i.e. incompressible), and measuring size with
"ls -l ; sleep 30 ; ls -l" on a separate non-tunneled connection. Given the
large scp block size of 16 kB, this gives a resolution of 4.3 kbit/s, which
explains why many values are exactly equal.
explains why some values are exactly equal.
Ping round-trip times measured with "ping -c100", presented are average rtt
and mean deviation (indicating spread around the average), in milliseconds.
@ -185,43 +271,28 @@ Laptop -> Wifi AP -> Home server -> DSL provider -> Datacenter
------------------------------------------------------------------------------
iodine -> Wifi AP :53
-Tnull (= -Oraw) 982 39.3 148.5 26.7 3.1 26.6 3.0
-Tnull (= -Oraw) 982 43.6 131.0 28.0 4.6 26.8 3.4
iodine -> Home server :53
-Tnull (= -Oraw) 1174 43.6 174.7 25.2 4.0 25.5 3.4
-Tnull (= -Oraw) 1174 48.0 305.8 26.6 5.0 26.9 8.4
iodine -> DSL provider :53
-Tnull (= -Oraw) 1174 52.4 200.9 20.3 3.2 20.3 2.7
-Ttxt -Obase32 730 52.4 192.2*
-Ttxt -Obase64 874 52.4 192.2
-Ttxt -Oraw 1162 52.4 192.2
-Tcname -Obase32 148 52.4 48.0
-Tcname -Obase64 181 52.4 61.1
-Tnull (= -Oraw) 1174 56.7 367.0 20.6 3.1 21.2 4.4
-Ttxt -Obase32 730 56.7 174.7*
-Ttxt -Obase64 874 56.7 174.7
-Ttxt -Obase128 1018 56.7 174.7
-Ttxt -Oraw 1162 56.7 358.2
-Tsrv -Obase128 910 56.7 174.7
-Tcname -Obase32 151 56.7 43.6
-Tcname -Obase128 212 56.7 52.4
iodine -> DSL provider :53
wired (no Wifi) -Tnull 1174 65.5 244.6 17.7 1.9 17.8 1.6
wired (no Wifi) -Tnull 1174 74.2 585.4 20.2 5.6 19.6 3.4
[192.2* : nice, because still 2frag/packet]
[174.7* : these all have 2frag/packet]
Situation 2:
Laptop -> (wire) -> (Home server) -> (DSL) -> opendns.com -> Datacenter
iodine DNS cache iodined
downstr. upstream downstr. ping-up ping-down
fragsize kbit/s kbit/s avg +/-mdev avg +/-mdev
------------------------------------------------------------------------------
iodine -> opendns.com :53
-Tnull -L1 (lazy mode) 230 - - 404.4 196.2 663.8 679.6
(20% lost) (2% lost)
-Tnull -L0 (legacy mode) 230 5.6 7.4 197.3 4.7 610.8 323.5
[Note: Throughput measured over 300 seconds to get better resolution]
Situation 3:
Laptop -> Wifi+vpn / wired -> Home server
iodine iodined
@ -229,9 +300,9 @@ Laptop -> Wifi+vpn / wired -> Home server
fragsize kbit/s kbit/s avg +/-mdev avg +/-mdev
------------------------------------------------------------------------------
wifi + openvpn -Tnull 1186 183.5 611.6 5.7 1.4 7.0 2.7
wifi + openvpn -Tnull 1186 166.0 1022.3 6.3 1.3 6.6 1.6
wired -Tnull 1186 685.9 2350.5 1.3 0.1 1.4 0.4
wired -Tnull 1186 677.2 2464.1 1.3 0.2 1.3 0.1
Performance is strongly coupled to low ping times, as iodine requires

100
doc/proto_00000501.txt → doc/proto_00000502.txt
View file

@ -1,4 +1,4 @@
Detailed specification of protocol in version 00000501
Detailed specification of protocol in version 00000502
======================================================
Note: work in progress!!
@ -7,6 +7,22 @@ Note: work in progress!!
1. DNS protocol
======================================================
Quick alphabetical index / register:
0-9 Data packet
A-F Data packet
I IP address
L Login
N Downstream fragsize (NS.topdomain A-type reply)
O Options
P Ping
R Downstream fragsize probe
S Switch upstream codec
V Version
W (WWW.topdomain A-type reply)
Y Downstream codec check
Z Upstream codec check
CMC = 2 byte Cache Miss Counter, increased every time it is used
Version:
@ -38,29 +54,55 @@ IP Request:
Client sends:
First byte i or I
5 bits coded as Base32 char, meaning userid
CMC
CMC as 3 Base32 chars
Server replies
BADIP if bad userid, or
I and then 4 bytes network order external IP address of iodined server
Case check:
Upstream codec check / bounce:
Client sends:
First byte z or Z
Lots of data that should not be decoded
Server replies:
The requested domain copied raw
The requested domain copied raw, in the lowest-grade downstream codec
available for the request type.
Downstream codec check:
Client sends:
First byte y or Y
1 char, meaning downstream codec to use
5 bits coded as Base32 char, meaning check variant
CMC as 3 Base32 chars
Possibly extra data, depending on check variant
Server sends:
Data encoded with requested downstream codec; data content depending
on check variant number.
BADCODEC if requested downstream codec not available.
BADLEN if check variant is not available, or problem with extra data.
Downstream codec chars are same as in 'O' Option request, below.
Check variants:
1: Send encoded DOWNCODECCHECK1 string as defined in encoding.h
(Other variants reserved; possibly variant that sends a decoded-encoded
copy of Base32-encoded extra data in the request)
Switch codec:
Client sends:
First byte s or S
5 bits coded as Base32 char, meaning userid
5 bits coded as Base32 char, with value 5 or 6, representing number of raw
bits per encoded byte
CMC
5 bits coded as Base32 char, representing number of raw bits per
encoded byte:
5: Base32 (a-z0-5)
6: Base64 (a-zA-Z0-9+-)
26: Base64u (a-zA-Z0-9_-)
7: Base128 (a-zA-Z0-9\274-\375)
CMC as 3 Base32 chars
Server sends:
Name of codec if accepted. After this all upstream data packets must
be encoded with the new codec.
BADCODEC if not accepted. Client must then revert to Base32
BADCODEC if not accepted. Client must then revert to previous codec
BADLEN if length of query is too short
Options:
@ -68,6 +110,7 @@ Client sends:
First byte o or O
5 bits coded as Base32 char, meaning userid
1 char, meaning option
CMC as 3 Base32 chars
Server sends:
Full name of option if accepted. After this, option immediately takes
effect in server.
@ -77,6 +120,8 @@ Server sends:
Option chars:
t or T: Downstream encoding Base32, for TXT/CNAME/A/MX (default)
s or S: Downstream encoding Base64, for TXT/CNAME/A/MX
u or U: Downstream encoding Base64u, for TXT/CNAME/A/MX
v or V: Downstream encoding Base128, for TXT/CNAME/A/MX
r or R: Downstream encoding Raw, for TXT/NULL (default for NULL)
If codec unsupported for request type, server will use Base32; note
that server will answer any mix of request types that a client sends.
@ -96,8 +141,10 @@ Client sends:
meaning 4 bits userid, 11 bits fragment size
Then follows a long random query which contents does not matter
Server sends:
Requested number of bytes as a response. The first two bytes contains
the requested length. Rest of message can be any data.
Requested number of bytes as a response. The first two bytes contain
the requested length. The third byte is 107 (0x6B). The fourth byte
is a random value, and each following byte is incremented with 107.
This is checked by the client to determine corruption.
BADFRAG if requested length not accepted.
Set downstream fragment size:
@ -114,10 +161,10 @@ Server sends:
Data:
Upstream data header:
3210 432 10 43 210 4321 0
+----+---+--+--+---+----+-+
|UUUU|SSS|FF|FF|DDD|GGGG|L|
+----+---+--+--+---+----+-+
3210 432 10 43 210 4321 0 43210
+----+---+--+--+---+----+-+-----+
|UUUU|SSS|FF|FF|DDD|GGGG|L|UDCMC|
+----+---+--+--+---+----+-+-----+
Downstream data header:
7 654 3210 765 4321 0
@ -132,9 +179,11 @@ FFFF = Upstream fragment number
DDD = Downstream packet sequence number
GGGG = Downstream fragment number
C = Compression enabled for downstream packet
UDCMC = Upstream Data CMC, 36 steps a-z0-9, case-insensitive
Upstream data packet starts with 1 byte ASCII hex coded user byte, then 3 bytes
Base32 encoded header, then comes the payload data, encoded with chosen codec.
Upstream data packet starts with 1 byte ASCII hex coded user byte; then 3 bytes
Base32 encoded header; then 1 char data-CMC; then comes the payload data,
encoded with the chosen upstream codec.
Downstream data starts with 2 byte header. Then payload data, which may be
compressed.
@ -147,10 +196,18 @@ TXT:
<=255 bytes)
t or T: Base32 encoded before chop, decoded after un-chop
s or S: Base64 encoded before chop, decoded after un-chop
u or U: Base64u encoded before chop, decoded after un-chop
v or V: Base128 encoded before chop, decoded after un-chop
r or R: Raw no encoding, only DNS-chop
CNAME/A/MX:
SRV/MX/CNAME/A:
h or H: Hostname encoded with Base32
i or I: Hostname encoded with Base64
j or J: Hostname encoded with Base64u
k or K: Hostname encoded with Base128
SRV and MX may reply with multiple hostnames, each encoded separately. Each
has a 10-multiple priority, and encoding/decoding is done in strictly
increasing priority sequence 10, 20, 30, etc. without gaps. Note that some DNS
relays will shuffle the answer records in the response.
Ping:
Client sends:
@ -162,10 +219,11 @@ Client sends:
4 bits downstream fragment
CMC
The server response to Ping and Data packets is a DNS NULL type response:
If server has nothing to send, data length is 0 bytes.
If server has something to send, it will send a downstream data packet,
prefixed with 2 bytes header as shown above.
The server response to Ping and Data packets is a DNS NULL/TXT/.. type response,
always starting with the 2 bytes downstream data header as shown above.
If server has nothing to send, no data is added after the header.
If server has something to send, it will add the downstream data packet
(or some fragment of it) after the header.
"Lazy-mode" operation

185
man/iodine.8
View file

@ -1,5 +1,5 @@
.\" groff -man -Tascii iodine.8
.TH IODINE 8 "SEP 2009" "User Manuals"
.TH IODINE 8 "DEC 2009" "User Manuals"
.SH NAME
iodine, iodined \- tunnel IPv4 over DNS
.SH SYNOPSIS
@ -19,6 +19,8 @@ iodine, iodined \- tunnel IPv4 over DNS
.I device
.B ] [-m
.I fragsize
.B ] [-M
.I namelen
.B ] [-z
.I context
.B ] [-F
@ -84,6 +86,10 @@ downstream.
is the client application,
.B iodined
is the server.
Note: server and client are required to speak the exact same protocol. In most
cases, this means running the same iodine version. Unfortunately, implementing
backward and forward protocol compatibility is usually not feasible.
.SH OPTIONS
.SS Common Options:
.TP
@ -127,49 +133,85 @@ will be sent to the server instead of the DNS relay.
Force maximum downstream fragment size. Not setting this will cause the
client to automatically probe the maximum accepted downstream fragment size.
.TP
.B -M namelen
Maximum length of upstream hostnames, default 255.
Usable range ca. 100 to 255.
Use this option to scale back upstream bandwidth in favor of downstream
bandwidth.
Also useful for DNS servers that perform unreliably when using full-length
hostnames, noticable when fragment size autoprobe returns very
different results each time.
.TP
.B -T dnstype
DNS request type.
.I NULL
is default. If this doesn't work, try
.I TXT
(some less bandwidth) or
DNS request type override.
By default, autodetection will probe for working DNS request types, and
will select the request type that is expected to provide the most bandwidth.
However, it may turn out that a DNS relay imposes limits that skew the
picture, which may lead to an "unexpected" DNS request type providing
more bandwidth.
In that case, use this option to override the autodetection.
In (expected) decreasing bandwidth order, the supported DNS request types are:
.IR NULL ,
.IR TXT ,
.IR SRV ,
.IR MX ,
.I CNAME
(much less bandwidth). Also supported are
and
.I A
(returning CNAME) and
(returning CNAME).
Note that
.IR SRV ,
.I MX
requests, but these may/will cause additional lookups by "smart" caching
and
.I A
may/will cause additional lookups by "smart" caching
nameservers to get an actual IP address, which may either slow down or fail
completely.
.TP
.B -O downenc
Downstream encoding for all query type responses except NULL.
Force downstream encoding type for all query type responses except NULL.
Default is autodetected, but may not spot all problems for the more advanced
codecs.
Use this option to override the autodetection.
.I Base32
is default and should always work.
is the lowest-grade codec and should always work; this is used when
autodetection fails.
.I Base64
provides more bandwidth, but may not work on all nameservers.
.I Base64u
is equal to Base64 except in using underscore ('_')
instead of plus sign ('+'), possibly working where
.I Base64
does not.
.I Base128
uses high byte values (mostly accented letters in iso8859-1),
which might work with some nameservers.
For TXT queries,
.I Raw
will provide maximum performance. This will only work if the nameserver
will provide maximum performance, but this will only work if the nameserver
path is fully 8-bit-clean for responses that are assumed to be "legible text".
.TP
.B -L 0|1
Lazy-mode switch.
\-L1 (default): Use lazy mode if server supports it, for improved
performance and decreased latency.
Some DNS servers, notably the opendns.com network, appear unstable when
handling lazy mode DNS traffic and will re-order requests. If this occurs,
you will notice fluctuating response speed in interactive sessions.
The iodine client will eventually detect this and switch back to legacy
mode automatically. Use \-L0 to force running in legacy mode
\-L1 (default): Use lazy mode for improved performance and decreased latency.
A very small minority of DNS relays appears to be unable to handle the
lazy mode traffic pattern, resulting in no or very little data coming through.
The iodine client will detect this and try to switch back to legacy mode,
but this may not always work.
In these situations use \-L0 to force running in legacy mode
(implies \-I1).
.TP
.B -I interval
Maximum interval between requests (pings) so that intermediate DNS
servers will not time out. Default is 4 in lazy mode, which will work
fine in almost all cases. Decrease if you get SERVFAIL errors in periods
without tunneled data traffic. To get absolute minimum DNS traffic,
increase well above 4 until SERVFAIL errors start to occur.
fine in most cases. When too many SERVFAIL errors occur, iodine
will automatically reduce this to 1.
To get absolute minimum DNS traffic,
increase well above 4, but not so high that SERVFAIL errors start to occur.
There are some DNS relays with very small timeouts,
notably dnsadvantage.com (ultradns), that will give
SERVFAIL errors even with \-I1; data will still get trough,
and these errors can be ignored.
Maximum useful value is 59, since iodined will close a client's
connection after 60 seconds of inactivity.
.SS Server Options:
@ -190,11 +232,16 @@ Increase debug level. Level 1 prints info about each RX/TX packet.
Implies the
.B -f
option.
On level 2 (-DD) or higher, DNS queries will be printed literally.
When using Base128 upstream encoding, this is best viewed as
ISO Latin-1 text instead of (illegal) UTF-8.
This is easily done with : "LC_ALL=C luit iodined -DD ..."
(see luit(1)).
.TP
.B -m mtu
Set 'mtu' as mtu size for the tun device.
This will be sent to the client on login, and the client will use the same mtu
for its tun device. Default 1200. Note that the DNS traffic will be
for its tun device. Default 1130. Note that the DNS traffic will be
automatically fragmented when needed.
.TP
.B -l listen_ip
@ -236,97 +283,22 @@ must be the same on both the client and the server.
.SS Server Arguments:
.TP
.B tunnel_ip[/netmask]
+This is the server's ip address on the tun interface. The client will be
This is the server's ip address on the tun interface. The client will be
given the next ip number in the range. It is recommended to use the
10.0.0.0 or 172.16.0.0 ranges. The default netmask is /27, can be overriden
by specifying it here. Using a smaller network will limit the number of
concurrent users.
.TP
.B topdomain
+The dns traffic is expected to arrive as queries for
The dns traffic is expected to arrive as queries for
subdomains under 'topdomain'. This is normally a subdomain to a domain you
own. Use a short domain name to get better throughput. This argument must be
the same on both the client and the server. Queries for domains other
than 'topdomain' will be forwarded when the \-b option is given, otherwise
they will be dropped.
.SH EXAMPLES
.SS Quickstart:
.TP
Try it out within your own LAN! Follow these simple steps:
.TP
- On your server, run: ./iodined \-f 10.0.0.1 test.asdf
(If you already use the 10.0.0.0 network, use another internal net like
172.16.0.0)
.TP
- Enter a password
.TP
- On the client, run: ./iodine \-f 192.168.0.1 test.asdf
(Replace 192.168.0.1 with the server's ip address)
.TP
- Enter the same password
.TP
- Now the client has the tunnel ip 10.0.0.2 and the server has 10.0.0.1
.TP
- Try pinging each other through the tunnel
.TP
- Done! :)
.TP
To actually use it through a relaying nameserver, see below.
.SS Full setup:
.TP
.B Server side:
To use this tunnel, you need control over a real domain (like mytunnel.com),
and a server with a public IP number. If the server already runs a DNS
server, change the listening port and then use the \-b option to let
iodined forward the DNS requests. Then, delegate a subdomain
(say, tunnel1.mytunnel.com) to the server. If you use BIND for the domain,
add these lines to the zone file (replace 10.15.213.99 with your server ip):
.nf
tunnel1host IN A 10.15.213.99
tunnel1 IN NS tunnel1host.mytunnel.com.
.fi
Now any DNS querys for domains ending with tunnel1.mytunnnel.com will be sent
to your server. Start iodined on the server. The first argument is the tunnel
IP address (like 192.168.99.1) and the second is the assigned domain (in this
case tunnel1.mytunnel.com). The \-f argument will keep iodined running in the
foreground, which helps when testing. iodined will start a virtual interface,
and also start listening for DNS queries on UDP port 53. Either enter a
password on the commandline (\-P pass) or after the server has started. Now
everything is ready for the client.
.TP
.B Client side:
All the setup is done, just start iodine. It also takes two
arguments, the first is the local relaying DNS server and the second is the
domain used (tunnel1.mytunnnel.com). If DNS queries are allowed to any
computer, you can use the tunnel endpoint (example: 10.15.213.99 or
tunnel1host.mytunnel.com) as the first argument. The tunnel interface will get
an IP close to the servers (in this case 192.168.99.2) and a suitable MTU.
Enter the same password as on the server either by argument or after the client
has started. Now you should be able to ping the other end of the tunnel from
either side.
.TP
.B Routing:
The normal case is to route all traffic through the DNS tunnel. To do this, first
add a route to the nameserver you use with the default gateway as gateway. Then
replace the default gateway with the servers IP address within the DNS tunnel,
and configure the server to do NAT.
.TP
.B Troubleshooting:
Use the \-D option on the server to show received and sent queries, or use a
tool like Wireshark/tcpdump. The iodined server replies to NS requests sent for
subdomains of the tunnel domain. If your domain is tunnel.com, send a NS
request for foo.tunnel.com to see if the delegation works. dig is a good tool
for this:
.nf
dig \-t NS foo123.tunnel.com
.fi
.TP
.B MTU issues:
These issues should be solved now, with automatic fragmentation of downstream
packets. There should be no need to set the MTU explicitly on the server.
See the README file for both a quick test scenario, and a detailed description
of real-world deployment.
.SH SECURITY
Login is a relatively secure challenge-response MD5 hash, with the
password never passing the wire.
@ -336,10 +308,9 @@ encrypted in any way. The DNS traffic is also vulnerable to replay,
injection and man-in-the-middle attacks, especially when iodined is used
with the \-c option. Use of ssh or vpn tunneling is strongly recommended.
On both server and client, use
.I iptables
,
.IR iptables ,
.I pf
or other firewlls to block all traffic coming in from the tun interfaces,
or other firewalls to block all traffic coming in from the tun interfaces,
except to the used ssh or vpn ports.
.SH ENVIRONMENT
.SS IODINE_PASS
@ -348,14 +319,14 @@ If the environment variable
is set, iodine will use the value it is set to as password instead of asking
for one. The
.B -P
option still has preference.
option still has precedence.
.SS IODINED_PASS
If the environment variable
.B IODINED_PASS
is set, iodined will use the value it is set to as password instead of asking
for one. The
.B -P
option still has preference.
option still has precedence.
.El
.SH SEE ALSO
The README file in the source distribution contains some more elaborate

14
src/Makefile
View file

@ -1,4 +1,4 @@
COMMONOBJS = tun.o dns.o read.o encoding.o login.o base32.o base64.o md5.o common.o
COMMONOBJS = tun.o dns.o read.o encoding.o login.o base32.o base64.o base64u.o base128.o md5.o common.o
CLIENTOBJS = iodine.o client.o util.o
CLIENT = ../bin/iodine
SERVEROBJS = iodined.o user.o fw_query.o
@ -30,7 +30,17 @@ $(SERVER): $(COMMONOBJS) $(SERVEROBJS)
@echo CC $<
@$(CC) $(CFLAGS) $< -o $@
base64u.o client.o iodined.o: base64u.h
base64u.c: base64.c
@echo Making $@
@echo '/* No use in editing, produced by Makefile! */' > $@
@sed -e 's/\(base64\)/\1u/ig ; s/0123456789+/0123456789_/' < $< >> $@
base64u.h: base64.h
@echo Making $@
@echo '/* No use in editing, produced by Makefile! */' > $@
@sed -e 's/\(base64\)/\1u/ig ; s/0123456789+/0123456789_/' < $< >> $@
clean:
@echo "Cleaning src/"
@rm -f $(CLIENT){,.exe} $(SERVER){,.exe} *~ *.o *.core
@rm -f $(CLIENT){,.exe} $(SERVER){,.exe} *~ *.o *.core base64u.*

291
src/base128.c Normal file
View file

@ -0,0 +1,291 @@
/*
* Copyright (C) 2009 J.A.Bezemer@opensourcepartners.nl
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* raw 76543210 76543210 76543210 76543210 76543210 76543210 76543210
* enc 65432106 54321065 43210654 32106543 21065432 10654321 06543210
* ^ ^ ^ ^ ^ ^ ^ ^
*
* 0001 1 0001 1
* 0011 3 0011 3
* 0111 7 0111 7
* 1111 f 0110 6
* 1110 e 0100 4
* 1100 c
* 1000 8
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "encoding.h"
#include "base128.h"
#define BLKSIZE_RAW 7
#define BLKSIZE_ENC 8
/* Don't use '-' (restricted to middle of labels), prefer iso_8859-1
* accent chars since they might readily be entered in normal use,
* don't use 254-255 because of possible function overloading in DNS systems.
*/
static const unsigned char cb128[] =
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
"\274\275\276\277"
"\300\301\302\303\304\305\306\307\310\311\312\313\314\315\316\317"
"\320\321\322\323\324\325\326\327\330\331\332\333\334\335\336\337"
"\340\341\342\343\344\345\346\347\350\351\352\353\354\355\356\357"
"\360\361\362\363\364\365\366\367\370\371\372\373\374\375";
static unsigned char rev128[256];
static int reverse_init = 0;
static int base128_encode(char *, size_t *, const void *, size_t);
static int base128_decode(void *, size_t *, const char *, size_t);
static int base128_handles_dots();
static int base128_blksize_raw();
static int base128_blksize_enc();
static struct encoder base128_encoder =
{
"Base128",
base128_encode,
base128_decode,
base128_handles_dots,
base128_handles_dots,
base128_blksize_raw,
base128_blksize_enc
};
struct encoder
*get_base128_encoder()
{
return &base128_encoder;
}
static int
base128_handles_dots()
{
return 0;
}
static int
base128_blksize_raw()
{
return BLKSIZE_RAW;
}
static int
base128_blksize_enc()
{
return BLKSIZE_ENC;
}
inline static void
base128_reverse_init()
{
int i;
unsigned char c;
if (!reverse_init) {
memset (rev128, 0, 256);
for (i = 0; i < 128; i++) {
c = cb128[i];
rev128[(int) c] = i;
}
reverse_init = 1;
}
}
static int
base128_encode(char *buf, size_t *buflen, const void *data, size_t size)
/*
* Fills *buf with max. *buflen characters, encoding size bytes of *data.
*
* NOTE: *buf space should be at least 1 byte _more_ than *buflen
* to hold the trailing '\0'.
*
* return value : #bytes filled in buf (excluding \0)
* sets *buflen to : #bytes encoded from data
*/
{
unsigned char *ubuf = (unsigned char *) buf;
unsigned char *udata = (unsigned char *) data;
int iout = 0; /* to-be-filled output char */
int iin = 0; /* one more than last input byte that can be
successfully decoded */
/* Note: Don't bother to optimize manually. GCC optimizes
better(!) when using simplistic array indexing. */
while (1) {
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[((udata[iin] & 0xfe) >> 1)];
iout++;
if (iout >= *buflen || iin >= size) {
iout--; /* previous char is useless */
break;
}
ubuf[iout] = cb128[((udata[iin] & 0x01) << 6) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xfc) >> 2) : 0)];
iin++; /* 0 complete, iin=1 */
iout++;
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[((udata[iin] & 0x03) << 5) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xf8) >> 3) : 0)];
iin++; /* 1 complete, iin=2 */
iout++;
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[((udata[iin] & 0x07) << 4) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xf0) >> 4) : 0)];
iin++; /* 2 complete, iin=3 */
iout++;
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[((udata[iin] & 0x0f) << 3) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xe0) >> 5) : 0)];
iin++; /* 3 complete, iin=4 */
iout++;
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[((udata[iin] & 0x1f) << 2) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xc0) >> 6) : 0)];
iin++; /* 4 complete, iin=5 */
iout++;
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[((udata[iin] & 0x3f) << 1) |
((iin + 1 < size) ?
((udata[iin + 1] & 0x80) >> 7) : 0)];
iin++; /* 5 complete, iin=6 */
iout++;
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[(udata[iin] & 0x7f)];
iin++; /* 6 complete, iin=7 */
iout++;
}
ubuf[iout] = '\0';
/* store number of bytes from data that was used */
*buflen = iin;
return iout;
}
#define REV128(x) rev128[(int) (x)]
static int
base128_decode(void *buf, size_t *buflen, const char *str, size_t slen)
/*
* Fills *buf with max. *buflen bytes, decoded from slen chars in *str.
* Decoding stops early when *str contains \0.
* Illegal encoded chars are assumed to decode to zero.
*
* NOTE: *buf space should be at least 1 byte _more_ than *buflen
* to hold a trailing '\0' that is added (though *buf will usually
* contain full-binary data).
*
* return value : #bytes filled in buf (excluding \0)
*/
{
unsigned char *ustr = (unsigned char *) str;
unsigned char *ubuf = (unsigned char *) buf;
int iout = 0; /* to-be-filled output byte */
int iin = 0; /* next input char to use in decoding */
base128_reverse_init ();
/* Note: Don't bother to optimize manually. GCC optimizes
better(!) when using simplistic array indexing. */
while (1) {
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x7f) << 1) |
((REV128(ustr[iin + 1]) & 0x40) >> 6);
iin++; /* 0 used up, iin=1 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x3f) << 2) |
((REV128(ustr[iin + 1]) & 0x60) >> 5);
iin++; /* 1 used up, iin=2 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x1f) << 3) |
((REV128(ustr[iin + 1]) & 0x70) >> 4);
iin++; /* 2 used up, iin=3 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x0f) << 4) |
((REV128(ustr[iin + 1]) & 0x78) >> 3);
iin++; /* 3 used up, iin=4 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x07) << 5) |
((REV128(ustr[iin + 1]) & 0x7c) >> 2);
iin++; /* 4 used up, iin=5 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x03) << 6) |
((REV128(ustr[iin + 1]) & 0x7e) >> 1);
iin++; /* 5 used up, iin=6 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x01) << 7) |
((REV128(ustr[iin + 1]) & 0x7f));
iin += 2; /* 6,7 used up, iin=8 */
iout++;
}
ubuf[iout] = '\0';
return iout;
}

22
src/base128.h Normal file
View file

@ -0,0 +1,22 @@
/*
* Copyright (C) 2009 J.A.Bezemer@opensourcepartners.nl
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef __BASE128_H__
#define __BASE128_H__
struct encoder *get_base128_encoder(void);
#endif

244
src/base32.c
View file

@ -1,5 +1,6 @@
/*
* Copyright (c) 2006-2009 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
* Mostly rewritten 2009 J.A.Bezemer@opensourcepartners.nl
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
@ -28,10 +29,11 @@ static const char cb32[] =
"abcdefghijklmnopqrstuvwxyz012345";
static const char cb32_ucase[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ012345";
static unsigned char rev32[128];
static unsigned char rev32[256];
static int reverse_init = 0;
static int base32_decode(void *, size_t *, const char *, size_t);
static int base32_encode(char *, size_t *, const void *, size_t);
static int base32_decode(void *, size_t *, const char *, size_t);
static int base32_handles_dots();
static int base32_blksize_raw();
static int base32_blksize_enc();
@ -71,14 +73,14 @@ base32_blksize_enc()
return BLKSIZE_ENC;
}
static void
inline static void
base32_reverse_init()
{
int i;
unsigned char c;
static int reverse_init = 0;
if (!reverse_init) {
memset (rev32, 0, 256);
for (i = 0; i < 32; i++) {
c = cb32[i];
rev32[(int) c] = i;
@ -104,123 +106,165 @@ b32_8to5(int in)
static int
base32_encode(char *buf, size_t *buflen, const void *data, size_t size)
/*
* Fills *buf with max. *buflen characters, encoding size bytes of *data.
*
* NOTE: *buf space should be at least 1 byte _more_ than *buflen
* to hold the trailing '\0'.
*
* return value : #bytes filled in buf (excluding \0)
* sets *buflen to : #bytes encoded from data
*/
{
size_t newsize;
size_t maxsize;
unsigned char *p;
unsigned char *q;
int i;
unsigned char *udata = (unsigned char *) data;
int iout = 0; /* to-be-filled output char */
int iin = 0; /* one more than last input byte that can be
successfully decoded */
memset(buf, 0, *buflen);
/* Note: Don't bother to optimize manually. GCC optimizes
better(!) when using simplistic array indexing. */
/* how many chars can we encode within the buf */
maxsize = BLKSIZE_RAW * (*buflen / BLKSIZE_ENC);
/* how big will the encoded data be */
newsize = BLKSIZE_ENC * (size / BLKSIZE_RAW);
if (size % BLKSIZE_RAW) {
newsize += BLKSIZE_ENC;
while (1) {
if (iout >= *buflen || iin >= size)
break;
buf[iout] = cb32[((udata[iin] & 0xf8) >> 3)];
iout++;
if (iout >= *buflen || iin >= size) {
iout--; /* previous char is useless */
break;
}
/* if the buffer is too small, eat some of the data */
if (*buflen < newsize) {
size = maxsize;
buf[iout] = cb32[((udata[iin] & 0x07) << 2) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xc0) >> 6) : 0)];
iin++; /* 0 complete, iin=1 */
iout++;
if (iout >= *buflen || iin >= size)
break;
buf[iout] = cb32[((udata[iin] & 0x3e) >> 1)];
iout++;
if (iout >= *buflen || iin >= size) {
iout--; /* previous char is useless */
break;
}
buf[iout] = cb32[((udata[iin] & 0x01) << 4) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xf0) >> 4) : 0)];
iin++; /* 1 complete, iin=2 */
iout++;
if (iout >= *buflen || iin >= size)
break;
buf[iout] = cb32[((udata[iin] & 0x0f) << 1) |
((iin + 1 < size) ?
((udata[iin + 1] & 0x80) >> 7) : 0)];
iin++; /* 2 complete, iin=3 */
iout++;
if (iout >= *buflen || iin >= size)
break;
buf[iout] = cb32[((udata[iin] & 0x7c) >> 2)];
iout++;
if (iout >= *buflen || iin >= size) {
iout--; /* previous char is useless */
break;
}
buf[iout] = cb32[((udata[iin] & 0x03) << 3) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xe0) >> 5) : 0)];
iin++; /* 3 complete, iin=4 */
iout++;
if (iout >= *buflen || iin >= size)
break;
buf[iout] = cb32[((udata[iin] & 0x1f))];
iin++; /* 4 complete, iin=5 */
iout++;
}
p = (unsigned char *) buf;
q = (unsigned char *)data;
for(i=0;i<size;i+=BLKSIZE_RAW) {
p[0] = cb32[((q[0] & 0xf8) >> 3)];
p[1] = cb32[(((q[0] & 0x07) << 2) | ((q[1] & 0xc0) >> 6))];
p[2] = (i+1 < size) ? cb32[((q[1] & 0x3e) >> 1)] : '\0';
p[3] = (i+1 < size) ? cb32[((q[1] & 0x01) << 4) | ((q[2] & 0xf0) >> 4)] : '\0';
p[4] = (i+2 < size) ? cb32[((q[2] & 0x0f) << 1) | ((q[3] & 0x80) >> 7)] : '\0';
p[5] = (i+3 < size) ? cb32[((q[3] & 0x7c) >> 2)] : '\0';
p[6] = (i+3 < size) ? cb32[((q[3] & 0x03) << 3) | ((q[4] & 0xe0) >> 5)] : '\0';
p[7] = (i+4 < size) ? cb32[((q[4] & 0x1f))] : '\0';
q += BLKSIZE_RAW;
p += BLKSIZE_ENC;
}
*p = 0;
buf[iout] = '\0';
/* store number of bytes from data that was used */
*buflen = size;
*buflen = iin;
return strlen(buf);
return iout;
}
#define DECODE_ERROR 0xffffffff
#define REV32(x) rev32[(int) (x)]
static int
decode_token(const unsigned char *t, unsigned char *data, size_t len)
{
if (len < 2)
return 0;
data[0] = ((REV32(t[0]) & 0x1f) << 3) |
((REV32(t[1]) & 0x1c) >> 2);
if (len < 4)
return 1;
data[1] = ((REV32(t[1]) & 0x03) << 6) |
((REV32(t[2]) & 0x1f) << 1) |
((REV32(t[3]) & 0x10) >> 4);
if (len < 5)
return 2;
data[2] = ((REV32(t[3]) & 0x0f) << 4) |
((REV32(t[4]) & 0x1e) >> 1);
if (len < 7)
return 3;
data[3] = ((REV32(t[4]) & 0x01) << 7) |
((REV32(t[5]) & 0x1f) << 2) |
((REV32(t[6]) & 0x18) >> 3);
if (len < 8)
return 4;
data[4] = ((REV32(t[6]) & 0x07) << 5) |
((REV32(t[7]) & 0x1f));
return 5;
}
static int
base32_decode(void *buf, size_t *buflen, const char *str, size_t slen)
/*
* Fills *buf with max. *buflen bytes, decoded from slen chars in *str.
* Decoding stops early when *str contains \0.
* Illegal encoded chars are assumed to decode to zero.
*
* NOTE: *buf space should be at least 1 byte _more_ than *buflen
* to hold a trailing '\0' that is added (though *buf will usually
* contain full-binary data).
*
* return value : #bytes filled in buf (excluding \0)
*/
{
unsigned char *q;
size_t newsize;
size_t maxsize;
const char *p;
int len;
unsigned char *ubuf = (unsigned char *) buf;
int iout = 0; /* to-be-filled output byte */
int iin = 0; /* next input char to use in decoding */
base32_reverse_init ();
/* chars needed to decode slen */
newsize = BLKSIZE_RAW * (slen / BLKSIZE_ENC + 1) + 1;
/* encoded chars that fit in buf */
maxsize = BLKSIZE_ENC * (*buflen / BLKSIZE_RAW + 1) + 1;
/* if the buffer is too small, eat some of the data */
if (*buflen < newsize) {
slen = maxsize;
}
/* Note: Don't bother to optimize manually. GCC optimizes
better(!) when using simplistic array indexing. */
q = buf;
for (p = str; *p && strchr(cb32, *p); p += BLKSIZE_ENC) {
len = decode_token((unsigned char *) p, (unsigned char *) q, slen);
q += len;
slen -= BLKSIZE_ENC;
if (len < BLKSIZE_RAW)
while (1) {
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
}
*q = '\0';
ubuf[iout] = ((REV32(str[iin]) & 0x1f) << 3) |
((REV32(str[iin + 1]) & 0x1c) >> 2);
iin++; /* 0 used up, iin=1 */
iout++;
return q - (unsigned char *) buf;
if (iout >= *buflen || iin + 2 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0' ||
str[iin + 2] == '\0')
break;
ubuf[iout] = ((REV32(str[iin]) & 0x03) << 6) |
((REV32(str[iin + 1]) & 0x1f) << 1) |
((REV32(str[iin + 2]) & 0x10) >> 4);
iin += 2; /* 1,2 used up, iin=3 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV32(str[iin]) & 0x0f) << 4) |
((REV32(str[iin + 1]) & 0x1e) >> 1);
iin++; /* 3 used up, iin=4 */
iout++;
if (iout >= *buflen || iin + 2 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0' ||
str[iin + 2] == '\0')
break;
ubuf[iout] = ((REV32(str[iin]) & 0x01) << 7) |
((REV32(str[iin + 1]) & 0x1f) << 2) |
((REV32(str[iin + 2]) & 0x18) >> 3);
iin += 2; /* 4,5 used up, iin=6 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV32(str[iin]) & 0x07) << 5) |
((REV32(str[iin + 1]) & 0x1f));
iin += 2; /* 6,7 used up, iin=8 */
iout++;
}
ubuf[iout] = '\0';
return iout;
}

217
src/base64.c
View file

@ -1,5 +1,6 @@
/*
* Copyright (c) 2006-2009 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
* Mostly rewritten 2009 J.A.Bezemer@opensourcepartners.nl
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
@ -19,15 +20,16 @@
#include <string.h>
#include "encoding.h"
#include "common.h"
#include "base64.h"
#define BLKSIZE_RAW 3
#define BLKSIZE_ENC 4
/* Note: the "unofficial" char is last here, which means that the \377 pattern
in DOWNCODECCHECK1 ('Y' request) will properly test it. */
static const char cb64[] =
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-0123456789+";
static unsigned char rev64[128];
static unsigned char rev64[256];
static int reverse_init = 0;
static int base64_encode(char *, size_t *, const void *, size_t);
@ -36,8 +38,6 @@ static int base64_handles_dots();
static int base64_blksize_raw();
static int base64_blksize_enc();
#define REV64(x) rev64[(int) (x)]
static struct encoder base64_encoder =
{
"Base64",
@ -73,122 +73,133 @@ base64_blksize_enc()
return BLKSIZE_ENC;
}
static int
base64_encode(char *buf, size_t *buflen, const void *data, size_t size)
inline static void
base64_reverse_init()
{
size_t newsize;
size_t maxsize;
unsigned char *s;
unsigned char *p;
unsigned char *q;
int i;
memset(buf, 0, *buflen);
/* how many chars can we encode within the buf */
maxsize = BLKSIZE_RAW * (*buflen / BLKSIZE_ENC);
/* how big will the encoded data be */
newsize = BLKSIZE_ENC * (size / BLKSIZE_RAW);
if (size % BLKSIZE_RAW) {
newsize += BLKSIZE_ENC;
}
/* if the buffer is too small, eat some of the data */
if (*buflen < newsize) {
size = maxsize;
}
p = s = (unsigned char *) buf;
q = (unsigned char *)data;
for(i=0;i<size;i+=BLKSIZE_RAW) {
p[0] = cb64[((q[0] & 0xfc) >> 2)];
p[1] = cb64[(((q[0] & 0x03) << 4) | ((q[1] & 0xf0) >> 4))];
p[2] = (i+1 < size) ? cb64[((q[1] & 0x0f) << 2 ) | ((q[2] & 0xc0) >> 6)] : '\0';
p[3] = (i+2 < size) ? cb64[(q[2] & 0x3f)] : '\0';
q += BLKSIZE_RAW;
p += BLKSIZE_ENC;
}
*p = 0;
/* store number of bytes from data that was used */
*buflen = size;
return strlen(buf);
}
#define DECODE_ERROR 0xffffffff
static int
decode_token(const unsigned char *t, unsigned char *data, size_t len)
{
if (len < 2)
return 0;
data[0] = ((REV64(t[0]) & 0x3f) << 2) |
((REV64(t[1]) & 0x30) >> 4);
if (len < 3)
return 1;
data[1] = ((REV64(t[1]) & 0x0f) << 4) |
((REV64(t[2]) & 0x3c) >> 2);
if (len < 4)
return 2;
data[2] = ((REV64(t[2]) & 0x03) << 6) |
(REV64(t[3]) & 0x3f);
return 3;
}
static int
base64_decode(void *buf, size_t *buflen, const char *str, size_t slen)
{
unsigned char *q;
size_t newsize;
size_t maxsize;
const char *p;
unsigned char c;
unsigned char block[BLKSIZE_ENC];
int len;
int i;
if (!reverse_init) {
memset (rev64, 0, 256);
for (i = 0; i < 64; i++) {
c = cb64[i];
rev64[(int) c] = i;
}
reverse_init = 1;
}
/* chars needed to decode slen */
newsize = BLKSIZE_RAW * (slen / BLKSIZE_ENC + 1) + 1;
/* encoded chars that fit in buf */
maxsize = BLKSIZE_ENC * (*buflen / BLKSIZE_RAW + 1) + 1;
/* if the buffer is too small, eat some of the data */
if (*buflen < newsize) {
slen = maxsize;
}
static int
base64_encode(char *buf, size_t *buflen, const void *data, size_t size)
/*
* Fills *buf with max. *buflen characters, encoding size bytes of *data.
*
* NOTE: *buf space should be at least 1 byte _more_ than *buflen
* to hold the trailing '\0'.
*
* return value : #bytes filled in buf (excluding \0)
* sets *buflen to : #bytes encoded from data
*/
{
unsigned char *udata = (unsigned char *) data;
int iout = 0; /* to-be-filled output char */
int iin = 0; /* one more than last input byte that can be
successfully decoded */
q = buf;
for (p = str; *p; p += BLKSIZE_ENC) {
/* since the str is const, we unescape in another buf */
for (i = 0; i < BLKSIZE_ENC; i++) {
block[i] = p[i];
}
len = decode_token(block, (unsigned char *) q, slen);
q += len;
slen -= BLKSIZE_ENC;
/* Note: Don't bother to optimize manually. GCC optimizes
better(!) when using simplistic array indexing. */
if (len < BLKSIZE_RAW)
while (1) {
if (iout >= *buflen || iin >= size)
break;
buf[iout] = cb64[((udata[iin] & 0xfc) >> 2)];
iout++;
if (iout >= *buflen || iin >= size) {
iout--; /* previous char is useless */
break;
}
*q = '\0';
buf[iout] = cb64[((udata[iin] & 0x03) << 4) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xf0) >> 4) : 0)];
iin++; /* 0 complete, iin=1 */
iout++;
return q - (unsigned char *) buf;
if (iout >= *buflen || iin >= size)
break;
buf[iout] = cb64[((udata[iin] & 0x0f) << 2 ) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xc0) >> 6) : 0)];
iin++; /* 1 complete, iin=2 */
iout++;
if (iout >= *buflen || iin >= size)
break;
buf[iout] = cb64[(udata[iin] & 0x3f)];
iin++; /* 2 complete, iin=3 */
iout++;
}
buf[iout] = '\0';
/* store number of bytes from data that was used */
*buflen = iin;
return iout;
}
#define REV64(x) rev64[(int) (x)]
static int
base64_decode(void *buf, size_t *buflen, const char *str, size_t slen)
/*
* Fills *buf with max. *buflen bytes, decoded from slen chars in *str.
* Decoding stops early when *str contains \0.
* Illegal encoded chars are assumed to decode to zero.
*
* NOTE: *buf space should be at least 1 byte _more_ than *buflen
* to hold a trailing '\0' that is added (though *buf will usually
* contain full-binary data).
*
* return value : #bytes filled in buf (excluding \0)
*/
{
unsigned char *ubuf = (unsigned char *) buf;
int iout = 0; /* to-be-filled output byte */
int iin = 0; /* next input char to use in decoding */
base64_reverse_init ();
/* Note: Don't bother to optimize manually. GCC optimizes
better(!) when using simplistic array indexing. */
while (1) {
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV64(str[iin]) & 0x3f) << 2) |
((REV64(str[iin + 1]) & 0x30) >> 4);
iin++; /* 0 used up, iin=1 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV64(str[iin]) & 0x0f) << 4) |
((REV64(str[iin + 1]) & 0x3c) >> 2);
iin++; /* 1 used up, iin=2 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV64(str[iin]) & 0x03) << 6) |
(REV64(str[iin + 1]) & 0x3f);
iin += 2; /* 2,3 used up, iin=4 */
iout++;
}
ubuf[iout] = '\0';
return iout;
}

1319
src/client.c
View file

File diff suppressed because it is too large Load diff

2
src/client.h
View file

@ -27,9 +27,11 @@ void client_set_nameserver(const char *cp, int port);
void client_set_topdomain(const char *cp);
void client_set_password(const char *cp);
void set_qtype(char *qtype);
char *get_qtype();
void set_downenc(char *encoding);
void client_set_selecttimeout(int select_timeout);
void client_set_lazymode(int lazy_mode);
void client_set_hostname_maxlen(int i);
int client_handshake(int dns_fd, int raw_mode, int autodetect_frag_size, int fragsize);
int client_tunnel(int tun_fd, int dns_fd);

7
src/common.h
View file

@ -74,6 +74,9 @@ extern const unsigned char raw_header[RAW_HDR_LEN];
# define DONT_FRAG_VALUE 1
#endif
#define T_UNSET 65432
/* Unused RR type; "private use" range, see http://www.bind9.net/dns-parameters */
struct packet
{
int len; /* Total packet length */
@ -89,10 +92,12 @@ struct query {
unsigned short type;
unsigned short rcode;
unsigned short id;
unsigned short iddupe; /* only used for dupe checking */
struct in_addr destination;
struct sockaddr from;
int fromlen;
unsigned short id2;
struct sockaddr from2;
int fromlen2;
};
enum connection {

274
src/dns.c
View file

@ -39,6 +39,8 @@
#include "encoding.h"
#include "read.h"
int dnsc_use_edns0 = 1;
#define CHECKLEN(x) if (buflen - (p-buf) < (x)) return 0
int
@ -48,6 +50,7 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
short name;
char *p;
int len;
int ancnt;
if (buflen < sizeof(HEADER))
return 0;
@ -68,7 +71,6 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
switch (qr) {
case QR_ANSWER:
header->ancount = htons(1);
header->qdcount = htons(1);
name = 0xc000 | ((p - buf) & 0x3fff);
@ -81,56 +83,115 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
putshort(&p, C_IN);
/* Answer section */
if (q->type == T_CNAME || q->type == T_A) {
/* data is expected to be like "Hblabla.host.name.com\0" */
char *startp;
int namelen;
CHECKLEN(10);
putshort(&p, name);
if (q->type == T_A)
putshort(&p, T_CNAME); /* answer CNAME to A question */
/* answer CNAME to A question */
putshort(&p, T_CNAME);
else
putshort(&p, q->type);
putshort(&p, C_IN);
putlong(&p, 0); /* TTL */
if (q->type == T_CNAME || q->type == T_A || q->type == T_MX) {
/* data is expected to be like "Hblabla.host.name.com\0" */
char *startp = p;
int namelen;
startp = p;
p += 2; /* skip 2 bytes length */
CHECKLEN(2);
if (q->type == T_MX)
putshort(&p, 10); /* preference */
putname(&p, buflen - (p - buf), data);
CHECKLEN(0);
namelen = p - startp;
namelen -= 2;
putshort(&startp, namelen);
ancnt = 1;
} else if (q->type == T_MX || q->type == T_SRV) {
/* Data is expected to be like
"Hblabla.host.name.com\0Hanother.com\0\0"
For SRV, see RFC2782.
*/
char *mxdata = data;
char *startp;
int namelen;
ancnt = 1;
while (1) {
CHECKLEN(10);
putshort(&p, name);
putshort(&p, q->type);
putshort(&p, C_IN);
putlong(&p, 0); /* TTL */
startp = p;
p += 2; /* skip 2 bytes length */
CHECKLEN(2);
putshort(&p, 10 * ancnt); /* preference */
if (q->type == T_SRV) {
/* weight, port (5060 = SIP) */
CHECKLEN(4);
putshort(&p, 10);
putshort(&p, 5060);
}
putname(&p, buflen - (p - buf), mxdata);
CHECKLEN(0);
namelen = p - startp;
namelen -= 2;
putshort(&startp, namelen);
mxdata = mxdata + strlen(mxdata) + 1;
if (*mxdata == '\0')
break;
ancnt++;
}
} else if (q->type == T_TXT) {
/* TXT has binary or base-X data */
char *startp = p;
char *startp;
int txtlen;
CHECKLEN(10);
putshort(&p, name);
putshort(&p, q->type);
putshort(&p, C_IN);
putlong(&p, 0); /* TTL */
startp = p;
p += 2; /* skip 2 bytes length */
puttxtbin(&p, buflen - (p - buf), data, datalen);
CHECKLEN(0);
txtlen = p - startp;
txtlen -= 2;
putshort(&startp, txtlen);
ancnt = 1;
} else {
/* NULL has raw binary data */
CHECKLEN(10);
putshort(&p, name);
putshort(&p, q->type);
putshort(&p, C_IN);
putlong(&p, 0); /* TTL */
datalen = MIN(datalen, buflen - (p - buf));
CHECKLEN(2);
putshort(&p, datalen);
CHECKLEN(datalen);
putdata(&p, data, datalen);
CHECKLEN(0);
ancnt = 1;
}
header->ancount = htons(ancnt);
break;
case QR_QUERY:
/* Note that iodined also uses this for forward queries */
header->qdcount = htons(1);
header->arcount = htons(1);
datalen = MIN(datalen, buflen - (p - buf));
putname(&p, datalen, data);
@ -141,6 +202,9 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
/* EDNS0 to advertise maximum response length
(even CNAME/A/MX, 255+255+header would be >512) */
if (dnsc_use_edns0) {
header->arcount = htons(1);
/*XXX START adjust indent 1 tab forward*/
CHECKLEN(11);
putbyte(&p, 0x00); /* Root */
putshort(&p, 0x0029); /* OPT */
@ -148,6 +212,9 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
putshort(&p, 0x0000); /* Higher bits/edns version */
putshort(&p, 0x8000); /* Z */
putshort(&p, 0x0000); /* Data length */
/*XXX END adjust indent 1 tab forward*/
}
break;
}
@ -159,13 +226,14 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
int
dns_encode_ns_response(char *buf, size_t buflen, struct query *q, char *topdomain)
/* Only used when iodined gets an NS type query */
/* Mostly same as dns_encode_a_response() below */
{
HEADER *header;
int len;
short name;
short topname;
short nsname;
char *domain;
char *ipp;
int domain_len;
char *p;
@ -193,13 +261,16 @@ dns_encode_ns_response(char *buf, size_t buflen, struct query *q, char *topdomai
/* pointer to start of name */
name = 0xc000 | ((p - buf) & 0x3fff);
domain = strstr(q->name, topdomain);
if (domain) {
domain_len = (int) (domain - q->name);
} else {
domain_len = strlen(q->name) - strlen(topdomain);
if (domain_len < 0 || domain_len == 1)
return -1;
}
/* pointer to start of topdomain */
if (strcasecmp(q->name + domain_len, topdomain))
return -1;
if (domain_len >= 1 && q->name[domain_len - 1] != '.')
return -1;
/* pointer to start of topdomain; instead of dots at the end
we have length-bytes in front, so total length is the same */
topname = 0xc000 | ((p - buf + domain_len) & 0x3fff);
/* Query section */
@ -233,12 +304,72 @@ dns_encode_ns_response(char *buf, size_t buflen, struct query *q, char *topdomai
putshort(&p, 4); /* Data length */
/* ugly hack to output IP address */
domain = (char *) &q->destination;
ipp = (char *) &q->destination;
CHECKLEN(4);
putbyte(&p, *domain++);
putbyte(&p, *domain++);
putbyte(&p, *domain++);
putbyte(&p, *domain);
putbyte(&p, *(ipp++));
putbyte(&p, *(ipp++));
putbyte(&p, *(ipp++));
putbyte(&p, *ipp);
len = p - buf;
return len;
}
int
dns_encode_a_response(char *buf, size_t buflen, struct query *q)
/* Only used when iodined gets an A type query for ns.topdomain or www.topdomain */
/* Mostly same as dns_encode_ns_response() above */
{
HEADER *header;
int len;
short name;
char *ipp;
char *p;
if (buflen < sizeof(HEADER))
return 0;
memset(buf, 0, buflen);
header = (HEADER*)buf;
header->id = htons(q->id);
header->qr = 1;
header->opcode = 0;
header->aa = 1;
header->tc = 0;
header->rd = 0;
header->ra = 0;
p = buf + sizeof(HEADER);
header->qdcount = htons(1);
header->ancount = htons(1);
/* pointer to start of name */
name = 0xc000 | ((p - buf) & 0x3fff);
/* Query section */
putname(&p, buflen - (p - buf), q->name); /* Name */
CHECKLEN(4);
putshort(&p, q->type); /* Type */
putshort(&p, C_IN); /* Class */
/* Answer section */
CHECKLEN(12);
putshort(&p, name); /* Name */
putshort(&p, q->type); /* Type */
putshort(&p, C_IN); /* Class */
putlong(&p, 3600); /* TTL */
putshort(&p, 4); /* Data length */
/* ugly hack to output IP address */
ipp = (char *) &q->destination;
CHECKLEN(4);
putbyte(&p, *(ipp++));
putbyte(&p, *(ipp++));
putbyte(&p, *(ipp++));
putbyte(&p, *ipp);
len = p - buf;
return len;
@ -276,6 +407,7 @@ dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet, siz
int id;
int rv;
q->id2 = 0;
rv = 0;
header = (HEADER*)packet;
@ -324,11 +456,15 @@ dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet, siz
}
if (ancount < 1) {
/* We may get both CNAME and A, then ancount=2 */
/* DNS errors like NXDOMAIN have ancount=0 and
stop here. CNAME may also have A; MX/SRV may have
multiple results. */
return -1;
}
/* Assume that first answer is NULL/CNAME that we wanted */
/* Here type is still the question type */
if (type == T_NULL) {
/* Assume that first answer is what we wanted */
readname(packet, packetlen, &data, name, sizeof(name));
CHECKLEN(10);
readshort(packet, &data, &type);
@ -336,7 +472,6 @@ dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet, siz
readlong(packet, &data, &ttl);
readshort(packet, &data, &rlen);
if (type == T_NULL) {
rv = MIN(rlen, sizeof(rdata));
rv = readdata(packet, &data, rdata, rv);
if (rv >= 2 && buf) {
@ -346,9 +481,15 @@ dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet, siz
rv = 0;
}
}
if ((type == T_CNAME || type == T_MX) && buf) {
if (type == T_MX)
data += 2; /* skip preference */
else if ((type == T_A || type == T_CNAME) && buf) {
/* Assume that first answer is what we wanted */
readname(packet, packetlen, &data, name, sizeof(name));
CHECKLEN(10);
readshort(packet, &data, &type);
readshort(packet, &data, &class);
readlong(packet, &data, &ttl);
readshort(packet, &data, &rlen);
memset(name, 0, sizeof(name));
readname(packet, packetlen, &data, name, sizeof(name) - 1);
name[sizeof(name)-1] = '\0';
@ -356,7 +497,74 @@ dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet, siz
buf[buflen - 1] = '\0';
rv = strlen(buf);
}
if (type == T_TXT && buf) {
else if ((type == T_MX || type == T_SRV) && buf) {
/* We support 250 records, 250*(255+header) ~= 64kB.
Only exact 10-multiples are accepted, and gaps in
numbering are not jumped over (->truncated).
Hopefully DNS servers won't mess around too much.
*/
char names[250][QUERY_NAME_SIZE];
char *rdatastart;
short pref;
int i;
int offset;
memset(names, 0, sizeof(names));
for (i=0; i < ancount; i++) {
readname(packet, packetlen, &data, name, sizeof(name));
CHECKLEN(12);
readshort(packet, &data, &type);
readshort(packet, &data, &class);
readlong(packet, &data, &ttl);
readshort(packet, &data, &rlen);
rdatastart = data;
readshort(packet, &data, &pref);
if (type == T_SRV) {
/* skip weight, port */
data += 4;
CHECKLEN(0);
}
if (pref % 10 == 0 && pref >= 10 &&
pref < 2500) {
readname(packet, packetlen, &data,
names[pref / 10 - 1],
QUERY_NAME_SIZE - 1);
names[pref / 10 - 1][QUERY_NAME_SIZE-1] = '\0';
}
/* always trust rlen, not name encoding */
data = rdatastart + rlen;
CHECKLEN(0);
}
/* output is like Hname10.com\0Hname20.com\0\0 */
offset = 0;
i = 0;
while (names[i][0] != '\0') {
int l = MIN(strlen(names[i]), buflen-offset-2);
if (l <= 0)
break;
memcpy(buf + offset, names[i], l);
offset += l;
*(buf + offset) = '\0';
offset++;
i++;
}
*(buf + offset) = '\0';
rv = offset;
}
else if (type == T_TXT && buf) {
/* Assume that first answer is what we wanted */
readname(packet, packetlen, &data, name, sizeof(name));
CHECKLEN(10);
readshort(packet, &data, &type);
readshort(packet, &data, &class);
readlong(packet, &data, &ttl);
readshort(packet, &data, &rlen);
rv = readtxtbin(packet, &data, rlen, rdata, sizeof(rdata));
if (rv >= 1) {
rv = MIN(rv, buflen);
@ -365,6 +573,8 @@ dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet, siz
rv = 0;
}
}
/* Here type is the answer type (note A->CNAME) */
if (q != NULL)
q->type = type;
break;

3
src/dns.h
View file

@ -24,8 +24,11 @@ typedef enum {
QR_ANSWER = 1
} qr_t;
extern int dnsc_use_edns0;
int dns_encode(char *, size_t, struct query *, qr_t, char *, size_t);
int dns_encode_ns_response(char *buf, size_t buflen, struct query *q, char *topdomain);
int dns_encode_a_response(char *buf, size_t buflen, struct query *q);
unsigned short dns_get_id(char *packet, size_t packetlen);
int dns_decode(char *, size_t, struct query *, qr_t, char *, size_t);

6
src/encoding.c
View file

@ -21,13 +21,15 @@
int
build_hostname(char *buf, size_t buflen,
const char *data, const size_t datalen,
const char *topdomain, struct encoder *encoder)
const char *topdomain, struct encoder *encoder, int maxlen)
{
int encsize;
size_t space;
char *b;
space = MIN(0xFF, buflen) - strlen(topdomain) - 7;
space = MIN(maxlen, buflen) - strlen(topdomain) - 8;
/* 8 = 5 max header length + 1 dot before topdomain + 2 safety */
if (!encoder->places_dots())
space -= (space / 57); /* space for dots */

9
src/encoding.h
View file

@ -17,6 +17,13 @@
#ifndef _ENCODING_H_
#define _ENCODING_H_
/* All-0, all-1, 01010101, 10101010: each 4 times to make sure the pattern
spreads across multiple encoded chars -> 16 bytes total.
Followed by 32 bytes from my /dev/random; should be enough.
*/
#define DOWNCODECCHECK1 "\000\000\000\000\377\377\377\377\125\125\125\125\252\252\252\252\201\143\310\322\307\174\262\027\137\117\316\311\111\055\122\041\141\251\161\040\045\263\006\163\346\330\104\060\171\120\127\277"
#define DOWNCODECCHECK1_LEN 48
struct encoder {
char name[8];
int (*encode) (char *, size_t *, const void *, size_t);
@ -27,7 +34,7 @@ struct encoder {
int (*blocksize_encoded)(void);
};
int build_hostname(char *, size_t, const char *, const size_t, const char *, struct encoder *);
int build_hostname(char *, size_t, const char *, const size_t, const char *, struct encoder *, int);
int unpack_data(char *, size_t, char *, size_t, struct encoder *);
int inline_dotify(char *, size_t);
int inline_undotify(char *, size_t);

43
src/iodine.c
View file

@ -61,7 +61,7 @@ usage() {
extern char *__progname;
fprintf(stderr, "Usage: %s [-v] [-h] [-f] [-r] [-u user] [-t chrootdir] [-d device] "
"[-P password] [-m maxfragsize] [-T type] [-O enc] [-L 0|1] [-I sec] "
"[-P password] [-m maxfragsize] [-M maxlen] [-T type] [-O enc] [-L 0|1] [-I sec] "
"[-z context] [-F pidfile] [nameserver] topdomain\n", __progname);
exit(2);
}
@ -72,21 +72,25 @@ help() {
fprintf(stderr, "iodine IP over DNS tunneling client\n");
fprintf(stderr, "Usage: %s [-v] [-h] [-f] [-r] [-u user] [-t chrootdir] [-d device] "
"[-P password] [-m maxfragsize] [-T type] [-O enc] [-L 0|1] [-I sec] "
"[-P password] [-m maxfragsize] [-M maxlen] [-T type] [-O enc] [-L 0|1] [-I sec] "
"[-z context] [-F pidfile] [nameserver] topdomain\n", __progname);
fprintf(stderr, "Options to try if connection doesn't work:\n");
fprintf(stderr, " -T force dns type: NULL, TXT, SRV, MX, CNAME, A (default: autodetect)\n");
fprintf(stderr, " -O force downstream encoding for -T other than NULL: Base32, Base64, Base64u,\n");
fprintf(stderr, " Base128, or (only for TXT:) Raw (default: autodetect)\n");
fprintf(stderr, " -I max interval between requests (default 4 sec) to prevent DNS timeouts\n");
fprintf(stderr, " -L 1: use lazy mode for low-latency (default). 0: don't (implies -I1)\n");
fprintf(stderr, " -m max size of downstream fragments (default: autodetect)\n");
fprintf(stderr, " -M max size of upstream hostnames (~100-255, default: 255)\n");
fprintf(stderr, " -r to skip raw UDP mode attempt\n");
fprintf(stderr, " -P password used for authentication (max 32 chars will be used)\n");
fprintf(stderr, "Other options:\n");
fprintf(stderr, " -v to print version info and exit\n");
fprintf(stderr, " -h to print this help and exit\n");
fprintf(stderr, " -f to keep running in foreground\n");
fprintf(stderr, " -r to skip raw UDP mode attempt\n");
fprintf(stderr, " -u name to drop privileges and run as user 'name'\n");
fprintf(stderr, " -t dir to chroot to directory dir\n");
fprintf(stderr, " -d device to set tunnel device name\n");
fprintf(stderr, " -P password used for authentication (max 32 chars will be used)\n");
fprintf(stderr, " -m maxfragsize, to limit size of downstream packets\n");
fprintf(stderr, " -T dns type: NULL (default, fastest), TXT, CNAME, A (CNAME answer), MX\n");
fprintf(stderr, " -O downstream encoding (!NULL): Base32(default), Base64, or Raw (only TXT)\n");
fprintf(stderr, " -L 1: try lazy mode for low-latency (default). 0: don't (implies -I1)\n");
fprintf(stderr, " -I max interval between requests (default 4 sec) to prevent server timeouts\n");
fprintf(stderr, " -z context, to apply specified SELinux context after initialization\n");
fprintf(stderr, " -F pidfile to write pid to a file\n");
fprintf(stderr, "nameserver is the IP number/hostname of the relaying nameserver. if absent, /etc/resolv.conf is used\n");
@ -131,6 +135,7 @@ main(int argc, char **argv)
int raw_mode;
int lazymode;
int selecttimeout;
int hostname_maxlen;
nameserv_addr = NULL;
topdomain = NULL;
@ -152,6 +157,7 @@ main(int argc, char **argv)
raw_mode = 1;
lazymode = 1;
selecttimeout = 4;
hostname_maxlen = 0xFF;
#ifdef WINDOWS32
WSAStartup(req_version, &wsa_data);
@ -168,7 +174,7 @@ main(int argc, char **argv)
__progname++;
#endif
while ((choice = getopt(argc, argv, "vfhru:t:d:P:m:F:T:O:L:I:")) != -1) {
while ((choice = getopt(argc, argv, "vfhru:t:d:P:m:M:F:T:O:L:I:")) != -1) {
switch(choice) {
case 'v':
version();
@ -203,6 +209,13 @@ main(int argc, char **argv)
autodetect_frag_size = 0;
max_downstream_frag_size = atoi(optarg);
break;
case 'M':
hostname_maxlen = atoi(optarg);
if (hostname_maxlen > 255)
hostname_maxlen = 255;
if (hostname_maxlen < 10)
hostname_maxlen = 10;
break;
case 'z':
context = optarg;
break;
@ -283,6 +296,7 @@ main(int argc, char **argv)
client_set_selecttimeout(selecttimeout);
client_set_lazymode(lazymode);
client_set_topdomain(topdomain);
client_set_hostname_maxlen(hostname_maxlen);
if (username != NULL) {
#ifndef WINDOWS32
@ -315,17 +329,20 @@ main(int argc, char **argv)
signal(SIGINT, sighandler);
signal(SIGTERM, sighandler);
fprintf(stderr, "Sending DNS queries for %s to %s\n",
topdomain, nameserv_addr);
if (client_handshake(dns_fd, raw_mode, autodetect_frag_size, max_downstream_frag_size)) {
retval = 1;
goto cleanup2;
}
if (client_get_conn() == CONN_DNS_NULL) {
fprintf(stderr, "Sending queries for %s to %s\n", topdomain, nameserv_addr);
} else {
if (client_get_conn() == CONN_RAW_UDP) {
fprintf(stderr, "Sending raw traffic directly to %s\n", client_get_raw_addr());
}
fprintf(stderr, "Connection setup complete, transmitting data.\n");
if (foreground == 0)
do_detach();

698
src/iodined.c
View file

File diff suppressed because it is too large Load diff

16
src/user.h
View file

@ -24,7 +24,14 @@
lead to massive dropping in multi-user situations with high traffic. */
#define DNSCACHE_LEN 4
/* Undefine to disable. MUST be less than 7; also see comments in iodined.c */
/* Undefine to disable. Should be less than 18; also see comments in iodined.c */
#define QMEMPING_LEN 30
/* Max advisable: 64k/2 = 32000. Total mem usage: QMEMPING_LEN * USERS * 6 bytes */
#define QMEMDATA_LEN 15
/* Max advisable: 36/2 = 18. Total mem usage: QMEMDATA_LEN * USERS * 6 bytes */
struct user {
char id;
@ -35,7 +42,6 @@ struct user {
in_addr_t tun_ip;
struct in_addr host;
struct query q;
struct query q_prev;
struct query q_sendrealsoon;
int q_sendrealsoon_new;
struct packet inpacket;
@ -48,6 +54,12 @@ struct user {
int fragsize;
enum connection conn;
int lazy;
unsigned char qmemping_cmc[QMEMPING_LEN * 4];
unsigned short qmemping_type[QMEMPING_LEN];
int qmemping_lastfilled;
unsigned char qmemdata_cmc[QMEMDATA_LEN * 4];
unsigned short qmemdata_type[QMEMDATA_LEN];
int qmemdata_lastfilled;
#ifdef OUTPACKETQ_LEN
struct packet outpacketq[OUTPACKETQ_LEN];
int outpacketq_nexttouse;

2
src/version.h
View file

@ -19,7 +19,7 @@
/* This is the version of the network protocol
It is usually equal to the latest iodine version number */
#define VERSION 0x00000501
#define VERSION 0x00000502
#endif /* _VERSION_H_ */