In order to simulate delayed packets, there are occasions where responses
to those packets need to be ignored insofar as they modify relative sequence
numbers or timestamps. For example a retransmitted SYN or SYN-ACK might be delayed
until after the TCP session ends, but a combination of bugs on the client and server
might result in the session persisting as if it never ended.

inbound injected packet:  0.100034 S 0:0(0) win 65535 <mss 1460,nop,wscale 6,sackOK,TS val 100 ecr 0>
outbound sniffed packet:  0.100083 S. 3079308609:3079308609(0) ack 1 win 65535 <mss 1460,nop,wscale 4,sackOK,TS val 3206488061 ecr 100>
inbound injected packet:  0.150127 . 1:101(100) ack 3079308610 win 1031 <nop,nop,TS val 150 ecr 3206488061>
outbound sniffed packet:  0.150170 . 3079308610:3079308610(0) ack 101 win 12495 <nop,nop,TS val 3206488111 ecr 150>
outbound sniffed packet:  0.150192 P. 3079308610:3079309010(400) ack 101 win 12501 <nop,nop,TS val 3206488111 ecr 150>
inbound injected packet:  0.200251 . 101:101(0) ack 3079309010 win 1024 <nop,nop,TS val 200 ecr 3206488111>
inbound injected packet:  0.200271 F. 101:101(0) ack 3079309010 win 1031 <nop,nop,TS val 200 ecr 3206488111>
outbound sniffed packet:  0.200287 . 3079309010:3079309010(0) ack 102 win 12501 <nop,nop,TS val 3206488161 ecr 200>
outbound sniffed packet:  0.200324 F. 3079309010:3079309010(0) ack 102 win 12501 <nop,nop,TS val 3206488161 ecr 200>
inbound injected packet:  0.250354 . 102:102(0) ack 3079309011 win 1031 <nop,nop,TS val 250 ecr 3206488161>
inbound injected packet:  0.265380 S 0:0(0) win 65535 <mss 1460,nop,wscale 6,sackOK,TS val 100 ecr 0>
outbound sniffed packet:  0.265402 S. 3079308609:3079308609(0) ack 1 win 65535 <mss 1460,nop,wscale 4,sackOK,TS val 3118763918 ecr 100>
inbound injected packet:  0.300437 . 1:1(0) ack 3079308610 win 1031 <nop,nop,TS val 150 ecr 3206488061>
outbound sniffed packet:  0.300455 R 3079308610:3079308610(0) win 0

 0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+0.000 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+0.000 bind(3, ..., ...) = 0
+0.000 listen(3, 1) = 0
+0.100 < S  0:0(0) win 65535 <mss 1460,nop,wscale 6,sackOK,TS val 100 ecr 0>
+0.000 > S. 0:0(0) ack 1 win 65535 <mss 1460,nop,wscale 4,sackOK,TS val 200 ecr 100>
+0.050 < . 1:101(100) ack 1 win 1031 <nop, nop, TS val 150 ecr 200>
+0.000 accept(3, ..., ...) = 4
+0.000 read(4, ..., 100) = 100
+0.000 write(4, ..., 400) = 400
+0.000 > . 1:1(0) ack 101 win 12495 <nop, nop, TS val 250 ecr 150>
+0.000 > P. 1:401(400) ack 101 win 12501 <nop, nop, TS val 250 ecr 150>
+0.050 < . 101:101(0) ack 401 win 1024 <nop, nop, TS val 200 ecr 250>
+0.000 < F. 101:101(0) ack 401 win 1031 <nop, nop, TS val 200 ecr 250>
+0.000 > . 401:401(0) ack 102 win 12501 <nop, nop, TS val 300 ecr 200>
+0.000 close(4) = 0
+0.000 > F. 401:401(0) ack 102 win 12501 <nop, nop, TS val 300 ecr 200>
+0.050 < . 102:102(0) ack 402 win 1031 <nop, nop, TS val 250 ecr 300>
+0.015 < S  0:0(0) win 65535 <mss 1460,nop,wscale 6,sackOK,TS val 100 ecr 0!>
+0.000 > S. ...(0) ack 1 win 65535 <mss 1460,nop,wscale 4,sackOK,TS val ... ecr 100>
+0.035 < . 1:1(0) ack 1 win 1031 <nop, nop, TS val 150 ecr 200>
+0.000 > . 1:1(0) ack 1 win 12501 <nop, nop, TS val 200 ecr 150>

Sponsored by:	Netflix, Inc.

This allows to support a mixture of encapsulated and non-encapsulated
packets in a single script file.

Sponsored by:	Netflix, Inc.

This adds support for SCTP/UDP and TCP/UDP including ICMP
support.

Sponsored by:	Netflix, Inc.

This is based on a patch from Jason Eggleston with minor modifications
from me.

The main engine for handling encapsualted packets in packetdrill,
including:

- parsing scripts with encapsulation
- parsing packets with encapsulation
- injecting packets with encapsulation

Encapsulated packets look like the following, which has an IP header,
GRE header, and then regular IP/TCP header:

+0 > ipv4 1.1.1.1 > 2.2.2.2: gre: . 1:1001(1000) ack 1

See other patches in the series for more detailed examples.


Change-Id: Ia8c7580e268f5b0347bd9d3fdc73b096f751a79d

Initial commit for the packetdrill network stack testing tool:

  https://code.google.com/p/packetdrill/



Signed-off-by: Neal Cardwell <ncardwell@google.com>