TCP: Add support for the AE (AccECN) flag.

Print the new flag using lowercase "e" to avoid confusion with the
existing uppercase flags and "." for ACK.  Add/update tests.  Document
it in the man page using "AE" as the shorthand.

diff --git a/CHANGES b/CHANGES
index 68ccb9d0cd8358418e820fd328025ca343add745..fa07f3c26ad4e07e46ab959e941cffc457763c10 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -26,6 +26,7 @@ DayOfTheWeek, Month DD, YYYY / The Tcpdump Group
         advance the packet data pointer
       OSPF: Print more truncation indications
       OSPF: Add more length checks
+      TCP: Add support for the AE (AccECN) flag.
     User interface:
       Add optional unit suffix on -C file size.
       Add --print-sampling to print every Nth packet instead of all.

diff --git a/print-tcp.c b/print-tcp.c
index 308915bcb7e1610b19d53b10a41e45be3ecf90fe..dacdd8054e7d49430b5bc153723f15a7636fe46c 100644 (file)
--- a/print-tcp.c
+++ b/print-tcp.c
@@ -113,6 +113,7 @@ const struct tok tcp_flag_values[] = {
         { TH_URG, "U" },
         { TH_ECNECHO, "E" },
         { TH_CWR, "W" },
+        { TH_AE, "e" },
         { 0, NULL }
 };
 
@@ -166,7 +167,7 @@ tcp_print(netdissect_options *ndo,
 {
         const struct tcphdr *tp;
         const struct ip *ip;
-        u_char flags;
+        uint16_t flags;
         u_int hlen;
         char ch;
         uint16_t sport, dport, win, urp;
@@ -248,7 +249,7 @@ tcp_print(netdissect_options *ndo,
                 return;
         }
 
-        flags = GET_U_1(tp->th_flags);
+        flags = tcp_get_flags(tp);
         ND_PRINT("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
 
         if (!ndo->ndo_Sflag && (flags & TH_ACK)) {

diff --git a/tcp.h b/tcp.h
index 268869a45c60aff0e029f68de8dffc1e2709f448..6be42737f5dda7613a6056683d24c2c0870c1879 100644 (file)
--- a/tcp.h
+++ b/tcp.h
@@ -50,6 +50,8 @@ struct tcphdr {
 };
 
 #define TH_OFF(th)     ((GET_U_1((th)->th_offx2) & 0xf0) >> 4)
+#define tcp_get_flags(th)      ((GET_U_1((th)->th_flags)) | \
+                       ((GET_U_1((th)->th_offx2) & 0x0f) << 8))
 
 /* TCP flags */
 #define        TH_FIN     0x01
@@ -60,6 +62,7 @@ struct tcphdr {
 #define        TH_URG     0x20
 #define TH_ECNECHO 0x40        /* ECN Echo */
 #define TH_CWR    0x80 /* ECN Cwnd Reduced */
+#define        TH_AE     0x100 /* AccECN (draft-ietf-tcpm-accurate-ecn;rfc7560) part of L4S (rfc9330) */
 extern const struct tok tcp_flag_values[];
 
 

diff --git a/tcpdump.1.in b/tcpdump.1.in
index 0100ff4413242f3858d007d0ba16f7d04602e3e4..9513009774f92412661661b8129f547b7f6e2e88 100644 (file)
--- a/tcpdump.1.in
+++ b/tcpdump.1.in
@@ -1380,8 +1380,8 @@ The general format of a TCP protocol line is:
 .RE
 \fISrc\fP and \fIdst\fP are the source and destination IP
 addresses and ports.
-\fITcpflags\fP are some combination of S (SYN),
-F (FIN), P (PSH), R (RST), U (URG), W (CWR), E (ECE) or
+\fITcpflags\fP are some combination of S (SYN), F (FIN),
+P (PSH), R (RST), U (URG), W (CWR), E (ECE), e (AE) or
 `.' (ACK), or `none' if no flags are set.
 \fIData-seqno\fP describes the portion of sequence space covered
 by the data in this packet (see example below).
@@ -1472,10 +1472,10 @@ long enough for the options to actually be there, \fItcpdump\fP reports
 it as ``[\fIbad hdr length\fP]''.
 .SS Particular TCP Flag Combinations (SYN-ACK, URG-ACK, etc.)
 .PP
-There are 8 bits in the control bits section of the TCP header:
-.IP
-.I CWR | ECE | URG | ACK | PSH | RST | SYN | FIN
-.PP
+There are 9 bits in the control bits section of the TCP header:
+.LP
+\fIAE(e) CWR(W) ECE(E) URG(U) ACK(.) PSH(P) RST(R) SYN(S) FIN(F)\fP
+.LP
 Let's assume that we want to watch packets used in establishing
 a TCP connection.
 Recall that TCP uses a 3-way handshake protocol
@@ -1510,7 +1510,9 @@ Recall the structure of a TCP header without options:
 -----------------------------------------------------------------
 |                     acknowledgment number                     |
 -----------------------------------------------------------------
-|  HL   | rsvd  |C|E|U|A|P|R|S|F|        window size            |
+|header |re   |A|C|E|U|A|P|R|S|F|                               |
+|length |serv |E|W|C|R|C|S|S|Y|I|        window size            |
+|       |  ed | |R|E|G|K|H|T|N|N|                               |
 -----------------------------------------------------------------
 |         TCP checksum          |       urgent pointer          |
 -----------------------------------------------------------------
@@ -1522,12 +1524,14 @@ The first line of the graph contains octets 0 - 3, the
 second line shows octets 4 - 7 etc.
 .PP
 Starting to count with 0, the relevant TCP control bits are contained
-in octet 13:
+in octets 12 and 13:
 .PP
 .nf
  0             7|             15|             23|             31
 ----------------|---------------|---------------|----------------
-|  HL   | rsvd  |C|E|U|A|P|R|S|F|        window size            |
+|header |re   |A|C|E|U|A|P|R|S|F|                               |
+|length |serv |E|W|C|R|C|S|S|Y|I|        window size            |
+|       |  ed | |R|E|G|K|H|T|N|N|                               |
 ----------------|---------------|---------------|----------------
 |               |  13th octet   |               |               |
 .fi
@@ -1538,6 +1542,8 @@ Let's have a closer look at octet no. 13:
                 |               |
                 |---------------|
                 |C|E|U|A|P|R|S|F|
+                |W|C|R|C|S|S|Y|I|
+                |R|E|G|K|H|T|N|N|
                 |---------------|
                 |7   5   3     0|
 .fi
@@ -1553,6 +1559,8 @@ with the SYN bit set in its header:
 .PP
 .nf
                 |C|E|U|A|P|R|S|F|
+                |W|C|R|C|S|S|Y|I|
+                |R|E|G|K|H|T|N|N|
                 |---------------|
                 |0 0 0 0 0 0 1 0|
                 |---------------|
@@ -1602,6 +1610,8 @@ with SYN-ACK set arrives:
 .PP
 .nf
      |C|E|U|A|P|R|S|F|
+     |W|C|R|C|S|S|Y|I|
+     |R|E|G|K|H|T|N|N|
      |---------------|
      |0 0 0 1 0 0 1 0|
      |---------------|

diff --git a/tests/TESTLIST b/tests/TESTLIST
index 281cd1ff439637a30d98d2c421a287a5c2f1b1bf..f6b217c81a576891cd708136f04212e14462f967 100644 (file)
--- a/tests/TESTLIST
+++ b/tests/TESTLIST
@@ -971,3 +971,6 @@ ip6-snmp-oid-unsigned ip6-snmp-oid-unsigned.pcap ip6-snmp-oid-unsigned.out
 lwres-pointer-arithmetic-ub lwres-pointer-arithmetic-ub.pcap lwres-pointer-arithmetic-ub.out
 ospf-signed-integer-ubsan       ospf-signed-integer-ubsan.pcap          ospf-signed-integer-ubsan.out -vv
 bgp-ub bgp-ub.pcap bgp-ub.out -v
+
+# AccECN tests
+accecn_handshake       accecn_handshake.pcap           accecn_handshake.out    -v

diff --git a/tests/accecn_handshake.out b/tests/accecn_handshake.out
new file mode 100644 (file)
index 0000000..79b12ad
--- /dev/null
+++ b/tests/accecn_handshake.out
@@ -0,0 +1,25 @@
+    1  2022-07-26 06:26:07.794026 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 60)
+    31.133.146.248.16433 > 66.228.43.12.80: Flags [SEWe], cksum 0x209c (incorrect -> 0xe443), seq 1948076589, win 65535, options [mss 1460,nop,wscale 6,sackOK,TS val 112147477 ecr 0], length 0
+    2  2022-07-26 06:26:08.016156 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 72)
+    66.228.43.12.80 > 31.133.146.248.16433: Flags [S.W], cksum 0x22a8 (correct), seq 2972234643, ack 1948076590, win 65160, options [mss 1460,sackOK,TS val 2783239876 ecr 112147477,exp-acc0,wscale 7], length 0
+    3  2022-07-26 06:26:08.016573 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 68)
+    31.133.146.248.16433 > 66.228.43.12.80: Flags [.W], cksum 0x20a4 (incorrect -> 0x3b19), ack 1, win 1027, options [nop,nop,TS val 112147698 ecr 2783239876,exp-acc0,eol], length 0
+    4  2022-07-26 06:26:08.017141 IP (tos 0x2,ECT(0), ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 130)
+    31.133.146.248.16433 > 66.228.43.12.80: Flags [P.Ee], cksum 0x20e2 (incorrect -> 0x9373), seq 1:79, ack 1, win 1027, options [nop,nop,TS val 112147698 ecr 2783239876], length 78: HTTP, length: 78
+       GET /1M HTTP/1.1
+       Host: 66.228.43.12
+       User-Agent: curl/7.69.1
+       Accept: */*
+       
+    5  2022-07-26 06:26:08.056144 IP (tos 0x1,ECT(1), ttl 54, id 45724, offset 0, flags [DF], proto TCP (6), length 52)
+    66.228.43.12.80 > 31.133.146.248.16433: Flags [.Ee], cksum 0x26c6 (correct), ack 79, win 509, options [nop,nop,TS val 2783239918 ecr 112147698], length 0
+    6  2022-07-26 06:26:08.075386 IP (tos 0x1,ECT(1), ttl 54, id 45725, offset 0, flags [DF], proto TCP (6), length 1500)
+    66.228.43.12.80 > 31.133.146.248.16433: Flags [.Ee], cksum 0xcfbd (correct), seq 1:1449, ack 79, win 509, options [nop,nop,TS val 2783239922 ecr 112147698], length 1448: HTTP, length: 1448
+       HTTP/1.1 200 OK
+       Date: Mon, 25 Jul 2022 15:45:42 GMT
+       Server: Apache/2.4.41 (Ubuntu)
+       Last-Modified: Sun, 24 Jul 2022 18:49:15 GMT
+       ETag: "f4240-5e491862a86d8"
+       Accept-Ranges: bytes
+       Content-Length: 1000000
+       

diff --git a/tests/accecn_handshake.pcap b/tests/accecn_handshake.pcap
new file mode 100644 (file)
index 0000000..b328dcd
Binary files /dev/null and b/tests/accecn_handshake.pcap differ

diff --git a/tests/babel_update_oobr.out b/tests/babel_update_oobr.out
index 7785775eedd65d4cd4ca5905fca61b7ec0749d55..890dc9d38a9742f84922a4ae3a38aedc5c0423dd 100644 (file)
--- a/tests/babel_update_oobr.out
+++ b/tests/babel_update_oobr.out
@@ -6,8 +6,8 @@
        0x0010:  b1b1 b1b1 b158 5e0a 02f4 0ab1 0402 0f0f  .....X^.........
        0x0020:  ff80 0f0f 0f0f 0f00 80a1 00b2 b2b2 b20d  ................
        0x0030:  0d3a 3400 0001 00                        .:4....
-    5  1970-03-17 20:26:40.2097152 IP 6.3.218.255.6379 > 0.1.31.99.52759: Flags [S.UW], seq 2751463404:2751463426, ack 1006637056, win 45746, urg 25778, length 22: RESP [|resp]
-    6  1970-03-17 20:27:12.000000 IP 6.3.208.255.6379 > 0.1.31.99.52759: Flags [S.UW], seq 2751463404:2751463426, ack 1006640128, win 45746, urg 25778, length 22: RESP "M-2M-2M-2M-2M-2M-7dM-2M-2M-2M-2M-2" [|resp]
+    5  1970-03-17 20:26:40.2097152 IP 6.3.218.255.6379 > 0.1.31.99.52759: Flags [S.UWe], seq 2751463404:2751463426, ack 1006637056, win 45746, urg 25778, length 22: RESP [|resp]
+    6  1970-03-17 20:27:12.000000 IP 6.3.208.255.6379 > 0.1.31.99.52759: Flags [S.UWe], seq 2751463404:2751463426, ack 1006640128, win 45746, urg 25778, length 22: RESP "M-2M-2M-2M-2M-2M-7dM-2M-2M-2M-2M-2" [|resp]
     7  1970-03-17 20:27:12.000000 IP 208.21.10.1.654 > 31.99.100.232.80:  aodv rrep 34  prefix 4 hops 11
        dst 237.34.38.84 dseq 32203525 src 232.11.2.0 67108864 ms
        ext 0 0

diff --git a/tests/beep-oobr.out b/tests/beep-oobr.out
index 56deca8e18c2bcb2b1e600108863b2e0b3969433..c711733e2aa7cfe51c3c2622a4ed4659e66eff19 100644 (file)
--- a/tests/beep-oobr.out
+++ b/tests/beep-oobr.out
@@ -1,2 +1,2 @@
     1  1995-08-15 05:27:12.808464432 unknown ip 3
-    2  1995-08-15 05:27:12.808464432 IP6 3030:3030:3030:3030:3030:3030:3030:3030.10288 > 3030:3030:3030:3030:3030:3030:3030:3030.12336: Flags [.U], seq 808464432:808476740, ack 808464432, win 12336, urg 12336, options [eol], length 12308 [remaining caplen(24) < header length(28)] [|tcp]
+    2  1995-08-15 05:27:12.808464432 IP6 3030:3030:3030:3030:3030:3030:3030:3030.10288 > 3030:3030:3030:3030:3030:3030:3030:3030.12336: Flags [.Ue], seq 808464432:808476740, ack 808464432, win 12336, urg 12336, options [eol], length 12308 [remaining caplen(24) < header length(28)] [|tcp]

diff --git a/tests/bgp-bgp_capabilities_print-oobr-1.out b/tests/bgp-bgp_capabilities_print-oobr-1.out
index 068a0760854511393f86e7a0896c874324a8172a..234a4aeaafb1b1c135bc88ceef5c36fc5e7c1ec3 100644 (file)
--- a/tests/bgp-bgp_capabilities_print-oobr-1.out
+++ b/tests/bgp-bgp_capabilities_print-oobr-1.out
@@ -1,5 +1,5 @@
     1  1970-03-16 01:04:13.49220352 IP (tos 0x1f,CE, ttl 254, id 38671, offset 0, flags [+, DF, rsvd], proto TCP (6), length 4135, bad cksum 200 (->1fdd)!)
-    226.219.0.0.179 > 16.233.34.0.100: Flags [SPUE], seq 347537408:347541483, win 511, urg 65535, options [eol], length 4075: BGP [|bgp]
+    226.219.0.0.179 > 16.233.34.0.100: Flags [SPUEe], seq 347537408:347541483, win 511, urg 65535, options [eol], length 4075: BGP [|bgp]
        Open Message (1), length: 59
          Version 255, my AS 65528, Holdtime 4324s, ID 144.8.32.4
          Optional parameters, length: 29

diff --git a/tests/bgp-bgp_capabilities_print-oobr-2.out b/tests/bgp-bgp_capabilities_print-oobr-2.out
index c519480b7b1eb035668f55db286baeed1700cc80..d518de49c7fef637ad68c6944cad36c8287c65b4 100644 (file)
--- a/tests/bgp-bgp_capabilities_print-oobr-2.out
+++ b/tests/bgp-bgp_capabilities_print-oobr-2.out
@@ -1,5 +1,5 @@
     1  1970-03-16 01:04:13.49220352 IP (tos 0x1f,CE, ttl 254, id 38671, offset 0, flags [+, DF, rsvd], proto TCP (6), length 4135, bad cksum 200 (->1fdd)!)
-    226.219.0.0.179 > 16.233.34.0.100: Flags [SPUE], seq 347537408:347541483, win 511, urg 65535, options [eol], length 4075: BGP [|bgp]
+    226.219.0.0.179 > 16.233.34.0.100: Flags [SPUEe], seq 347537408:347541483, win 511, urg 65535, options [eol], length 4075: BGP [|bgp]
        Open Message (1), length: 59
          Version 255, my AS 65528, Holdtime 4324s, ID 144.8.32.4
          Optional parameters, length: 29

diff --git a/tests/bgp_mp_reach_nlri-oobr.out b/tests/bgp_mp_reach_nlri-oobr.out
index 5797b766b4fc749fa7897828a81d468390865a73..f6f0d3f193363e975e6b0769cd8b7323861b88c8 100644 (file)
--- a/tests/bgp_mp_reach_nlri-oobr.out
+++ b/tests/bgp_mp_reach_nlri-oobr.out
@@ -1,5 +1,5 @@
     1  1975-04-27 04:29:01.371655446 IP (tos 0xff,CE, ttl 254, id 32783, offset 0, flags [rsvd], proto TCP (6), length 65535, bad cksum 8e15 (->5bbf)!)
-    241.0.128.39.179 > 239.0.0.1.0: Flags [none], seq 4144029695:4144095150, win 65535, options [eol], length 65455: BGP [|bgp]
+    241.0.128.39.179 > 239.0.0.1.0: Flags [e], seq 4144029695:4144095150, win 65535, options [eol], length 65455: BGP [|bgp]
        Update Message (2), length: 45
          Withdrawn routes:
            (illegal prefix length) [|bgp] [|bgp]

diff --git a/tests/heapoverflow-tcp_print.out b/tests/heapoverflow-tcp_print.out
index 8527a1da3d0dbab067a1c2402728880dd664ef41..f7f70730a4151145691e725cc3c1e36676340d52 100644 (file)
--- a/tests/heapoverflow-tcp_print.out
+++ b/tests/heapoverflow-tcp_print.out
@@ -1,2 +1,2 @@
     1  1995-08-15 05:27:12.808464432 IP (tos 0x30, ttl 48, id 12336, offset 0, flags [DF], proto TCP (6), length 12336, bad cksum 3030 (->29a8)!)
-    48.48.48.48.12336 > 48.48.48.48.12336: Flags [.U], seq 808464432:808476688, ack 808464432, win 12336, urg 12336, options [unknown-48 0x3030303030303030 [|tcp]
+    48.48.48.48.12336 > 48.48.48.48.12336: Flags [.Ue], seq 808464432:808476688, ack 808464432, win 12336, urg 12336, options [unknown-48 0x3030303030303030 [|tcp]

diff --git a/tests/rpki-rtr-oobr.out b/tests/rpki-rtr-oobr.out
index a892848c0cab6b4a7d3a195715647a47649f8f0f..4468bbf8628061a049e7258680381f54ae18d6f0 100644 (file)
--- a/tests/rpki-rtr-oobr.out
+++ b/tests/rpki-rtr-oobr.out
@@ -1,3 +1,3 @@
     1  1975-04-27 03:20:48.134349590 IP [total length 62 > length 50] (invalid) (tos 0x0, ttl 254, id 13327, offset 0, flags [+, DF, rsvd], proto TCP (6), length 62, bad cksum 8e7f (->c283)!)
-    19.128.128.20.323 > 76.19.6.127.49600: Flags [none], seq 2684354563:2684354585, win 28672, length 22
+    19.128.128.20.323 > 76.19.6.127.49600: Flags [e], seq 2684354563:2684354585, win 28672, length 22
        RPKI-RTRv171 (unknown)