| // SPDX-License-Identifier: GPL-2.0 |
| // Test ECN: verify that Linux TCP ECN sending code uses ECT0 (not ECT1). |
| // |
| `./defaults.sh |
| sysctl -q net.ipv4.tcp_ecn=1 # fully enabled |
| ` |
| |
| // Initialize connection |
| 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4 |
| |
| // ECN handshake: send EW flags in SYN packet, E flag in SYN-ACK response |
| +.002 ... 0.004 connect(4, ..., ...) = 0 |
| |
| +0 > SEW 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8> |
| +.002 < SE. 0:0(0) ack 1 win 32767 <mss 1000,nop,wscale 6,nop,nop,sackOK> |
| +0 > . 1:1(0) ack 1 |
| |
| // Write 1 MSS. |
| +.002 write(4, ..., 1000) = 1000 |
| // Send 1 MSS with ect0. |
| +0 > [ect0] P. 1:1001(1000) ack 1 |
