kk Blog —— 通用基础


date [-d @int|str] [+%s|"+%F %T"]
netstat -ltunp
sar -n DEV 1

MPTCP 回复一样的option

对方回复一模一样的option

例如

curl ksurl.cn

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01:42:57.092471 IP 192.168.8.162.34366 > 103.102.200.3.80: Flags [S], seq 846976861, win 64240, options [mss 1460,nop,nop,sackOK,nop,wscale 7,mptcp capable csum {0xc7c6d84045bd8248}], length 0
01:42:57.130413 IP 103.102.200.3.80 > 192.168.8.162.34366: Flags [S.], seq 668917669, ack 846976862, win 0, options [mss 1452,nop,nop,sackOK,nop,nop,nop,nop,mptcp capable csum {0xc7c6d84045bd8248}], length 0
01:42:57.130498 IP 192.168.8.162.34366 > 103.102.200.3.80: Flags [.], ack 1, win 64240, options [mptcp capable csum {0xc7c6d84045bd8248,0xc7c6d84045bd8248},mptcp dss ack 1200875982], length 0
01:42:57.130525 IP 192.168.8.162.34366 > 103.102.200.3.80: Flags [.], ack 1, win 64240, options [mptcp add-addr id 3 11.0.0.1,mptcp dss ack 1200875982], length 0
01:42:57.616370 IP 192.168.8.162.34366 > 103.102.200.3.80: Flags [.], ack 1, win 64240, options [mptcp dss ack 1200875982], length 0
01:42:57.654157 IP 103.102.200.3.80 > 192.168.8.162.34366: Flags [.], ack 1, win 29200, length 0
01:42:58.612344 IP 192.168.8.162.34366 > 103.102.200.3.80: Flags [.], ack 1, win 64240, options [mptcp dss ack 1200875982], length 0
01:42:58.650740 IP 103.102.200.3.80 > 192.168.8.162.34366: Flags [.], ack 1, win 29200, length 0
01:43:00.560359 IP 192.168.8.162.34366 > 103.102.200.3.80: Flags [.], ack 1, win 64240, options [mptcp dss ack 1200875982], length 0
01:43:00.598942 IP 103.102.200.3.80 > 192.168.8.162.34366: Flags [.], ack 1, win 29200, length 0
...

修复

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diff --git a/src/4.15.18/tcp_input.c b/src/4.15.18/tcp_input.c
index 1c36791..397cb89 100644
--- a/src/4.15.18/tcp_input.c
+++ b/src/4.15.18/tcp_input.c
@@ -5845,6 +5845,11 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
                if (tp->request_mptcp || mptcp(tp)) {
                        int ret;
 
+                       if (!mptcp(tp) && mopt.saw_mpc) {
+                               struct tcp_sock *meta_tp = tcp_sk(sk);
+                               if (meta_tp->mptcp_loc_key == mopt.mptcp_sender_key)
+                                       mopt.saw_mpc = 0;
+                       }
                        rcu_read_lock();
                        local_bh_disable();
                        ret = mptcp_rcv_synsent_state_process(sk, &sk,

修复后

curl ksurl.cn

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01:48:11.136480 IP 192.168.8.162.34388 > 103.102.200.3.80: Flags [S], seq 1334883078, win 65320, options [mss 1420,nop,nop,sackOK,nop,wscale 7,mptcp capable csum {0xa48a1610f304b3a}], length 0
01:48:11.174632 IP 103.102.200.3.80 > 192.168.8.162.34388: Flags [S.], seq 2018132645, ack 1334883079, win 0, options [mss 1420,nop,nop,sackOK,nop,nop,nop,nop,mptcp capable csum {0xa48a1610f304b3a}], length 0
01:48:11.174720 IP 192.168.8.162.34388 > 103.102.200.3.80: Flags [.], ack 1, win 65320, length 0
01:48:11.213236 IP 103.102.200.3.80 > 192.168.8.162.34388: Flags [.], ack 1, win 29200, length 0
01:48:11.213283 IP 192.168.8.162.34388 > 103.102.200.3.80: Flags [P.], seq 1:73, ack 1, win 65320, length 72: HTTP: GET / HTTP/1.1
01:48:11.252192 IP 103.102.200.3.80 > 192.168.8.162.34388: Flags [.], ack 73, win 29200, length 0
01:48:11.253261 IP 103.102.200.3.80 > 192.168.8.162.34388: Flags [P.], seq 1:397, ack 73, win 29200, length 396: HTTP: HTTP/1.1 302 Moved Temporarily
01:48:11.253300 IP 192.168.8.162.34388 > 103.102.200.3.80: Flags [.], ack 397, win 64924, length 0
01:48:11.253541 IP 192.168.8.162.34388 > 103.102.200.3.80: Flags [F.], seq 73, ack 397, win 64924, length 0
01:48:11.292118 IP 103.102.200.3.80 > 192.168.8.162.34388: Flags [F.], seq 397, ack 74, win 29200, length 0
01:48:11.292182 IP 192.168.8.162.34388 > 103.102.200.3.80: Flags [.], ack 398, win 64923, length 0

MPTCP_OPTION

解析见 mptcp_parse_options()

MPTCP_SUB_CAPABLE

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#define MPTCP_SUB_CAPABLE                       0
#define MPTCP_SUB_LEN_CAPABLE_SYN               12
#define MPTCP_SUB_LEN_CAPABLE_SYN_ALIGN         12
#define MPTCP_SUB_LEN_CAPABLE_ACK               20
#define MPTCP_SUB_LEN_CAPABLE_ACK_ALIGN         20

最初的三次握手时用

MPTCP_SUB_JOIN

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#define MPTCP_SUB_JOIN                  1
#define MPTCP_SUB_LEN_JOIN_SYN          12
#define MPTCP_SUB_LEN_JOIN_SYN_ALIGN    12
#define MPTCP_SUB_LEN_JOIN_SYNACK       16
#define MPTCP_SUB_LEN_JOIN_SYNACK_ALIGN 16
#define MPTCP_SUB_LEN_JOIN_ACK          24
#define MPTCP_SUB_LEN_JOIN_ACK_ALIGN    24

第二次、第三次、。。。握手时用

MPTCP_SUB_DSS

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#define MPTCP_SUB_DSS           2

MPTCP_SUB_ADD_ADDR, MPTCP_SUB_REMOVE_ADDR

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#define MPTCP_SUB_ADD_ADDR              3
#define MPTCP_SUB_LEN_ADD_ADDR4         8
#define MPTCP_SUB_LEN_ADD_ADDR4_VER1    16
#define MPTCP_SUB_LEN_ADD_ADDR6         20
#define MPTCP_SUB_LEN_ADD_ADDR6_VER1    28
#define MPTCP_SUB_LEN_ADD_ADDR4_ALIGN   8
#define MPTCP_SUB_LEN_ADD_ADDR4_ALIGN_VER1      16
#define MPTCP_SUB_LEN_ADD_ADDR6_ALIGN   20
#define MPTCP_SUB_LEN_ADD_ADDR6_ALIGN_VER1      28

#define MPTCP_SUB_REMOVE_ADDR   4
#define MPTCP_SUB_LEN_REMOVE_ADDR       4

fullmesh 模式通告ip

MPTCP_SUB_PRIO

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#define MPTCP_SUB_PRIO          5
#define MPTCP_SUB_LEN_PRIO      3
#define MPTCP_SUB_LEN_PRIO_ADDR 4
#define MPTCP_SUB_LEN_PRIO_ALIGN        4

./ip/ip link set dev enp0s3 multipath off/on/backup

backup命令就是将该接口设置为backup模式，并且会通过PRIO option通知对方，两边会标记low_prio、rcv_low_prio。但目前所有pm都没有用到low_prio。

MPTCP_SUB_FAIL

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#define MPTCP_SUB_FAIL          6
#define MPTCP_SUB_LEN_FAIL      12 
#define MPTCP_SUB_LEN_FAIL_ALIGN        12

MPTCP_SUB_FCLOSE

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#define MPTCP_SUB_FCLOSE        7
#define MPTCP_SUB_LEN_FCLOSE    12
#define MPTCP_SUB_LEN_FCLOSE_ALIGN      12

MPTCP_VERSION

mptcp_version

只有两个版本 v0、v1

v1: 在option=MPTCP_SUB_ADD_ADDR 时需要加密，收包时在 mptcp_handle_add_addr 验证。

v0: 没有加密