Chore: Three small fixes

[patterniha]

merge of #4909, #4910, #4911

1. fix a (nearly impossible) situation problem when a udp packet received exactly after 2 minutes of inactivity(a race condition problem may happen)

2. fix some rare situations problem when udpConn is closed, but connEntry not closed(for example when we have two interface and one is down...)

3. fix redundant request to vless fallback when connection is closed

///

for 1 and 2, if you want I can fully explain the situation and 3 is also clear.

[RPRX]

发了下个版本后再看

[Fangliding]

突出一个孜孜不倦

[patterniha]

@RPRX

I checked and test, Im sure about this PR, I fully trace the code for all.

Some bugs like udp-mismatched-address, sniff-infinite-loop and close-connecion-not-belong is important and some like this is small, but code should be perfect and all small and big bugs should be fixed.

I think you can trust me after about 25 fixed bugs

[patterniha]

Check it out after the next version is released

If you have any doubts about any of them, I can explain them in full now.

[RPRX]

那等我给 README 加完 NFT 图像就合，反正等下 pre-release 测下你们这些 PR 有没有问题

[Fangliding]

最好晾会 不然发版之后估计还得来几个small refines

[RPRX]

@patterniha 还会有吗

[patterniha]

Not for this version.

I'm trying to solve the WireGuard and some xhttp problems, but it won't reach this version

[RPRX]

！

有精力的话研究一下 WireGuard 吧，目前出入站都有点小问题

[patterniha]

OK, so please merge this PR for today new version.

[RPRX]

其实 VLESS 回落那里的话，原本的代码可以输出个日志，并且返回时最好包一层 errors.New()

不过算了，REALITY 出来后 VLESS fallbacks 的代码都没那么重要了，我懒得改