Add KCP(UDPSession) as a transport for v2ray, reslove #162

[xiaokangwang]

TCP连接在高延迟，高带宽，较高丢包环境下，不能有效利用带宽。目前TCP连接下的VMess协议在这种网络环境下速度缓慢，甚至出现连接超时错误。

KCP可以更加有效的利用带宽降低延迟，很大程度上减少因为恶劣的网络环境导致的连接不稳。

通过提高代理连接的速度，可以有效的改善使用v2ray的体验。

新增加了一部分API，请查看 #162 了解详情。

需要注意的是：引入了 github.com/xtaci/kcp-go 库， 这个库的API的稳定性值得怀疑，在合并时可以考虑将该库的地址替换为V2ray可以有效控制的地址。

[xiaokangwang]

KCP连接不会自行关闭，如果proxy声明支持KCP，应该自行调用Close。

未来的proxy如果想使用KCP协议，需要双向同时调用Close

[xiaokangwang]

我先看一下失败的测试

[xiaokangwang]

go test -tags json github.com/v2ray/v2ray-core/...
# github.com/v2ray/v2ray-core/testing/scenarios
testing/scenarios/shadowsocks_test.go:11:2: cannot find package "github.com/shadowsocks/shadowsocks-go/shadowsocks" in any of:
    ------/github.com/shadowsocks/shadowsocks-go/shadowsocks (from $GOROOT)
    ------/src/github.com/shadowsocks/shadowsocks-go/shadowsocks (from $GOPATH)
FAIL    github.com/v2ray/v2ray-core/testing/scenarios [setup failed]
?       github.com/v2ray/v2ray-core [no test files]
?       github.com/v2ray/v2ray-core/app [no test files]
?       github.com/v2ray/v2ray-core/app/api [no test files]
?       github.com/v2ray/v2ray-core/app/dispatcher  [no test files]
?       github.com/v2ray/v2ray-core/app/dispatcher/impl [no test files]
?       github.com/v2ray/v2ray-core/app/dispatcher/testing  [no test files]
ok      github.com/v2ray/v2ray-core/app/dns 0.121s
?       github.com/v2ray/v2ray-core/app/proxyman    [no test files]
?       github.com/v2ray/v2ray-core/app/router  [no test files]
ok      github.com/v2ray/v2ray-core/app/router/rules    0.072s
?       github.com/v2ray/v2ray-core/common  [no test files]
ok      github.com/v2ray/v2ray-core/common/alloc    0.013s
ok      github.com/v2ray/v2ray-core/common/collect  0.015s
ok      github.com/v2ray/v2ray-core/common/crypto   0.004s
?       github.com/v2ray/v2ray-core/common/crypto/internal  [no test files]
?       github.com/v2ray/v2ray-core/common/dice [no test files]
ok      github.com/v2ray/v2ray-core/common/io   0.021s
?       github.com/v2ray/v2ray-core/common/loader   [no test files]
?       github.com/v2ray/v2ray-core/common/log  [no test files]
ok      github.com/v2ray/v2ray-core/common/log/internal 0.003s
ok      github.com/v2ray/v2ray-core/common/net  0.004s
?       github.com/v2ray/v2ray-core/common/net/testing  [no test files]
?       github.com/v2ray/v2ray-core/common/platform [no test files]
?       github.com/v2ray/v2ray-core/common/predicate    [no test files]
ok      github.com/v2ray/v2ray-core/common/protocol 0.006s
ok      github.com/v2ray/v2ray-core/common/protocol/raw 0.025s
ok      github.com/v2ray/v2ray-core/common/retry    8.023s
?       github.com/v2ray/v2ray-core/common/serial   [no test files]
?       github.com/v2ray/v2ray-core/common/signal   [no test files]
ok      github.com/v2ray/v2ray-core/common/uuid 0.010s
?       github.com/v2ray/v2ray-core/common/web  [no test files]
?       github.com/v2ray/v2ray-core/common/web/hooks    [no test files]
?       github.com/v2ray/v2ray-core/proxy   [no test files]
ok      github.com/v2ray/v2ray-core/proxy/blackhole 0.006s
ok      github.com/v2ray/v2ray-core/proxy/dokodemo  0.014s
ok      github.com/v2ray/v2ray-core/proxy/freedom   0.539s
ok      github.com/v2ray/v2ray-core/proxy/http  0.022s
?       github.com/v2ray/v2ray-core/proxy/internal  [no test files]
?       github.com/v2ray/v2ray-core/proxy/repo  [no test files]
ok      github.com/v2ray/v2ray-core/proxy/shadowsocks   0.003s
ok      github.com/v2ray/v2ray-core/proxy/socks 0.011s
ok      github.com/v2ray/v2ray-core/proxy/socks/protocol    0.005s
?       github.com/v2ray/v2ray-core/proxy/testing   [no test files]
?       github.com/v2ray/v2ray-core/proxy/testing/mocks [no test files]
ok      github.com/v2ray/v2ray-core/proxy/vmess 0.024s
?       github.com/v2ray/v2ray-core/proxy/vmess/inbound [no test files]
ok      github.com/v2ray/v2ray-core/proxy/vmess/io  0.469s
ok      github.com/v2ray/v2ray-core/proxy/vmess/outbound    0.003s
?       github.com/v2ray/v2ray-core/release/mobile  [no test files]
?       github.com/v2ray/v2ray-core/release/server  [no test files]
ok      github.com/v2ray/v2ray-core/shell/point 0.035s
?       github.com/v2ray/v2ray-core/testing/assert  [no test files]
?       github.com/v2ray/v2ray-core/testing/servers/http    [no test files]
?       github.com/v2ray/v2ray-core/testing/servers/tcp [no test files]
?       github.com/v2ray/v2ray-core/testing/servers/udp [no test files]
?       github.com/v2ray/v2ray-core/tools   [no test files]
ok      github.com/v2ray/v2ray-core/tools/build 40.259s
ok      github.com/v2ray/v2ray-core/tools/git   0.033s
?       github.com/v2ray/v2ray-core/transport   [no test files]
ok      github.com/v2ray/v2ray-core/transport/hub   0.375s
?       github.com/v2ray/v2ray-core/transport/hub/kcpv  [no test files]
?       github.com/v2ray/v2ray-core/transport/ray   [no test files]

我这里测试通过，不知道是什么原因。。。

[xiaokangwang]

在检测问题

[xiaokangwang]

a8792b2 is the first bad commit
commit a8792b2
Author: Shelikhoo [email protected]
Date: Sat Jun 11 19:51:02 2016 +0800

Added Config for KCP connetions

:040000 040000 6c82ef1fa81091b0dfe30afb3125c5f9b2bda670 515f79c71edff5e1e84d6d535abb2d048fd6eecd M transport
用git找了一下问题，看看怎么解决

[xiaokangwang]

我暂时无法确定到底是哪里出了问题。

[v2ray]

https://github.com/xiaokangwang/v2ray-core/blob/kcptransport/transport/config_json.go#L27

你没有判断 jsonConfig.KcpConfig = nil

[xiaokangwang]

你是通过什么看出来的？
难道是在自己没有启用KCP的配置文件上一运行就知道了。。。

[v2ray]

Travis 的 log 里面有：

/home/travis/gopath/src/github.com/v2ray/v2ray-core/transport/config_json.go:27 +0x106

[xiaokangwang]

日志太多，眼花了😂