环境

golang 1.9

websocket包采用的是github.com/gorilla/websocket

在小程序H5页面与websocket联调的时候出现了如下错误，Sec-Websocket-Protocol参数应该是小程序中自己添加进去的，后端要做一些处理。

问题

image

Error during Websocket handshake: Sent non-empty 'Sec-Websocket-Protocol'header but no response was received

处理

一般而言，websocket出现这种问题只要获取请求头的Sec-Websocket-Protocol参数，随后将参数添加到response的请求头中即可。但我在尝试之后，问题并没有解决。

在部门大佬的指导下，去看了github.com/gorilla/websocket包的源代码，发现包里对于这个参数已经做了处理

    //源码
    // Subprotocols specifies the server's supported protocols in order of
    // preference. If this field is not nil, then the Upgrade method negotiates a
    // subprotocol by selecting the first match in this list with a protocol
    // requested by the client. If there's no match, then no protocol is
    // negotiated (the Sec-Websocket-Protocol header is not included in the
    // handshake response).
    Subprotocols []string
    
    
    func (u *Upgrader) selectSubprotocol(r *http.Request, responseHeader http.Header) string {
    if u.Subprotocols != nil {
        clientProtocols := Subprotocols(r)
        for _, serverProtocol := range u.Subprotocols {
            for _, clientProtocol := range clientProtocols {
                if clientProtocol == serverProtocol {
                    return clientProtocol
                }
            }
        }
    } else if responseHeader != nil {
        return responseHeader.Get("Sec-Websocket-Protocol")
    }
    return ""
}

所以我们只需要将获取的参数放进Subprotocols即可

var upgrade = websocket.Upgrader{
        // cross origin domain
        CheckOrigin: func(r *http.Request) bool {   //这个是解决跨域问题
            return true
        },
        Subprotocols:[]string{s.Ctx.Input.Header("Sec-WebSocket-Protocol")},  
        //将获取的参数放进这个数组，问题解决
    }

在引用第三方包的时候，遇到问题，多读源码