go-proxy-http

[!Note]

项目：go-proxy-http

知识点

监听端口

监听tcp端口

con, err := net.Listen("tcp", fmt.Sprintf(":%v", port))
if err != nil {
   log.Panic(err)
}

接收回答

client, err := con.Accept()
if err != nil {
            continue
}

读到接收的数据，传入b byte数组

var b = make([]byte, max)
    _, err := client.Read(b[:])

    if err != nil {
        return
}

Sscanf

以空格为分割读取数据

fmt.Sscanf(string(b[:bytes.IndexByte(b[:], '\n')]), "%v %v %v", &method, &proxyUrl, &httpProtocolVersion)

net.Dial

建立tcp连接

server, err := net.Dial("tcp", serverAddress)

写入报文

server.Write(b[:])

将client 写入 server

go io.Copy(server, client)

完整代码

package main

import (
    "bytes"
    "flag"
    "fmt"
    "io"
    "log"
    "net"
    "net/url"
    "strings"
)

var (
    port int
    max  int
)

func Banner() {

    fmt.Println(`
           __.__  .__       _______   
__  _  __ |__|  | |__| ____ \   _  \  
\ \/ \/ / |  |  | |  |/    \/  /_\  \ 
 \     /  |  |  |_|  |   |  \  \_/   \
  \/\_/\__|  |____/__|___|  /\_____  /
      \______|            \/       \/ 
        go-proxy-http `)
}
func Init() {
    flag.IntVar(&port, "port", 1024, "端口")
    flag.IntVar(&max, "max", 1024, "报文大小")
}
func main() {
    Init()
    Banner()
    flag.Parse()
    checkArgs()
    log.Printf("代理端口: %v 最大报文大小: %v", port, max)
    con, err := net.Listen("tcp", fmt.Sprintf(":%v", port))

    if err != nil {
        log.Panic(err)
    }
    for {
        client, err := con.Accept()
        if err != nil {
            continue
        }
        go handleConnection(client)
    }
}

func checkArgs() {
    //flag.Usage()
    if max < 1024 {
        log.Panic("报文大小最好不小于1024个字节")
    }
}

func handleConnection(client net.Conn) {
    var b = make([]byte, max)
    _, err := client.Read(b[:])

    if err != nil {
        return
    }
    var method, proxyUrl, httpProtocolVersion, serverAddress string
    fmt.Sscanf(string(b[:bytes.IndexByte(b[:], '\n')]), "%v %v %v", &method, &proxyUrl, &httpProtocolVersion)
    urlParse, err := url.Parse(proxyUrl)
    if err != nil {
        return
    }

    if method == "CONNECT" {
        serverAddress = urlParse.Scheme + fmt.Sprintf(":%v", urlParse.Opaque)

    } else {
        if strings.Index(urlParse.Host, ":") == -1 { //host不带端口， 默认80
            serverAddress = urlParse.Host + ":80"
        } else {
            serverAddress = urlParse.Host
        }
    }
    server, err := net.Dial("tcp", serverAddress)
    if err != nil {
        return
    }
    if method == "CONNECT" {
        _, err := client.Write([]byte("HTTP/1.1 200 Connection established\r\n\r\n"))
        if err != nil {
            return
        }
    } else {
        server.Write(b[:])
    }
    go io.Copy(server, client)
    go io.Copy(client, server)
    fmt.Printf("%v -> %v\n", client.RemoteAddr(), server.RemoteAddr())
}

运行实例