package main
import (
"bytes"
"crypto/tls"
"flag"
"fmt"
"io"
"io/ioutil"
"math/rand"
"net"
"net/http"
"net/http/httputil"
"runtime"
"time"
)
// Console flags
//参数解析
var (
listen = flag.String("l", ":8888", "port to accept requests") //接收请求端口 默认渡口是8888 targetProduction = flag.String("a", "localhost:8080", "where production traffic goes. http://localhost:8080/production") //a代表产品机器 默认端口是8080 altTarget = flag.String("b", "localhost:8081", "where testing traffic goes. response are skipped. http://localhost:8081/test") //b 测试机器 端口是8081 debug = flag.Bool("debug", false, "more logging, showing ignored output") //日志开关 productionTimeout = flag.Int("a.timeout", 3, "timeout in seconds for production traffic")// 生产机器请求超时时间 alternateTimeout = flag.Int("b.timeout", 1, "timeout in seconds for alternate site traffic")//测试机器清酒超时时间 productionHostRewrite = flag.Bool("a.rewrite", false, "rewrite the host header when proxying production traffic") //生产机器是重定向开关 alternateHostRewrite = flag.Bool("b.rewrite", false, "rewrite the host header when proxying alternate site traffic")//测试机器是否重定向开关 percent = flag.Float64("p", 100.0, "float64 percentage of traffic to send to testing")// 生产数据发给测试机器数据的百分比 流量分割 tlsPrivateKey = flag.String("key.file", "", "path to the TLS private key file") //TSL 私钥证书 tlsCertificate = flag.String("cert.file", "", "path to the TLS certificate file")//Tsl 龚玥证书)
// handler contains the address of the main Target and the one for the Alternative target
//handler 包含连个地址 其中一个是生产服务器 另个一是测试服务器
type handler struct { Target string
Alternative string
Randomizer rand.Rand
}
// ServeHTTP duplicates the incoming request (req) and does the request to the Target and the Alternate target discading the Alternate response
//sereHttp 复制获取到的req 并且发送到生产服务器和测试服务器 测试服务器丢弃响应结果
func (h handler) ServeHTTP(w http.ResponseWriter, req *http.Request) { var productionRequest, alternativeRequest *http.Request
if *percent == 100.0 || h.Randomizer.Float64()*100 < *percent { alternativeRequest, productionRequest = DuplicateRequest(req) //复制数据到生产和测试请求中
go func() { defer func() { if r := recover(); r != nil && *debug { fmt.Println("Recovered in f", r) }
}()
// Open new TCP connection to the server
//获取客户端连接 带有超时时间
clientTcpConn, err := net.DialTimeout("tcp", h.Alternative, time.Duration(time.Duration(*alternateTimeout)*time.Second)) if err != nil { if *debug { fmt.Printf("Failed to connect to %s
", h.Alternative) }
return
}
clientHttpConn := httputil.NewClientConn(clientTcpConn, nil) // Start a new HTTP connection on it
defer clientHttpConn.Close() // Close the connection to the server
if *alternateHostRewrite { alternativeRequest.Host = h.Alternative
}
err = clientHttpConn.Write(alternativeRequest) // Pass on the request
if err != nil { if *debug { fmt.Printf("Failed to send to %s: %v
", h.Alternative, err) }
return
}
_, err = clientHttpConn.Read(alternativeRequest) // Read back the reply
if err != nil { if *debug { fmt.Printf("Failed to receive from %s: %v
", h.Alternative, err) }
return
}
}()
} else { productionRequest = req
}
defer func() { if r := recover(); r != nil && *debug { fmt.Println("Recovered in f", r) }
}()
// Open new TCP connection to the server
//生产服务器
clientTcpConn, err := net.DialTimeout("tcp", h.Target, time.Duration(time.Duration(*productionTimeout)*time.Second)) if err != nil { fmt.Printf("Failed to connect to %s
", h.Target) return
}
clientHttpConn := httputil.NewClientConn(clientTcpConn, nil) // Start a new HTTP connection on it
defer clientHttpConn.Close() // Close the connection to the server
if *productionHostRewrite { productionRequest.Host = h.Target
}
err = clientHttpConn.Write(productionRequest) // Pass on the request
if err != nil { fmt.Printf("Failed to send to %s: %v
", h.Target, err) return
}
resp, err := clientHttpConn.Read(productionRequest) // Read back the reply
if err != nil { fmt.Printf("Failed to receive from %s: %v
", h.Target, err) return
}
defer resp.Body.Close()
for k, v := range resp.Header { w.Header()[k] = v
}
w.WriteHeader(resp.StatusCode)
body, _ := ioutil.ReadAll(resp.Body)
w.Write(body)
}
func main() { flag.Parse()
runtime.GOMAXPROCS(runtime.NumCPU())
var err error
var listener net.Listener
if len(*tlsPrivateKey) > 0 { cer, err := tls.LoadX509KeyPair(*tlsCertificate, *tlsPrivateKey)
if err != nil { fmt.Printf("Failed to load certficate: %s and private key: %s", *tlsCertificate, *tlsPrivateKey) return
}
config := &tls.Config{Certificates: []tls.Certificate{cer}} listener, err = tls.Listen("tcp", *listen, config) if err != nil { fmt.Printf("Failed to listen to %s: %s
", *listen, err) return
}
} else { listener, err = net.Listen("tcp", *listen) if err != nil { fmt.Printf("Failed to listen to %s: %s
", *listen, err) return
}
}
h := handler{ Target: *targetProduction,
Alternative: *altTarget,
Randomizer: *rand.New(rand.NewSource(time.Now().UnixNano())),
}
http.Serve(listener, h)
}
type nopCloser struct { io.Reader
}
func (nopCloser) Close() error { return nil }//复制req到生茶服务器和测试服务器
func DuplicateRequest(request *http.Request) (request1 *http.Request, request2 *http.Request) { b1 := new(bytes.Buffer)
b2 := new(bytes.Buffer)
w := io.MultiWriter(b1, b2) //同时向多个对象中写入数据
io.Copy(w, request.Body) //复制数据到 w中
defer request.Body.Close()
request1 = &http.Request{ Method: request.Method,
URL: request.URL,
Proto: request.Proto,
ProtoMajor: request.ProtoMajor,
ProtoMinor: request.ProtoMinor,
Header: request.Header,
Body: nopCloser{b1}, Host: request.Host,
ContentLength: request.ContentLength,
}
request2 = &http.Request{ Method: request.Method,
URL: request.URL,
Proto: request.Proto,
ProtoMajor: request.ProtoMajor,
ProtoMinor: request.ProtoMinor,
Header: request.Header,
Body: nopCloser{b2}, Host: request.Host,
ContentLength: request.ContentLength,
}
return
}