initial commit

cmd/cmd.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"fmt"
+	"github.com/sduden/simpleproxy"
+	"os"
+)
+
+// simpleproxy is a simple proxy server.
+// the first argument passed to the program is the address of the server to proxy to.
+// the second argument is the address to listen on.
+// if not specified, listens on 0.0.0.0:8080
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Printf("Usage: %s <server> [listen]\n", os.Args[0])
+		os.Exit(1)
+	}
+
+	server := os.Args[1]
+
+	listen := ":8080"
+
+	if len(os.Args) > 2 {
+		listen = os.Args[2]
+	}
+
+	fmt.Printf("Listening on %s, proxying to %s\n", listen, server)
+
+	proxy := simpleproxy.NewProxy(listen, server)
+	proxy.ListenAndServe()
+}

go.mod

@@ -0,0 +1,3 @@
+module github.com/sduden/simpleproxy
+
+go 1.21

proxy.go

@@ -0,0 +1,82 @@
+package simpleproxy
+
+import (
+	"io"
+	"net/http"
+	"net/url"
+)
+
+type Proxy struct {
+	ListenAddr string
+	ServerAddr string
+
+	u *url.URL
+}
+
+// NewProxy creates a new proxy server.
+func NewProxy(listenAddr, serverAddr string) *Proxy {
+	u, err := url.Parse(serverAddr)
+	if err != nil {
+		panic(err)
+	}
+
+	return &Proxy{
+		ListenAddr: listenAddr,
+		ServerAddr: serverAddr,
+		u:          u,
+	}
+}
+
+// ListenAndServe starts the proxy server.
+func (p *Proxy) ListenAndServe() error {
+	srv := &http.Server{
+		Addr:    p.ListenAddr,
+		Handler: p,
+	}
+
+	return srv.ListenAndServe()
+
+}
+
+// ServeHTTP is the main handler for the proxy server.
+// all requests here should be proxied to the server.
+func (p *Proxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	// all requests should be proxied to the server.
+	req, err := http.NewRequest(r.Method, p.ServerAddr+r.URL.String(), r.Body)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	// copy headers
+	for k, v := range r.Header {
+		req.Header[k] = v
+	}
+
+	// make the request
+	resp, err := http.DefaultClient.Do(req)
+
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	mirrorResponse(w, resp)
+
+}
+
+func mirrorResponse(w http.ResponseWriter, resp *http.Response) {
+	// Copy all headers from the original response
+	for key, values := range resp.Header {
+		for _, value := range values {
+			w.Header().Add(key, value)
+		}
+	}
+
+	// Copy the status code from the original response
+	w.WriteHeader(resp.StatusCode)
+
+	// Copy the response body
+	io.Copy(w, resp.Body)
+	resp.Body.Close()
+}