refactor: do some experimental restructure

Author: CoolSpring8

cmd/rwppa/main.go

@@ -17,7 +17,7 @@
 // In other words, on receiving requests, they will be sent to rvpn.zju.edu.cn and corresponding results will be passed back to the browser,
 // or any other HTTP-proxy-capable requesters, like clients that only utilizes HTTP protocol.
 
-// In short, users are given the ability to browse ZJU intranet sites,
+// In short, users are given the ability to access ZJU intranet sites,
 // with a ZJU internet service account required, and via ZJU RVPN web portal (view rvpn.zju.edu.cn on phones to see).
 // Hopefully it can replace the role of Sangfor EasyConnect, to a certain extent.
 
@@ -32,8 +32,8 @@ package main
 import (
 	"fmt"
 
-	"github.com/coolspring8/rwppa/internal/login"
 	"github.com/coolspring8/rwppa/internal/proxy"
+	"github.com/coolspring8/rwppa/internal/rvpn"
 )
 
 func main() {
@@ -52,6 +52,12 @@ func main() {
 	if err != nil {
 		panic(err)
 	}
-	twfid := login.LoginRVPNWebPortal(username, password)
-	proxy.StartProxyServer(listenAddr, twfid)
+
+	w := rvpn.WebPortal{Username: username, Password: password}
+	twfid, err := w.LogIn()
+	if err != nil {
+		panic(err)
+	}
+
+	proxy.StartProxyServer(listenAddr, *twfid)
 }

internal/cert/cert.go

@@ -1,48 +1,31 @@
-// This file was partly from https://github.com/elazarl/goproxy/blob/master/examples/goproxy-customca/cert.go
+// Copyright (C) 2020  CoolSpring8
 
-// Copyright (c) 2012 Elazar Leibovich. All rights reserved.
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
 
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
 
-//    * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//    * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//    * Neither the name of Elazar Leibovich. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+// Package cert provides operation functions on CA cert and key.
 package cert
 
 import (
 	"crypto/rand"
 	"crypto/rsa"
-	"crypto/tls"
 	"crypto/x509"
 	"crypto/x509/pkix"
 	"encoding/pem"
 	"io/ioutil"
 	"math/big"
 	"os"
 	"time"
-
-	"github.com/elazarl/goproxy"
 )
 
 // GetCA returns a CA cert, a CA key or an error in file reading or writing process.
@@ -114,24 +97,6 @@ func GetCA() ([]byte, []byte, error) {
 	return caCert, caKey, err
 }
 
-// SetCA takes CA cert and CA key, and sets up goproxy CA.
-// Returns error in parsing and setting CA.
-func SetCA(caCert, caKey []byte) error {
-	goproxyCa, err := tls.X509KeyPair(caCert, caKey)
-	if err != nil {
-		return err
-	}
-	if goproxyCa.Leaf, err = x509.ParseCertificate(goproxyCa.Certificate[0]); err != nil {
-		return err
-	}
-	goproxy.GoproxyCa = goproxyCa
-	goproxy.OkConnect = &goproxy.ConnectAction{Action: goproxy.ConnectAccept, TLSConfig: goproxy.TLSConfigFromCA(&goproxyCa)}
-	goproxy.MitmConnect = &goproxy.ConnectAction{Action: goproxy.ConnectMitm, TLSConfig: goproxy.TLSConfigFromCA(&goproxyCa)}
-	goproxy.HTTPMitmConnect = &goproxy.ConnectAction{Action: goproxy.ConnectHTTPMitm, TLSConfig: goproxy.TLSConfigFromCA(&goproxyCa)}
-	goproxy.RejectConnect = &goproxy.ConnectAction{Action: goproxy.ConnectReject, TLSConfig: goproxy.TLSConfigFromCA(&goproxyCa)}
-	return nil
-}
-
 // fileExists checks if a file exists and is not a directory.
 func fileExists(filename string) bool {
 	info, err := os.Stat(filename)

internal/proxy/proxy.go

@@ -13,9 +13,12 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+// Package proxy provides things to set up a proxy.
 package proxy
 
 import (
+	"crypto/tls"
+	"crypto/x509"
 	"fmt"
 	"log"
 	"net"
@@ -70,7 +73,7 @@ func StartProxyServer(listenAddr, twfid string) {
 	if err != nil {
 		panic(err)
 	}
-	err = cert.SetCA(caCert, caKey)
+	err = SetCA(caCert, caKey)
 	if err != nil {
 		panic(err)
 	}
@@ -144,3 +147,21 @@ func StartProxyServer(listenAddr, twfid string) {
 	fmt.Println("Listen Address:" + listenAddr)
 	log.Fatal(http.ListenAndServe(listenAddr, proxy))
 }
+
+// SetCA takes CA cert and CA key, and sets up goproxy CA.
+// Returns error in parsing and setting CA.
+func SetCA(caCert, caKey []byte) error {
+	goproxyCa, err := tls.X509KeyPair(caCert, caKey)
+	if err != nil {
+		return err
+	}
+	if goproxyCa.Leaf, err = x509.ParseCertificate(goproxyCa.Certificate[0]); err != nil {
+		return err
+	}
+	goproxy.GoproxyCa = goproxyCa
+	goproxy.OkConnect = &goproxy.ConnectAction{Action: goproxy.ConnectAccept, TLSConfig: goproxy.TLSConfigFromCA(&goproxyCa)}
+	goproxy.MitmConnect = &goproxy.ConnectAction{Action: goproxy.ConnectMitm, TLSConfig: goproxy.TLSConfigFromCA(&goproxyCa)}
+	goproxy.HTTPMitmConnect = &goproxy.ConnectAction{Action: goproxy.ConnectHTTPMitm, TLSConfig: goproxy.TLSConfigFromCA(&goproxyCa)}
+	goproxy.RejectConnect = &goproxy.ConnectAction{Action: goproxy.ConnectReject, TLSConfig: goproxy.TLSConfigFromCA(&goproxyCa)}
+	return nil
+}

internal/login/login.go internal/rvpn/rvpn.gointernal/login/login.go renamed to internal/rvpn/rvpn.go

@@ -13,7 +13,8 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-package login
+// Package rvpn deals with things related to ZJU RVPN web portal.
+package rvpn
 
 import (
 	"net/http"
@@ -23,28 +24,37 @@ import (
 
 const (
 	// endpointURL is where ZJU RVPN web portal's login interface locates.
-	// TODO: try to find out if some of the parameters are not necessary.
+	// TODO: find out if some of the parameters are not necessary.
 	endpointURL string = "https://rvpn.zju.edu.cn/por/login_psw.csp?type=cs&dev=android-phone&dev=android-phone&language=zh_CN"
 )
 
-// LoginRVPNWebPortal takes username and password, returns TWFID.
+// WebPortal refers to ZJU RVPN web portal.
+type WebPortal struct {
+	Username string // Username is ZJU network service account username.
+	Password string // Password is ZJU network service account password.
+}
+
+// LogIn uses username and password to get a TWFID.
 // TWFID is used by the web portal for authentication.
 // Incorrect or empty username and password will simply lead to a useless TWFID.
-// TODO: verify before returning. throw an error if not working.
-func LoginRVPNWebPortal(username, password string) string {
+// TODO: verify, throw an error if not working.
+func (webPortal WebPortal) LogIn() (*string, error) {
 	data := url.Values{}
-	data.Set("svpn_name", username)
-	data.Set("svpn_password", password)
+	data.Set("svpn_name", webPortal.Username)
+	data.Set("svpn_password", webPortal.Password)
 
 	client := &http.Client{}
-	r, _ := http.NewRequest("POST", endpointURL, strings.NewReader(data.Encode()))
+	req, err := http.NewRequest("POST", endpointURL, strings.NewReader(data.Encode()))
+	if err != nil {
+		return nil, err
+	}
 
-	resp, err := client.Do(r)
+	resp, err := client.Do(req)
 	if err != nil {
-		panic(err)
+		return nil, err
 	}
 
 	twfid := resp.Cookies()[0].Value
 
-	return twfid
+	return &twfid, nil
 }