1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
| package main
import (
"context"
"fmt"
"io"
"net"
"net/http"
"net/url"
"strings"
"time"
)
type SSRFProtector struct {
AllowedSchemes []string
AllowedPorts []int
Timeout time.Duration
MaxBodySize int64
}
func NewSSRFProtector() *SSRFProtector {
return &SSRFProtector{
AllowedSchemes: []string{"http", "https"},
AllowedPorts: []int{80, 443, 8080},
Timeout: 10 * time.Second,
MaxBodySize: 10 * 1024 * 1024,
}
}
func (p *SSRFProtector) ValidateURL(urlStr string) error {
parsedURL, err := url.Parse(urlStr)
if err != nil {
return fmt.Errorf("无效的URL: %v", err)
}
schemeAllowed := false
for _, scheme := range p.AllowedSchemes {
if strings.ToLower(parsedURL.Scheme) == scheme {
schemeAllowed = true
break
}
}
if !schemeAllowed {
return fmt.Errorf("不允许的协议: %s", parsedURL.Scheme)
}
hostname := parsedURL.Hostname()
if hostname == "" {
return fmt.Errorf("无效的主机名")
}
ips, err := net.LookupIP(hostname)
if err != nil {
return fmt.Errorf("无法解析域名: %v", err)
}
for _, ip := range ips {
if isPrivateIP(ip) {
return fmt.Errorf("禁止访问内网地址: %s", ip.String())
}
}
port := parsedURL.Port()
if port == "" {
if parsedURL.Scheme == "https" {
port = "443"
} else {
port = "80"
}
}
portAllowed := false
for _, allowedPort := range p.AllowedPorts {
if port == fmt.Sprintf("%d", allowedPort) {
portAllowed = true
break
}
}
if !portAllowed {
return fmt.Errorf("不允许的端口: %s", port)
}
return nil
}
func isPrivateIP(ip net.IP) bool {
if ip.IsLoopback() || ip.IsLinkLocalUnicast() || ip.IsLinkLocalMulticast() {
return true
}
privateIPBlocks := []*net.IPNet{
{IP: net.IPv4(10, 0, 0, 0), Mask: net.CIDRMask(8, 32)},
{IP: net.IPv4(172, 16, 0, 0), Mask: net.CIDRMask(12, 32)},
{IP: net.IPv4(192, 168, 0, 0), Mask: net.CIDRMask(16, 32)},
{IP: net.IPv4(169, 254, 0, 0), Mask: net.CIDRMask(16, 32)},
}
for _, block := range privateIPBlocks {
if block.Contains(ip) {
return true
}
}
if ip.String() == "169.254.169.254" {
return true
}
return false
}
func (p *SSRFProtector) SafeRequest(urlStr string) ([]byte, error) {
if err := p.ValidateURL(urlStr); err != nil {
return nil, err
}
client := &http.Client{
Timeout: p.Timeout,
CheckRedirect: func(req *http.Request, via []*http.Request) error {
return http.ErrUseLastResponse
},
}
ctx, cancel := context.WithTimeout(context.Background(), p.Timeout)
defer cancel()
req, err := http.NewRequestWithContext(ctx, "GET", urlStr, nil)
if err != nil {
return nil, err
}
resp, err := client.Do(req)
if err != nil {
return nil, err
}
defer resp.Body.Close()
limitedReader := io.LimitReader(resp.Body, p.MaxBodySize)
body, err := io.ReadAll(limitedReader)
if err != nil {
return nil, err
}
return body, nil
}
func fetchHandler(w http.ResponseWriter, r *http.Request) {
urlStr := r.URL.Query().Get("url")
if urlStr == "" {
http.Error(w, "缺少URL参数", http.StatusBadRequest)
return
}
protector := NewSSRFProtector()
body, err := protector.SafeRequest(urlStr)
if err != nil {
http.Error(w, fmt.Sprintf("请求失败: %v", err), http.StatusForbidden)
return
}
w.Write(body)
}
func main() {
http.HandleFunc("/fetch", fetchHandler)
fmt.Println("Server starting on :8080")
http.ListenAndServe(":8080", nil)
}
|
