💾 Archived View for anachronauts.club › cgi-bin › repos › cgi › gmikit.git › tree › trunk › client.g… captured on 2022-01-08 at 14:05:33. Gemini links have been rewritten to link to archived content
⬅️ Previous capture (2021-12-05)
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1 package gmikit
2
3 import (
4 "bufio"
5 "context"
6 "crypto/tls"
7 "crypto/x509"
8 "errors"
9 "fmt"
10 "io"
11 "net"
12 "net/url"
13 "strconv"
14 "time"
15 )
16
17 var (
18 ErrInvalidURL = errors.New("gemini: invalid URL")
19 ErrInvalidStatus = errors.New("gemini: invalid status")
20 ErrMetaTooLong = errors.New("gemini: meta too long")
21 ErrMalformedHeader = errors.New("gemini: malformed header")
22 )
23
24 var crlf = []byte("\r\n")
25
26 type Status int
27
28 const (
29 StatusInput Status = 10
30 StatusSensitiveInput Status = 11
31 StatusSuccess Status = 20
32 StatusRedirect Status = 30
33 StatusPermanentRedirect Status = 31
34 StatusTemporaryFailure Status = 40
35 StatusServerUnavailable Status = 41
36 StatusCGIError Status = 42
37 StatusProxyError Status = 43
38 StatusSlowDown Status = 44
39 StatusPermanentFailure Status = 50
40 StatusNotFound Status = 51
41 StatusGone Status = 52
42 StatusProxyRequestRefused Status = 53
43 StatusBadRequest Status = 59
44 StatusCertificateRequired Status = 60
45 StatusCertificateNotAuthorized Status = 61
46 StatusCertificateNotValid Status = 62
47 )
48
49 type StatusClass int
50
51 const (
52 StatusClassInput StatusClass = 1
53 StatusClassSuccess StatusClass = 2
54 StatusClassRedirect StatusClass = 3
55 StatusClassTemporaryFailure StatusClass = 4
56 StatusClassPermanentFailure StatusClass = 5
57 StatusClassCertificateRequired StatusClass = 6
58 )
59
60 var statusStrings = map[Status]string{
61 // 1x
62 StatusInput: "INPUT",
63 StatusSensitiveInput: "SENSITIVE INPUT",
64
65 // 2x
66 StatusSuccess: "SUCCESS",
67
68 // 3x
69 StatusRedirect: "REDIRECT - TEMPORARY",
70 StatusPermanentRedirect: "REDIRECT - PERMANENT",
71
72 // 4x
73 StatusTemporaryFailure: "TEMPORARY FAILURE",
74 StatusServerUnavailable: "SERVER UNAVAILABLE",
75 StatusCGIError: "CGI ERROR",
76 StatusProxyError: "PROXY ERROR",
77 StatusSlowDown: "SLOW DOWN",
78
79 // 5x
80 StatusPermanentFailure: "PERMANENT FAILURE",
81 StatusNotFound: "NOT FOUND",
82 StatusGone: "GONE",
83 StatusProxyRequestRefused: "PROXY REQUEST REFUSED",
84 StatusBadRequest: "BAD REQUEST",
85
86 // 6x
87 StatusCertificateRequired: "CLIENT CERTIFICATE REQUIRED",
88 StatusCertificateNotAuthorized: "CERTIFICATE NOT AUTHORIZED",
89 StatusCertificateNotValid: "CERTIFICATE NOT VALID",
90 }
91
92 func (s Status) Class() StatusClass {
93 return StatusClass(s / 10)
94 }
95
96 func (s Status) String() string {
97 str, ok := statusStrings[s]
98 if !ok {
99 str, ok = statusStrings[Status(s.Class()*10)]
100 }
101 if !ok {
102 str = ""
103 }
104 return fmt.Sprintf("%d %s", s, str)
105 }
106
107 type Request struct {
108 URL *url.URL
109 Certificate *tls.Certificate
110 Context context.Context
111 Host string
112 }
113
114 func NewRequest(url *url.URL) *Request {
115 req := &Request{
116 URL: url,
117 Host: url.Host,
118 }
119 if url.Port() == "" {
120 req.Host = fmt.Sprintf("%s:1965", url.Host)
121 }
122 return req
123 }
124
125 func (r *Request) Write(w *bufio.Writer) error {
126 url := r.URL.String()
127 if r.URL.User != nil || len(url) > 1024 {
128 return ErrInvalidURL
129 }
130 if _, err := w.WriteString(url); err != nil {
131 return err
132 }
133 if _, err := w.Write(crlf); err != nil {
134 return err
135 }
136 return nil
137 }
138
139 type Response struct {
140 Status Status
141 Meta string
142 Body io.Reader
143 TLS tls.ConnectionState
144 closer io.Closer
145 }
146
147 func ReadResponse(rc io.ReadCloser) (*Response, error) {
148 resp := &Response{}
149 br := bufio.NewReader(rc)
150
151 statusB := make([]byte, 2)
152 if _, err := br.Read(statusB); err != nil {
153 return nil, err
154 }
155 status, err := strconv.Atoi(string(statusB))
156 if err != nil {
157 return nil, err
158 }
159 if status < 10 || status >= 70 {
160 return nil, ErrInvalidStatus
161 }
162 resp.Status = Status(status)
163
164 if b, err := br.ReadByte(); err != nil {
165 return nil, err
166 } else if b != ' ' {
167 return nil, ErrMalformedHeader
168 }
169
170 meta, err := br.ReadString('\r')
171 if err != nil {
172 return nil, err
173 }
174 meta = meta[:len(meta)-1]
175 if len(meta) > 1024 {
176 return nil, ErrMetaTooLong
177 }
178 if resp.Status.Class() == StatusClassSuccess && meta == "" {
179 meta = "text/gemini; charset=utf-8"
180 }
181 resp.Meta = meta
182
183 if b, err := br.ReadByte(); err != nil {
184 return nil, err
185 } else if b != '\n' {
186 return nil, ErrMalformedHeader
187 }
188
189 if resp.Status.Class() != StatusClassSuccess {
190 rc.Close()
191 } else {
192 resp.Body = br
193 resp.closer = rc
194 }
195
196 return resp, nil
197 }
198
199 func (r *Response) Close() error {
200 if r.closer != nil {
201 if err := r.closer.Close(); err != nil {
202 return err
203 }
204 r.closer = nil
205 }
206 return nil
207 }
208
209 type Client struct {
210 TrustCertificate func(hostname string, cert *x509.Certificate) error
211 Timeout time.Duration
212 }
213
214 func (c *Client) Do(req *Request) (*Response, error) {
215 config := &tls.Config{
216 InsecureSkipVerify: true,
217 MinVersion: tls.VersionTLS12,
218 GetClientCertificate: func(_ *tls.CertificateRequestInfo) (*tls.Certificate, error) {
219 if req.Certificate != nil {
220 return req.Certificate, nil
221 } else {
222 return &tls.Certificate{}, nil
223 }
224 },
225 VerifyConnection: func(cs tls.ConnectionState) error {
226 if c.TrustCertificate != nil {
227 cert := cs.PeerCertificates[0]
228 return c.TrustCertificate(req.URL.Host, cert)
229 } else {
230 return nil
231 }
232 },
233 ServerName: req.URL.Host,
234 }
235
236 ctx := req.Context
237 if ctx == nil {
238 ctx = context.Background()
239 }
240
241 start := time.Now()
242 dialer := net.Dialer{
243 Timeout: c.Timeout,
244 }
245
246 netConn, err := dialer.DialContext(ctx, "tcp", req.Host)
247 if err != nil {
248 return nil, err
249 }
250
251 conn := tls.Client(netConn, config)
252 if c.Timeout != 0 {
253 err := conn.SetDeadline(start.Add(c.Timeout))
254 if err != nil {
255 return nil, fmt.Errorf("failed to set connection deadline: %w", err)
256 }
257 }
258
259 resp, err := c.do(conn, req)
260 if err != nil {
261 _ = conn.Close()
262 return nil, err
263 }
264
265 resp.TLS = conn.ConnectionState()
266
267 return resp, nil
268 }
269
270 func (c *Client) do(conn *tls.Conn, req *Request) (*Response, error) {
271 w := bufio.NewWriter(conn)
272 err := req.Write(w)
273 if err != nil {
274 return nil, fmt.Errorf("failed to write request: %w", err)
275 }
276
277 if err := w.Flush(); err != nil {
278 return nil, err
279 }
280
281 resp, err := ReadResponse(conn)
282 if err != nil {
283 return nil, err
284 }
285
286 return resp, nil
287 }