go-gemini/client.go

165 lines
3.2 KiB
Go

package gemini
import (
"bytes"
"crypto/tls"
"errors"
"io/ioutil"
"net/url"
"strconv"
"strings"
)
var (
ErrProtocol = errors.New("Protocol error")
ErrInvalidURL = errors.New("Invalid URL")
)
// Client is a Gemini client.
type Client struct{}
// Request makes a request for the provided URL. The host is inferred from the URL.
func (c *Client) Request(url string) (*Response, error) {
if len(url) > 1024 {
return nil, ErrInvalidURL
}
req, err := NewRequest(url)
if err != nil {
return nil, err
}
return c.Do(req)
}
// ProxyRequest requests the provided URL from the provided host.
func (c *Client) ProxyRequest(host, url string) (*Response, error) {
if len(url) > 1024 {
return nil, ErrInvalidURL
}
req, err := NewProxyRequest(host, url)
if err != nil {
return nil, err
}
return c.Do(req)
}
// Request is a Gemini request.
//
// A Request can optionally be configured with a client certificate. Example:
//
// req := NewRequest(url)
// cert, err := tls.LoadX509KeyPair("client.crt", "client.key")
// if err != nil {
// panic(err)
// }
// req.Certificates = append(req.Certificates, cert)
//
type Request struct {
Host string // host or host:port
URL *url.URL // the requested URL
Certificates []tls.Certificate // client certificates
}
// NewRequest returns a new request. The host is inferred from the provided url.
func NewRequest(rawurl string) (*Request, error) {
u, err := url.Parse(rawurl)
if err != nil {
return nil, err
}
// Ignore UserInfo if present
u.User = nil
return &Request{
Host: u.Host,
URL: u,
}, nil
}
// NewProxyRequest makes a new request using the provided host.
func NewProxyRequest(host, rawurl string) (*Request, error) {
u, err := url.Parse(rawurl)
if err != nil {
return nil, err
}
// Ignore UserInfo if present
u.User = nil
return &Request{
Host: host,
URL: u,
}, nil
}
// Do sends a Gemini request and returns a Gemini response.
func (c *Client) Do(req *Request) (*Response, error) {
host := req.Host
if strings.LastIndex(host, ":") == -1 {
// The default port is 1965
host += ":1965"
}
// Allow self signed certificates
config := tls.Config{}
config.InsecureSkipVerify = true
config.Certificates = req.Certificates
conn, err := tls.Dial("tcp", host, &config)
if err != nil {
return nil, err
}
defer conn.Close()
// Write the request
request := req.URL.String() + "\r\n"
if _, err := conn.Write([]byte(request)); err != nil {
return nil, err
}
// Read the response
b, err := ioutil.ReadAll(conn)
if err != nil {
return nil, err
}
// Ensure that the response is long enough
// The minimum response: <STATUS><SPACE><CR><LF> (5 bytes)
if len(b) < 5 {
return nil, ErrProtocol
}
// Parse the response header
status, err := strconv.Atoi(string(b[:2]))
if err != nil {
return nil, err
}
// Read one space
if b[2] != ' ' {
return nil, ErrProtocol
}
// Find the first <CR><LF>
i := bytes.Index(b, []byte("\r\n"))
if i < 3 {
return nil, ErrProtocol
}
// Read the meta
meta := string(b[3:i])
if len(meta) > 1024 {
return nil, ErrProtocol
}
// Read the response body
body := b[i+2:]
return &Response{
Status: status,
Meta: meta,
Body: body,
}, nil
}