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// +build ignore
package main
import (
"bufio"
"crypto/tls"
"crypto/x509"
"fmt"
"io/ioutil"
"os"
"time"
"git.sr.ht/~adnano/go-gemini"
)
var (
scanner = bufio.NewScanner(os.Stdin)
client = &gemini.Client{}
)
func init() {
client.KnownHosts.LoadDefault()
client.TrustCertificate = func(hostname string, cert *x509.Certificate, knownHosts *gemini.KnownHosts) error {
err := knownHosts.Lookup(hostname, cert)
if err != nil {
switch err {
case gemini.ErrCertificateNotTrusted:
// Alert the user that the certificate is not trusted
fmt.Printf("Warning: Certificate for %s is not trusted!\n", hostname)
fmt.Println("This could indicate a Man-in-the-Middle attack.")
case gemini.ErrCertificateUnknown:
// Prompt the user to trust the certificate
trust := trustCertificate(cert)
switch trust {
case trustOnce:
// Temporarily trust the certificate
knownHosts.AddTemporary(hostname, cert)
return nil
case trustAlways:
// Add the certificate to the known hosts file
knownHosts.Add(hostname, cert)
return nil
}
}
}
return err
}
client.GetCertificate = func(req *gemini.Request, store *gemini.ClientCertificateStore) *tls.Certificate {
// If the certificate is in the store, return it
if cert, err := store.Lookup(req.URL.Hostname(), req.URL.Path); err == nil {
return cert
}
// Otherwise, generate a certificate
fmt.Println("Generating client certificate for", req.URL.Hostname()+req.URL.Path)
duration := time.Hour
cert, err := gemini.NewCertificate("", duration)
if err != nil {
return nil
}
// Store and return the certificate
store.Add(req.URL.Hostname()+req.URL.Path, cert)
return &cert
}
client.GetInput = func(prompt string, sensitive bool) (string, bool) {
fmt.Printf("%s: ", prompt)
scanner.Scan()
return scanner.Text(), true
}
}
// sendRequest sends a request to the given URL.
func sendRequest(req *gemini.Request) error {
resp, err := client.Do(req)
if err != nil {
return err
}
switch resp.Status.Class() {
case gemini.StatusClassInput:
fmt.Printf("%s: ", resp.Meta)
scanner.Scan()
req.URL.RawQuery = url.QueryEscape(scanner.Text())
return sendRequest(req)
case gemini.StatusClassSuccess:
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
return err
}
fmt.Print(string(body))
return nil
case gemini.StatusClassRedirect:
// This should not happen unless CheckRedirect returns false.
return fmt.Errorf("Failed to redirect to %s", resp.Meta)
case gemini.StatusClassTemporaryFailure:
return fmt.Errorf("Temporary failure: %s", resp.Meta)
case gemini.StatusClassPermanentFailure:
return fmt.Errorf("Permanent failure: %s", resp.Meta)
case gemini.StatusClassCertificateRequired:
// Note that this should not happen unless the server responds with
// CertificateRequired even after we send a certificate.
// CertificateNotAuthorized and CertificateNotValid are handled here.
return fmt.Errorf("Certificate required: %s", resp.Meta)
}
panic("unreachable")
}
type trust int
const (
trustAbort trust = iota
trustOnce
trustAlways
)
const trustPrompt = `The certificate offered by this server is of unknown trust. Its fingerprint is:
%s
If you knew the fingerprint to expect in advance, verify that this matches.
Otherwise, this should be safe to trust.
[t]rust always; trust [o]nce; [a]bort
=> `
func trustCertificate(cert *x509.Certificate) trust {
fmt.Printf(trustPrompt, gemini.Fingerprint(cert))
scanner.Scan()
switch scanner.Text() {
case "t":
return trustAlways
case "o":
return trustOnce
default:
return trustAbort
}
}
func main() {
if len(os.Args) < 2 {
fmt.Printf("usage: %s gemini://...", os.Args[0])
os.Exit(1)
}
url := os.Args[1]
req, err := gemini.NewRequest(url)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
if err := sendRequest(req); err != nil {
fmt.Println(err)
os.Exit(1)
}
}
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