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package main
import (
"bytes"
"context"
"crypto/md5"
"crypto/tls"
"crypto/x509"
"encoding/hex"
"fmt"
"log"
"net"
"os"
"strings"
"tildegit.org/tjp/gus/gemini"
guslog "tildegit.org/tjp/gus/contrib/log"
)
func main() {
// Get TLS files from the environment
certfile, keyfile := envConfig()
// build a TLS configuration suitable for gemini
tlsconf, err := gemini.FileTLS(certfile, keyfile)
if err != nil {
log.Fatal(err)
}
// set up the network listener
listener, err := net.Listen("tcp4", ":1965")
if err != nil {
log.Fatal(err)
}
// add stdout logging to the request handler
handler := guslog.Requests(os.Stdout, nil)(inspectHandler)
// run the server
gemini.NewServer(context.Background(), tlsconf, listener, handler).Serve()
}
func envConfig() (string, string) {
certfile, ok := os.LookupEnv("SERVER_CERTIFICATE")
if !ok {
log.Fatal("missing SERVER_CERTIFICATE environment variable")
}
keyfile, ok := os.LookupEnv("SERVER_PRIVATEKEY")
if !ok {
log.Fatal("missing SERVER_PRIVATEKEY environment variable")
}
return certfile, keyfile
}
func inspectHandler(ctx context.Context, req *gemini.Request) *gemini.Response {
// build and return a ```-wrapped description of the connection TLS state
body := "```\n" + displayTLSState(req.TLSState) + "\n```"
return gemini.Success("text/gemini", bytes.NewBufferString(body))
}
func displayTLSState(state *tls.ConnectionState) string {
builder := &strings.Builder{}
builder.WriteString("Version: ")
builder.WriteString(map[uint16]string{
tls.VersionTLS10: "TLSv1.0",
tls.VersionTLS11: "TLSv1.1",
tls.VersionTLS12: "TLSv1.2",
tls.VersionTLS13: "TLSv1.3",
tls.VersionSSL30: "SSLv3",
}[state.Version])
builder.WriteString("\n")
builder.WriteString(fmt.Sprintf("Handshake complete: %t\n", state.HandshakeComplete))
builder.WriteString(fmt.Sprintf("Did resume: %t\n", state.DidResume))
builder.WriteString(fmt.Sprintf("Cipher suite: %x\n", state.CipherSuite))
builder.WriteString(fmt.Sprintf("Negotiated protocol: %q\n", state.NegotiatedProtocol))
builder.WriteString(fmt.Sprintf("Server name: %s\n", state.ServerName))
builder.WriteString(fmt.Sprintf("Certificates (%d)\n", len(state.PeerCertificates)))
for i, cert := range state.PeerCertificates {
builder.WriteString(fmt.Sprintf(" #%d: %s\n", i+1, fingerprint(cert)))
}
return builder.String()
}
func fingerprint(cert *x509.Certificate) []byte {
raw := md5.Sum(cert.Raw)
dst := make([]byte, hex.EncodedLen(len(raw)))
hex.Encode(dst, raw[:])
return dst
}
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