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package main
import (
"bytes"
"context"
"crypto/sha256"
"crypto/tls"
"crypto/x509"
"encoding/hex"
"fmt"
"log"
"os"
"strings"
"github.com/go-kit/log/level"
sr "tildegit.org/tjp/sliderule"
"tildegit.org/tjp/sliderule/gemini"
"tildegit.org/tjp/sliderule/logging"
)
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)
}
baseLog := logging.Base()
// add stdout logging to the request handler
handler := logging.LogRequests(level.Info(baseLog))(inspectHandler)
// run the server
server, err := gemini.NewServer(context.Background(), "localhost", "tcp4", ":1965", handler, baseLog, tlsconf)
if err != nil {
log.Fatal(err)
}
server.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
}
var inspectHandler = sr.HandlerFunc(func(ctx context.Context, req *sr.Request) *sr.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 := sha256.Sum256(cert.Raw)
dst := make([]byte, hex.EncodedLen(len(raw)))
hex.Encode(dst, raw[:])
return dst
}
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