1 files changed, 95 insertions, 0 deletions
diff --git a/examples/inspectls/main.go b/examples/inspectls/main.go
new file mode 100644
index 0000000..a315e40
--- /dev/null
+++ b/examples/inspectls/main.go
@@ -0,0 +1,95 @@
+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
+}