First working prototype

This commit contains the first working prototype.

.gitignore

@@ -5,6 +5,7 @@
 *.dll
 *.so
 *.dylib
+/orion
 
 # Test binary, built with `go test -c`
 *.test
@@ -13,5 +14,8 @@
 *.out
 
 # Dependency directories (remove the comment below to include it)
-# vendor/
+vendor/
 
+# Certificates
+*.crt
+*.key

Makefile

@@ -0,0 +1,10 @@
+default: all
+
+all: orion
+
+orion: cmd/orion/orion.go cmd/orion/gemini.go cmd/orion/config.go
+	go build -o $@ $^
+
+cert:
+	openssl genrsa -out orion.key 2048
+	openssl req -x509 -nodes -days 3650 -key orion.key -out orion.crt

cmd/orion/config.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+type Config struct {
+	Hostname   string // Server hostname
+	CertFile   string // Certificate filename
+	Keyfile    string // Key file
+	BindAddr   string // Optional binding address
+	ContentDir string // Gemini content directory to serve
+}
+
+func (cf *Config) SetDefaults() {
+	cf.Hostname = "localhost"
+	cf.CertFile = "orion.crt"
+	cf.Keyfile = "orion.key"
+	cf.BindAddr = ":1967"
+	cf.ContentDir = "gemini/"
+}
+
+func (cf *Config) LoadConfigFile(filename string) error {
+	file, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	scanner := bufio.NewScanner(file)
+	scanner.Split(bufio.ScanLines)
+	lineCount := 0
+	for scanner.Scan() {
+		lineCount++
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" || line[0] == '#' {
+			continue
+		}
+		i := strings.Index(line, "=")
+		if i < 0 {
+			return fmt.Errorf("Syntax error in line %d", lineCount)
+		}
+		name, value := strings.ToLower(strings.TrimSpace(line[:i])), strings.TrimSpace(line[i+1:])
+		if name == "hostname" {
+			cf.Hostname = value
+		} else if name == "certfile" {
+			cf.CertFile = value
+		} else if name == "keyfile" {
+			cf.Keyfile = value
+		} else if name == "bind" {
+			cf.BindAddr = value
+		} else if name == "contentdir" {
+			cf.ContentDir = value
+		} else {
+			return fmt.Errorf("Unknown setting in line %d", lineCount)
+		}
+
+	}
+	return file.Close()
+}

cmd/orion/gemini.go

@@ -4,10 +4,12 @@ import (
 	"crypto/tls"
 	"fmt"
 	"io"
+	"net"
 	"net/url"
 	"os"
 	"path/filepath"
 	"strings"
+	"unicode"
 )
 
 const (
@@ -20,18 +22,20 @@ const (
 
 type GeminiHandler func(path string, conn io.ReadWriteCloser) error
 
-func ServerGemini(hostname string, bindAddr string, cert tls.Certificate, handler GeminiHandler) error {
-	// TLS session
-	cfg := &tls.Config{Certificates: []tls.Certificate{cert}, ServerName: hostname, MinVersion: tls.VersionTLS12}
-	listener, err := tls.Listen("tcp", bindAddr, cfg)
-	if err != nil {
-		return err
-	}
+type GeminiServer struct {
+	server net.Listener
+}
+
+func (srv *GeminiServer) Close() error {
+	return srv.server.Close()
+}
+
+func (srv *GeminiServer) Loop(handler GeminiHandler) error {
 	for {
-		conn, err := listener.Accept()
+		conn, err := srv.server.Accept()
 		if err != nil {
 			if err == io.EOF {
-				break
+				return nil
 			} else {
 				fmt.Fprintf(os.Stderr, "accept error: %s\n", err)
 				continue
@@ -39,34 +43,68 @@ func ServerGemini(hostname string, bindAddr string, cert tls.Certificate, handle
 		}
 		go handleConnection(conn, handler)
 	}
-	return nil
 }
 
-func sendResponse(conn io.ReadWriteCloser, statusCode int, meta string) error {
+func CreateGeminiServer(hostname string, bindAddr string, cert tls.Certificate) (GeminiServer, error) {
+	var srv GeminiServer
+	var err error
+	// TLS session
+	cfg := &tls.Config{Certificates: []tls.Certificate{cert}, ServerName: hostname, MinVersion: tls.VersionTLS12}
+	srv.server, err = tls.Listen("tcp", bindAddr, cfg)
+	return srv, err
+}
+
+func SendResponse(conn io.WriteCloser, statusCode int, meta string) error {
 	header := fmt.Sprintf("%d %s\r\n", statusCode, meta)
 	_, err := conn.Write([]byte(header))
 	return err
 }
 
+func SendContent(conn io.WriteCloser, content []byte, meta string) error {
+	if err := SendResponse(conn, StatusSuccess, meta); err != nil {
+		return err
+	}
+	_, err := conn.Write(content)
+	return err
+}
+
+// sanitize an input path, ignores all characters that are not alphanumeric or a path separator /
+func sanitizePath(path string) string {
+	var ret string
+	chars := []rune(path)
+	for _, c := range chars {
+		if unicode.IsLetter(c) || unicode.IsDigit(c) || c == '/' || c == '.' {
+			ret += string(c)
+		}
+	}
+	return ret
+}
+
 func handleConnection(conn io.ReadWriteCloser, handler GeminiHandler) error {
 	defer conn.Close()
 
+	// 1500 matches the typical MTU size
 	buf := make([]byte, 1500)
 	n, err := conn.Read(buf)
 	if err != nil {
 		return err
 	}
 	if n > 1024 {
-		return sendResponse(conn, statusPermanentFailure, "Request exceeds maximum permitted length")
+		return SendResponse(conn, StatusPermanentFailure, "Request exceeds maximum permitted length")
 	}
 	// Parse incoming request URL.
-	reqURL, err := url.Parse(string(buf))
+	surl := strings.TrimSpace(string(buf[:n]))
+	reqURL, err := url.Parse(surl)
 	if err != nil {
-		return sendResponse(conn, statusPermanentFailure, "URL incorrectly formatted")
+		return SendResponse(conn, StatusPermanentFailure, "URL incorrectly formatted")
 	}
 
-	// If the URL ends with a '/' character, assume that the user wants the index.gmi
-	// file in the corresponding directory.
+	// Do not allow traverse paths
+	if strings.Contains(reqURL.Path, "..") {
+		return SendResponse(conn, StatusPermanentFailure, "Path traverse not supported by this server")
+	}
+
+	// If the URL ends with a '/', serve the index.gmi
 	var reqPath string
 	if strings.HasSuffix(reqURL.Path, "/") || reqURL.Path == "" {
 		reqPath = filepath.Join(reqURL.Path, "index.gmi")
@@ -74,6 +112,7 @@ func handleConnection(conn io.ReadWriteCloser, handler GeminiHandler) error {
 		reqPath = reqURL.Path
 	}
 
-	cleanPath := filepath.Clean(reqPath)
+	cleanPath := sanitizePath(filepath.Clean(reqPath))
+
 	return handler(cleanPath, conn)
 }

cmd/orion/orion.go

@@ -1,5 +1,150 @@
 package main
 
-func main() {
+import (
+	"crypto/tls"
+	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"os/signal"
+	"strings"
+	"syscall"
+)
 
+var config Config
+
+func DirectoryExists(dirpath string) bool {
+	stat, err := os.Stat(dirpath)
+	if err != nil {
+		return false
+	}
+	return stat.IsDir()
+}
+
+func FileExists(dirpath string) bool {
+	// Quick and dirty check
+	_, err := os.Stat(dirpath)
+	return err == nil
+}
+
+// try to load the given config file. Ignores the file if not present. Exits the program on failure
+func tryLoadConfig(filename string) {
+	if FileExists(filename) {
+		if err := config.LoadConfigFile(filename); err != nil {
+			fmt.Fprintf(os.Stderr, "Error loading %s: %s\n", filename, err)
+			os.Exit(1)
+		}
+	}
+}
+
+func main() {
+	config.SetDefaults()
+
+	customConfigFile := flag.String("config", "", "Configuration file")
+	flag.Parse()
+
+	if *customConfigFile != "" {
+		if err := config.LoadConfigFile(*customConfigFile); err != nil {
+			fmt.Fprintf(os.Stderr, "Error loading %s: %s\n", *customConfigFile, err)
+			os.Exit(1)
+		}
+	} else {
+		// Load default configuration files, if existing
+		tryLoadConfig("/etc/orion.conf")
+		tryLoadConfig("./orion.conf")
+	}
+
+	// Make the content dir absolute
+	if !strings.HasPrefix(config.ContentDir, "/") {
+		workDir, err := os.Getwd()
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "error getting the work directory: %s\n", err)
+			os.Exit(1)
+		}
+		config.ContentDir = workDir + "/" + config.ContentDir
+	}
+	// Terminate content directory with a '/'
+	if !strings.HasSuffix(config.ContentDir, "/") {
+		config.ContentDir += "/"
+	}
+
+	// Check settings
+	if !FileExists(config.Keyfile) {
+		fmt.Fprintf(os.Stderr, "Server key file not found: %s\n", config.Keyfile)
+		os.Exit(1)
+	}
+	if !FileExists(config.CertFile) {
+		fmt.Fprintf(os.Stderr, "Certificate file not found: %s\n", config.CertFile)
+		os.Exit(1)
+	}
+
+	// Content warnings should point user at wrong configuration early in the program
+	if !DirectoryExists(config.ContentDir) {
+		fmt.Fprintf(os.Stderr, "WARNING: Content directory does not exist: %s\n", config.ContentDir)
+	} else {
+		if !FileExists(config.ContentDir + "/index.gmi") {
+			fmt.Fprintf(os.Stderr, "WARNING: index.gmi does not exists in content directory: %s/index.gmi\n", config.ContentDir)
+		}
+	}
+
+	// Setup gemini server
+	cert, err := tls.LoadX509KeyPair(config.CertFile, config.Keyfile)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "certificate error: %s\n", err)
+		os.Exit(1)
+	}
+	server, err := CreateGeminiServer(config.Hostname, config.BindAddr, cert)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "server error: %s\n", err)
+		os.Exit(1)
+	}
+
+	// Termination signal handling (SIGINT or SIGTERM)
+	sigs := make(chan os.Signal, 1)
+	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
+	go func() {
+		sig := <-sigs
+		fmt.Println(sig)
+		os.Exit(2)
+	}()
+
+	log.Printf("Serving %s on %s\n", config.Hostname, config.BindAddr)
+	if err := server.Loop(geminiHandle); err != nil {
+		fmt.Fprintf(os.Stderr, "server loop error: %s\n", err)
+		os.Exit(5)
+	}
+}
+
+func geminiHandle(path string, conn io.ReadWriteCloser) error {
+	log.Printf("GET %s", path)
+	if f, err := os.OpenFile(config.ContentDir+"/"+path, os.O_RDONLY, 0400); err != nil {
+		if err == os.ErrNotExist {
+			log.Printf("ERR: File not found: %s", path)
+			return SendResponse(conn, StatusPermanentFailure, "Resource not found")
+		} else {
+			log.Printf("ERR: File error: %s", err)
+			return SendResponse(conn, StatusPermanentFailure, "Resource error")
+		}
+	} else {
+		defer f.Close()
+
+		// TODO: Replace by proper stream handling. For now it's good because I only serve small files
+		content, err := ioutil.ReadAll(f)
+		if err != nil {
+			log.Printf("ERR: File read error: %s", err)
+			return SendResponse(conn, StatusPermanentFailure, "Resource error")
+		}
+
+		// Get MIME
+		var mime string
+		if strings.HasSuffix(path, ".gmi") {
+			mime = "text/gemini; lang=en; charset=utf-8"
+		} else {
+			mime = http.DetectContentType(content)
+		}
+		return SendContent(conn, content, mime)
+	}
 }

go.mod

@@ -0,0 +1,3 @@
+module orion/m/v2
+
+go 1.17

orion.conf

@@ -0,0 +1,15 @@
+## orion configuration file example
+## Please modify this file to your needs
+## lines starting with a '#' are comments and will be ignored
+
+# Server hostname and listen address
+# Bind ':1965' will bind to any IP address and port 1965
+Hostname = localhost
+Bind = :1965
+
+# TLS certificate
+Certfile = orion.crt
+Keyfile = orion.key
+
+# Content directory
+ContentDir = ./gemini/