Support requesting user input

Resolves #3.

CONFIGURATION.md

@@ -62,24 +62,46 @@ Fixed string paths will match with and without a trailing slash.
 
 When accessing a directory the file `index.gemini` or `index.gmi` is served.
 
-### Path attributes
+### Path
 
-#### Root
+#### Resources
+
+One resource must be defined for each path.
+
+##### Root
 
 Serve static files from specified root directory.
 
-Directory listing may be enabled by adding `listdirectory: true`.
+##### Proxy
-
-#### Proxy
 
 Forward request to Gemini server at specified URL.
 
 Use the pseudo-scheme `gemini-insecure://` to disable certificate verification.
 
-#### Command
+##### Command
 
 Serve output of system command.
 
+When input is requested from the user, it is available as a pseudo-variable
+`$USERINPUT` which does not require surrounding quotes. It may be used as an
+argument to the command, otherwise user input is passed via standard input.
+
+#### Attributes
+
+Any number of attributes may be defined for a path.
+
+##### ListDirectory
+
+Directory listing may be enabled by adding `listdirectory: true`.
+
+##### Input
+
+Request text input from user.
+
+##### SensitiveInput
+
+Request sensitive text input from the user. Text will not be shown as it is entered.
+
 # Example config.yaml
 
 ```yaml

README.md

@@ -10,6 +10,7 @@ Breaking changes may be made.
 ## Features
 
 - Serve static files
+  - Directory listing may be enabled
 - Serve the output of system commands
 - Reverse proxy requests
 

config.go

@@ -22,6 +22,12 @@ type pathConfig struct {
 	Proxy   string
 	Command string
 
+	// Request input
+	Input string
+
+	// Request sensitive input
+	SensitiveInput string
+
 	// List directory entries
 	ListDirectory bool
 

server.go

@@ -51,7 +51,11 @@ func writeStatus(c net.Conn, code int) {
 }
 
 func serveDirectory(c net.Conn, request *url.URL, dirPath string) {
-	var files []os.FileInfo
+	var (
+		files    []os.FileInfo
+		numDirs  int
+		numFiles int
+	)
 	err := filepath.Walk(dirPath, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
 			return err
@@ -59,6 +63,11 @@ func serveDirectory(c net.Conn, request *url.URL, dirPath string) {
 			return nil
 		}
 		files = append(files, info)
+		if info.IsDir() || info.Mode()&os.ModeSymlink != 0 {
+			numDirs++
+		} else {
+			numFiles++
+		}
 		if info.IsDir() {
 			return filepath.SkipDir
 		}
@@ -80,7 +89,27 @@ func serveDirectory(c net.Conn, request *url.URL, dirPath string) {
 
 	writeHeader(c, gemini.StatusSuccess, "text/gemini; charset=utf-8")
 
-	c.Write([]byte("# " + request.Path + "\r\n\r\n"))
+	fmt.Fprintf(c, "# %s\r\n", request.Path)
+	if numDirs > 0 || numFiles > 0 {
+		if numDirs > 0 {
+			if numDirs == 1 {
+				c.Write([]byte("1 directory"))
+			} else {
+				fmt.Fprintf(c, "%d directories", numDirs)
+			}
+		}
+		if numFiles > 0 {
+			if numDirs > 0 {
+				c.Write([]byte(" and "))
+			}
+			if numDirs == 1 {
+				c.Write([]byte("1 file"))
+			} else {
+				fmt.Fprintf(c, "%d files", numFiles)
+			}
+		}
+		c.Write([]byte("\r\n\n"))
+	}
 
 	if request.Path != "/" {
 		c.Write([]byte("=> ../ ../\r\n\r\n"))
@@ -212,7 +241,7 @@ func serveProxy(c net.Conn, requestData, proxyURL string) {
 	}
 }
 
-func serveCommand(c net.Conn, command []string) {
+func serveCommand(c net.Conn, userInput string, command []string) {
 	var args []string
 	if len(command) > 0 {
 		args = command[1:]
@@ -220,6 +249,9 @@ func serveCommand(c net.Conn, command []string) {
 	cmd := exec.Command(command[0], args...)
 
 	var buf bytes.Buffer
+	if userInput != "" {
+		cmd.Stdin = strings.NewReader(userInput + "\n")
+	}
 	cmd.Stdout = &buf
 	cmd.Stderr = &buf
 
@@ -253,6 +285,17 @@ func scanCRLF(data []byte, atEOF bool) (advance int, token []byte, err error) {
 	return 0, nil, nil
 }
 
+func replaceWithUserInput(command []string, userInput string) []string {
+	newCommand := make([]string, len(command))
+	copy(newCommand, command)
+	for i, piece := range newCommand {
+		if strings.Contains(piece, "$USERINPUT") {
+			newCommand[i] = strings.ReplaceAll(piece, "$USERINPUT", userInput)
+		}
+	}
+	return newCommand
+}
+
 func handleConn(c net.Conn) {
 	if verbose {
 		t := time.Now()
@@ -329,6 +372,11 @@ func handleConn(c net.Conn) {
 	if strippedPath[0] == '/' {
 		strippedPath = strippedPath[1:]
 	}
+	requestQuery, err := url.QueryUnescape(request.RawQuery)
+	if err != nil {
+		writeStatus(c, gemini.StatusBadRequest)
+		return
+	}
 
 	var matchedHost bool
 	for hostname := range config.Hosts {
@@ -338,22 +386,53 @@ func handleConn(c net.Conn) {
 		matchedHost = true
 
 		for _, serve := range config.Hosts[hostname] {
-			if serve.r != nil && serve.r.Match(pathBytes) {
+			matchedRegexp := serve.r != nil && serve.r.Match(pathBytes)
+			matchedPrefix := serve.r == nil && strings.HasPrefix(request.Path, serve.Path)
+			if !matchedRegexp && !matchedPrefix {
+				continue
+			}
+
+			requireInput := serve.Input != "" || serve.SensitiveInput != ""
+			if requestQuery == "" && requireInput {
+				if serve.Input != "" {
+					writeHeader(c, gemini.StatusInput, serve.Input)
+					return
+				} else if serve.SensitiveInput != "" {
+					writeHeader(c, gemini.StatusSensitiveInput, serve.SensitiveInput)
+					return
+				}
+			}
+
+			if matchedRegexp {
 				if serve.Proxy != "" {
 					serveProxy(c, requestData, serve.Proxy)
 					return
 				} else if serve.cmd != nil {
-					serveCommand(c, serve.cmd)
+					if requireInput {
+						newCommand := replaceWithUserInput(serve.cmd, requestQuery)
+						if newCommand != nil {
+							serveCommand(c, "", newCommand)
+							return
+						}
+					}
+					serveCommand(c, requestQuery, serve.cmd)
 					return
 				}
 				serveFile(c, request, requestData, path.Join(serve.Root, strippedPath), serve.ListDirectory)
 				return
-			} else if serve.r == nil && strings.HasPrefix(request.Path, serve.Path) {
+			} else if matchedPrefix {
 				if serve.Proxy != "" {
 					serveProxy(c, requestData, serve.Proxy)
 					return
 				} else if serve.cmd != nil {
-					serveCommand(c, serve.cmd)
+					if requireInput {
+						newCommand := replaceWithUserInput(serve.cmd, requestQuery)
+						if newCommand != nil {
+							serveCommand(c, "", newCommand)
+							return
+						}
+					}
+					serveCommand(c, requestQuery, serve.cmd)
 					return
 				}
 				filePath := request.Path[len(serve.Path):]