CGI improvements

contrib/cgi/cgi.go

@@ -16,18 +16,24 @@ import (
 	"tildegit.org/tjp/gus/gemini"
 )
 
-func CGIHandler(pathPrefix, rootDir string) gemini.Handler {
-	rootDir = strings.TrimRight(rootDir, "/")
+// CGIDirectory runs any executable files relative to a root directory on the file system.
+//
+// It will also find and run any executables _part way_ through the path, so for example
+// a request for /foo/bar/baz can also run an executable found at /foo or  /foo/bar. In
+// such a case the PATH_INFO environment variable will include the remaining portion of
+// the URI path.
+func CGIDirectory(pathRoot, fsRoot string) gemini.Handler {
+	fsRoot = strings.TrimRight(fsRoot, "/")
 
 	return func(ctx context.Context, req *gemini.Request) *gemini.Response {
-		if !strings.HasPrefix(req.Path, pathPrefix) {
+		if !strings.HasPrefix(req.Path, pathRoot) {
 			return gemini.NotFound("Resource does not exist.")
 		}
 
-		path := req.Path[len(pathPrefix):]
+		path := req.Path[len(pathRoot):]
 		segments := strings.Split(strings.TrimLeft(path, "/"), "/")
 		for i := range append(segments, "") {
-			path := strings.Join(append([]string{rootDir}, segments[:i]...), "/")
+			path := strings.Join(append([]string{fsRoot}, segments[:i]...), "/")
 			path = strings.TrimRight(path, "/")
 			isDir, isExecutable, err := executableFile(path)
 			if err != nil {
@@ -35,11 +41,11 @@ func CGIHandler(pathPrefix, rootDir string) gemini.Handler {
 			}
 
 			if isExecutable {
-				pathInfo := ""
+				pathInfo := "/"
 				if len(segments) > i+1 {
-					pathInfo = strings.Join(segments[i+1:], "/")
+					pathInfo = strings.Join(segments[i:], "/")
 				}
-				return runCGI(ctx, req.Server, req, path, pathInfo)
+				return RunCGI(ctx, req, path, pathInfo)
 			}
 
 			if !isDir {
@@ -88,38 +94,46 @@ func isNotExistError(err error) bool {
 	return false
 }
 
-func runCGI(
+// RunCGI runs a specific program as a CGI script.
+func RunCGI(
 	ctx context.Context,
-	server *gemini.Server,
 	req *gemini.Request,
-	filePath string,
+	executable string,
 	pathInfo string,
 ) *gemini.Response {
-	pathSegments := strings.Split(filePath, "/")
+	pathSegments := strings.Split(executable, "/")
 
 	dirPath := "."
 	if len(pathSegments) > 1 {
 		dirPath = strings.Join(pathSegments[:len(pathSegments)-1], "/")
 	}
-	filePath = "./" + pathSegments[len(pathSegments)-1]
+	basename := pathSegments[len(pathSegments)-1]
 
-	cmd := exec.CommandContext(ctx, filePath)
-	cmd.Env = prepareCGIEnv(ctx, server, req, filePath, pathInfo)
+	scriptName := req.Path[:len(req.Path)-len(pathInfo)]
+	if strings.HasSuffix(scriptName, "/") {
+		scriptName = scriptName[:len(scriptName)-1]
+	}
+
+	cmd := exec.CommandContext(ctx, "./" + basename)
+	cmd.Env = prepareCGIEnv(ctx, req, scriptName, pathInfo)
 	cmd.Dir = dirPath
 
 	responseBuffer := &bytes.Buffer{}
 	cmd.Stdout = responseBuffer
 
+	fmt.Printf("running %s in %s\n", basename, dirPath)
 	if err := cmd.Run(); err != nil {
 		var exErr *exec.ExitError
 		if errors.As(err, &exErr) {
-			return gemini.CGIError(fmt.Sprintf("CGI returned with exit code %d", exErr.ExitCode()))
+			errMsg := fmt.Sprintf("CGI returned exit code %d", exErr.ExitCode())
+			return gemini.CGIError(errMsg)
 		}
 		return gemini.Failure(err)
 	}
 
 	response, err := gemini.ParseResponse(responseBuffer)
 	if err != nil {
+		fmt.Printf("response: %q\n", responseBuffer)
 		return gemini.Failure(err)
 	}
 	return response
@@ -127,7 +141,6 @@ func runCGI(
 
 func prepareCGIEnv(
 	ctx context.Context,
-	server *gemini.Server,
 	req *gemini.Request,
 	scriptName string,
 	pathInfo string,
@@ -136,7 +149,6 @@ func prepareCGIEnv(
 	if len(req.TLSState.PeerCertificates) > 0 {
 		authType = "Certificate"
 	}
-
 	environ := []string{
 		"AUTH_TYPE=" + authType,
 		"CONTENT_LENGTH=",
@@ -155,8 +167,8 @@ func prepareCGIEnv(
 		"REMOTE_HOST=",
 		"REMOTE_IDENT=",
 		"SCRIPT_NAME="+scriptName,
-		"SERVER_NAME="+server.Hostname(),
-		"SERVER_PORT="+server.Port(),
+		"SERVER_NAME="+req.Server.Hostname(),
+		"SERVER_PORT="+req.Server.Port(),
 		"SERVER_PROTOCOL=GEMINI",
 		"SERVER_SOFTWARE=GUS",
 	)
@@ -166,6 +178,10 @@ func prepareCGIEnv(
 		environ = append(
 			environ,
 			"TLS_CLIENT_HASH="+fingerprint(cert.Raw),
+			"TLS_CLIENT_ISSUER="+cert.Issuer.String(),
+			"TLS_CLIENT_ISSUER_CN="+cert.Issuer.CommonName,
+			"TLS_CLIENT_SUBJECT="+cert.Subject.String(),
+			"TLS_CLIENT_SUBJECT_CN="+cert.Subject.CommonName,
 		)
 	}
 

examples/cgi/cgi-bin/cowsay

@@ -2,8 +2,7 @@
 
 set -euo pipefail
 
-if [ -z "$QUERY_STRING" ];
-then
+if [[ -z "$QUERY_STRING" ]]; then
 	printf "10 Enter a phrase.\r\n"
 	exit 0
 fi

examples/cgi/cgi-bin/environ

@@ -0,0 +1,8 @@
+#!/usr/bin/env sh
+
+set -euo pipefail
+
+printf "20 text/gemini\r\n"
+echo "\`\`\`env(1) output"
+env
+echo "\`\`\`"

examples/cgi/main.go

@@ -21,7 +21,7 @@ func main() {
 	}
 
 	// make use of a CGI request handler
-	cgiHandler := cgi.CGIHandler("/cgi-bin", "cgi-bin")
+	cgiHandler := cgi.CGIDirectory("/cgi-bin", "./cgi-bin")
 
 	// add stdout logging to the request handler
 	handler := guslog.Requests(os.Stdout, nil)(cgiHandler)