1 files changed, 201 insertions, 0 deletions
diff --git a/src/pkg/http/cgi/cgi.go b/src/pkg/http/cgi/cgi.go
new file mode 100644
index 000000000..dba59efa2
--- /dev/null
+++ b/src/pkg/http/cgi/cgi.go
@@ -0,0 +1,201 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package cgi implements CGI (Common Gateway Interface) as specified
+// in RFC 3875.
+//
+// Note that using CGI means starting a new process to handle each
+// request, which is typically less efficient than using a
+// long-running server.  This package is intended primarily for
+// compatibility with existing systems.
+package cgi
+
+import (
+	"encoding/line"
+	"exec"
+	"fmt"
+	"http"
+	"io"
+	"log"
+	"os"
+	"path"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var trailingPort = regexp.MustCompile(`:([0-9]+)$`)
+
+// Handler runs an executable in a subprocess with a CGI environment.
+type Handler struct {
+	Path   string      // path to the CGI executable
+	Root   string      // root URI prefix of handler or empty for "/"
+	Env    []string    // extra environment variables to set, if any
+	Logger *log.Logger // optional log for errors or nil to use log.Print
+}
+
+func (h *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
+	root := h.Root
+	if root == "" {
+		root = "/"
+	}
+
+	if len(req.TransferEncoding) > 0 && req.TransferEncoding[0] == "chunked" {
+		rw.WriteHeader(http.StatusBadRequest)
+		rw.Write([]byte("Chunked request bodies are not supported by CGI."))
+		return
+	}
+
+	pathInfo := req.URL.Path
+	if root != "/" && strings.HasPrefix(pathInfo, root) {
+		pathInfo = pathInfo[len(root):]
+	}
+
+	port := "80"
+	if matches := trailingPort.FindStringSubmatch(req.Host); len(matches) != 0 {
+		port = matches[1]
+	}
+
+	env := []string{
+		"SERVER_SOFTWARE=go",
+		"SERVER_NAME=" + req.Host,
+		"HTTP_HOST=" + req.Host,
+		"GATEWAY_INTERFACE=CGI/1.1",
+		"REQUEST_METHOD=" + req.Method,
+		"QUERY_STRING=" + req.URL.RawQuery,
+		"REQUEST_URI=" + req.URL.RawPath,
+		"PATH_INFO=" + pathInfo,
+		"SCRIPT_NAME=" + root,
+		"SCRIPT_FILENAME=" + h.Path,
+		"REMOTE_ADDR=" + rw.RemoteAddr(),
+		"REMOTE_HOST=" + rw.RemoteAddr(),
+		"SERVER_PORT=" + port,
+	}
+
+	for k, _ := range req.Header {
+		k = strings.Map(upperCaseAndUnderscore, k)
+		env = append(env, "HTTP_"+k+"="+req.Header.Get(k))
+	}
+
+	if req.ContentLength > 0 {
+		env = append(env, fmt.Sprintf("CONTENT_LENGTH=%d", req.ContentLength))
+	}
+	if ctype := req.Header.Get("Content-Type"); ctype != "" {
+		env = append(env, "CONTENT_TYPE="+ctype)
+	}
+
+	if h.Env != nil {
+		env = append(env, h.Env...)
+	}
+
+	// TODO: use filepath instead of path when available
+	cwd, pathBase := path.Split(h.Path)
+	if cwd == "" {
+		cwd = "."
+	}
+
+	cmd, err := exec.Run(
+		pathBase,
+		[]string{h.Path},
+		env,
+		cwd,
+		exec.Pipe,        // stdin
+		exec.Pipe,        // stdout
+		exec.PassThrough, // stderr (for now)
+	)
+	if err != nil {
+		rw.WriteHeader(http.StatusInternalServerError)
+		h.printf("CGI error: %v", err)
+		return
+	}
+	defer func() {
+		cmd.Stdin.Close()
+		cmd.Stdout.Close()
+		cmd.Wait(0) // no zombies
+	}()
+
+	if req.ContentLength != 0 {
+		go io.Copy(cmd.Stdin, req.Body)
+	}
+
+	linebody := line.NewReader(cmd.Stdout, 1024)
+	headers := make(map[string]string)
+	statusCode := http.StatusOK
+	for {
+		line, isPrefix, err := linebody.ReadLine()
+		if isPrefix {
+			rw.WriteHeader(http.StatusInternalServerError)
+			h.printf("CGI: long header line from subprocess.")
+			return
+		}
+		if err == os.EOF {
+			break
+		}
+		if err != nil {
+			rw.WriteHeader(http.StatusInternalServerError)
+			h.printf("CGI: error reading headers: %v", err)
+			return
+		}
+		if len(line) == 0 {
+			break
+		}
+		parts := strings.Split(string(line), ":", 2)
+		if len(parts) < 2 {
+			h.printf("CGI: bogus header line: %s", string(line))
+			continue
+		}
+		header, val := parts[0], parts[1]
+		header = strings.TrimSpace(header)
+		val = strings.TrimSpace(val)
+		switch {
+		case header == "Status":
+			if len(val) < 3 {
+				h.printf("CGI: bogus status (short): %q", val)
+				return
+			}
+			code, err := strconv.Atoi(val[0:3])
+			if err != nil {
+				h.printf("CGI: bogus status: %q", val)
+				h.printf("CGI: line was %q", line)
+				return
+			}
+			statusCode = code
+		default:
+			headers[header] = val
+		}
+	}
+	for h, v := range headers {
+		rw.SetHeader(h, v)
+	}
+	rw.WriteHeader(statusCode)
+
+	_, err = io.Copy(rw, linebody)
+	if err != nil {
+		h.printf("CGI: copy error: %v", err)
+	}
+}
+
+func (h *Handler) printf(format string, v ...interface{}) {
+	if h.Logger != nil {
+		h.Logger.Printf(format, v...)
+	} else {
+		log.Printf(format, v...)
+	}
+}
+
+func upperCaseAndUnderscore(rune int) int {
+	switch {
+	case rune >= 'a' && rune <= 'z':
+		return rune - ('a' - 'A')
+	case rune == '-':
+		return '_'
+	case rune == '=':
+		// Maybe not part of the CGI 'spec' but would mess up
+		// the environment in any case, as Go represents the
+		// environment as a slice of "key=value" strings.
+		return '_'
+	}
+	// TODO: other transformations in spec or practice?
+	return rune
+}