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Diffstat (limited to 'src/net/http/cgi/host.go')
-rw-r--r--src/net/http/cgi/host.go377
1 files changed, 377 insertions, 0 deletions
diff --git a/src/net/http/cgi/host.go b/src/net/http/cgi/host.go
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+++ b/src/net/http/cgi/host.go
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+// 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.
+
+// This file implements the host side of CGI (being the webserver
+// parent process).
+
+// 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 (
+ "bufio"
+ "fmt"
+ "io"
+ "log"
+ "net/http"
+ "os"
+ "os/exec"
+ "path/filepath"
+ "regexp"
+ "runtime"
+ "strconv"
+ "strings"
+)
+
+var trailingPort = regexp.MustCompile(`:([0-9]+)$`)
+
+var osDefaultInheritEnv = map[string][]string{
+ "darwin": {"DYLD_LIBRARY_PATH"},
+ "freebsd": {"LD_LIBRARY_PATH"},
+ "hpux": {"LD_LIBRARY_PATH", "SHLIB_PATH"},
+ "irix": {"LD_LIBRARY_PATH", "LD_LIBRARYN32_PATH", "LD_LIBRARY64_PATH"},
+ "linux": {"LD_LIBRARY_PATH"},
+ "openbsd": {"LD_LIBRARY_PATH"},
+ "solaris": {"LD_LIBRARY_PATH", "LD_LIBRARY_PATH_32", "LD_LIBRARY_PATH_64"},
+ "windows": {"SystemRoot", "COMSPEC", "PATHEXT", "WINDIR"},
+}
+
+// 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 "/"
+
+ // Dir specifies the CGI executable's working directory.
+ // If Dir is empty, the base directory of Path is used.
+ // If Path has no base directory, the current working
+ // directory is used.
+ Dir string
+
+ Env []string // extra environment variables to set, if any, as "key=value"
+ InheritEnv []string // environment variables to inherit from host, as "key"
+ Logger *log.Logger // optional log for errors or nil to use log.Print
+ Args []string // optional arguments to pass to child process
+
+ // PathLocationHandler specifies the root http Handler that
+ // should handle internal redirects when the CGI process
+ // returns a Location header value starting with a "/", as
+ // specified in RFC 3875 ยง 6.3.2. This will likely be
+ // http.DefaultServeMux.
+ //
+ // If nil, a CGI response with a local URI path is instead sent
+ // back to the client and not redirected internally.
+ PathLocationHandler http.Handler
+}
+
+// removeLeadingDuplicates remove leading duplicate in environments.
+// It's possible to override environment like following.
+// cgi.Handler{
+// ...
+// Env: []string{"SCRIPT_FILENAME=foo.php"},
+// }
+func removeLeadingDuplicates(env []string) (ret []string) {
+ n := len(env)
+ for i := 0; i < n; i++ {
+ e := env[i]
+ s := strings.SplitN(e, "=", 2)[0]
+ found := false
+ for j := i + 1; j < n; j++ {
+ if s == strings.SplitN(env[j], "=", 2)[0] {
+ found = true
+ break
+ }
+ }
+ if !found {
+ ret = append(ret, e)
+ }
+ }
+ return
+}
+
+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,
+ "SERVER_PROTOCOL=HTTP/1.1",
+ "HTTP_HOST=" + req.Host,
+ "GATEWAY_INTERFACE=CGI/1.1",
+ "REQUEST_METHOD=" + req.Method,
+ "QUERY_STRING=" + req.URL.RawQuery,
+ "REQUEST_URI=" + req.URL.RequestURI(),
+ "PATH_INFO=" + pathInfo,
+ "SCRIPT_NAME=" + root,
+ "SCRIPT_FILENAME=" + h.Path,
+ "REMOTE_ADDR=" + req.RemoteAddr,
+ "REMOTE_HOST=" + req.RemoteAddr,
+ "SERVER_PORT=" + port,
+ }
+
+ if req.TLS != nil {
+ env = append(env, "HTTPS=on")
+ }
+
+ for k, v := range req.Header {
+ k = strings.Map(upperCaseAndUnderscore, k)
+ joinStr := ", "
+ if k == "COOKIE" {
+ joinStr = "; "
+ }
+ env = append(env, "HTTP_"+k+"="+strings.Join(v, joinStr))
+ }
+
+ 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...)
+ }
+
+ envPath := os.Getenv("PATH")
+ if envPath == "" {
+ envPath = "/bin:/usr/bin:/usr/ucb:/usr/bsd:/usr/local/bin"
+ }
+ env = append(env, "PATH="+envPath)
+
+ for _, e := range h.InheritEnv {
+ if v := os.Getenv(e); v != "" {
+ env = append(env, e+"="+v)
+ }
+ }
+
+ for _, e := range osDefaultInheritEnv[runtime.GOOS] {
+ if v := os.Getenv(e); v != "" {
+ env = append(env, e+"="+v)
+ }
+ }
+
+ env = removeLeadingDuplicates(env)
+
+ var cwd, path string
+ if h.Dir != "" {
+ path = h.Path
+ cwd = h.Dir
+ } else {
+ cwd, path = filepath.Split(h.Path)
+ }
+ if cwd == "" {
+ cwd = "."
+ }
+
+ internalError := func(err error) {
+ rw.WriteHeader(http.StatusInternalServerError)
+ h.printf("CGI error: %v", err)
+ }
+
+ cmd := &exec.Cmd{
+ Path: path,
+ Args: append([]string{h.Path}, h.Args...),
+ Dir: cwd,
+ Env: env,
+ Stderr: os.Stderr, // for now
+ }
+ if req.ContentLength != 0 {
+ cmd.Stdin = req.Body
+ }
+ stdoutRead, err := cmd.StdoutPipe()
+ if err != nil {
+ internalError(err)
+ return
+ }
+
+ err = cmd.Start()
+ if err != nil {
+ internalError(err)
+ return
+ }
+ if hook := testHookStartProcess; hook != nil {
+ hook(cmd.Process)
+ }
+ defer cmd.Wait()
+ defer stdoutRead.Close()
+
+ linebody := bufio.NewReaderSize(stdoutRead, 1024)
+ headers := make(http.Header)
+ statusCode := 0
+ headerLines := 0
+ sawBlankLine := false
+ for {
+ line, isPrefix, err := linebody.ReadLine()
+ if isPrefix {
+ rw.WriteHeader(http.StatusInternalServerError)
+ h.printf("cgi: long header line from subprocess.")
+ return
+ }
+ if err == io.EOF {
+ break
+ }
+ if err != nil {
+ rw.WriteHeader(http.StatusInternalServerError)
+ h.printf("cgi: error reading headers: %v", err)
+ return
+ }
+ if len(line) == 0 {
+ sawBlankLine = true
+ break
+ }
+ headerLines++
+ parts := strings.SplitN(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.Add(header, val)
+ }
+ }
+ if headerLines == 0 || !sawBlankLine {
+ rw.WriteHeader(http.StatusInternalServerError)
+ h.printf("cgi: no headers")
+ return
+ }
+
+ if loc := headers.Get("Location"); loc != "" {
+ if strings.HasPrefix(loc, "/") && h.PathLocationHandler != nil {
+ h.handleInternalRedirect(rw, req, loc)
+ return
+ }
+ if statusCode == 0 {
+ statusCode = http.StatusFound
+ }
+ }
+
+ if statusCode == 0 && headers.Get("Content-Type") == "" {
+ rw.WriteHeader(http.StatusInternalServerError)
+ h.printf("cgi: missing required Content-Type in headers")
+ return
+ }
+
+ if statusCode == 0 {
+ statusCode = http.StatusOK
+ }
+
+ // Copy headers to rw's headers, after we've decided not to
+ // go into handleInternalRedirect, which won't want its rw
+ // headers to have been touched.
+ for k, vv := range headers {
+ for _, v := range vv {
+ rw.Header().Add(k, v)
+ }
+ }
+
+ rw.WriteHeader(statusCode)
+
+ _, err = io.Copy(rw, linebody)
+ if err != nil {
+ h.printf("cgi: copy error: %v", err)
+ // And kill the child CGI process so we don't hang on
+ // the deferred cmd.Wait above if the error was just
+ // the client (rw) going away. If it was a read error
+ // (because the child died itself), then the extra
+ // kill of an already-dead process is harmless (the PID
+ // won't be reused until the Wait above).
+ cmd.Process.Kill()
+ }
+}
+
+func (h *Handler) printf(format string, v ...interface{}) {
+ if h.Logger != nil {
+ h.Logger.Printf(format, v...)
+ } else {
+ log.Printf(format, v...)
+ }
+}
+
+func (h *Handler) handleInternalRedirect(rw http.ResponseWriter, req *http.Request, path string) {
+ url, err := req.URL.Parse(path)
+ if err != nil {
+ rw.WriteHeader(http.StatusInternalServerError)
+ h.printf("cgi: error resolving local URI path %q: %v", path, err)
+ return
+ }
+ // TODO: RFC 3875 isn't clear if only GET is supported, but it
+ // suggests so: "Note that any message-body attached to the
+ // request (such as for a POST request) may not be available
+ // to the resource that is the target of the redirect." We
+ // should do some tests against Apache to see how it handles
+ // POST, HEAD, etc. Does the internal redirect get the same
+ // method or just GET? What about incoming headers?
+ // (e.g. Cookies) Which headers, if any, are copied into the
+ // second request?
+ newReq := &http.Request{
+ Method: "GET",
+ URL: url,
+ Proto: "HTTP/1.1",
+ ProtoMajor: 1,
+ ProtoMinor: 1,
+ Header: make(http.Header),
+ Host: url.Host,
+ RemoteAddr: req.RemoteAddr,
+ TLS: req.TLS,
+ }
+ h.PathLocationHandler.ServeHTTP(rw, newReq)
+}
+
+func upperCaseAndUnderscore(r rune) rune {
+ switch {
+ case r >= 'a' && r <= 'z':
+ return r - ('a' - 'A')
+ case r == '-':
+ return '_'
+ case r == '=':
+ // 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 r
+}
+
+var testHookStartProcess func(*os.Process) // nil except for some tests