services/arv-git-httpd/git_handler.go

   1 // Copyright (C) The Arvados Authors. All rights reserved.
   2 //
   3 // SPDX-License-Identifier: AGPL-3.0
   4
   5 package main
   6
   7 import (
   8         "log"
   9         "net"
  10         "net/http"
  11         "net/http/cgi"
  12         "os"
  13
  14         "git.arvados.org/arvados.git/sdk/go/arvados"
  15 )
  16
  17 // gitHandler is an http.Handler that invokes git-http-backend (or
  18 // whatever backend is configured) via CGI, with appropriate
  19 // environment variables in place for git-http-backend or
  20 // gitolite-shell.
  21 type gitHandler struct {
  22         cgi.Handler
  23 }
  24
  25 func newGitHandler(cluster *arvados.Cluster) http.Handler {
  26         const glBypass = "GL_BYPASS_ACCESS_CHECKS"
  27         const glHome = "GITOLITE_HTTP_HOME"
  28         var env []string
  29         path := os.Getenv("PATH")
  30         if cluster.Git.GitoliteHome != "" {
  31                 env = append(env,
  32                         glHome+"="+cluster.Git.GitoliteHome,
  33                         glBypass+"=1")
  34                 path = path + ":" + cluster.Git.GitoliteHome + "/bin"
  35         } else if home, bypass := os.Getenv(glHome), os.Getenv(glBypass); home != "" || bypass != "" {
  36                 env = append(env, glHome+"="+home, glBypass+"="+bypass)
  37                 log.Printf("DEPRECATED: Passing through %s and %s environment variables. Use GitoliteHome configuration instead.", glHome, glBypass)
  38         }
  39
  40         var listen arvados.URL
  41         for listen = range cluster.Services.GitHTTP.InternalURLs {
  42                 break
  43         }
  44         env = append(env,
  45                 "GIT_PROJECT_ROOT="+cluster.Git.Repositories,
  46                 "GIT_HTTP_EXPORT_ALL=",
  47                 "SERVER_ADDR="+listen.Host,
  48                 "PATH="+path)
  49         return &gitHandler{
  50                 Handler: cgi.Handler{
  51                         Path: cluster.Git.GitCommand,
  52                         Dir:  cluster.Git.Repositories,
  53                         Env:  env,
  54                         Args: []string{"http-backend"},
  55                 },
  56         }
  57 }
  58
  59 func (h *gitHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
  60         remoteHost, remotePort, err := net.SplitHostPort(r.RemoteAddr)
  61         if err != nil {
  62                 log.Printf("Internal error: SplitHostPort(r.RemoteAddr==%q): %s", r.RemoteAddr, err)
  63                 w.WriteHeader(http.StatusInternalServerError)
  64                 return
  65         }
  66
  67         // Copy the wrapped cgi.Handler, so these request-specific
  68         // variables don't leak into the next request.
  69         handlerCopy := h.Handler
  70         handlerCopy.Env = append(handlerCopy.Env,
  71                 // In Go1.5 we can skip this, net/http/cgi will do it for us:
  72                 "REMOTE_HOST="+remoteHost,
  73                 "REMOTE_ADDR="+remoteHost,
  74                 "REMOTE_PORT="+remotePort,
  75                 // Ideally this would be a real username:
  76                 "REMOTE_USER="+r.RemoteAddr,
  77         )
  78         handlerCopy.ServeHTTP(w, r)
  79 }