services/githttpd/git_handler.go

   1 // Copyright (C) The Arvados Authors. All rights reserved.
   2 //
   3 // SPDX-License-Identifier: AGPL-3.0
   4
   5 package githttpd
   6
   7 import (
   8         "context"
   9         "net"
  10         "net/http"
  11         "net/http/cgi"
  12         "os"
  13
  14         "git.arvados.org/arvados.git/sdk/go/arvados"
  15         "git.arvados.org/arvados.git/sdk/go/ctxlog"
  16 )
  17
  18 // gitHandler is an http.Handler that invokes git-http-backend (or
  19 // whatever backend is configured) via CGI, with appropriate
  20 // environment variables in place for git-http-backend or
  21 // gitolite-shell.
  22 type gitHandler struct {
  23         cgi.Handler
  24 }
  25
  26 func newGitHandler(ctx context.Context, cluster *arvados.Cluster) http.Handler {
  27         const glBypass = "GL_BYPASS_ACCESS_CHECKS"
  28         const glHome = "GITOLITE_HTTP_HOME"
  29         var env []string
  30         path := os.Getenv("PATH")
  31         if cluster.Git.GitoliteHome != "" {
  32                 env = append(env,
  33                         glHome+"="+cluster.Git.GitoliteHome,
  34                         glBypass+"=1")
  35                 path = path + ":" + cluster.Git.GitoliteHome + "/bin"
  36         } else if home, bypass := os.Getenv(glHome), os.Getenv(glBypass); home != "" || bypass != "" {
  37                 env = append(env, glHome+"="+home, glBypass+"="+bypass)
  38                 ctxlog.FromContext(ctx).Printf("DEPRECATED: Passing through %s and %s environment variables. Use GitoliteHome configuration instead.", glHome, glBypass)
  39         }
  40
  41         var listen arvados.URL
  42         for listen = range cluster.Services.GitHTTP.InternalURLs {
  43                 break
  44         }
  45         env = append(env,
  46                 "GIT_PROJECT_ROOT="+cluster.Git.Repositories,
  47                 "GIT_HTTP_EXPORT_ALL=",
  48                 "SERVER_ADDR="+listen.Host,
  49                 "PATH="+path)
  50         return &gitHandler{
  51                 Handler: cgi.Handler{
  52                         Path: cluster.Git.GitCommand,
  53                         Dir:  cluster.Git.Repositories,
  54                         Env:  env,
  55                         Args: []string{"http-backend"},
  56                 },
  57         }
  58 }
  59
  60 func (h *gitHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
  61         remoteHost, remotePort, err := net.SplitHostPort(r.RemoteAddr)
  62         if err != nil {
  63                 ctxlog.FromContext(r.Context()).Errorf("Internal error: SplitHostPort(r.RemoteAddr==%q): %s", r.RemoteAddr, err)
  64                 w.WriteHeader(http.StatusInternalServerError)
  65                 return
  66         }
  67
  68         // Copy the wrapped cgi.Handler, so these request-specific
  69         // variables don't leak into the next request.
  70         handlerCopy := h.Handler
  71         handlerCopy.Env = append(handlerCopy.Env,
  72                 // In Go1.5 we can skip this, net/http/cgi will do it for us:
  73                 "REMOTE_HOST="+remoteHost,
  74                 "REMOTE_ADDR="+remoteHost,
  75                 "REMOTE_PORT="+remotePort,
  76                 // Ideally this would be a real username:
  77                 "REMOTE_USER="+r.RemoteAddr,
  78         )
  79         handlerCopy.ServeHTTP(w, r)
  80 }