cgi/snapshot.cgi

   1 #!/bin/sh
   2
   3 # snapshot.cgi -- throttle snapshot requests
   4 # Copyright (C) 2015 Kyle J. McKay.  All rights reserved.
   5 # License GPLv2+: GNU GPL version 2 or later.
   6 # www.gnu.org/licenses/gpl-2.0.html
   7 # This is free software: you are free to change and redistribute it.
   8 # There is NO WARRANTY, to the extent permitted by law.
   9
  10 set -e
  11
  12 . @basedir@/shlib.sh
  13
  14 # Set to non-empty to throttle if the initial throttle service connect fails
  15 throttle_on_connect_fail=
  16
  17 # Supplemental message to be included in the throttle result
  18 throttle_msg=\
  19 'Ravenous roving robots are probably greedily chowing down on our services
  20 right now.
  21
  22 We are valiantly trying to fight them off to improve service availability.'
  23
  24 hdrout()
  25 {
  26         _kw="$1"
  27         shift
  28         printf '%s: %s\r\n' "$_kw" "$*"
  29 }
  30
  31 errorhdrsct()
  32 {
  33         _ct="$1"; shift
  34         printf '%s\r\n' "Status: $1 $2"
  35         printf '%s\r\n' "Expires: Fri, 01 Jan 1980 00:00:00 GMT"
  36         printf '%s\r\n' "Pragma: no-cache"
  37         printf '%s\r\n' "Cache-Control: no-cache,max-age=0,must-revalidate"
  38         [ -z "$3" ] || printf '%s\r\n' "$3"
  39         printf '%s\r\n' "Content-Type: $_ct"
  40         printf '\r\n'
  41 }
  42
  43 errorhdrs()
  44 {
  45         errorhdrsct 'text/plain' "$@"
  46 }
  47
  48 msglines()
  49 {
  50         while [ $# -gt 0 ]; do
  51                 printf '%s\n' "$1"
  52                 shift
  53         done
  54 }
  55
  56 methodnotallowed()
  57 {
  58         errorhdrs 405 "Method Not Allowed" "Allow: GET"
  59         if [ $# -eq 0 ]; then
  60                 msglines "Method Not Allowed"
  61         else
  62                 msglines "$@"
  63         fi
  64         exit 0
  65 }
  66
  67 forbidden()
  68 {
  69         errorhdrs 403 Forbidden
  70         if [ $# -eq 0 ]; then
  71                 msglines "Forbidden"
  72         else
  73                 msglines "$@"
  74         fi
  75         exit 0
  76 }
  77
  78 notfound()
  79 {
  80         errorhdrs 404 "Not Found"
  81         if [ $# -eq 0 ]; then
  82                 msglines "Not Found"
  83         else
  84                 msglines "$@"
  85         fi
  86         exit 0
  87 }
  88
  89 # Snapshots are too expensive to allow HEAD
  90 [ "$REQUEST_METHOD" = "GET" ] || methodnotallowed
  91
  92 # The project must be valid
  93 suffix="${PATH_INFO#*.git/}"
  94 project="${PATH_INFO%/"$suffix"}"
  95 project="${project#/}"
  96 [ -n "$project" ] || forbidden
  97 case "$suffix" in snapshot|snapshot/*) :;; *) forbidden; esac
  98 suffix="${suffix#snapshot}"
  99 suffix="${suffix#/}"
 100
 101 # Perform some basic sanity checking
 102 if [ -z "$suffix" ]; then
 103         # Must have an "h=" argument
 104         case "&$QUERY_STRING&" in *[\&\;]"h="[!\&\;]*) :;; *) forbidden; esac
 105 fi
 106 case "$suffix" in [!A-Za-z0-9_]*) forbidden; esac
 107 case "/$project/" in *"/../"*|*"/./"*|*"/_"*|*"//"*) forbidden; esac
 108 is_git_dir "$cfg_reporoot/$project" || notfound
 109
 110 # Give the 'bots indigestion
 111 sleep 5
 112
 113 # Attempt to trigger a SIGPIPE if the connection has already been closed
 114 hdrout "X-Project" "${project%.git}"
 115 sleep 1
 116 hdrout "X-Snapshot" "${suffix:-$QUERY_STRING}"
 117 sleep 1
 118
 119 # Off to the races
 120 projname="${project%.git}"
 121 "$cfg_basedir/bin/throttle" ${throttle_on_connect_fail:+-t} -c snapshot \
 122         -d "$projname" -m "$throttle_msg" "$cfg_cgiroot/gitweb.cgi"
 123 exit 0