X-Git-Url: http://git.plutz.net/?p=cgilite;a=blobdiff_plain;f=session.sh;h=ee5c4993a72df047fe0fc67b3c384f2b5733be48;hp=3f3839ae8b167975a5e5231582509c5484d1f025;hb=HEAD;hpb=41bcab02ff4b11d22a2624e7afabc50e9c33ae2f

diff --git a/session.sh b/session.sh
index 3f3839a..c3a44e8 100755
--- a/session.sh
+++ b/session.sh
@@ -1,11 +1,50 @@
 #!/bin/sh
 
+# Copyright 2018 - 2022 Paul Hänsch
+# 
+# Permission to use, copy, modify, and/or distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+# 
+# THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+# SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
+# IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
 [ -n "$include_session" ] && return 0
 include_session="$0"
 
+export _DATE="$(date +%s)"
+SESSION_TIMEOUT="${SESSION_TIMEOUT:-7200}"
+
+if ! which uuencode >/dev/null; then
+  uuencode() { busybox uuencode "$@"; }
+fi
+if ! which sha256sum >/dev/null; then
+  sha256sum() { busybox sha256sum "$@"; }
+fi
+
+if which openssl >/dev/null; then
+  session_mac(){ { [ $# -gt 0 ] && printf %s "$*" || cat; } | openssl dgst -sha1 -hmac "$(server_key)" -binary |slopecode; }
+else
+  # Gonzo MAC if openssl is unavailable
+  session_mac(){
+    { server_key | dd status=none bs=256 count=1 skip=1
+      { server_key | dd status=none bs=256 count=1
+        [ $# -gt 0 ] && printf %s "$*" || cat
+      } \
+      | sha256sum -;
+    } \
+    | sha256sum | cut -d\  -f1
+  }
+fi
+
 server_key(){
   IDFILE="${IDFILE:-${_DATA:-.}/serverkey}"
-  if ! grep -m1 -xE '.{512}' "$IDFILE"; then
+  if [ "$(stat -c %s "$IDFILE")" -ne 512 ] || ! cat "$IDFILE"; then
     dd count=1 bs=512 if=/dev/urandom \
     | tee "$IDFILE"
   fi 2>&-
@@ -15,19 +54,20 @@ slopecode(){
   # 6-Bit Code that retains sort order of input data, while beeing safe to use
   # in ascii transmissions, unix file names, HTTP URLs, and HTML attributes
 
-  uuencode -m - | sed '
+  { [ $# -gt 0 ] && printf %s "$*" || cat; } \
+  | uuencode -m - | sed '
     1d;$d; 
     y;ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/;0123456789:=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz;
   '
 }
 
 randomid(){
-  dd bs=12 count=1 if=/dev/urandom \
-  | slopecode 2>&-
+  dd bs=12 count=1 if=/dev/urandom 2>&- \
+  | slopecode
 }
 
 timeid(){
-  d=$(($(date +%s) % 4294967296))
+  d=$(($_DATE % 4294967296))
   { printf "$(
       printf \\%o \
         $((d / 16777216 % 256)) \
@@ -35,34 +75,78 @@ timeid(){
         $((d / 256 % 256)) \
         $((d % 256))
     )"
-    dd bs=8 count=1 if=/dev/urandom
-  } | slopecode 2>&-
+    dd bs=8 count=1 if=/dev/urandom 2>&-
+  } | slopecode
 }
 
-checkid(){ grep -m 1 -xE '[0-9a-zA-Z:_]{16}'; }
+transid(){
+  # transaction ID to modify a given file
+  local file="$1"
+  session_mac "$(stat -c %F%i%n%N%s%Y "$file" 2>&-)" "$SESSION_ID"
+}
+
+checkid(){ { [ $# -gt 0 ] && printf %s "$*" || cat; } | grep -m 1 -xE '[0-9a-zA-Z:=]{16}'; }
 
 update_session(){
-  local session sid time sig serverkey checksig
+  local session sid time sig checksig
+  unset SESSION_KEY SESSION_ID
 
-  IFS=- read -r sid time sig <<-END
-	$(COOKIE session)
+  read -r sid time sig <<-END
+	$(POST session_key || COOKIE session)
 	END
-  serverkey="$(server_key)"
   
-  checksig="$(printf %s "$sid" "$time" "$serverkey" | sha256sum)"
-  checksig="${checksig%% *}"
-  d=$(date +%s)
+  checksig="$(session_mac "$sid" "$time")"
   
-  if [ "$checksig" != "$sig" -o "$time" -lt "$d" ] 2>&-; then
-    sid="$(randomid)"
+  if [ "$checksig" = "$sig" \
+       -a "$time" -ge "$_DATE" \
+       -a "$(checkid "$sid")" ] 2>&-
+  then
+    time=$(( $_DATE + $SESSION_TIMEOUT ))
+    sig="$(session_mac "$sid" "$time")"
+
+    SESSION_KEY="${sid} ${time} ${sig}"
+    SESSION_ID="${sid}"
+    return 0
+  else
+    return 1
+  fi
+
+}
+
+new_session(){
+  local sid time sig
+
+  debug "Setting up new session"
+  sid="$(randomid)"
+  time=$(( $_DATE + $SESSION_TIMEOUT ))
+  sig="$(session_mac "$sid" "$time")"
+
+  SESSION_KEY="${sid} ${time} ${sig}"
+  SESSION_ID="${sid}"
+}
+
+SESSION_BIND() {
+  # Set tamper-proof authenticated cookie
+  local key="$1" value="$2"
+  SET_COOKIE session "$key"="${value} $(session_mac "$value" "$SESSION_ID")" Path="/${_BASE#/}" SameSite=Strict HttpOnly
+}
+
+SESSION_VAR() {
+  # read authenticated cookie
+  # fail if value has been tampered with
+  local key="$1" value sig
+  value="$(COOKIE "$key")"
+  sig="${value##* }" value="${value% *}"
+  if [ "$sig" = "$(session_mac "$value" "$SESSION_ID")" ]; then
+    printf %s\\n "$value"
+  else
+    return 1
   fi
+}
 
-  time=$(( $(date +%s) + 7200 ))
-  sig="$(printf %s "$sid" "$time" "$serverkey" |sha256sum)"
-  sig="${sig%% *}"
-  printf %s\\n "${sid}-${time}-${sig}"
+SESSION_COOKIE() {
+  [ "$1" = new ] && new_session
+  SET_COOKIE 0 session="$SESSION_KEY" Path="/${_BASE#/}" SameSite=Strict HttpOnly
 }
 
-SESSION_ID="$(update_session)"
-SET_COOKIE 0 "session=$SESSION_ID" HttpOnly
-SESSION_ID="${SESSION_ID%%-*}"
+update_session || new_session