prefer hmac for session security

[cgilite] / session.sh

diff --git a/session.sh b/session.sh
index ad31dfddbf6df8e77a6bfc0aef620e6bfd8e3e94..0a2a2e8b6583ad95c1d95735de392f9d64e35615 100755 (executable)
--- a/session.sh
+++ b/session.sh
@@ -24,6 +24,14 @@ slopecode(){
   '
 }
 
+session_mac(){
+  if which openssl >/dev/null; then
+    openssl dgst -sha1 -hmac "$(server_key)" -binary |slopecode
+  else
+    { cat; server_key; } |sha256sum |cut -d\  -f1
+  fi
+}
+
 randomid(){
   dd bs=12 count=1 if=/dev/urandom 2>&- \
   | slopecode
@@ -49,8 +57,7 @@ transid(){
   local file="$1"
   { stat -c %F%i%n%N%s%Y "$file" 2>&-
     printf %s "$SESSION_ID"
-    server_key
-  } | sha256sum | cut -d\  -f1
+  } | session_mac
 }
 
 update_session(){
@@ -61,20 +68,18 @@ update_session(){
        END
   serverkey="$(server_key)"
   
-  checksig="$(printf %s "$sid" "$time" "$serverkey" | sha256sum)"
-  checksig="${checksig%% *}"
+  checksig="$(printf %s "$sid" "$time" |session_mac)"
   
   if ! [ "$checksig" = "$sig" \
     -a "$time" -ge "$_DATE" \
     -a "$(printf %s "$sid" |checkid)" ] 2>&-
   then
-    debug Setting up new session
+    debug "Setting up new session"
     sid="$(randomid)"
   fi
 
   time=$(( $_DATE + $SESSION_TIMEOUT ))
-  sig="$(printf %s "$sid" "$time" "$serverkey" |sha256sum)"
-  sig="${sig%% *}"
+  sig="$(printf %s "$sid" "$time" |session_mac)"
   printf %s\\n "${sid}-${time}-${sig}"
 }