- FIX #189 with a smart check, introduced global var SERVER_SIZE_LIMIT_BUG

- introduced "has_server_protocol()" which can be used to check b4 connecting if protocol is a/v

testssl.sh

@@ -151,7 +151,7 @@ JSONFILE=${JSONFILE:-""}                # jsonfile if used
 CSVFILE=${CSVFILE:-""}                  # csvfile if used
 HAS_IPv6=${HAS_IPv6:-false}             # if you have OpenSSL with IPv6 support AND IPv6 networking set it to yes
 UNBRACKTD_IPV6=${UNBRACKTD_IPV6:-false} # some versions of OpenSSL (like Gentoo) don't support [bracketed] IPv6 addresses 
-SIZELMT_W_ARND=${SIZELMT_W_ARND:-false} # workaround for servers which have either a ClientHello total size limit or cipher limit of ~128 ciphers (e.g. old ASAs)
+SERVER_SIZE_LIMIT_BUG=false             # Some servers have either a ClientHello total size limit or cipher limit of ~128 ciphers (e.g. old ASAs)
 
 # tuning vars, can not be set by a cmd line switch
 EXPERIMENTAL=${EXPERIMENTAL:-false}
@@ -2226,6 +2226,15 @@ add_tls_offered() {
      grep -w "$1" <<< "$PROTOS_OFFERED" || PROTOS_OFFERED+="$1 "
 }
 
+# function which checks whether SSLv2 - TLS 1.2 is being offereed
+has_server_protocol() {
+     [[ -z "$PROTOS_OFFERED" ]] && return 0            # if empty we rather return 0, means check at additional cost=connect will be done
+     if grep -w "$1" <<< "$PROTOS_OFFERED"; then
+          return 0
+     fi
+     return 1
+}
+
 
 # the protocol check needs to be revamped. It sucks, see above
 run_protocols() {
@@ -2237,8 +2246,6 @@ run_protocols() {
      outln; pr_headline " Testing protocols "
      via="Protocol tested "
 
-     #FIXME: use PROTOS_OFFERED here
-
      if $SSL_NATIVE; then
           using_sockets=false
           pr_headlineln "(via native openssl)"
@@ -2258,7 +2265,7 @@ run_protocols() {
 
      pr_bold " SSLv2      ";
      if ! $SSL_NATIVE; then
-          sslv2_sockets                                                    #FIXME: messages need to be moved to this higher level
+          sslv2_sockets                                                    #FIXME: messages/output need to be moved to this (higher) level
      else
           run_prototest_openssl "-ssl2"
           case $? in
@@ -2785,6 +2792,7 @@ check_tls12_pref() {
 cipher_pref_check() {
      local p proto protos npn_protos
      local tested_cipher cipher order
+     local overflow_probe_cipherlist="ALL:-ECDHE-RSA-AES256-GCM-SHA384:-AES128-SHA:-DES-CBC3-SHA"
 
      pr_bold " Cipher order"
 
@@ -2798,6 +2806,7 @@ cipher_pref_check() {
                out "\n    SSLv3:     "; local_problem "$OPENSSL doesn't support \"s_client -ssl3\"";
                continue
           fi
+          # with the supplied binaries SNI works also for SSLv2 (+ SSLv3)
           $OPENSSL s_client $STARTTLS -"$p" $BUGS -connect $NODEIP:$PORT $PROXY $SNI </dev/null 2>$ERRFILE >$TMPFILE
           if sclient_connect_successful $? $TMPFILE; then
                tested_cipher=""
@@ -2808,12 +2817,19 @@ cipher_pref_check() {
                printf "    %-10s" "$proto: "
                tested_cipher="-"$cipher
                order="$cipher"
-               if [[ $p == tls1_2 ]] && "$SIZELMT_W_ARND"; then
+               if [[ $p == tls1_2 ]]; then
-                    # for some servers the ServerHello is limited to 128 ciphers or the ServerHello itself has a length restriction
+                    # for some servers the ClientHello is limited to 128 ciphers or the ClientHello itself has a length restriction.
-                    # thus we reduce the number of ciphers we throw at the server and put later everything together
+                    # So far, this was only observed in TLS 1.2, affected are e.g. old Cisco LBs or ASAs, see issue #189
-                    # see #189
+                    # To check whether a workaround is needed we send a laaarge list of ciphers/big client hello. If connect fails, 
-                    # so far, this was only observed in TLS 1.2
+                    # we hit the bug and automagically do the workround. Cost: this is for all servers only 1x more connect
+                    $OPENSSL s_client $STARTTLS -tls1_2 $BUGS -cipher "$overflow_probe_cipherlist" -connect $NODEIP:$PORT $PROXY $SNI </dev/null 2>>$ERRFILE >$TMPFILE
+                    if ! sclient_connect_successful $? $TMPFILE; then
+                         SERVER_SIZE_LIMIT_BUG=true
+                    fi
+               fi
+               if [[ $p == tls1_2 ]] && "$SERVER_SIZE_LIMIT_BUG"; then
                     order=$(check_tls12_pref "$cipher")
+                    out "$order"
                else
                     out " $cipher"  # this is the first cipher for protocol
                     while true; do
@@ -7314,6 +7330,7 @@ reset_hostdepended_vars() {
      TLS_EXTENSIONS=""
      PROTOS_OFFERED=""
      OPTIMAL_PROTO=""
+     SERVER_SIZE_LIMIT_BUG=false
 }
 
 
@@ -7453,4 +7470,4 @@ fi
 exit $?
 
 
-#  $Id: testssl.sh,v 1.496 2016/06/07 21:06:57 dirkw Exp $
+#  $Id: testssl.sh,v 1.498 2016/06/09 09:04:39 dirkw Exp $