Add --cafile <filename.crt>, alongside --capath <dirpath/>.

For unknown reasons, while we previously supported --capath we did not
support --cafile. This forces the --cafile autodetection logic to run
every time, unnecessarily, when we have a specific file in mind to use.

This patch relocates the -CAfile autodetection logic to run *only if*
the --cafile parameter is not provided. If it is not provided, the
autodetection logic occurs precisely as before.

This patch declines to address what happens if both --capath and
--cafile are passed. The previous logic already ensured that the CA file
was *always* set, and then only sometimes was the CA path set. The new
logic maintains that behavior precisely, reserving logic flow changes
for a separate commit.

cipherscan

@@ -54,19 +54,7 @@ if [[ -e $DIRNAMEPATH/openssl.cnf ]]; then
     export OPENSSL_CONF="$DIRNAMEPATH/openssl.cnf"
 fi
 
-# find a list of trusted CAs on the local system, or use the provided list
-if [[ -z "$CACERTS" ]]; then
-    for f in /etc/pki/tls/certs/ca-bundle.crt /etc/ssl/certs/ca-certificates.crt; do
-        if [[ -e "$f" ]]; then
-            CACERTS="$f"
-            break
-        fi
-    done
-fi
-if [[ ! -e "$CACERTS" ]]; then
-    CACERTS="$DIRNAMEPATH/ca-bundle.crt"
-fi
-
+CACERTS=""
 # RSA ciphers are put at the end to force Google servers to accept ECDSA ciphers
 # (probably a result of a workaround for the bug in Apple implementation of ECDSA)
 CIPHERSUITE="ALL:COMPLEMENTOFALL:+aRSA"
@@ -1313,6 +1301,10 @@ do
             DELAY=$2
             shift 2
             ;;
+        --cafile)
+            CACERTS="$2"
+            shift 2
+            ;;
         --capath)
             CAPATH="$2"
             shift 2
@@ -1380,6 +1372,19 @@ if [[ $TEST_CURVES == "True" ]]; then
     fi
 fi
 
+# find a list of trusted CAs on the local system, or use the provided list
+if [[ -z "$CACERTS" ]]; then
+    for f in /etc/pki/tls/certs/ca-bundle.crt /etc/ssl/certs/ca-certificates.crt; do
+        if [[ -e "$f" ]]; then
+            CACERTS="$f"
+            break
+        fi
+    done
+fi
+if [[ ! -e "$CACERTS" ]]; then
+    CACERTS="$DIRNAMEPATH/ca-bundle.crt"
+fi
+
 if [[ $VERBOSE != 0 ]] ; then
     [[ -n "$CACERTS" ]] && echo "Using trust anchors from $CACERTS"
     echo "Loading $($OPENSSLBIN ciphers -v $CIPHERSUITE 2>/dev/null|grep Kx|wc -l) ciphersuites from $(echo -n $($OPENSSLBIN version 2>/dev/null))"