runtests.pl: add a -P option to specify an external proxy

... that should be used when executing the tests.

The assumption is that the proxy is an HTTP proxy.

This option should be used together with -L to provide
a customized compareparts() version that knows which
proxy-specific header differences should be ignored.

This option doesn't work for all test types yet.

tests/runtests.pl

@@ -163,6 +163,9 @@ my $SMBSPORT=$noport;    # SMBS server port
 my $TELNETPORT=$noport;  # TELNET server port with negotiation
 my $HTTPUNIXPATH;        # HTTP server Unix domain socket path
 
+my $use_external_proxy = 0;
+my $proxy_address;
+
 my $SSHSRVMD5 = "[uninitialized]"; # MD5 of ssh server public key
 my $VERSION;             # curl's reported version number
 
@@ -840,6 +843,13 @@ sub stopserver {
     }
 }
 
+#######################################################################
+# Return flags to let curl use an external HTTP proxy
+#
+sub getexternalproxyflags {
+    return " --proxy $proxy_address ";
+}
+
 #######################################################################
 # Verify that the server that runs on $ip, $port is our server.  This also
 # implies that we can speak with it, as there might be occasions when the
@@ -874,6 +884,9 @@ sub verifyhttp {
     $flags .= "--globoff ";
     $flags .= "--unix-socket '$port_or_path' " if $ipvnum eq "unix";
     $flags .= "--insecure " if($proto eq 'https');
+    if($use_external_proxy) {
+        $flags .= getexternalproxyflags();
+    }
     $flags .= "\"$proto://$ip:$port/${bonus}verifiedserver\"";
 
     my $cmd = "$VCURL $flags 2>$verifylog";
@@ -948,6 +961,9 @@ sub verifyftp {
     $flags .= "--verbose ";
     $flags .= "--globoff ";
     $flags .= $extra;
+    if($use_external_proxy) {
+        $flags .= getexternalproxyflags();
+    }
     $flags .= "\"$proto://$ip:$port/verifiedserver\"";
 
     my $cmd = "$VCURL $flags 2>$verifylog";
@@ -1010,6 +1026,9 @@ sub verifyrtsp {
     $flags .= "--silent ";
     $flags .= "--verbose ";
     $flags .= "--globoff ";
+    if($use_external_proxy) {
+        $flags .= getexternalproxyflags();
+    }
     # currently verification is done using http
     $flags .= "\"http://$ip:$port/verifiedserver\"";
 
@@ -1151,6 +1170,9 @@ sub verifyhttptls {
     $flags .= "--tlsauthtype SRP ";
     $flags .= "--tlsuser jsmith ";
     $flags .= "--tlspassword abc ";
+    if($use_external_proxy) {
+        $flags .= getexternalproxyflags();
+    }
     $flags .= "\"https://$ip:$port/verifiedserver\"";
 
     my $cmd = "$VCURL $flags 2>$verifylog";
@@ -3660,6 +3682,10 @@ sub singletest {
             }
         }
     }
+    if($use_external_proxy) {
+        $ENV{http_proxy} = $proxy_address;
+        $ENV{HTTPS_PROXY} = $proxy_address;
+    }
 
     if(!$why) {
         my @precheck = getpart("client", "precheck");
@@ -3906,6 +3932,9 @@ sub singletest {
             $fail_due_event_based--;
         }
         $cmdargs .= $cmd;
+        if ($use_external_proxy) {
+            $cmdargs .= " --proxy $proxy_address ";
+        }
     }
     else {
         $cmdargs = " $cmd"; # $cmd is the command line for the test file
@@ -5355,6 +5384,11 @@ while(@ARGV) {
     elsif($ARGV[0] eq "-p") {
         $postmortem=1;
     }
+    elsif($ARGV[0] eq "-P") {
+        shift @ARGV;
+        $use_external_proxy=1;
+        $proxy_address=$ARGV[0];
+    }
     elsif($ARGV[0] eq "-l") {
         # lists the test case names only
         $listonly=1;
@@ -5406,6 +5440,7 @@ Usage: runtests.pl [options] [test selection(s)]
   -k       keep stdout and stderr files present after tests
   -l       list all test case names/descriptions
   -n       no valgrind
+  -P proxy use the specified proxy
   -p       print log file contents when a test fails
   -R       scrambled order (uses the random seed, see --seed)
   -r       run time statistics