HttpClient: send AddVariable params as query string on GETs and read them on the server (#1107)

Two related fixes for AddVariable usage on GET requests.

Client side (HttpClientJavaLib + GXHttpClient):
On GET, variables added with AddVariable were serialized as a multipart
body. Servers, proxies and CDNs ignore the body of a GET so the values
never reached the destination. They now go to the URL query string,
URL-encoded in UTF-8. POST/PUT/DELETE keep using the body as before.

Server side (HttpContextWeb):
HttpRequest.GetVariable() consulted only the request body. On a GET
this body is empty so values sent via the query string were invisible.
Now, only on GET, if the body parsed empty we fall back to the query
string. POST and any other verb are unchanged: the body still has
precedence and the query string is not consulted.

Author: iroqueta

common/src/main/java/com/genexus/internet/GXHttpClient.java

@@ -15,6 +15,7 @@
 import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.parsers.ParserConfigurationException;
 import java.io.*;
+import java.net.URLEncoder;
 import java.util.Hashtable;
 import java.util.Vector;
 
@@ -571,21 +572,51 @@ protected String setPathUrl(String url) {
 	}
 
 	boolean firstMultiPart;
-	@SuppressWarnings("unchecked")
+
 	protected byte[] getData()
+	{
+		return getData(true);
+	}
+
+	protected String getQueryStringFromVariables()
+	{
+		if (getVariablesToSend() == null || getVariablesToSend().isEmpty())
+			return "";
+		StringBuilder sb = new StringBuilder();
+		boolean first = true;
+		for (Object key : getVariablesToSend().keySet())
+		{
+			if (!first) sb.append('&');
+			try
+			{
+				sb.append(URLEncoder.encode((String) key, "UTF-8"))
+				  .append('=')
+				  .append(URLEncoder.encode((String) getVariablesToSend().get(key), "UTF-8"));
+			}
+			catch (UnsupportedEncodingException ignored) { /* UTF-8 always supported */ }
+			first = false;
+		}
+		return sb.toString();
+	}
+
+	@SuppressWarnings("unchecked")
+	protected byte[] getData(boolean includeVariablesAsMultipart)
 	{
 		byte[] out = new byte[0];
 
 		firstMultiPart = false;
-		int variablesCount = getVariablesToSend().size();
-		int count = 1;
-		for (Object key: getVariablesToSend().keySet())
+		if (includeVariablesAsMultipart)
 		{
-			if (count == variablesCount)
-				firstMultiPart = true;
-			String value = getMultipartTemplate().getFormDataTemplate((String)key, (String)getVariablesToSend().get(key));
-			getContentToSend().add(0, value); //Variables al principio
-			count++;
+			int variablesCount = getVariablesToSend().size();
+			int count = 1;
+			for (Object key: getVariablesToSend().keySet())
+			{
+				if (count == variablesCount)
+					firstMultiPart = true;
+				String value = getMultipartTemplate().getFormDataTemplate((String)key, (String)getVariablesToSend().get(key));
+				getContentToSend().add(0, value); //Variables al principio
+				count++;
+			}
 		}
 
 		for (int idx = 0; idx < getContentToSend().size(); idx++)

java/src/main/java/com/genexus/internet/HttpClientJavaLib.java

@@ -547,9 +547,17 @@ public void execute(String method, String url) {
 
 			try (CloseableHttpClient httpClient = this.httpClientBuilder.build()) {
 				if (method.equalsIgnoreCase("GET")) {
-					byte[] data = getData();
+					// Variables added via addVariable are appended to the query string,
+					// not serialized as a multipart body (which servers ignore on GETs).
+					String queryFromVars = getQueryStringFromVariables();
+					String finalUrl = url;
+					if (!queryFromVars.isEmpty()) {
+						finalUrl = url + (url.contains("?") ? "&" : "?") + queryFromVars;
+					}
+
+					byte[] data = getData(false);   // body only from addBytes/addString, no variables
 					if (data.length > 0) {
-						HttpGetWithBody httpGetWithBody = new HttpGetWithBody(url.trim());
+						HttpGetWithBody httpGetWithBody = new HttpGetWithBody(finalUrl.trim());
 						httpGetWithBody.setConfig(reqConfig);
 						Set<String> keys = getheadersToSend().keySet();
 						for (String header : keys) {
@@ -559,7 +567,7 @@ public void execute(String method, String url) {
 						response = httpClient.execute(httpGetWithBody, httpClientContext);
 					}
 					else {
-						HttpGet httpget = new HttpGet(url.trim());
+						HttpGet httpget = new HttpGet(finalUrl.trim());
 						httpget.setConfig(reqConfig);
 						Set<String> keys = getheadersToSend().keySet();
 						for (String header : keys) {

java/src/main/java/com/genexus/webpanels/HttpContextWeb.java

@@ -1242,7 +1242,15 @@ static private Hashtable<String, String[]> parseMultipartPostData(FileItemCollec
 	static public Hashtable<String, String[]> parsePostData(IHttpServletRequest request, IServletInputStream in) {
 		try {
 			// Nuestra versión del parsePostData utiliza UTF-8
-			return com.genexus.webpanels.HttpUtils.parsePostData(in);
+			Hashtable<String, String[]> postData = com.genexus.webpanels.HttpUtils.parsePostData(in);
+			// On GET requests, if the body yielded no variables, fall back to the query string.
+			// POST/PUT/DELETE/... behavior is unchanged: only the body is read.
+			if ((postData == null || postData.isEmpty())
+					&& request != null
+					&& "GET".equalsIgnoreCase(request.getMethod())) {
+				return com.genexus.webpanels.HttpUtils.parsePostData(request);
+			}
+			return postData;
 		} catch (IllegalArgumentException e) {
 			return com.genexus.webpanels.HttpUtils.parsePostData(request);
 		}