From f8f2c7f7472b87ac95814ae53649e3ee3413ba08 Mon Sep 17 00:00:00 2001
From: Michael Jumper <mjumper@apache.org>
Date: Wed, 1 Jul 2020 18:09:13 -0700
Subject: [PATCH] GUACAMOLE-221: Allow callers to request that argument values
 be automatically echoed to all connected users.

---
 src/libguac/argv.c                     | 14 ++++++++++++--
 src/libguac/guacamole/argv-constants.h |  7 +++++++
 src/libguac/guacamole/argv-fntypes.h   |  6 +++++-
 src/libguac/guacamole/argv.h           |  3 ++-
 4 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/src/libguac/argv.c b/src/libguac/argv.c
index 893ffffe..a4462c4c 100644
--- a/src/libguac/argv.c
+++ b/src/libguac/argv.c
@@ -20,6 +20,7 @@
 #include "config.h"
 
 #include "guacamole/argv.h"
+#include "guacamole/client.h"
 #include "guacamole/protocol.h"
 #include "guacamole/socket.h"
 #include "guacamole/stream.h"
@@ -51,7 +52,7 @@ typedef struct guac_argv_state {
 
     /**
      * Bitwise OR of all option flags that should affect processing of this
-     * argument. The only current flag is GUAC_ARGV_OPTION_ONCE.
+     * argument.
      */
     int options;
 
@@ -243,6 +244,8 @@ static int guac_argv_blob_handler(guac_user* user, guac_stream* stream,
  */
 static int guac_argv_end_handler(guac_user* user, guac_stream* stream) {
 
+    int result = 0;
+
     /* Append null terminator to value */
     guac_argv* argv = (guac_argv*) stream->data;
     argv->buffer[argv->length] = '\0';
@@ -254,7 +257,14 @@ static int guac_argv_end_handler(guac_user* user, guac_stream* stream) {
     guac_argv_state* state = argv->state;
     if (!(state->options & GUAC_ARGV_OPTION_ONCE) || !state->received) {
         if (state->callback != NULL)
-            state->callback(user, argv->mimetype, state->name, argv->buffer, state->data);
+            result = state->callback(user, argv->mimetype, state->name, argv->buffer, state->data);
+    }
+
+    /* Alert connected clients regarding newly-accepted values if echo is
+     * enabled */
+    if (!result && (state->options & GUAC_ARGV_OPTION_ECHO)) {
+        guac_client* client = user->client;
+        guac_client_stream_argv(client, client->socket, argv->mimetype, state->name, argv->buffer);
     }
 
     /* Notify that argument has been received */
diff --git a/src/libguac/guacamole/argv-constants.h b/src/libguac/guacamole/argv-constants.h
index 88402299..a244a156 100644
--- a/src/libguac/guacamole/argv-constants.h
+++ b/src/libguac/guacamole/argv-constants.h
@@ -34,6 +34,13 @@
  */
 #define GUAC_ARGV_OPTION_ONCE 1
 
+/**
+ * Option flag which declares to guac_argv_register() that the values received
+ * and accepted for the associated argument should be echoed to all connected
+ * users via outbound "argv" streams.
+ */
+#define GUAC_ARGV_OPTION_ECHO 2
+
 /**
  * The maximum number of bytes to allow for any argument value received via an
  * argv stream and processed using guac_argv_received(), including null
diff --git a/src/libguac/guacamole/argv-fntypes.h b/src/libguac/guacamole/argv-fntypes.h
index d8c49e60..bf4ff374 100644
--- a/src/libguac/guacamole/argv-fntypes.h
+++ b/src/libguac/guacamole/argv-fntypes.h
@@ -50,8 +50,12 @@
  * @param data
  *     Any arbitrary data that was provided when the received argument was
  *     registered with guac_argv_register().
+ *
+ * @return
+ *     Zero if the received argument value has been accepted and has either
+ *     taken effect or is being intentionally ignored, non-zero otherwise.
  */
-typedef void guac_argv_callback(guac_user* user, const char* mimetype,
+typedef int guac_argv_callback(guac_user* user, const char* mimetype,
         const char* name, const char* value, void* data);
 
 #endif
diff --git a/src/libguac/guacamole/argv.h b/src/libguac/guacamole/argv.h
index e2d60921..3cc4806e 100644
--- a/src/libguac/guacamole/argv.h
+++ b/src/libguac/guacamole/argv.h
@@ -43,6 +43,7 @@
  * @see GUAC_ARGV_MAX_REGISTERED
  *
  * @see GUAC_ARGV_OPTION_ONCE
+ * @see GUAC_ARGV_OPTION_ECHO
  *
  * @param name
  *     The name of the argument that should be handled by the given callback.
@@ -57,7 +58,7 @@
  *
  * @param options
  *     Bitwise OR of all option flags that should affect processing of this
- *     argument. The only current flag is GUAC_ARGV_OPTION_ONCE.
+ *     argument.
  *
  * @return
  *     Zero if the callback was successfully registered, non-zero if the