GUACAMOLE-279: Handle xterm palette assignments, parsing each color as an X11 color spec.

src/terminal/Makefile.am

@@ -32,7 +32,8 @@ noinst_HEADERS =                 \
     terminal/terminal.h          \
     terminal/terminal_handlers.h \
     terminal/types.h             \
-    terminal/typescript.h
+    terminal/typescript.h        \
+    terminal/xparsecolor.h
 
 libguac_terminal_la_SOURCES =   \
     buffer.c                    \
@@ -43,7 +44,8 @@ libguac_terminal_la_SOURCES =   \
     scrollbar.c                 \
     terminal.c                  \
     terminal_handlers.c         \
-    typescript.c
+    typescript.c                \
+    xparsecolor.c
 
 libguac_terminal_la_CFLAGS = \
     -Werror -Wall            \

src/terminal/terminal/xparsecolor.h

@@ -0,0 +1,48 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef GUAC_TERMINAL_XPARSECOLOR_H
+#define GUAC_TERMINAL_XPARSECOLOR_H
+
+#include "config.h"
+
+#include "terminal/palette.h"
+
+/**
+ * Parses an X11 color spec, as defined by Xlib's XParseColor(), storing the
+ * result in the provided guac_terminal_color structure. If the color spec is
+ * not valid, the provided guac_terminal_color is not touched.
+ *
+ * Currently, only the "rgb:*" format color specs are supported.
+ *
+ * @param spec
+ *     The X11 color spec to parse.
+ *
+ * @param color
+ *     A pointer to the guac_terminal_color structure which should receive the
+ *     parsed result.
+ *
+ * @returns
+ *     Zero if the color spec was successfully parsed, non-zero otherwise.
+ */
+int guac_terminal_xparsecolor(const char* spec,
+        guac_terminal_color* color);
+
+#endif
+

src/terminal/terminal_handlers.c

@@ -24,6 +24,7 @@
 #include "terminal/terminal.h"
 #include "terminal/terminal_handlers.h"
 #include "terminal/types.h"
+#include "terminal/xparsecolor.h"
 
 #include <guacamole/client.h>
 #include <guacamole/protocol.h>
@@ -1212,8 +1213,76 @@ int guac_terminal_window_title(guac_terminal* term, unsigned char c) {
 
 int guac_terminal_xterm_palette(guac_terminal* term, unsigned char c) {
 
-    /* NOTE: Currently unimplemented. Attempts to set the 256-color palette
-     * are ignored. */
+    /**
+     * Whether we are currently reading the color spec. If false, we are
+     * currently reading the color index.
+     */
+    static bool read_color_spec = false;
+
+    /**
+     * The index of the palette entry being modified.
+     */
+    static int index = 0;
+
+    /**
+     * The color spec string, valid only if read_color_spec is true.
+     */
+    static char color_spec[256];
+
+    /**
+     * The current position within the color spec string, valid only if
+     * read_color_spec is true.
+     */
+    static int color_spec_pos = 0;
+
+    /* If not reading the color spec, parse the index */
+    if (!read_color_spec) {
+
+        /* If digit, append to index */
+        if (c >= '0' && c <= '9')
+            index = index * 10 + c - '0';
+
+        /* If end of parameter, switch to reading the color */
+        else if (c == ';') {
+            read_color_spec = true;
+            color_spec_pos = 0;
+        }
+
+    }
+
+    /* Once the index has been parsed, read the color spec */
+    else {
+
+        /* Modify palette once index/spec pair has been read */
+        if (c == ';' || c == 0x9C || c == 0x5C || c == 0x07) {
+
+            guac_terminal_color color;
+
+            /* Terminate color spec string */
+            color_spec[color_spec_pos] = '\0';
+
+            /* Modify palette if color spec is valid */
+            if (!guac_terminal_xparsecolor(color_spec, &color))
+                guac_terminal_display_assign_color(term->display,
+                        index, &color);
+            else
+                guac_client_log(term->client, GUAC_LOG_DEBUG,
+                        "Invalid XParseColor() color spec: \"%s\"",
+                        color_spec);
+
+            /* Resume parsing index */
+            read_color_spec = false;
+            index = 0;
+
+        }
+
+        /* Append characters to color spec as long as available space is not
+         * exceeded */
+        else if (color_spec_pos < 255) {
+            color_spec[color_spec_pos++] = c;
+        }
+
+    }
 
     /* Stop on ECMA-48 ST (String Terminator */
     if (c == 0x9C || c == 0x5C || c == 0x07)

src/terminal/xparsecolor.c

@@ -0,0 +1,70 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include "config.h"
+
+#include "terminal/named-colors.h"
+#include "terminal/palette.h"
+
+#include <stdio.h>
+
+int guac_terminal_xparsecolor(const char* spec,
+        guac_terminal_color* color) {
+
+    int red;
+    int green;
+    int blue;
+
+    /* 12-bit RGB ("rgb:h/h/h"), zero-padded to 24-bit */
+    if (sscanf(spec, "rgb:%1x/%1x/%1x", &red, &green, &blue) == 3) {
+        color->red   = red   << 4;
+        color->green = green << 4;
+        color->blue  = blue  << 4;
+        return 0;
+    }
+
+    /* 24-bit RGB ("rgb:hh/hh/hh") */
+    if (sscanf(spec, "rgb:%2x/%2x/%2x", &red, &green, &blue) == 3) {
+        color->red   = red;
+        color->green = green;
+        color->blue  = blue;
+        return 0;
+    }
+
+    /* 36-bit RGB ("rgb:hhh/hhh/hhh"), truncated to 24-bit */
+    if (sscanf(spec, "rgb:%3x/%3x/%3x", &red, &green, &blue) == 3) {
+        color->red   = red   >> 4;
+        color->green = green >> 4;
+        color->blue  = blue  >> 4;
+        return 0;
+    }
+
+    /* 48-bit RGB ("rgb:hhhh/hhhh/hhhh"), truncated to 24-bit */
+    if (sscanf(spec, "rgb:%4x/%4x/%4x", &red, &green, &blue) == 3) {
+        color->red   = red   >> 8;
+        color->green = green >> 8;
+        color->blue  = blue  >> 8;
+        return 0;
+    }
+
+    /* Invalid color spec */
+    return 1;
+
+}
+