From f1bf70a4a20dcbf5264b559b94e7c8e9d839b525 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Thu, 22 Feb 2018 14:56:40 -0500
Subject: [PATCH 01/22] GUACAMOLE-269: Add basic support for sending TTY mode
 encoding.

---
 src/protocols/ssh/Makefile.am |  1 +
 src/protocols/ssh/ssh.c       |  5 +++--
 src/protocols/ssh/ttymode.h   | 36 +++++++++++++++++++++++++++++++++++
 3 files changed, 40 insertions(+), 2 deletions(-)
 create mode 100644 src/protocols/ssh/ttymode.h

diff --git a/src/protocols/ssh/Makefile.am b/src/protocols/ssh/Makefile.am
index 3a5c7f73..7306b8bc 100644
--- a/src/protocols/ssh/Makefile.am
+++ b/src/protocols/ssh/Makefile.am
@@ -38,6 +38,7 @@ noinst_HEADERS =                \
     settings.h                  \
     sftp.h                      \
     ssh.h                       \
+    ttymode.h                   \
     user.h
 
 # Add agent sources if enabled
diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 0ea60bc4..88614feb 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -26,6 +26,7 @@
 #include "sftp.h"
 #include "ssh.h"
 #include "terminal/terminal.h"
+#include "ttymode.h"
 
 #ifdef ENABLE_SSH_AGENT
 #include "ssh_agent.h"
@@ -297,8 +298,8 @@ void* ssh_client_thread(void* data) {
     }
 
     /* Request PTY */
-    if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1, NULL, 0,
-            ssh_client->term->term_width, ssh_client->term->term_height, 0, 0)) {
+    if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1, guac_tty_modes,
+            sizeof(guac_tty_modes), ssh_client->term->term_width, ssh_client->term->term_height, 0, 0)) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_UPSTREAM_ERROR, "Unable to allocate PTY.");
         return NULL;
     }
diff --git a/src/protocols/ssh/ttymode.h b/src/protocols/ssh/ttymode.h
new file mode 100644
index 00000000..f248ed82
--- /dev/null
+++ b/src/protocols/ssh/ttymode.h
@@ -0,0 +1,36 @@
+/*
+ * 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_SSH_TTYMODE_H
+#define GUAC_SSH_TTYMODE_H
+
+#include "config.h"
+
+#define TTY_OP_END 0
+#define TTY_OP_VERASE 3
+
+#define GUAC_SSH_TERM_DEFAULT_BACKSPACE 127
+
+char guac_tty_modes[] = {
+    TTY_OP_VERASE,
+    0, 0, 0, GUAC_SSH_TERM_DEFAULT_BACKSPACE,
+    TTY_OP_END
+};
+
+#endif

From 5583748b548c8d4a9be5865251d956c290e1338a Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Thu, 22 Feb 2018 19:56:05 -0500
Subject: [PATCH 02/22] GUACAMOLE-269: Move constant declaration to ttymode.c

---
 src/protocols/ssh/Makefile.am |  1 +
 src/protocols/ssh/ssh.c       |  4 ++--
 src/protocols/ssh/ttymode.c   | 27 +++++++++++++++++++++++++++
 src/protocols/ssh/ttymode.h   | 10 +++-------
 4 files changed, 33 insertions(+), 9 deletions(-)
 create mode 100644 src/protocols/ssh/ttymode.c

diff --git a/src/protocols/ssh/Makefile.am b/src/protocols/ssh/Makefile.am
index 7306b8bc..6a6de034 100644
--- a/src/protocols/ssh/Makefile.am
+++ b/src/protocols/ssh/Makefile.am
@@ -29,6 +29,7 @@ libguac_client_ssh_la_SOURCES = \
     settings.c                  \
     sftp.c                      \
     ssh.c                       \
+    ttymode.c                   \
     user.c
 
 noinst_HEADERS =                \
diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 88614feb..62bfbb25 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -298,8 +298,8 @@ void* ssh_client_thread(void* data) {
     }
 
     /* Request PTY */
-    if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1, guac_tty_modes,
-            sizeof(guac_tty_modes), ssh_client->term->term_width, ssh_client->term->term_height, 0, 0)) {
+    if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1, GUAC_SSH_TTY_MODES,
+            sizeof(GUAC_SSH_TTY_MODES), ssh_client->term->term_width, ssh_client->term->term_height, 0, 0)) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_UPSTREAM_ERROR, "Unable to allocate PTY.");
         return NULL;
     }
diff --git a/src/protocols/ssh/ttymode.c b/src/protocols/ssh/ttymode.c
new file mode 100644
index 00000000..e5baff4f
--- /dev/null
+++ b/src/protocols/ssh/ttymode.c
@@ -0,0 +1,27 @@
+/*
+ * 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 "ttymode.h"
+
+const char GUAC_SSH_TTY_MODES[6] = {
+    GUAC_SSH_TTY_OP_VERASE,
+    0, 0, 0, GUAC_SSH_TERM_DEFAULT_BACKSPACE,
+    GUAC_SSH_TTY_OP_END
+};
diff --git a/src/protocols/ssh/ttymode.h b/src/protocols/ssh/ttymode.h
index f248ed82..524051e6 100644
--- a/src/protocols/ssh/ttymode.h
+++ b/src/protocols/ssh/ttymode.h
@@ -22,15 +22,11 @@
 
 #include "config.h"
 
-#define TTY_OP_END 0
-#define TTY_OP_VERASE 3
+#define GUAC_SSH_TTY_OP_END 0
+#define GUAC_SSH_TTY_OP_VERASE 3
 
 #define GUAC_SSH_TERM_DEFAULT_BACKSPACE 127
 
-char guac_tty_modes[] = {
-    TTY_OP_VERASE,
-    0, 0, 0, GUAC_SSH_TERM_DEFAULT_BACKSPACE,
-    TTY_OP_END
-};
+extern const char GUAC_SSH_TTY_MODES[6];
 
 #endif

From 2ace9385a27d77e3fbf1f987b3bf3f0ce6af7ebc Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Thu, 22 Feb 2018 20:10:16 -0500
Subject: [PATCH 03/22] GUACAMOLE-269: Add documentation for the defines and
 variables.

---
 src/protocols/ssh/ttymode.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/protocols/ssh/ttymode.h b/src/protocols/ssh/ttymode.h
index 524051e6..e1a0101f 100644
--- a/src/protocols/ssh/ttymode.h
+++ b/src/protocols/ssh/ttymode.h
@@ -22,11 +22,31 @@
 
 #include "config.h"
 
+/**
+ * The SSH TTY mode encoding opcode that terminates
+ * the list of TTY modes.
+ */
 #define GUAC_SSH_TTY_OP_END 0
+
+/**
+ * The SSH tty mode encoding opcode that configures
+ * the TTY erase code to configure the server
+ * backspace key.
+ */
 #define GUAC_SSH_TTY_OP_VERASE 3
 
+/**
+ * The default ASCII code to send for the backspace
+ * key that will be sent to the SSH server.
+ */
 #define GUAC_SSH_TERM_DEFAULT_BACKSPACE 127
 
+/**
+ * The array of TTY mode encoding data to send to the
+ * SSH server.  These consist of pairs of byte codes
+ * and uint32 (4-byte) values, with a 0 to terminate
+ * the list.
+ */
 extern const char GUAC_SSH_TTY_MODES[6];
 
 #endif

From 46e908c06eae26d419f72bd3bd071287ca4c02f6 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Fri, 23 Feb 2018 22:14:11 -0500
Subject: [PATCH 04/22] GUACAMOLE-269: Allow backspace key to be configured.

---
 src/protocols/ssh/settings.c     | 13 +++++++++++++
 src/protocols/ssh/settings.h     |  5 +++++
 src/protocols/ssh/ssh.c          |  2 +-
 src/protocols/telnet/settings.c  | 11 +++++++++++
 src/protocols/telnet/settings.h  |  7 +++++++
 src/protocols/telnet/telnet.c    |  2 +-
 src/terminal/terminal.c          |  9 +++++++--
 src/terminal/terminal/terminal.h | 12 +++++++++++-
 8 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/src/protocols/ssh/settings.c b/src/protocols/ssh/settings.c
index 7c803eaa..89b6e82b 100644
--- a/src/protocols/ssh/settings.c
+++ b/src/protocols/ssh/settings.c
@@ -56,6 +56,7 @@ const char* GUAC_SSH_CLIENT_ARGS[] = {
     "create-recording-path",
     "read-only",
     "server-alive-interval",
+    "backspace",
     NULL
 };
 
@@ -209,6 +210,13 @@ enum SSH_ARGS_IDX {
      */
     IDX_SERVER_ALIVE_INTERVAL,
 
+    /**
+     * The ASCII code, in decimal, to send for the backspace key, as configured
+     * by the SSH connection from the client.  By default this will be 0x7f,
+     * the ASCII DELETE code.
+     */
+    IDX_BACKSPACE,
+
     SSH_ARGS_COUNT
 };
 
@@ -348,6 +356,11 @@ guac_ssh_settings* guac_ssh_parse_args(guac_user* user,
         guac_user_parse_args_int(user, GUAC_SSH_CLIENT_ARGS, argv,
                 IDX_SERVER_ALIVE_INTERVAL, 0);
 
+    /* Parse backspace key setting */
+    settings->backspace =
+        guac_user_parse_args_int(user, GUAC_SSH_CLIENT_ARGS, argv,
+                IDX_BACKSPACE, 127);
+
     /* Parsing was successful */
     return settings;
 
diff --git a/src/protocols/ssh/settings.h b/src/protocols/ssh/settings.h
index 689d4258..65f60fa8 100644
--- a/src/protocols/ssh/settings.h
+++ b/src/protocols/ssh/settings.h
@@ -223,6 +223,11 @@ typedef struct guac_ssh_settings {
      */
     int server_alive_interval;
 
+    /**
+     * The decismal ASCII code of the command to send for backspace.
+     */
+    int backspace;
+
 } guac_ssh_settings;
 
 /**
diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 62bfbb25..86ebddbc 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -207,7 +207,7 @@ void* ssh_client_thread(void* data) {
     ssh_client->term = guac_terminal_create(client,
             settings->font_name, settings->font_size,
             settings->resolution, settings->width, settings->height,
-            settings->color_scheme);
+            settings->color_scheme, settings->backspace);
 
     /* Fail if terminal init failed */
     if (ssh_client->term == NULL) {
diff --git a/src/protocols/telnet/settings.c b/src/protocols/telnet/settings.c
index 082cff48..acb1f905 100644
--- a/src/protocols/telnet/settings.c
+++ b/src/protocols/telnet/settings.c
@@ -50,6 +50,7 @@ const char* GUAC_TELNET_CLIENT_ARGS[] = {
     "recording-include-keys",
     "create-recording-path",
     "read-only",
+    "backspace",
     NULL
 };
 
@@ -174,6 +175,11 @@ enum TELNET_ARGS_IDX {
      */
     IDX_READ_ONLY,
 
+    /**
+     * ASCII code to use for the backspace key, or 127 if not specified.
+     */
+    IDX_BACKSPACE,
+
     TELNET_ARGS_COUNT
 };
 
@@ -328,6 +334,11 @@ guac_telnet_settings* guac_telnet_parse_args(guac_user* user,
         guac_user_parse_args_boolean(user, GUAC_TELNET_CLIENT_ARGS, argv,
                 IDX_CREATE_RECORDING_PATH, false);
 
+    /* Parse backspae key code */
+    settings->backspace =
+        guac_user_parse_args_int(user, GUAC_TELNET_CLIENT_ARGS, argv,
+                IDX_BACKSPACE, 127);
+
     /* Parsing was successful */
     return settings;
 
diff --git a/src/protocols/telnet/settings.h b/src/protocols/telnet/settings.h
index 11761c63..71c807a3 100644
--- a/src/protocols/telnet/settings.h
+++ b/src/protocols/telnet/settings.h
@@ -207,6 +207,13 @@ typedef struct guac_telnet_settings {
      */
     bool recording_include_keys;
 
+    /**
+     * The ASCII code, in decimal, that the telnet client will use when the
+     * backspace key is pressed.  By default, this is 0x7f, ASCII delete,
+     * but can be configured in the client settings.
+     */
+    int backspace;
+
 } guac_telnet_settings;
 
 /**
diff --git a/src/protocols/telnet/telnet.c b/src/protocols/telnet/telnet.c
index 2a4000d8..040d10be 100644
--- a/src/protocols/telnet/telnet.c
+++ b/src/protocols/telnet/telnet.c
@@ -480,7 +480,7 @@ void* guac_telnet_client_thread(void* data) {
     telnet_client->term = guac_terminal_create(client,
             settings->font_name, settings->font_size,
             settings->resolution, settings->width, settings->height,
-            settings->color_scheme);
+            settings->color_scheme, settings->backspace);
 
     /* Fail if terminal init failed */
     if (telnet_client->term == NULL) {
diff --git a/src/terminal/terminal.c b/src/terminal/terminal.c
index 4d2171a0..0dae5ccd 100644
--- a/src/terminal/terminal.c
+++ b/src/terminal/terminal.c
@@ -257,7 +257,8 @@ void* guac_terminal_thread(void* data) {
 
 guac_terminal* guac_terminal_create(guac_client* client,
         const char* font_name, int font_size, int dpi,
-        int width, int height, const char* color_scheme) {
+        int width, int height, const char* color_scheme,
+        const int backspace) {
 
     int default_foreground;
     int default_background;
@@ -406,6 +407,10 @@ guac_terminal* guac_terminal_create(guac_client* client,
         return NULL;
     }
 
+    /* Configure backspace */
+    term->backspace = backspace;
+    guac_client_log(client, GUAC_LOG_DEBUG, "Backspace has been set to %d", term->backspace);
+
     return term;
 
 }
@@ -1594,7 +1599,7 @@ static int __guac_terminal_send_key(guac_terminal* term, int keysym, int pressed
         /* Non-printable keys */
         else {
 
-            if (keysym == 0xFF08) return guac_terminal_send_string(term, "\x7F"); /* Backspace */
+            if (keysym == 0xFF08) return guac_terminal_send_string(term, &term->backspace); /* Backspace */
             if (keysym == 0xFF09 || keysym == 0xFF89) return guac_terminal_send_string(term, "\x09"); /* Tab */
             if (keysym == 0xFF0D || keysym == 0xFF8D) return guac_terminal_send_string(term, "\x0D"); /* Enter */
             if (keysym == 0xFF1B) return guac_terminal_send_string(term, "\x1B"); /* Esc */
diff --git a/src/terminal/terminal/terminal.h b/src/terminal/terminal/terminal.h
index 37b07484..90cf06ac 100644
--- a/src/terminal/terminal/terminal.h
+++ b/src/terminal/terminal/terminal.h
@@ -432,6 +432,11 @@ struct guac_terminal {
      */
     guac_common_clipboard* clipboard;
 
+    /**
+     * Hexidecimal ASCII code sent when backspace is pressed.
+     */
+    char backspace;
+
 };
 
 /**
@@ -464,13 +469,18 @@ struct guac_terminal {
  *     invalid, a warning will be logged, and the terminal will fall back on
  *     GUAC_TERMINAL_SCHEME_GRAY_BLACK.
  *
+ * @param backspace
+ *     The decimal ASCII code to send when backspace is pressed in
+ *     this terminal.
+ *
  * @return
  *     A new guac_terminal having the given font, dimensions, and attributes
  *     which renders all text to the given client.
  */
 guac_terminal* guac_terminal_create(guac_client* client,
         const char* font_name, int font_size, int dpi,
-        int width, int height, const char* color_scheme);
+        int width, int height, const char* color_scheme,
+        const int backspace);
 
 /**
  * Frees all resources associated with the given terminal.

From fd58d31eeae1857f33d3d679da782b465c289026 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Sun, 25 Feb 2018 08:41:14 -0500
Subject: [PATCH 05/22] GUACAMOLE-269: Use backspace config to set up tty
 modes.

---
 src/protocols/ssh/ssh.c     | 10 ++++--
 src/protocols/ssh/ttymode.c | 61 ++++++++++++++++++++++++++++++++++---
 src/protocols/ssh/ttymode.h | 52 ++++++++++++++++++++++++++-----
 3 files changed, 108 insertions(+), 15 deletions(-)

diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 86ebddbc..6b90a197 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -192,6 +192,9 @@ void* ssh_client_thread(void* data) {
         return NULL;
     }
 
+    /* Initialize a ttymode array */
+    guac_ssh_ttymodes ssh_ttymodes = init_ttymodes();
+
     /* Set up screen recording, if requested */
     if (settings->recording_path != NULL) {
         ssh_client->recording = guac_common_recording_create(client,
@@ -209,6 +212,9 @@ void* ssh_client_thread(void* data) {
             settings->resolution, settings->width, settings->height,
             settings->color_scheme, settings->backspace);
 
+    /* Add the backspace key to the ttymode array */
+    add_ttymode(&ssh_ttymodes, GUAC_SSH_TTY_OP_VERASE, settings->backspace);
+
     /* Fail if terminal init failed */
     if (ssh_client->term == NULL) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR,
@@ -298,8 +304,8 @@ void* ssh_client_thread(void* data) {
     }
 
     /* Request PTY */
-    if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1, GUAC_SSH_TTY_MODES,
-            sizeof(GUAC_SSH_TTY_MODES), ssh_client->term->term_width, ssh_client->term->term_height, 0, 0)) {
+    if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1, ttymodes_to_array(&ssh_ttymodes),
+            sizeof_ttymodes(&ssh_ttymodes), ssh_client->term->term_width, ssh_client->term->term_height, 0, 0)) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_UPSTREAM_ERROR, "Unable to allocate PTY.");
         return NULL;
     }
diff --git a/src/protocols/ssh/ttymode.c b/src/protocols/ssh/ttymode.c
index e5baff4f..286f124f 100644
--- a/src/protocols/ssh/ttymode.c
+++ b/src/protocols/ssh/ttymode.c
@@ -20,8 +20,59 @@
 #include "config.h"
 #include "ttymode.h"
 
-const char GUAC_SSH_TTY_MODES[6] = {
-    GUAC_SSH_TTY_OP_VERASE,
-    0, 0, 0, GUAC_SSH_TERM_DEFAULT_BACKSPACE,
-    GUAC_SSH_TTY_OP_END
-};
+#include <stdlib.h>
+#include <string.h>
+
+guac_ssh_ttymodes init_ttymodes() {
+    // Simple allocation for a placeholder
+    guac_ssh_ttymode* ttymode_array = malloc(1);
+    
+    // Set up the initial data structure.
+    guac_ssh_ttymodes empty_modes = {
+        ttymode_array,
+        0
+    };
+
+    return empty_modes;
+}
+
+void add_ttymode(guac_ssh_ttymodes *tty_modes, char opcode, uint32_t value) {
+    tty_modes->num_opcodes++;
+    tty_modes->ttymode_array = realloc(tty_modes->ttymode_array, sizeof(guac_ssh_ttymode) * tty_modes->num_opcodes);
+    tty_modes->ttymode_array[tty_modes->num_opcodes - 1].opcode = opcode;
+    tty_modes->ttymode_array[tty_modes->num_opcodes - 1].value = value;
+
+}
+
+int sizeof_ttymodes(guac_ssh_ttymodes *tty_modes) {
+    // Each opcode pair is 5 bytes (1 opcode, 4 value)
+    // Add one for the ending opcode
+    return (tty_modes->num_opcodes * 5) + 1;
+}
+
+char* ttymodes_to_array(guac_ssh_ttymodes *tty_modes) {
+    // Total data size should be number of tracked opcodes
+    // plus one final byte for the TTY_OP_END code.
+    int data_size = (tty_modes->num_opcodes * 5) + 1;
+    char* temp = malloc(data_size);
+
+    // Loop through the array based on number of tracked
+    // opcodes and convert each one.
+    for (int i = 0; i < tty_modes->num_opcodes; i++) {
+        int idx = i * 5;
+        uint32_t value = tty_modes->ttymode_array[i].value;
+        // Opcode goes in first byte.
+        temp[idx] = tty_modes->ttymode_array[i].opcode;
+
+        // Convert 32-bit int to individual bytes.
+        temp[idx+1] = (value >> 24) & 0xFF;
+        temp[idx+2] = (value >> 16) & 0xFF;
+        temp[idx+3] = (value >> 8) & 0xFF;
+        temp[idx+4] = value & 0xFF;
+    }
+    
+    // Add the ending opcode
+    temp[data_size - 1] = GUAC_SSH_TTY_OP_END;
+
+    return temp;
+}
diff --git a/src/protocols/ssh/ttymode.h b/src/protocols/ssh/ttymode.h
index e1a0101f..93f85bf1 100644
--- a/src/protocols/ssh/ttymode.h
+++ b/src/protocols/ssh/ttymode.h
@@ -22,6 +22,8 @@
 
 #include "config.h"
 
+#include <stdint.h>
+
 /**
  * The SSH TTY mode encoding opcode that terminates
  * the list of TTY modes.
@@ -36,17 +38,51 @@
 #define GUAC_SSH_TTY_OP_VERASE 3
 
 /**
- * The default ASCII code to send for the backspace
- * key that will be sent to the SSH server.
+ * A data type which holds a single opcode
+ * and the value for that opcode.
  */
-#define GUAC_SSH_TERM_DEFAULT_BACKSPACE 127
+typedef struct guac_ssh_ttymode {
+    char opcode;
+    uint32_t value;
+} guac_ssh_ttymode;
 
 /**
- * The array of TTY mode encoding data to send to the
- * SSH server.  These consist of pairs of byte codes
- * and uint32 (4-byte) values, with a 0 to terminate
- * the list.
+ * A data type which holds an array of 
+ * guac_ssh_ttymode data, along with the count of
+ * the number of opcodes currently in the array.
  */
-extern const char GUAC_SSH_TTY_MODES[6];
+typedef struct guac_ssh_ttymodes {
+    guac_ssh_ttymode* ttymode_array;
+    int num_opcodes;
+} guac_ssh_ttymodes;
+
+
+/**
+ * Initialize an empty guac_ssh_ttymodes data structure,
+ * with a null array of guac_ssh_ttymode and opcodes
+ * set to zero.
+ */
+guac_ssh_ttymodes init_ttymodes();
+
+/**
+ * Add an item to the opcode array.  This resizes the
+ * array, increments the number of opcodes, and adds
+ * the specified opcode and value pair to the data
+ * structure.
+ */
+void add_ttymode(guac_ssh_ttymodes *tty_modes, char opcode, uint32_t value);
+
+/**
+ * Retrieve the size, in bytes, of the ttymode_array
+ * in the given guac_ssh_ttymodes data structure.
+ */
+int sizeof_ttymodes(guac_ssh_ttymodes *tty_modes);
+
+/**
+ * Convert the ttymodes data structure into a char
+ * pointer array suitable for passing into the
+ * libssh2_channel_request_pty_ex() function.
+ */
+char* ttymodes_to_array(guac_ssh_ttymodes *tty_modes);
 
 #endif

From 9bd28321e5d4b900765539422a9baae917542d1a Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Tue, 27 Feb 2018 09:13:01 -0500
Subject: [PATCH 06/22] GUACAMOLE-269: Fix up style in comments.

---
 src/protocols/ssh/settings.h |  2 +-
 src/protocols/ssh/ttymode.c  | 24 +++++++++++++-----------
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/src/protocols/ssh/settings.h b/src/protocols/ssh/settings.h
index 65f60fa8..175ece93 100644
--- a/src/protocols/ssh/settings.h
+++ b/src/protocols/ssh/settings.h
@@ -224,7 +224,7 @@ typedef struct guac_ssh_settings {
     int server_alive_interval;
 
     /**
-     * The decismal ASCII code of the command to send for backspace.
+     * The integer ASCII code of the command to send for backspace.
      */
     int backspace;
 
diff --git a/src/protocols/ssh/ttymode.c b/src/protocols/ssh/ttymode.c
index 286f124f..f1e21d3f 100644
--- a/src/protocols/ssh/ttymode.c
+++ b/src/protocols/ssh/ttymode.c
@@ -24,10 +24,10 @@
 #include <string.h>
 
 guac_ssh_ttymodes init_ttymodes() {
-    // Simple allocation for a placeholder
+    /* Simple allocation for a placeholder */
     guac_ssh_ttymode* ttymode_array = malloc(1);
     
-    // Set up the initial data structure.
+    /* Set up the initial data structure. */
     guac_ssh_ttymodes empty_modes = {
         ttymode_array,
         0
@@ -45,33 +45,35 @@ void add_ttymode(guac_ssh_ttymodes *tty_modes, char opcode, uint32_t value) {
 }
 
 int sizeof_ttymodes(guac_ssh_ttymodes *tty_modes) {
-    // Each opcode pair is 5 bytes (1 opcode, 4 value)
-    // Add one for the ending opcode
+    /* Each opcode pair is 5 bytes (1 opcode, 4 value)
+       Add one for the ending opcode */
+     
     return (tty_modes->num_opcodes * 5) + 1;
 }
 
 char* ttymodes_to_array(guac_ssh_ttymodes *tty_modes) {
-    // Total data size should be number of tracked opcodes
-    // plus one final byte for the TTY_OP_END code.
+    /* Total data size should be number of tracked opcodes
+       plus one final byte for the TTY_OP_END code. */
     int data_size = (tty_modes->num_opcodes * 5) + 1;
     char* temp = malloc(data_size);
 
-    // Loop through the array based on number of tracked
-    // opcodes and convert each one.
+    /* Loop through the array based on number of tracked
+       opcodes and convert each one. */
     for (int i = 0; i < tty_modes->num_opcodes; i++) {
         int idx = i * 5;
         uint32_t value = tty_modes->ttymode_array[i].value;
-        // Opcode goes in first byte.
+
+        /* Opcode goes in first byte. */
         temp[idx] = tty_modes->ttymode_array[i].opcode;
 
-        // Convert 32-bit int to individual bytes.
+        /* Convert 32-bit int to individual bytes. */
         temp[idx+1] = (value >> 24) & 0xFF;
         temp[idx+2] = (value >> 16) & 0xFF;
         temp[idx+3] = (value >> 8) & 0xFF;
         temp[idx+4] = value & 0xFF;
     }
     
-    // Add the ending opcode
+    /* Add the ending opcode */
     temp[data_size - 1] = GUAC_SSH_TTY_OP_END;
 
     return temp;

From c286668b797a149c77ae609d654d3e7899a9c36b Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Tue, 27 Feb 2018 09:23:30 -0500
Subject: [PATCH 07/22] GUACAMOLE-269: Name functions per Guacamole standards.

---
 src/protocols/ssh/ssh.c     | 9 +++++----
 src/protocols/ssh/ttymode.c | 8 ++++----
 src/protocols/ssh/ttymode.h | 8 ++++----
 3 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 6b90a197..6aecde0c 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -193,7 +193,7 @@ void* ssh_client_thread(void* data) {
     }
 
     /* Initialize a ttymode array */
-    guac_ssh_ttymodes ssh_ttymodes = init_ttymodes();
+    guac_ssh_ttymodes ssh_ttymodes = guac_ssh_ttymodes_init();
 
     /* Set up screen recording, if requested */
     if (settings->recording_path != NULL) {
@@ -213,7 +213,7 @@ void* ssh_client_thread(void* data) {
             settings->color_scheme, settings->backspace);
 
     /* Add the backspace key to the ttymode array */
-    add_ttymode(&ssh_ttymodes, GUAC_SSH_TTY_OP_VERASE, settings->backspace);
+    guac_ssh_ttymodes_add(&ssh_ttymodes, GUAC_SSH_TTY_OP_VERASE, settings->backspace);
 
     /* Fail if terminal init failed */
     if (ssh_client->term == NULL) {
@@ -304,8 +304,9 @@ void* ssh_client_thread(void* data) {
     }
 
     /* Request PTY */
-    if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1, ttymodes_to_array(&ssh_ttymodes),
-            sizeof_ttymodes(&ssh_ttymodes), ssh_client->term->term_width, ssh_client->term->term_height, 0, 0)) {
+    if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1,
+            guac_ssh_ttymodes_to_array(&ssh_ttymodes), guac_ssh_ttymodes_size(&ssh_ttymodes),
+            ssh_client->term->term_width, ssh_client->term->term_height, 0, 0)) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_UPSTREAM_ERROR, "Unable to allocate PTY.");
         return NULL;
     }
diff --git a/src/protocols/ssh/ttymode.c b/src/protocols/ssh/ttymode.c
index f1e21d3f..f21e9f7f 100644
--- a/src/protocols/ssh/ttymode.c
+++ b/src/protocols/ssh/ttymode.c
@@ -23,7 +23,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-guac_ssh_ttymodes init_ttymodes() {
+guac_ssh_ttymodes guac_ssh_ttymodes_init() {
     /* Simple allocation for a placeholder */
     guac_ssh_ttymode* ttymode_array = malloc(1);
     
@@ -36,7 +36,7 @@ guac_ssh_ttymodes init_ttymodes() {
     return empty_modes;
 }
 
-void add_ttymode(guac_ssh_ttymodes *tty_modes, char opcode, uint32_t value) {
+void guac_ssh_ttymodes_add(guac_ssh_ttymodes *tty_modes, char opcode, uint32_t value) {
     tty_modes->num_opcodes++;
     tty_modes->ttymode_array = realloc(tty_modes->ttymode_array, sizeof(guac_ssh_ttymode) * tty_modes->num_opcodes);
     tty_modes->ttymode_array[tty_modes->num_opcodes - 1].opcode = opcode;
@@ -44,14 +44,14 @@ void add_ttymode(guac_ssh_ttymodes *tty_modes, char opcode, uint32_t value) {
 
 }
 
-int sizeof_ttymodes(guac_ssh_ttymodes *tty_modes) {
+int guac_ssh_ttymodes_size(guac_ssh_ttymodes *tty_modes) {
     /* Each opcode pair is 5 bytes (1 opcode, 4 value)
        Add one for the ending opcode */
      
     return (tty_modes->num_opcodes * 5) + 1;
 }
 
-char* ttymodes_to_array(guac_ssh_ttymodes *tty_modes) {
+char* guac_ssh_ttymodes_to_array(guac_ssh_ttymodes *tty_modes) {
     /* Total data size should be number of tracked opcodes
        plus one final byte for the TTY_OP_END code. */
     int data_size = (tty_modes->num_opcodes * 5) + 1;
diff --git a/src/protocols/ssh/ttymode.h b/src/protocols/ssh/ttymode.h
index 93f85bf1..ca5569d4 100644
--- a/src/protocols/ssh/ttymode.h
+++ b/src/protocols/ssh/ttymode.h
@@ -62,7 +62,7 @@ typedef struct guac_ssh_ttymodes {
  * with a null array of guac_ssh_ttymode and opcodes
  * set to zero.
  */
-guac_ssh_ttymodes init_ttymodes();
+guac_ssh_ttymodes guac_ssh_ttymodes_init();
 
 /**
  * Add an item to the opcode array.  This resizes the
@@ -70,19 +70,19 @@ guac_ssh_ttymodes init_ttymodes();
  * the specified opcode and value pair to the data
  * structure.
  */
-void add_ttymode(guac_ssh_ttymodes *tty_modes, char opcode, uint32_t value);
+void guac_ssh_ttymodes_add(guac_ssh_ttymodes *tty_modes, char opcode, uint32_t value);
 
 /**
  * Retrieve the size, in bytes, of the ttymode_array
  * in the given guac_ssh_ttymodes data structure.
  */
-int sizeof_ttymodes(guac_ssh_ttymodes *tty_modes);
+int guac_ssh_ttymodes_size(guac_ssh_ttymodes *tty_modes);
 
 /**
  * Convert the ttymodes data structure into a char
  * pointer array suitable for passing into the
  * libssh2_channel_request_pty_ex() function.
  */
-char* ttymodes_to_array(guac_ssh_ttymodes *tty_modes);
+char* guac_ssh_ttymodes_to_array(guac_ssh_ttymodes *tty_modes);
 
 #endif

From dd78d230eae38f8063683f2c9335abdb6af664d3 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Tue, 27 Feb 2018 09:35:29 -0500
Subject: [PATCH 08/22] GUACAMOLE-269: Backspace key should send
 null-terminated string.

---
 src/terminal/terminal.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/terminal/terminal.c b/src/terminal/terminal.c
index 0dae5ccd..35810dcc 100644
--- a/src/terminal/terminal.c
+++ b/src/terminal/terminal.c
@@ -1599,7 +1599,12 @@ static int __guac_terminal_send_key(guac_terminal* term, int keysym, int pressed
         /* Non-printable keys */
         else {
 
-            if (keysym == 0xFF08) return guac_terminal_send_string(term, &term->backspace); /* Backspace */
+            if (keysym == 0xFF08) {
+                char* backspace_str = malloc(sizeof(char) * 2);
+                backspace_str[0] = term->backspace;
+                backspace_str[1] = '\0';
+                return guac_terminal_send_string(term, backspace_str); /* Backspace */
+            }
             if (keysym == 0xFF09 || keysym == 0xFF89) return guac_terminal_send_string(term, "\x09"); /* Tab */
             if (keysym == 0xFF0D || keysym == 0xFF8D) return guac_terminal_send_string(term, "\x0D"); /* Enter */
             if (keysym == 0xFF1B) return guac_terminal_send_string(term, "\x1B"); /* Esc */

From 33cca463462604669c40b235c6f2cd8371841147 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Tue, 27 Feb 2018 09:41:03 -0500
Subject: [PATCH 09/22] GUACAMOLE-269: Remove debug code.

---
 src/terminal/terminal.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/terminal/terminal.c b/src/terminal/terminal.c
index 35810dcc..70a2640a 100644
--- a/src/terminal/terminal.c
+++ b/src/terminal/terminal.c
@@ -409,7 +409,6 @@ guac_terminal* guac_terminal_create(guac_client* client,
 
     /* Configure backspace */
     term->backspace = backspace;
-    guac_client_log(client, GUAC_LOG_DEBUG, "Backspace has been set to %d", term->backspace);
 
     return term;
 

From 64ca77f3a59ea69ac42812705744ebece235ddae Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Tue, 27 Feb 2018 09:59:18 -0500
Subject: [PATCH 10/22] GUACAMOLE-269: Change struct to struct pointer.

---
 src/protocols/ssh/ssh.c     | 6 +++---
 src/protocols/ssh/ttymode.c | 9 ++++-----
 src/protocols/ssh/ttymode.h | 2 +-
 3 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 6aecde0c..eac4eced 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -193,7 +193,7 @@ void* ssh_client_thread(void* data) {
     }
 
     /* Initialize a ttymode array */
-    guac_ssh_ttymodes ssh_ttymodes = guac_ssh_ttymodes_init();
+    guac_ssh_ttymodes* ssh_ttymodes = guac_ssh_ttymodes_init();
 
     /* Set up screen recording, if requested */
     if (settings->recording_path != NULL) {
@@ -213,7 +213,7 @@ void* ssh_client_thread(void* data) {
             settings->color_scheme, settings->backspace);
 
     /* Add the backspace key to the ttymode array */
-    guac_ssh_ttymodes_add(&ssh_ttymodes, GUAC_SSH_TTY_OP_VERASE, settings->backspace);
+    guac_ssh_ttymodes_add(ssh_ttymodes, GUAC_SSH_TTY_OP_VERASE, settings->backspace);
 
     /* Fail if terminal init failed */
     if (ssh_client->term == NULL) {
@@ -305,7 +305,7 @@ void* ssh_client_thread(void* data) {
 
     /* Request PTY */
     if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1,
-            guac_ssh_ttymodes_to_array(&ssh_ttymodes), guac_ssh_ttymodes_size(&ssh_ttymodes),
+            guac_ssh_ttymodes_to_array(ssh_ttymodes), guac_ssh_ttymodes_size(ssh_ttymodes),
             ssh_client->term->term_width, ssh_client->term->term_height, 0, 0)) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_UPSTREAM_ERROR, "Unable to allocate PTY.");
         return NULL;
diff --git a/src/protocols/ssh/ttymode.c b/src/protocols/ssh/ttymode.c
index f21e9f7f..02fb54ba 100644
--- a/src/protocols/ssh/ttymode.c
+++ b/src/protocols/ssh/ttymode.c
@@ -23,15 +23,14 @@
 #include <stdlib.h>
 #include <string.h>
 
-guac_ssh_ttymodes guac_ssh_ttymodes_init() {
+guac_ssh_ttymodes* guac_ssh_ttymodes_init() {
     /* Simple allocation for a placeholder */
     guac_ssh_ttymode* ttymode_array = malloc(1);
     
     /* Set up the initial data structure. */
-    guac_ssh_ttymodes empty_modes = {
-        ttymode_array,
-        0
-    };
+    guac_ssh_ttymodes* empty_modes = malloc(sizeof(guac_ssh_ttymodes));
+    empty_modes->ttymode_array = ttymode_array;
+    empty_modes->num_opcodes = 0;
 
     return empty_modes;
 }
diff --git a/src/protocols/ssh/ttymode.h b/src/protocols/ssh/ttymode.h
index ca5569d4..ecc57de0 100644
--- a/src/protocols/ssh/ttymode.h
+++ b/src/protocols/ssh/ttymode.h
@@ -62,7 +62,7 @@ typedef struct guac_ssh_ttymodes {
  * with a null array of guac_ssh_ttymode and opcodes
  * set to zero.
  */
-guac_ssh_ttymodes guac_ssh_ttymodes_init();
+guac_ssh_ttymodes* guac_ssh_ttymodes_init();
 
 /**
  * Add an item to the opcode array.  This resizes the

From c3e1b2afefb76a12a8c21361c15195e05fecfc84 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Tue, 27 Feb 2018 15:49:57 -0500
Subject: [PATCH 11/22] GUACAMOLE-269: Fix minor style issues and update
 comments.

---
 src/protocols/ssh/settings.c     | 4 ++--
 src/protocols/ssh/ttymode.c      | 7 +++++--
 src/protocols/telnet/settings.c  | 3 ++-
 src/protocols/telnet/settings.h  | 6 +++---
 src/terminal/terminal.c          | 3 ++-
 src/terminal/terminal/terminal.h | 4 ++--
 6 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/src/protocols/ssh/settings.c b/src/protocols/ssh/settings.c
index 89b6e82b..983f7f08 100644
--- a/src/protocols/ssh/settings.c
+++ b/src/protocols/ssh/settings.c
@@ -211,8 +211,8 @@ enum SSH_ARGS_IDX {
     IDX_SERVER_ALIVE_INTERVAL,
 
     /**
-     * The ASCII code, in decimal, to send for the backspace key, as configured
-     * by the SSH connection from the client.  By default this will be 0x7f,
+     * The ASCII code, as an integer, to send for the backspace key, as configured
+     * by the SSH connection from the client.  By default this will be 127,
      * the ASCII DELETE code.
      */
     IDX_BACKSPACE,
diff --git a/src/protocols/ssh/ttymode.c b/src/protocols/ssh/ttymode.c
index 02fb54ba..39830904 100644
--- a/src/protocols/ssh/ttymode.c
+++ b/src/protocols/ssh/ttymode.c
@@ -36,17 +36,20 @@ guac_ssh_ttymodes* guac_ssh_ttymodes_init() {
 }
 
 void guac_ssh_ttymodes_add(guac_ssh_ttymodes *tty_modes, char opcode, uint32_t value) {
+    /* Increment number of opcodes */
     tty_modes->num_opcodes++;
+
+    /* Increase size of the pointer array */
     tty_modes->ttymode_array = realloc(tty_modes->ttymode_array, sizeof(guac_ssh_ttymode) * tty_modes->num_opcodes);
+
+    /* Add new values */
     tty_modes->ttymode_array[tty_modes->num_opcodes - 1].opcode = opcode;
     tty_modes->ttymode_array[tty_modes->num_opcodes - 1].value = value;
-
 }
 
 int guac_ssh_ttymodes_size(guac_ssh_ttymodes *tty_modes) {
     /* Each opcode pair is 5 bytes (1 opcode, 4 value)
        Add one for the ending opcode */
-     
     return (tty_modes->num_opcodes * 5) + 1;
 }
 
diff --git a/src/protocols/telnet/settings.c b/src/protocols/telnet/settings.c
index acb1f905..b49b773e 100644
--- a/src/protocols/telnet/settings.c
+++ b/src/protocols/telnet/settings.c
@@ -176,7 +176,8 @@ enum TELNET_ARGS_IDX {
     IDX_READ_ONLY,
 
     /**
-     * ASCII code to use for the backspace key, or 127 if not specified.
+     * ASCII code, as an integer to use for the backspace key, or 127
+     * if not specified.
      */
     IDX_BACKSPACE,
 
diff --git a/src/protocols/telnet/settings.h b/src/protocols/telnet/settings.h
index 71c807a3..9bc3dc37 100644
--- a/src/protocols/telnet/settings.h
+++ b/src/protocols/telnet/settings.h
@@ -208,9 +208,9 @@ typedef struct guac_telnet_settings {
     bool recording_include_keys;
 
     /**
-     * The ASCII code, in decimal, that the telnet client will use when the
-     * backspace key is pressed.  By default, this is 0x7f, ASCII delete,
-     * but can be configured in the client settings.
+     * The ASCII code, as an integer, that the telnet client will use when the
+     * backspace key is pressed.  By default, this is 127, ASCII delete, if
+     * not specified in the client settings.
      */
     int backspace;
 
diff --git a/src/terminal/terminal.c b/src/terminal/terminal.c
index 70a2640a..c19bd835 100644
--- a/src/terminal/terminal.c
+++ b/src/terminal/terminal.c
@@ -1598,11 +1598,12 @@ static int __guac_terminal_send_key(guac_terminal* term, int keysym, int pressed
         /* Non-printable keys */
         else {
 
+            /* Backspace can vary based on configuration of terminal by client. */
             if (keysym == 0xFF08) {
                 char* backspace_str = malloc(sizeof(char) * 2);
                 backspace_str[0] = term->backspace;
                 backspace_str[1] = '\0';
-                return guac_terminal_send_string(term, backspace_str); /* Backspace */
+                return guac_terminal_send_string(term, backspace_str);
             }
             if (keysym == 0xFF09 || keysym == 0xFF89) return guac_terminal_send_string(term, "\x09"); /* Tab */
             if (keysym == 0xFF0D || keysym == 0xFF8D) return guac_terminal_send_string(term, "\x0D"); /* Enter */
diff --git a/src/terminal/terminal/terminal.h b/src/terminal/terminal/terminal.h
index 90cf06ac..c071b402 100644
--- a/src/terminal/terminal/terminal.h
+++ b/src/terminal/terminal/terminal.h
@@ -433,7 +433,7 @@ struct guac_terminal {
     guac_common_clipboard* clipboard;
 
     /**
-     * Hexidecimal ASCII code sent when backspace is pressed.
+     * ASCII character to send when backspace is pressed.
      */
     char backspace;
 
@@ -470,7 +470,7 @@ struct guac_terminal {
  *     GUAC_TERMINAL_SCHEME_GRAY_BLACK.
  *
  * @param backspace
- *     The decimal ASCII code to send when backspace is pressed in
+ *     The integer ASCII code to send when backspace is pressed in
  *     this terminal.
  *
  * @return

From dd7522bd9fb8c23ea5f64309741b69a2764d20b4 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Sat, 3 Mar 2018 21:15:04 -0500
Subject: [PATCH 12/22] GUACAMOLE-269: Get rid of dynamic allocation and
 properly free up data structures.

---
 src/protocols/ssh/ssh.c     | 14 +++++++++---
 src/protocols/ssh/ttymode.c | 15 +++++--------
 src/protocols/ssh/ttymode.h | 44 +++++++++++++++++++++++++++++++++++--
 3 files changed, 58 insertions(+), 15 deletions(-)

diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index eac4eced..35d40134 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -193,7 +193,7 @@ void* ssh_client_thread(void* data) {
     }
 
     /* Initialize a ttymode array */
-    guac_ssh_ttymodes* ssh_ttymodes = guac_ssh_ttymodes_init();
+    guac_ssh_ttymodes* ssh_ttymodes = guac_ssh_ttymodes_init(1);
 
     /* Set up screen recording, if requested */
     if (settings->recording_path != NULL) {
@@ -303,14 +303,22 @@ void* ssh_client_thread(void* data) {
 
     }
 
+    /* Get char pointer array for TTY Mode Encoding */
+    int ttymode_size = guac_ssh_ttymodes_size(ssh_ttymodes);
+    char* ttymode_array = guac_ssh_ttymodes_to_array(ssh_ttymodes, ttymode_size);
+
     /* Request PTY */
     if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1,
-            guac_ssh_ttymodes_to_array(ssh_ttymodes), guac_ssh_ttymodes_size(ssh_ttymodes),
-            ssh_client->term->term_width, ssh_client->term->term_height, 0, 0)) {
+            ttymode_array, ttymode_size, ssh_client->term->term_width,
+            ssh_client->term->term_height, 0, 0)) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_UPSTREAM_ERROR, "Unable to allocate PTY.");
         return NULL;
     }
 
+    /* We're done with TTY Mode Encoding, so free structures. */
+    free(ttymode_array);
+    free(ssh_ttymodes);
+
     /* If a command is specified, run that instead of a shell */
     if (settings->command != NULL) {
         if (libssh2_channel_exec(ssh_client->term_channel, settings->command)) {
diff --git a/src/protocols/ssh/ttymode.c b/src/protocols/ssh/ttymode.c
index 39830904..1541da68 100644
--- a/src/protocols/ssh/ttymode.c
+++ b/src/protocols/ssh/ttymode.c
@@ -23,9 +23,9 @@
 #include <stdlib.h>
 #include <string.h>
 
-guac_ssh_ttymodes* guac_ssh_ttymodes_init() {
-    /* Simple allocation for a placeholder */
-    guac_ssh_ttymode* ttymode_array = malloc(1);
+guac_ssh_ttymodes* guac_ssh_ttymodes_init(int max_opcodes) {
+    /* Allocate enough space for the max opcodes */
+    guac_ssh_ttymode* ttymode_array = malloc(sizeof(guac_ssh_ttymode) * max_opcodes);
     
     /* Set up the initial data structure. */
     guac_ssh_ttymodes* empty_modes = malloc(sizeof(guac_ssh_ttymodes));
@@ -39,9 +39,6 @@ void guac_ssh_ttymodes_add(guac_ssh_ttymodes *tty_modes, char opcode, uint32_t v
     /* Increment number of opcodes */
     tty_modes->num_opcodes++;
 
-    /* Increase size of the pointer array */
-    tty_modes->ttymode_array = realloc(tty_modes->ttymode_array, sizeof(guac_ssh_ttymode) * tty_modes->num_opcodes);
-
     /* Add new values */
     tty_modes->ttymode_array[tty_modes->num_opcodes - 1].opcode = opcode;
     tty_modes->ttymode_array[tty_modes->num_opcodes - 1].value = value;
@@ -53,10 +50,8 @@ int guac_ssh_ttymodes_size(guac_ssh_ttymodes *tty_modes) {
     return (tty_modes->num_opcodes * 5) + 1;
 }
 
-char* guac_ssh_ttymodes_to_array(guac_ssh_ttymodes *tty_modes) {
-    /* Total data size should be number of tracked opcodes
-       plus one final byte for the TTY_OP_END code. */
-    int data_size = (tty_modes->num_opcodes * 5) + 1;
+char* guac_ssh_ttymodes_to_array(guac_ssh_ttymodes *tty_modes, int data_size) {
+ 
     char* temp = malloc(data_size);
 
     /* Loop through the array based on number of tracked
diff --git a/src/protocols/ssh/ttymode.h b/src/protocols/ssh/ttymode.h
index ecc57de0..30f36e61 100644
--- a/src/protocols/ssh/ttymode.h
+++ b/src/protocols/ssh/ttymode.h
@@ -61,20 +61,47 @@ typedef struct guac_ssh_ttymodes {
  * Initialize an empty guac_ssh_ttymodes data structure,
  * with a null array of guac_ssh_ttymode and opcodes
  * set to zero.
+ *
+ * @param max_opcodes
+ *     The maximum number of opcodes that will be allocated.
+ *
+ * @return
+ *     The pointer array for the gauc_ssh_ttymodes data
+ *     structure generated by the function.
  */
-guac_ssh_ttymodes* guac_ssh_ttymodes_init();
+guac_ssh_ttymodes* guac_ssh_ttymodes_init(int max_opcodes);
 
 /**
  * Add an item to the opcode array.  This resizes the
  * array, increments the number of opcodes, and adds
  * the specified opcode and value pair to the data
  * structure.
+ *
+ * @param tty_modes
+ *     The pointer to the guac_ssh_ttymodes data structure
+ *     to add the opcode to.
+ * 
+ * @param opcode
+ *     The single byte opcode as documented in section 8
+ *     of the SSH RFC.
+ *
+ * @param value
+ *     The four byte value of the opcodeto add to the
+ *     guac_ssh_ttymodes data structure.     
  */
 void guac_ssh_ttymodes_add(guac_ssh_ttymodes *tty_modes, char opcode, uint32_t value);
 
 /**
  * Retrieve the size, in bytes, of the ttymode_array
  * in the given guac_ssh_ttymodes data structure.
+ * 
+ * @param tty_modes
+ *     The pointer to the guac_ssh_ttymodes structure
+ *     whose size we are curious about.
+ *
+ * @return
+ *     The number of bytes of the opcodes and value paris
+ *     in the data structure.
  */
 int guac_ssh_ttymodes_size(guac_ssh_ttymodes *tty_modes);
 
@@ -82,7 +109,20 @@ int guac_ssh_ttymodes_size(guac_ssh_ttymodes *tty_modes);
  * Convert the ttymodes data structure into a char
  * pointer array suitable for passing into the
  * libssh2_channel_request_pty_ex() function.
+ *
+ * @param tty_modes
+ *     The pointer to the guac_ssh_ttymodes structure
+ *     that contains the opcode and value pairs
+ *     we want to convert to a character pointer array.
+ *
+ * @param data_size
+ *     The size of the resulting character pointer
+ *     array.
+ *
+ * @return
+ *     The character pointer array of opcode and
+ *     value pairs to be passed to a SSH session.
  */
-char* guac_ssh_ttymodes_to_array(guac_ssh_ttymodes *tty_modes);
+char* guac_ssh_ttymodes_to_array(guac_ssh_ttymodes *tty_modes, int data_size);
 
 #endif

From 45b832bfdc7ced13a8aa5a4a090a60dae818dffe Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Thu, 8 Mar 2018 09:32:19 -0500
Subject: [PATCH 13/22] GUACAMOLE-269: Remove all dynamic allocation and
 simplify implementation.

---
 src/protocols/ssh/ssh.c     |  19 +++----
 src/protocols/ssh/ttymode.c |  70 +++++++++---------------
 src/protocols/ssh/ttymode.h | 104 ++++++++++--------------------------
 3 files changed, 61 insertions(+), 132 deletions(-)

diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 35d40134..9881c304 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -193,7 +193,8 @@ void* ssh_client_thread(void* data) {
     }
 
     /* Initialize a ttymode array */
-    guac_ssh_ttymodes* ssh_ttymodes = guac_ssh_ttymodes_init(1);
+    const int num_tty_opcodes = 1;
+    char ssh_ttymodes[(GUAC_SSH_TTY_OPCODE_SIZE * num_tty_opcodes) + 1];
 
     /* Set up screen recording, if requested */
     if (settings->recording_path != NULL) {
@@ -212,9 +213,6 @@ void* ssh_client_thread(void* data) {
             settings->resolution, settings->width, settings->height,
             settings->color_scheme, settings->backspace);
 
-    /* Add the backspace key to the ttymode array */
-    guac_ssh_ttymodes_add(ssh_ttymodes, GUAC_SSH_TTY_OP_VERASE, settings->backspace);
-
     /* Fail if terminal init failed */
     if (ssh_client->term == NULL) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR,
@@ -303,22 +301,19 @@ void* ssh_client_thread(void* data) {
 
     }
 
-    /* Get char pointer array for TTY Mode Encoding */
-    int ttymode_size = guac_ssh_ttymodes_size(ssh_ttymodes);
-    char* ttymode_array = guac_ssh_ttymodes_to_array(ssh_ttymodes, ttymode_size);
+    /* Set up the ttymode array prior to requesting the PTY */
+    if (guac_ssh_ttymodes_init(ssh_ttymodes, sizeof(ssh_ttymodes),
+            num_tty_opcodes, (guac_ssh_ttymode){ GUAC_SSH_TTY_OP_VERASE, settings->backspace}))
+        guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR, "Error configuring TTY mode encoding.");
 
     /* Request PTY */
     if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1,
-            ttymode_array, ttymode_size, ssh_client->term->term_width,
+            ssh_ttymodes, sizeof(ssh_ttymodes), ssh_client->term->term_width,
             ssh_client->term->term_height, 0, 0)) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_UPSTREAM_ERROR, "Unable to allocate PTY.");
         return NULL;
     }
 
-    /* We're done with TTY Mode Encoding, so free structures. */
-    free(ttymode_array);
-    free(ssh_ttymodes);
-
     /* If a command is specified, run that instead of a shell */
     if (settings->command != NULL) {
         if (libssh2_channel_exec(ssh_client->term_channel, settings->command)) {
diff --git a/src/protocols/ssh/ttymode.c b/src/protocols/ssh/ttymode.c
index 1541da68..4c6091e5 100644
--- a/src/protocols/ssh/ttymode.c
+++ b/src/protocols/ssh/ttymode.c
@@ -20,58 +20,40 @@
 #include "config.h"
 #include "ttymode.h"
 
+#include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
 
-guac_ssh_ttymodes* guac_ssh_ttymodes_init(int max_opcodes) {
-    /* Allocate enough space for the max opcodes */
-    guac_ssh_ttymode* ttymode_array = malloc(sizeof(guac_ssh_ttymode) * max_opcodes);
-    
-    /* Set up the initial data structure. */
-    guac_ssh_ttymodes* empty_modes = malloc(sizeof(guac_ssh_ttymodes));
-    empty_modes->ttymode_array = ttymode_array;
-    empty_modes->num_opcodes = 0;
+int guac_ssh_ttymodes_init(char opcode_array[], const int array_size,
+        const int num_opcodes, ...) {
 
-    return empty_modes;
-}
+    /* Initialize the variable argument list. */
+    va_list args;
+    va_start(args, num_opcodes);
 
-void guac_ssh_ttymodes_add(guac_ssh_ttymodes *tty_modes, char opcode, uint32_t value) {
-    /* Increment number of opcodes */
-    tty_modes->num_opcodes++;
+    /* Check to make sure the array has enough space.
+       We need one extra byte at the end for the ending opcode. */
+    if ((num_opcodes * GUAC_SSH_TTY_OPCODE_SIZE) >= (array_size))
+        return 1;
 
-    /* Add new values */
-    tty_modes->ttymode_array[tty_modes->num_opcodes - 1].opcode = opcode;
-    tty_modes->ttymode_array[tty_modes->num_opcodes - 1].value = value;
-}
+    for (int i = 0; i < num_opcodes; i++) {
+        /* Calculate offset in array */
+        int offset = i * GUAC_SSH_TTY_OPCODE_SIZE;
 
-int guac_ssh_ttymodes_size(guac_ssh_ttymodes *tty_modes) {
-    /* Each opcode pair is 5 bytes (1 opcode, 4 value)
-       Add one for the ending opcode */
-    return (tty_modes->num_opcodes * 5) + 1;
-}
+        /* Get the next argument to this function */
+        guac_ssh_ttymode ttymode = va_arg(args, guac_ssh_ttymode);
 
-char* guac_ssh_ttymodes_to_array(guac_ssh_ttymodes *tty_modes, int data_size) {
- 
-    char* temp = malloc(data_size);
-
-    /* Loop through the array based on number of tracked
-       opcodes and convert each one. */
-    for (int i = 0; i < tty_modes->num_opcodes; i++) {
-        int idx = i * 5;
-        uint32_t value = tty_modes->ttymode_array[i].value;
-
-        /* Opcode goes in first byte. */
-        temp[idx] = tty_modes->ttymode_array[i].opcode;
-
-        /* Convert 32-bit int to individual bytes. */
-        temp[idx+1] = (value >> 24) & 0xFF;
-        temp[idx+2] = (value >> 16) & 0xFF;
-        temp[idx+3] = (value >> 8) & 0xFF;
-        temp[idx+4] = value & 0xFF;
+        /* Place opcode and value in array */
+        opcode_array[offset] = ttymode.opcode;
+        opcode_array[offset + 1] = (ttymode.value >> 24) & 0xFF;
+        opcode_array[offset + 2] = (ttymode.value >> 16) & 0xFF;
+        opcode_array[offset + 3] = (ttymode.value >> 8) & 0xFF;
+        opcode_array[offset + 4] = ttymode.value & 0xFF;
     }
-    
-    /* Add the ending opcode */
-    temp[data_size - 1] = GUAC_SSH_TTY_OP_END;
 
-    return temp;
+    /* Put the end opcode in the last opcode space */
+    opcode_array[num_opcodes * GUAC_SSH_TTY_OPCODE_SIZE] = GUAC_SSH_TTY_OP_END;
+
+    return 0;
+
 }
diff --git a/src/protocols/ssh/ttymode.h b/src/protocols/ssh/ttymode.h
index 30f36e61..be40b84c 100644
--- a/src/protocols/ssh/ttymode.h
+++ b/src/protocols/ssh/ttymode.h
@@ -24,6 +24,14 @@
 
 #include <stdint.h>
 
+/**
+ * The size of a TTY mode encoding opcode and
+ * value pair.  As defined in the SSH RFC, this
+ * is 5 bytes - a single byte for the opcode, and
+ * 4 bytes for the value.
+ */
+#define GUAC_SSH_TTY_OPCODE_SIZE 5
+
 /**
  * The SSH TTY mode encoding opcode that terminates
  * the list of TTY modes.
@@ -31,15 +39,15 @@
 #define GUAC_SSH_TTY_OP_END 0
 
 /**
- * The SSH tty mode encoding opcode that configures
+ * The SSH TTY mode encoding opcode that configures
  * the TTY erase code to configure the server
  * backspace key.
  */
 #define GUAC_SSH_TTY_OP_VERASE 3
 
 /**
- * A data type which holds a single opcode
- * and the value for that opcode.
+ * Simple structure that defines a opcode and
+ * value pair.
  */
 typedef struct guac_ssh_ttymode {
     char opcode;
@@ -47,82 +55,26 @@ typedef struct guac_ssh_ttymode {
 } guac_ssh_ttymode;
 
 /**
- * A data type which holds an array of 
- * guac_ssh_ttymode data, along with the count of
- * the number of opcodes currently in the array.
- */
-typedef struct guac_ssh_ttymodes {
-    guac_ssh_ttymode* ttymode_array;
-    int num_opcodes;
-} guac_ssh_ttymodes;
-
-
-/**
- * Initialize an empty guac_ssh_ttymodes data structure,
- * with a null array of guac_ssh_ttymode and opcodes
- * set to zero.
+ * Initialize an array with the specified opcode/value
+ * pairs, and return the size, in bytes, of the array.
  *
- * @param max_opcodes
- *     The maximum number of opcodes that will be allocated.
+ * @param opcode_array
+ *     Pointer to the opcode array.
+ *
+ * @param array_size
+ *     Size, in bytes, of the array.
+ *
+ * @param num_opcodes
+ *     Number of opcodes to expect.
+ *
+ * @params ...
+ *     A variable number of guac_ssh_ttymodes
+ *     to place in the array.
  *
  * @return
- *     The pointer array for the gauc_ssh_ttymodes data
- *     structure generated by the function.
+ *     The size, in bytes, of the array.
  */
-guac_ssh_ttymodes* guac_ssh_ttymodes_init(int max_opcodes);
-
-/**
- * Add an item to the opcode array.  This resizes the
- * array, increments the number of opcodes, and adds
- * the specified opcode and value pair to the data
- * structure.
- *
- * @param tty_modes
- *     The pointer to the guac_ssh_ttymodes data structure
- *     to add the opcode to.
- * 
- * @param opcode
- *     The single byte opcode as documented in section 8
- *     of the SSH RFC.
- *
- * @param value
- *     The four byte value of the opcodeto add to the
- *     guac_ssh_ttymodes data structure.     
- */
-void guac_ssh_ttymodes_add(guac_ssh_ttymodes *tty_modes, char opcode, uint32_t value);
-
-/**
- * Retrieve the size, in bytes, of the ttymode_array
- * in the given guac_ssh_ttymodes data structure.
- * 
- * @param tty_modes
- *     The pointer to the guac_ssh_ttymodes structure
- *     whose size we are curious about.
- *
- * @return
- *     The number of bytes of the opcodes and value paris
- *     in the data structure.
- */
-int guac_ssh_ttymodes_size(guac_ssh_ttymodes *tty_modes);
-
-/**
- * Convert the ttymodes data structure into a char
- * pointer array suitable for passing into the
- * libssh2_channel_request_pty_ex() function.
- *
- * @param tty_modes
- *     The pointer to the guac_ssh_ttymodes structure
- *     that contains the opcode and value pairs
- *     we want to convert to a character pointer array.
- *
- * @param data_size
- *     The size of the resulting character pointer
- *     array.
- *
- * @return
- *     The character pointer array of opcode and
- *     value pairs to be passed to a SSH session.
- */
-char* guac_ssh_ttymodes_to_array(guac_ssh_ttymodes *tty_modes, int data_size);
+int guac_ssh_ttymodes_init(char opcode_array[], const int array_size,
+        const int num_opcodes, ...);
 
 #endif

From 86dde85b2d0f63268942a7a9ba01b6d2e3bfbb73 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Sat, 24 Mar 2018 14:53:22 -0400
Subject: [PATCH 14/22] GUACAMOLE-269: Comment and spelling updates.

---
 src/protocols/ssh/ttymode.h     | 6 ++++--
 src/protocols/telnet/settings.c | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/protocols/ssh/ttymode.h b/src/protocols/ssh/ttymode.h
index be40b84c..869d0523 100644
--- a/src/protocols/ssh/ttymode.h
+++ b/src/protocols/ssh/ttymode.h
@@ -56,7 +56,8 @@ typedef struct guac_ssh_ttymode {
 
 /**
  * Initialize an array with the specified opcode/value
- * pairs, and return the size, in bytes, of the array.
+ * pairs, returning 0 if successful, or a non-zero value
+ * if a failure occurs.
  *
  * @param opcode_array
  *     Pointer to the opcode array.
@@ -72,7 +73,8 @@ typedef struct guac_ssh_ttymode {
  *     to place in the array.
  *
  * @return
- *     The size, in bytes, of the array.
+ *     Zero of the function is successful, non-zero
+ *     if a failure occurs.
  */
 int guac_ssh_ttymodes_init(char opcode_array[], const int array_size,
         const int num_opcodes, ...);
diff --git a/src/protocols/telnet/settings.c b/src/protocols/telnet/settings.c
index b49b773e..8f802915 100644
--- a/src/protocols/telnet/settings.c
+++ b/src/protocols/telnet/settings.c
@@ -335,7 +335,7 @@ guac_telnet_settings* guac_telnet_parse_args(guac_user* user,
         guac_user_parse_args_boolean(user, GUAC_TELNET_CLIENT_ARGS, argv,
                 IDX_CREATE_RECORDING_PATH, false);
 
-    /* Parse backspae key code */
+    /* Parse backspace key code */
     settings->backspace =
         guac_user_parse_args_int(user, GUAC_TELNET_CLIENT_ARGS, argv,
                 IDX_BACKSPACE, 127);

From 112ce5299e6534ef0dac6ac8280b0fd7c512eeeb Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Sat, 24 Mar 2018 14:54:27 -0400
Subject: [PATCH 15/22] GUACAMOLE-269: Remove unnecessary dynamic allocation.

---
 src/terminal/terminal.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/terminal/terminal.c b/src/terminal/terminal.c
index c19bd835..bfc36d1a 100644
--- a/src/terminal/terminal.c
+++ b/src/terminal/terminal.c
@@ -1600,7 +1600,7 @@ static int __guac_terminal_send_key(guac_terminal* term, int keysym, int pressed
 
             /* Backspace can vary based on configuration of terminal by client. */
             if (keysym == 0xFF08) {
-                char* backspace_str = malloc(sizeof(char) * 2);
+                char backspace_str[2];
                 backspace_str[0] = term->backspace;
                 backspace_str[1] = '\0';
                 return guac_terminal_send_string(term, backspace_str);

From 11136f7d7bd879eb10838506b8d40ca69ad4806b Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Sat, 24 Mar 2018 15:09:34 -0400
Subject: [PATCH 16/22] GUACAMOLE-269: More documentation updates.

---
 src/protocols/ssh/ttymode.h | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/src/protocols/ssh/ttymode.h b/src/protocols/ssh/ttymode.h
index 869d0523..59c5415d 100644
--- a/src/protocols/ssh/ttymode.h
+++ b/src/protocols/ssh/ttymode.h
@@ -46,21 +46,43 @@
 #define GUAC_SSH_TTY_OP_VERASE 3
 
 /**
- * Simple structure that defines a opcode and
- * value pair.
+ * The SSH protocol attempts to configure the remote
+ * terminal by sending pairs of opcodes and values, as
+ * described in Section 8 of RFC 4254.  These are
+ * comprised of a single byte opcode and a 4-byte
+ * value.  This data structure stores a single opcode
+ * and value pair.
  */
 typedef struct guac_ssh_ttymode {
+
+    /**
+     * The single byte opcode for defining the TTY
+     * encoding setting for the remote terminal.  The
+     * stadard codes are defined in Section 8 of
+     * the SSH RFC (4254).
+     */
     char opcode;
+
+    /**
+     * The four byte value of the setting for the
+     * defined opcode.
+     */
     uint32_t value;
+
 } guac_ssh_ttymode;
 
 /**
- * Initialize an array with the specified opcode/value
- * pairs, returning 0 if successful, or a non-zero value
- * if a failure occurs.
+ * Opcodes and value pairs are passed to the SSH connection
+ * in a single array, beginning with the opcode and followed
+ * by a four byte value, repeating until the end opcode is
+ * encountered.  This function takes the array, the array
+ * size, expected number of opcodes, and that number of
+ * guac_ssh_ttymode arguments and puts them in the array
+ * exepcted by the SSH connection.
  *
  * @param opcode_array
- *     Pointer to the opcode array.
+ *     Pointer to the opcode array that will ultimately
+ *     be passed to the SSH connection.
  *
  * @param array_size
  *     Size, in bytes, of the array.

From e16bfd783755fe7cc8019f28f0eb6e997678d8db Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Sat, 24 Mar 2018 15:50:11 -0400
Subject: [PATCH 17/22] GAUCAMOLE-269: Memory effeciency updates.

---
 src/protocols/ssh/ttymode.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/src/protocols/ssh/ttymode.c b/src/protocols/ssh/ttymode.c
index 4c6091e5..4526cc1f 100644
--- a/src/protocols/ssh/ttymode.c
+++ b/src/protocols/ssh/ttymode.c
@@ -36,23 +36,22 @@ int guac_ssh_ttymodes_init(char opcode_array[], const int array_size,
     if ((num_opcodes * GUAC_SSH_TTY_OPCODE_SIZE) >= (array_size))
         return 1;
 
+    char *current = opcode_array;
     for (int i = 0; i < num_opcodes; i++) {
-        /* Calculate offset in array */
-        int offset = i * GUAC_SSH_TTY_OPCODE_SIZE;
 
         /* Get the next argument to this function */
-        guac_ssh_ttymode ttymode = va_arg(args, guac_ssh_ttymode);
+        guac_ssh_ttymode* ttymode = va_arg(args, guac_ssh_ttymode*);
 
         /* Place opcode and value in array */
-        opcode_array[offset] = ttymode.opcode;
-        opcode_array[offset + 1] = (ttymode.value >> 24) & 0xFF;
-        opcode_array[offset + 2] = (ttymode.value >> 16) & 0xFF;
-        opcode_array[offset + 3] = (ttymode.value >> 8) & 0xFF;
-        opcode_array[offset + 4] = ttymode.value & 0xFF;
+        *(current++) = ttymode->opcode;
+        *(current++) = (ttymode->value >> 24) & 0xFF;
+        *(current++) = (ttymode->value >> 16) & 0xFF;
+        *(current++) = (ttymode->value >> 8) & 0xFF;
+        *(current++) = ttymode->value & 0xFF;
     }
 
     /* Put the end opcode in the last opcode space */
-    opcode_array[num_opcodes * GUAC_SSH_TTY_OPCODE_SIZE] = GUAC_SSH_TTY_OP_END;
+    *(current) = GUAC_SSH_TTY_OP_END;
 
     return 0;
 

From c898f35959099b45f85dda72d31a7f59693833c6 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Mon, 2 Apr 2018 07:47:49 -0400
Subject: [PATCH 18/22] GUACAMOLE-269: Clean up terminal backspace
 initialization.

---
 src/terminal/terminal.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/src/terminal/terminal.c b/src/terminal/terminal.c
index bfc36d1a..076305a9 100644
--- a/src/terminal/terminal.c
+++ b/src/terminal/terminal.c
@@ -1600,9 +1600,7 @@ static int __guac_terminal_send_key(guac_terminal* term, int keysym, int pressed
 
             /* Backspace can vary based on configuration of terminal by client. */
             if (keysym == 0xFF08) {
-                char backspace_str[2];
-                backspace_str[0] = term->backspace;
-                backspace_str[1] = '\0';
+                char backspace_str[] = { term->backspace, '\0' };
                 return guac_terminal_send_string(term, backspace_str);
             }
             if (keysym == 0xFF09 || keysym == 0xFF89) return guac_terminal_send_string(term, "\x09"); /* Tab */

From ea946f2492ade3245b7ad19c9111a846c738e927 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Mon, 2 Apr 2018 09:10:11 -0400
Subject: [PATCH 19/22] GUACAMOLE-269: Changes to initializing opcode array.

---
 src/protocols/ssh/ssh.c     | 11 +++++----
 src/protocols/ssh/ttymode.c | 49 +++++++++++++++++++++++--------------
 src/protocols/ssh/ttymode.h | 15 +++++-------
 3 files changed, 42 insertions(+), 33 deletions(-)

diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 9881c304..ace5d6fa 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -192,7 +192,6 @@ void* ssh_client_thread(void* data) {
         return NULL;
     }
 
-    /* Initialize a ttymode array */
     const int num_tty_opcodes = 1;
     char ssh_ttymodes[(GUAC_SSH_TTY_OPCODE_SIZE * num_tty_opcodes) + 1];
 
@@ -302,13 +301,15 @@ void* ssh_client_thread(void* data) {
     }
 
     /* Set up the ttymode array prior to requesting the PTY */
-    if (guac_ssh_ttymodes_init(ssh_ttymodes, sizeof(ssh_ttymodes),
-            num_tty_opcodes, (guac_ssh_ttymode){ GUAC_SSH_TTY_OP_VERASE, settings->backspace}))
-        guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR, "Error configuring TTY mode encoding.");
+    int ttymodeBytes = guac_ssh_ttymodes_init(ssh_ttymodes, sizeof(ssh_ttymodes),
+            GUAC_SSH_TTY_OP_VERASE, settings->backspace, GUAC_SSH_TTY_OP_END);
+    if (ttymodeBytes < 1)
+        guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR, "Error storing TTY mode encoding \
+                opcodes and values in array.");
 
     /* Request PTY */
     if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1,
-            ssh_ttymodes, sizeof(ssh_ttymodes), ssh_client->term->term_width,
+            ssh_ttymodes, ttymodeBytes, ssh_client->term->term_width,
             ssh_client->term->term_height, 0, 0)) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_UPSTREAM_ERROR, "Unable to allocate PTY.");
         return NULL;
diff --git a/src/protocols/ssh/ttymode.c b/src/protocols/ssh/ttymode.c
index 4526cc1f..9f60859d 100644
--- a/src/protocols/ssh/ttymode.c
+++ b/src/protocols/ssh/ttymode.c
@@ -21,38 +21,49 @@
 #include "ttymode.h"
 
 #include <stdarg.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 
 int guac_ssh_ttymodes_init(char opcode_array[], const int array_size,
-        const int num_opcodes, ...) {
+        ...) {
 
     /* Initialize the variable argument list. */
     va_list args;
-    va_start(args, num_opcodes);
-
-    /* Check to make sure the array has enough space.
-       We need one extra byte at the end for the ending opcode. */
-    if ((num_opcodes * GUAC_SSH_TTY_OPCODE_SIZE) >= (array_size))
-        return 1;
+    va_start(args, array_size);
 
+    /* Initialize array pointer and byte counter. */
     char *current = opcode_array;
-    for (int i = 0; i < num_opcodes; i++) {
+    int bytes = 0;
 
-        /* Get the next argument to this function */
-        guac_ssh_ttymode* ttymode = va_arg(args, guac_ssh_ttymode*);
+    /* Loop through variable argument list. */
+    while (true) {
+       
+        /* Check to make sure we don't overrun array. */ 
+        if (bytes >= array_size)
+            return -1;
 
-        /* Place opcode and value in array */
-        *(current++) = ttymode->opcode;
-        *(current++) = (ttymode->value >> 24) & 0xFF;
-        *(current++) = (ttymode->value >> 16) & 0xFF;
-        *(current++) = (ttymode->value >> 8) & 0xFF;
-        *(current++) = ttymode->value & 0xFF;
+        /* Next argument should be an opcode. */
+        char opcode = (char)va_arg(args, int);
+        *(current++) = opcode;
+        bytes += sizeof(char);
+
+        /* If it's the end opcode, we're done. */
+        if (opcode == GUAC_SSH_TTY_OP_END)
+            break;
+
+        /* Next argument should be 4-byte value. */
+        uint32_t value = va_arg(args, uint32_t);
+        *(current++) = (value >> 24) & 0xFF;
+        *(current++) = (value >> 16) & 0xFF;
+        *(current++) = (value >> 8) & 0xFF;
+        *(current++) = value & 0xFF;
+        bytes += sizeof(uint32_t);
     }
 
-    /* Put the end opcode in the last opcode space */
-    *(current) = GUAC_SSH_TTY_OP_END;
+    /* We're done processing arguments. */
+    va_end(args);
 
-    return 0;
+    return bytes;
 
 }
diff --git a/src/protocols/ssh/ttymode.h b/src/protocols/ssh/ttymode.h
index 59c5415d..96bf0b49 100644
--- a/src/protocols/ssh/ttymode.h
+++ b/src/protocols/ssh/ttymode.h
@@ -76,9 +76,9 @@ typedef struct guac_ssh_ttymode {
  * in a single array, beginning with the opcode and followed
  * by a four byte value, repeating until the end opcode is
  * encountered.  This function takes the array, the array
- * size, expected number of opcodes, and that number of
- * guac_ssh_ttymode arguments and puts them in the array
- * exepcted by the SSH connection.
+ * size, and a variable number of opcode and value pair
+ * arguments and puts them in the array expected by the
+ * SSH connection.
  *
  * @param opcode_array
  *     Pointer to the opcode array that will ultimately
@@ -87,18 +87,15 @@ typedef struct guac_ssh_ttymode {
  * @param array_size
  *     Size, in bytes, of the array.
  *
- * @param num_opcodes
- *     Number of opcodes to expect.
- *
  * @params ...
- *     A variable number of guac_ssh_ttymodes
+ *     A variable number of opcode and value pairs
  *     to place in the array.
  *
  * @return
- *     Zero of the function is successful, non-zero
+ *     Number of bytes written to the array, or zero
  *     if a failure occurs.
  */
 int guac_ssh_ttymodes_init(char opcode_array[], const int array_size,
-        const int num_opcodes, ...);
+        ...);
 
 #endif

From b441181c189e3ac8baa226f2022e82d8739532e3 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Mon, 2 Apr 2018 09:22:51 -0400
Subject: [PATCH 20/22] GUACAMOLE-269: Remove unnecessary data structure and
 array size, and update comments.

---
 src/protocols/ssh/ssh.c     |  5 ++--
 src/protocols/ssh/ttymode.c |  9 ++------
 src/protocols/ssh/ttymode.h | 46 +++++++++++--------------------------
 3 files changed, 17 insertions(+), 43 deletions(-)

diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index ace5d6fa..dca62084 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -192,8 +192,7 @@ void* ssh_client_thread(void* data) {
         return NULL;
     }
 
-    const int num_tty_opcodes = 1;
-    char ssh_ttymodes[(GUAC_SSH_TTY_OPCODE_SIZE * num_tty_opcodes) + 1];
+    char ssh_ttymodes[GUAC_SSH_TTYMODES_SIZE(1)];
 
     /* Set up screen recording, if requested */
     if (settings->recording_path != NULL) {
@@ -301,7 +300,7 @@ void* ssh_client_thread(void* data) {
     }
 
     /* Set up the ttymode array prior to requesting the PTY */
-    int ttymodeBytes = guac_ssh_ttymodes_init(ssh_ttymodes, sizeof(ssh_ttymodes),
+    int ttymodeBytes = guac_ssh_ttymodes_init(ssh_ttymodes,
             GUAC_SSH_TTY_OP_VERASE, settings->backspace, GUAC_SSH_TTY_OP_END);
     if (ttymodeBytes < 1)
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR, "Error storing TTY mode encoding \
diff --git a/src/protocols/ssh/ttymode.c b/src/protocols/ssh/ttymode.c
index 9f60859d..686cbbd3 100644
--- a/src/protocols/ssh/ttymode.c
+++ b/src/protocols/ssh/ttymode.c
@@ -25,12 +25,11 @@
 #include <stdlib.h>
 #include <string.h>
 
-int guac_ssh_ttymodes_init(char opcode_array[], const int array_size,
-        ...) {
+int guac_ssh_ttymodes_init(char opcode_array[], ...) {
 
     /* Initialize the variable argument list. */
     va_list args;
-    va_start(args, array_size);
+    va_start(args, opcode_array);
 
     /* Initialize array pointer and byte counter. */
     char *current = opcode_array;
@@ -39,10 +38,6 @@ int guac_ssh_ttymodes_init(char opcode_array[], const int array_size,
     /* Loop through variable argument list. */
     while (true) {
        
-        /* Check to make sure we don't overrun array. */ 
-        if (bytes >= array_size)
-            return -1;
-
         /* Next argument should be an opcode. */
         char opcode = (char)va_arg(args, int);
         *(current++) = opcode;
diff --git a/src/protocols/ssh/ttymode.h b/src/protocols/ssh/ttymode.h
index 96bf0b49..648d13e4 100644
--- a/src/protocols/ssh/ttymode.h
+++ b/src/protocols/ssh/ttymode.h
@@ -46,46 +46,27 @@
 #define GUAC_SSH_TTY_OP_VERASE 3
 
 /**
- * The SSH protocol attempts to configure the remote
- * terminal by sending pairs of opcodes and values, as
- * described in Section 8 of RFC 4254.  These are
- * comprised of a single byte opcode and a 4-byte
- * value.  This data structure stores a single opcode
- * and value pair.
+ * Macro for calculating the number of bytes required
+ * to pass a given number of opcodes, which calculates
+ * the size of the number of opcodes plus the single byte
+ * end opcode.
  */
-typedef struct guac_ssh_ttymode {
-
-    /**
-     * The single byte opcode for defining the TTY
-     * encoding setting for the remote terminal.  The
-     * stadard codes are defined in Section 8 of
-     * the SSH RFC (4254).
-     */
-    char opcode;
-
-    /**
-     * The four byte value of the setting for the
-     * defined opcode.
-     */
-    uint32_t value;
-
-} guac_ssh_ttymode;
+#define GUAC_SSH_TTYMODES_SIZE(num_opcodes) ((GUAC_SSH_TTY_OPCODE_SIZE * num_opcodes) + 1)
 
 /**
  * Opcodes and value pairs are passed to the SSH connection
  * in a single array, beginning with the opcode and followed
  * by a four byte value, repeating until the end opcode is
- * encountered.  This function takes the array, the array
- * size, and a variable number of opcode and value pair
- * arguments and puts them in the array expected by the
- * SSH connection.
+ * encountered.  This function takes the array that will be
+ * sent and a variable number of opcode and value pair
+ * arguments and places the opcode and values in the array
+ * as expected by the SSH connection.
  *
  * @param opcode_array
  *     Pointer to the opcode array that will ultimately
- *     be passed to the SSH connection.
- *
- * @param array_size
- *     Size, in bytes, of the array.
+ *     be passed to the SSH connection.  The array must
+ *     be size to handle 5 bytes for each opcode and value
+ *     pair, plus one additional byte for the end opcode.
  *
  * @params ...
  *     A variable number of opcode and value pairs
@@ -95,7 +76,6 @@ typedef struct guac_ssh_ttymode {
  *     Number of bytes written to the array, or zero
  *     if a failure occurs.
  */
-int guac_ssh_ttymodes_init(char opcode_array[], const int array_size,
-        ...);
+int guac_ssh_ttymodes_init(char opcode_array[], ...);
 
 #endif

From 7453bc8f4472cd41e90cf72cfdbbce3d5fa10140 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Mon, 2 Apr 2018 15:04:03 -0400
Subject: [PATCH 21/22] GUACAMOLE-269: Clean up logging and comments, and
 simplify code.

---
 src/protocols/ssh/ssh.c     | 4 ++--
 src/protocols/ssh/ttymode.c | 5 +----
 src/protocols/ssh/ttymode.h | 8 ++++++++
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index dca62084..1a7e6ef1 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -303,8 +303,8 @@ void* ssh_client_thread(void* data) {
     int ttymodeBytes = guac_ssh_ttymodes_init(ssh_ttymodes,
             GUAC_SSH_TTY_OP_VERASE, settings->backspace, GUAC_SSH_TTY_OP_END);
     if (ttymodeBytes < 1)
-        guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR, "Error storing TTY mode encoding \
-                opcodes and values in array.");
+        guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR, "Unable to set TTY modes."
+                "  Backspace may not work as expected.");
 
     /* Request PTY */
     if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1,
diff --git a/src/protocols/ssh/ttymode.c b/src/protocols/ssh/ttymode.c
index 686cbbd3..e6731b4a 100644
--- a/src/protocols/ssh/ttymode.c
+++ b/src/protocols/ssh/ttymode.c
@@ -33,7 +33,6 @@ int guac_ssh_ttymodes_init(char opcode_array[], ...) {
 
     /* Initialize array pointer and byte counter. */
     char *current = opcode_array;
-    int bytes = 0;
 
     /* Loop through variable argument list. */
     while (true) {
@@ -41,7 +40,6 @@ int guac_ssh_ttymodes_init(char opcode_array[], ...) {
         /* Next argument should be an opcode. */
         char opcode = (char)va_arg(args, int);
         *(current++) = opcode;
-        bytes += sizeof(char);
 
         /* If it's the end opcode, we're done. */
         if (opcode == GUAC_SSH_TTY_OP_END)
@@ -53,12 +51,11 @@ int guac_ssh_ttymodes_init(char opcode_array[], ...) {
         *(current++) = (value >> 16) & 0xFF;
         *(current++) = (value >> 8) & 0xFF;
         *(current++) = value & 0xFF;
-        bytes += sizeof(uint32_t);
     }
 
     /* We're done processing arguments. */
     va_end(args);
 
-    return bytes;
+    return current - opcode_array;
 
 }
diff --git a/src/protocols/ssh/ttymode.h b/src/protocols/ssh/ttymode.h
index 648d13e4..92e081b3 100644
--- a/src/protocols/ssh/ttymode.h
+++ b/src/protocols/ssh/ttymode.h
@@ -50,6 +50,14 @@
  * to pass a given number of opcodes, which calculates
  * the size of the number of opcodes plus the single byte
  * end opcode.
+ *
+ * @param num_opcodes
+ *     The number of opcodes for which a size in bytes
+ *     should be calculated.
+ *
+ * @returns
+ *     The number of bytes that the given number of
+ *     opcodes will require.
  */
 #define GUAC_SSH_TTYMODES_SIZE(num_opcodes) ((GUAC_SSH_TTY_OPCODE_SIZE * num_opcodes) + 1)
 

From dc1918b2176a90ce10a6e15584f8462c6a042ba7 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Mon, 2 Apr 2018 15:05:56 -0400
Subject: [PATCH 22/22] GUACAMOLE-269: Don't abort on ttymode issue, just log a
 warning.

---
 src/protocols/ssh/ssh.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 1a7e6ef1..7c76037a 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -303,7 +303,7 @@ void* ssh_client_thread(void* data) {
     int ttymodeBytes = guac_ssh_ttymodes_init(ssh_ttymodes,
             GUAC_SSH_TTY_OP_VERASE, settings->backspace, GUAC_SSH_TTY_OP_END);
     if (ttymodeBytes < 1)
-        guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR, "Unable to set TTY modes."
+        guac_client_log(client, GUAC_LOG_WARNING, "Unable to set TTY modes."
                 "  Backspace may not work as expected.");
 
     /* Request PTY */