GUACAMOLE-269: Use backspace config to set up tty modes.

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;
     }

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;
+}

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