GUAC-763: Adjust telnet login automation to accept a regex for the username parameter

src/protocols/telnet/client.c

@@ -48,6 +48,7 @@ const char* GUAC_CLIENT_ARGS[] = {
     "hostname",
     "port",
     "username",
+    "username-regex",
     "password",
     "password-regex",
     "font-name",
@@ -72,6 +73,12 @@ enum __TELNET_ARGS_IDX {
      */
     IDX_USERNAME,
 
+    /**
+     * The regular expression to use when searching for the username/login prompt.
+     * Optional
+     */
+    IDX_USERNAME_REGEX,
+
     /**
      * The password to use when logging in. Optional.
      */
@@ -96,6 +103,26 @@ enum __TELNET_ARGS_IDX {
     TELNET_ARGS_COUNT
 };
 
+/**
+ * Compile a regular expression and checks it return value. Returns NULL if compilation fails
+ */
+static regex_t* __guac_telnet_compile_regext(guac_client* client, char* pattern) {
+    int compile_result;
+    regex_t* regex = malloc(sizeof(regex_t));
+
+    /* Compile regular expression */
+    compile_result = regcomp(regex, pattern,REG_EXTENDED | REG_NOSUB | REG_ICASE | REG_NEWLINE);
+
+    /* Notify of failure to parse/compile */
+    if (compile_result != 0) {
+        guac_client_log_info(client, "Regular expression '%s' could not be compiled.", pattern);
+        free(regex);
+        return NULL;
+    }
+
+    return regex;
+}
+
 int guac_client_init(guac_client* client, int argc, char** argv) {
 
     guac_socket* socket = client->socket;
@@ -124,29 +151,25 @@ int guac_client_init(guac_client* client, int argc, char** argv) {
     strcpy(client_data->username,  argv[IDX_USERNAME]);
     strcpy(client_data->password,  argv[IDX_PASSWORD]);
 
-    /* Set password regex, if needed */
+    /* Set username regex, if needed */
-    if (client_data->password[0] != 0) {
+    if (client_data->username[0] != 0) {
-
-        int compile_result;
-
-        client_data->password_regex = malloc(sizeof(regex_t));
 
         /* Compile regular expression */
-        if (argv[IDX_PASSWORD_REGEX][0] != 0)
+        if (argv[IDX_USERNAME_REGEX][0] != 0)
-            compile_result = regcomp(client_data->password_regex, argv[IDX_PASSWORD_REGEX],
+            client_data->username_regex = __guac_telnet_compile_regext(client, argv[IDX_USERNAME_REGEX]);
-                    REG_EXTENDED | REG_NOSUB | REG_NEWLINE);
         else
-            compile_result = regcomp(client_data->password_regex, GUAC_TELNET_DEFAULT_REGEX,
+            client_data->username_regex = __guac_telnet_compile_regext(client, GUAC_TELNET_DEFAULT_USERNAME_REGEX);
-                    REG_EXTENDED | REG_NOSUB | REG_NEWLINE);
-
-        /* Notify of failure to parse/compile */
-        if (compile_result != 0) {
-            guac_client_log_info(client, "Password regular expression could not be compiled. "
-                                         "Password must be entered manually.");
-            free(client_data->password_regex);
-            client_data->password_regex = NULL;
     }
+    else
+        client_data->username_regex = NULL;
 
+    /* Set password regex, if needed */
+    if (client_data->password[0] != 0) {
+        /* Compile regular expression */
+        if (argv[IDX_PASSWORD_REGEX][0] != 0)
+            client_data->password_regex = __guac_telnet_compile_regext(client, argv[IDX_PASSWORD_REGEX]);
+        else
+            client_data->password_regex = __guac_telnet_compile_regext(client, GUAC_TELNET_DEFAULT_PASSWORD_REGEX);
     }
     else
         client_data->password_regex = NULL;

src/protocols/telnet/client.h

@@ -32,7 +32,8 @@
 
 #include <libtelnet.h>
 
-#define GUAC_TELNET_DEFAULT_REGEX "^Password:"
+#define GUAC_TELNET_DEFAULT_USERNAME_REGEX "login:"
+#define GUAC_TELNET_DEFAULT_PASSWORD_REGEX "password:"
 
 /**
  * Telnet-specific client data.
@@ -54,6 +55,13 @@ typedef struct guac_telnet_client_data {
      */
     char username[1024];
 
+    /**
+     * The regular expression to use when searching for the username
+     * prompt. This will be NULL unless the telnet client is currently
+     * searching for the username prompt.
+     */
+    regex_t* username_regex;
+
     /**
      * The password to give when authenticating.
      */

src/protocols/telnet/guac_handlers.c

@@ -71,6 +71,17 @@ int guac_telnet_client_key_handler(guac_client* client, int keysym, int pressed)
 
     }
 
+    /* Stop searching for username */
+    if (client_data->username_regex != NULL) {
+
+        guac_client_log_info(client, "Stopping username prompt search due to user input.");
+
+        regfree(client_data->username_regex);
+        free(client_data->username_regex);
+        client_data->username_regex = NULL;
+
+    }
+
     /* Send key */
     guac_terminal_send_key(term, keysym, pressed);
 

src/protocols/telnet/telnet_client.c

@@ -87,9 +87,10 @@ static int __guac_telnet_write_all(int fd, const char* buffer, int size) {
 /**
  * Searches for a line matching the stored password regex, appending the given
  * buffer to the internal pattern matching buffer. The internal pattern match
- * buffer is cleared whenever a newline is read.
+ * buffer is cleared whenever a newline is read. Returns TRUE if a match is found and the
+ * value is sent.
  */
-static void __guac_telnet_password_search(guac_client* client, const char* buffer, int size) {
+static bool __guac_telnet_regex_search(guac_client* client, regex_t* regex, char* value, const char* buffer, int size) {
 
     static char line_buffer[1024] = {0};
     static int length = 0;
@@ -110,7 +111,6 @@ static void __guac_telnet_password_search(guac_client* client, const char* buffe
             size -= i;
             i = 0;
         }
-
     }
 
     /* Truncate if necessary */
@@ -122,21 +122,26 @@ static void __guac_telnet_password_search(guac_client* client, const char* buffe
     length += size;
     line_buffer[length] = '\0';
 
+    /* Remove non-printable characters as they interfere with regex matching */
+    for (int i = 0; i < length; i++) {
+        if (line_buffer[i] <= 31 || (line_buffer[i] >= 128 && line_buffer[i] <= 255)) {
+            line_buffer[i] = ' ';
+        }
+    }
+
     /* Send password upon match */
-    if (regexec(client_data->password_regex, line_buffer, 0, NULL, 0) == 0) {
+    if (regexec(regex, line_buffer, 0, NULL, 0) == 0) {
 
         /* Send password */
-        guac_terminal_send_string(client_data->term, client_data->password);
+        guac_terminal_send_string(client_data->term, value);
         guac_terminal_send_key(client_data->term, 0xFF0D, 1);
         guac_terminal_send_key(client_data->term, 0xFF0D, 0);
 
         /* Stop searching for password */
-        regfree(client_data->password_regex);
+        return TRUE;
-        free(client_data->password_regex);
-        client_data->password_regex = NULL;
-
     }
 
+    return FALSE;
 }
 
 /**
@@ -155,10 +160,25 @@ static void __guac_telnet_event_handler(telnet_t* telnet, telnet_event_t* event,
         case TELNET_EV_DATA:
             guac_terminal_write_stdout(client_data->term, event->data.buffer, event->data.size);
 
-            /* Continue search for password prompt */
+            /* Continue search for username prompt */
-            if (client_data->password_regex != NULL)
+            if (client_data->username_regex != NULL) {
-                __guac_telnet_password_search(client, event->data.buffer, event->data.size);
+                if (__guac_telnet_regex_search(client, client_data->username_regex, client_data->username,
+                                           event->data.buffer, event->data.size)) {
+                    regfree(client_data->username_regex);
+                    free(client_data->username_regex);
+                    client_data->username_regex = NULL;
+                }
+            }
 
+            /* Continue search for password prompt */
+            if (client_data->password_regex != NULL) {
+                if (__guac_telnet_regex_search(client, client_data->password_regex, client_data->password,
+                                           event->data.buffer, event->data.size)) {
+                    regfree(client_data->password_regex);
+                    free(client_data->password_regex);
+                    client_data->password_regex = NULL;
+                }
+            }
             break;
 
         /* Data destined for remote end */
@@ -196,7 +216,6 @@ static void __guac_telnet_event_handler(telnet_t* telnet, telnet_event_t* event,
 
         /* Environment request */
         case TELNET_EV_ENVIRON:
-
             /* Only send USER if entire environment was requested */
             if (event->environ.size == 0)
                 guac_telnet_send_user(telnet, client_data->username);