diff --git a/libtelnet.c b/libtelnet.c
index b148d8e..f55b59a 100644
--- a/libtelnet.c
+++ b/libtelnet.c
@@ -1,11 +1,18 @@
 #include "libtelnet.h"
 
 /* initialize a telnet state tracker */
-void libtelnet_init(struct libtelnet_t *telnet) {
+libtelnet_error_t libtelnet_init(struct libtelnet_t *telnet) {
 	telnet->state = LIBTELNET_TEXT;
 	telnet->buffer = 0;
 	telnet->size = 0;
 	telnet->length = 0;
+
+	/* attempt to allocate default buffer */
+	telnet->buffer = (unsigned char *)malloc(LIBTELNET_BUFFER_SIZE);
+	if (telnet->buffer == 0)
+		return LIBTELNET_ERROR_NOMEM;
+
+	return LIBTELNET_ERROR_OK;
 }
 
 /* free up any memory allocated by a state tracker */
@@ -27,7 +34,7 @@
 			telnet->state = LIBTELNET_STATE_IAC;
 		/* regular input byte */
 		else
-			telnet->input_cb(telnet, byte, user_data);
+			libtelnet_input_cb(telnet, byte, user_data);
 		break;
 	case LIBTELNET_STATE_IAC:
 		switch (byte) {
@@ -55,25 +62,25 @@
 			break;
 		/* some other command */
 		default:
-			telnet->command_cb(telnet, byte, user_data);
+			libtelnet_command_cb(telnet, byte, user_data);
 			telnet->state = LIBTELNET_STATE_TEXT;
 		}
 		break;
 	/* DO negotiation */
 	case LIBTELNET_STATE_DO:
-		telnet->negotiate_cb(telnet, LIBTELNET_DO, byte, user_data);
+		libtelnet_negotiate_cb(telnet, LIBTELNET_DO, byte, user_data);
 		telnet->state = LIBTELNET_STATE_TEXT;
 		break;
 	case LIBTELNET_STATE_DONT:
-		telnet->negotiate_cb(telnet, LIBTELNET_DONT, byte, user_data);
+		libtelnet_negotiate_cb(telnet, LIBTELNET_DONT, byte, user_data);
 		telnet->state = LIBTELNET_STATE_TEXT;
 		break;
 	case LIBTELNET_STATE_WILL:
-		telnet->negotiate_cb(telnet, LIBTELNET_WILL, byte, user_data);
+		libtelnet_negotiate_cb(telnet, LIBTELNET_WILL, byte, user_data);
 		telnet->state = LIBTELNET_STATE_TEXT;
 		break;
 	case LIBTELNET_STATE_WONT:
-		telnet->negotiate_cb(telnet, LIBTELNET_WONT, byte, user_data);
+		libtelnet_negotiate_cb(telnet, LIBTELNET_WONT, byte, user_data);
 		telnet->state = LIBTELNET_STATE_TEXT;
 		break;
 	/* subrequest -- buffer bytes until end request */
@@ -90,7 +97,22 @@
 		switch (byte) {
 		/* end subrequest */
 		case LIBTELNET_SE:
-			/* FIXME: process */
+			/* zero-size buffer is a protocol error */
+			if (telnet->length == 0) {
+				libtelnet_error_cb(telnet, LIBTELNET_ERROR_PROTOCOL,
+					user_data);
+			/* process */
+			} else {
+				libtelnet_subrequest_cb(telnet, telnet->buffer[0],
+					telnet->buffer + 1, telnet->length - 1, user_data);
+
+				/* unallocate free buffer */
+				free(telnet->buffer);
+				telnet->size = 0;
+				telnet->length = 0;
+			}
+			
+			/* return to default state */
 			telnet->state = LIBTELNET_STATE_TEXT;
 			break;
 		/* escaped IAC byte */
@@ -100,7 +122,7 @@
 			break;
 		/* something else -- protocol error */
 		default:
-			telnet->error_cb(telnet, LIBTELNET_ERROR_PROTOCOL, user_data);
+			libtelnet_error_cb(telnet, LIBTELNET_ERROR_PROTOCOL, user_data);
 			telnet->state = LIBTELNET_STATE_TEXT;
 			break;
 		}
@@ -120,14 +142,14 @@
 void libtelnet_send_command(struct libtelnet_t *telnet, unsigned char cmd,
 		void *user_data) {
 	unsigned char bytes[2] = { IAC, cmd };
-	telnet->output_cb(telnet, bytes, 2, user_data);
+	libtelnet_output_cb(telnet, bytes, 2, user_data);
 }
 
 /* send negotiation */
 void libtelnet_send_negotiate(struct libtelnet_t *telnet, unsigned char cmd,
 		unsigned char opt, void *user_data) {
 	unsigned char bytes[3] = { IAC, cmd, opt };
-	telnet->output_cb(telnet, bytes, 3, user_data);
+	libtelnet_output_cb(telnet, bytes, 3, user_data);
 }
 
 /* send non-command data (escapes IAC bytes) */
@@ -139,7 +161,7 @@
 		if (buffer[i] == LIBTELNET_IAC) {
 			/* dump prior text if any */
 			if (i != l)
-				telnet->output_cb(telnet, buffer + l, i - l, user_data);
+				libtelnet_output_cb(telnet, buffer + l, i - l, user_data);
 			l = i + 1;
 
 			/* send escape */
@@ -149,7 +171,7 @@
 
 	/* send whatever portion of buffer is left */
 	if (i != l)
-		telnet->output_cb(telnet, buffer + l, i - l, user_data);
+		libtelnet_output_cb(telnet, buffer + l, i - l, user_data);
 }
 
 /* send sub-request */
diff --git a/libtelnet.h b/libtelnet.h
index a3cba24..e518601 100644
--- a/libtelnet.h
+++ b/libtelnet.h
@@ -41,24 +41,27 @@
 /* error codes */
 enum libtelnet_error_t {
 	LIBTELNET_ERROR_OK = 0,
+	LIBTELNET_ERROR_NOMEM, /* memory allocation failure */
 	LIBTELNET_ERROR_OVERFLOW, /* input exceeds buffer size */
 	LIBTELNET_ERROR_PROTOCOL, /* invalid sequence of special bytes */
 	LIBTELNET_ERROR_UNKNOWN, /* some crazy unexplainable unknown error */
 };
 
-/* callback prototypes */
-typedef (void)(*libtelnet_input)(struct libtelnet_t *telnet, unsigned char
+/* libtelnet callback declarations
+ * APPLICATION MUST IMPLEMENT THESE FUNCTIONS!!
+ */
+extern void libtelnet_input_cb(struct libtelnet_t *telnet, unsigned char
 		byte, void *user_data);
-typedef (void)(*libtelnet_output)(struct libtelnet_t *telnet, unsigned char
+extern void libtelnet_output_cb(struct libtelnet_t *telnet, unsigned char
 		byte, void *user_data);
-typedef (void)(*libtelnet_command)(struct libtelnet_t *telnet, unsigned char
+extern void libtelnet_command_cb(struct libtelnet_t *telnet, unsigned char
 		cmd, void *user_data);
-typedef (void)(*libtelnet_negotiate)(struct libtelnet_t *telnet, unsigned char
+extern void libtelnet_negotiate_cb(struct libtelnet_t *telnet, unsigned char
 		cmd, unsigned char opt, void *user_data);
-typedef (void)(*libtelnet_subrequest)(struct libtelnet_t *telnet, unsigned char
+extern void libtelnet_subrequest_cb(struct libtelnet_t *telnet, unsigned char
 		cmd, unsigned char type, unsigned char *data, size_t size,
 		void *user_data);
-typedef (void)(*libtelnet_error)(struct libtelnet_t *telnet,
+extern void libtelnet_error_cb(struct libtelnet_t *telnet,
 		enum libtelnet_error_t error, void *user_data);
 
 /* state tracker */
@@ -71,41 +74,34 @@
 	size_t size;
 	/* length of data in the buffer */
 	size_t length;
-
-	/* callbacks */
-	libtelnet_input input_cb;
-	libtelnet_output output_cb;
-	libtelnet_command command_cb;
-	libtelnet_negotiate negotiate_cb;
-	libtelnet_subrequest subrequest_cb;
 };
 
 /* initialize a telnet state tracker */
-void libtelnet_init(struct libtelnet_t *telnet);
+extern void libtelnet_init(struct libtelnet_t *telnet);
 
 /* free up any memory allocated by a state tracker */
-void libtelnet_close(struct libtelnet_t *telnet);
+extern void libtelnet_close(struct libtelnet_t *telnet);
 
 /* push a single byte into the state tracker */
-void libtelnet_push_byte(struct libtelnet_t *telnet, unsigned char byte,
+extern void libtelnet_push_byte(struct libtelnet_t *telnet, unsigned char byte,
 	void *user_data);
 
 /* push a byte buffer into the state tracker */
-void libtelnet_push_buffer(struct libtelnet_t *telnet, unsigned char *buffer,
-	size_t size, void *user_data);
+extern void libtelnet_push_buffer(struct libtelnet_t *telnet,
+	unsigned char *buffer, size_t size, void *user_data);
 
 /* send an iac command */
-void libtelnet_send_command(struct libtelnet_t *telnet, unsigned char cmd,
-	void *user_data);
+extern void libtelnet_send_command(struct libtelnet_t *telnet,
+	unsigned char cmd, void *user_data);
 
 /* send negotiation */
-void libtelnet_send_negotiate(struct libtelnet_t *telnet, unsigned char cmd,
-	unsigned char opt, void *user_data);
+extern void libtelnet_send_negotiate(struct libtelnet_t *telnet,
+	unsigned char cmd, unsigned char opt, void *user_data);
 
 /* send non-command data (escapes IAC bytes) */
-void libtelnet_send_data(struct libtelnet_t *telnet, unsigned char *buffer,
-	size_t size, void *user_data);
+extern void libtelnet_send_data(struct libtelnet_t *telnet,
+	unsigned char *buffer, size_t size, void *user_data);
 
 /* send sub-request */
-void libtelnet_send_subrequest(struct libtelnet_t *telnet, unsigned char type,
-	unsigned char *buffer, size_t size, void *user_data);
+extern void libtelnet_send_subrequest(struct libtelnet_t *telnet,
+	unsigned char type, unsigned char *buffer, size_t size, void *user_data);