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libtelnet
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work on buffer handling

This commit is contained in:
Sean Middleditch 2009-03-13 20:15:59 -04:00
parent b9e4864539
commit 51ad679e47
2 changed files with 68 additions and 25 deletions
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83
libtelnet.c
View File

@ -9,28 +9,68 @@
#include "libtelnet.h"
/* initialize a telnet state tracker */
libtelnet_error_t libtelnet_init(struct libtelnet_t *telnet) {
void 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 */
void libtelnet_close(struct libtelnet_t *telnet) {
if (telnet->buffer) {
void libtelnet_free(struct libtelnet_t *telnet) {
if (telnet->buffer != 0) {
free(telnet->buffer);
telnet->buffer = 0;
telnet->size = 0;
telnet->length = 0;
}
}
/* push a byte into the telnet buffer */
static enum libtelnet_error_t _libtelnet_buffer_byte(
struct libtelnet_t *telnet, unsigned char byte, void *user_data) {
/* check if we're out of room */
if (telnet->length == telnet->size) {
/* if we already have a large buffer, we're out of space, give up */
if (telnet->size == LIBTELNET_BUFFER_SIZE_LARGE) {
libtelnet_error_cb(telnet, LIBTELNET_ERROR_OVERFLOW, user_data);
libtelnet_free(telnet);
return LIBTELNET_ERROR_OVERFLOW;
/* if we have a small buffer, try to resize to a larger one */
} else if (telnet->size == LIBTELNET_BUFFER_SIZE_SMALL) {
unsigned char *new_buffer = (unsigned char *)realloc(
telnet->buffer, LIBTELNET_BUFFER_SIZE_LARGE);
if (new_buffer == 0) {
libtelnet_error_cb(telnet, LIBTELNET_ERROR_NOMEM,
user_data);
libtelnet_free(telnet);
return LIBTELNET_ERROR_NOMEM;
}
telnet->buffer = new_buffer;
telnet->size = LIBTELNET_BUFFER_SIZE_LARGE;
/* we have no buffer at all, so allocate one */
} else {
telnet->buffer = (unsigned char *)realloc(
telnet->buffer, LIBTELNET_BUFFER_SIZE_SMALL);
if (telnet->buffer == 0) {
libtelnet_error_cb(telnet, LIBTELNET_ERROR_NOMEM,
user_data);
libtelnet_free(telnet);
return LIBTELNET_ERROR_NOMEM;
}
telnet->size = LIBTELNET_BUFFER_SIZE_SMALL;
}
}
/* push the byte, all set */
telnet->buffer[telnet->length++] = byte;
return LIBTELNET_ERROR_OK;
}
/* push a single byte into the state tracker */
void libtelnet_push_byte(struct libtelnet_t *telnet, unsigned char byte,
void *user_data) {
@ -94,11 +134,14 @@ void libtelnet_push_byte(struct libtelnet_t *telnet, unsigned char byte,
/* subrequest -- buffer bytes until end request */
case LIBTELNET_STATE_SB:
/* IAC command in subrequest -- either IAC SE or IAC IAC */
if (byte == LIBTELNET_IAC) {
if (byte == LIBTELNET_IAC)
telnet->state = LIBTELNET_STATE_SB_IAC;
} else {
/* FIXME: buffer byte */
}
/* buffer the byte, or bail if we can't */
else if (_libtelnet_buffer_byte(telnet, LIBTELNET_IAC, user_data) !=
LIBTELNET_ERROR_OK)
telnet->state = LIBTELNET_STATE_TEXT;
else
telnet->state = LIBTELNET_STATE_SB;
break;
/* IAC escaping inside a subrequest */
case LIBTELNET_STATE_SB_IAC:
@ -113,10 +156,6 @@ void libtelnet_push_byte(struct libtelnet_t *telnet, unsigned char byte,
} 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;
}
@ -125,8 +164,12 @@ void libtelnet_push_byte(struct libtelnet_t *telnet, unsigned char byte,
break;
/* escaped IAC byte */
case LIBTELNET_IAC:
/* FIXME: buffer byte */
telnet->state = LIBTELNET_STATE_SB;
/* push IAC into buffer */
if (_libtelnet_buffer_byte(telnet, LIBTELNET_IAC, user_data) !=
LIBTELNET_ERROR_OK)
telnet->state = LIBTELNET_STATE_TEXT;
else
telnet->state = LIBTELNET_STATE_SB;
break;
/* something else -- protocol error */
default:

10
libtelnet.h
View File

@ -9,10 +9,10 @@
#if !defined(LIBTELNET_INCLUDE)
#define LIBTELNET 1
/* sub request buffer size increment (defualt 4K) */
#define LIBTELNET_BUFFER_SIZE (4 * 1024)
/* sub request buffer size (default 16K) */
#define LIBTELNET_BUFFER_SIZE_MAX (16 * 1024)
/* sub request buffer size, normal (defualt 1K) */
#define LIBTELNET_BUFFER_SIZE_SMALL (1 * 1024)
/* sub request buffer size, enlarged (default 16K) */
#define LIBTELNET_BUFFER_SIZE_LARGE (16 * 1024)
/* telnet special values */
#define LIBTELNET_IAC 255
@ -83,7 +83,7 @@ struct libtelnet_t {
extern void libtelnet_init(struct libtelnet_t *telnet);
/* free up any memory allocated by a state tracker */
extern void libtelnet_close(struct libtelnet_t *telnet);
extern void libtelnet_free(struct libtelnet_t *telnet);
/* push a single byte into the state tracker */
extern void libtelnet_push_byte(struct libtelnet_t *telnet, unsigned char byte,