mirror of https://gerrit.osmocom.org/libtelnet
initial commit
This commit is contained in:
Sean Middleditch
commit
2914485114
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#include "libtelnet.h"
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/* initialize a telnet state tracker */
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void libtelnet_init(struct libtelnet_t *telnet) {
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telnet->state = LIBTELNET_TEXT;
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telnet->buffer = 0;
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telnet->size = 0;
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telnet->length = 0;
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}
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/* free up any memory allocated by a state tracker */
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void libtelnet_close(struct libtelnet_t *telnet) {
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if (telnet->buffer) {
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free(telnet->buffer);
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telnet->buffer = 0;
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}
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}
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/* push a single byte into the state tracker */
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void libtelnet_push_byte(struct libtelnet_t *telnet, unsigned char byte,
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void *user_data) {
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switch (telnet->state) {
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/* regular data */
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case LIBTELNET_STATE_TEXT:
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/* enter IAC state on IAC byte */
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if (byte == LIBTELNET_IAC)
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telnet->state = LIBTELNET_STATE_IAC;
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/* regular input byte */
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else
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telnet->input_cb(telnet, byte, user_data);
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break;
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case LIBTELNET_STATE_IAC:
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switch (byte) {
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/* subrequest */
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case LIBTELNET_SB:
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telnet->state = LIBTELNET_STATE_SB;
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break;
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/* negotiation commands */
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case LIBTELNET_WILL:
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telnet->state = LIBTELNET_STATE_WILL;
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break;
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case LIBTELNET_WONT:
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telnet->state = LIBTELNET_STATE_WONT;
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break;
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case LIBTELNET_DO:
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telnet->state = LIBTELNET_STATE_DO;
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break;
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case LIBTELNET_DONT:
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telnet->state = LIBTELNET_STATE_DONT;
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break;
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/* IAC escaping */
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case LIBTELNET_IAC:
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telbet->input_cb(telnet, LIBTELNET_IAC, user_data);
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libtelnet->state = LIBTELNET_STATE_TEXT;
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break;
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/* some other command */
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default:
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telnet->command_cb(telnet, byte, user_data);
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telnet->state = LIBTELNET_STATE_TEXT;
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}
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break;
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/* DO negotiation */
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case LIBTELNET_STATE_DO:
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telnet->negotiate_cb(telnet, LIBTELNET_DO, byte, user_data);
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telnet->state = LIBTELNET_STATE_TEXT;
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break;
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case LIBTELNET_STATE_DONT:
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telnet->negotiate_cb(telnet, LIBTELNET_DONT, byte, user_data);
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telnet->state = LIBTELNET_STATE_TEXT;
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break;
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case LIBTELNET_STATE_WILL:
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telnet->negotiate_cb(telnet, LIBTELNET_WILL, byte, user_data);
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telnet->state = LIBTELNET_STATE_TEXT;
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break;
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case LIBTELNET_STATE_WONT:
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telnet->negotiate_cb(telnet, LIBTELNET_WONT, byte, user_data);
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telnet->state = LIBTELNET_STATE_TEXT;
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break;
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/* subrequest -- buffer bytes until end request */
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case LIBTELNET_STATE_SB:
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/* IAC command in subrequest -- either IAC SE or IAC IAC */
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if (byte == LIBTELNET_IAC) {
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telnet->state = LIBTELNET_STATE_SB_IAC;
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} else {
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/* FIXME: buffer byte */
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}
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break;
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/* IAC escaping inside a subrequest */
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case LIBTELNET_STATE_SB_IAC:
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switch (byte) {
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/* end subrequest */
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case LIBTELNET_SE:
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/* FIXME: process */
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telnet->state = LIBTELNET_STATE_TEXT;
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break;
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/* escaped IAC byte */
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case LIBTELNET_IAC:
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/* FIXME: buffer byte */
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telnet->state = LIBTELNET_STATE_SB;
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break;
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/* something else -- protocol error */
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default:
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telnet->error_cb(telnet, LIBTELNET_ERROR_PROTOCOL, user_data);
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telnet->state = LIBTELNET_STATE_TEXT;
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break;
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}
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break;
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}
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}
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/* push a byte buffer into the state tracker */
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void libtelnet_push_buffer(struct libtelnet_t *telnet, unsigned char *buffer,
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size_t size, void *user_data) {
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size_t i;
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for (i = 0; i != size; ++i)
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libtelnet_push_byte(telnet, buffer[i], user_data);
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}
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/* send an iac command */
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void libtelnet_send_command(struct libtelnet_t *telnet, unsigned char cmd,
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void *user_data) {
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unsigned char bytes[2] = { IAC, cmd };
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telnet->output_cb(telnet, bytes, 2, user_data);
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}
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/* send negotiation */
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void libtelnet_send_negotiate(struct libtelnet_t *telnet, unsigned char cmd,
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unsigned char opt, void *user_data) {
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unsigned char bytes[3] = { IAC, cmd, opt };
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telnet->output_cb(telnet, bytes, 3, user_data);
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}
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/* send non-command data (escapes IAC bytes) */
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void libtelnet_send_data(struct libtelnet_t *telnet, unsigned char *buffer,
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size_t size, void *user_data) {
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size_t i, l;
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for (l = i = 0; i != size; ++i) {
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/* dump prior portion of text, send escaped bytes */
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if (buffer[i] == LIBTELNET_IAC) {
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/* dump prior text if any */
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if (i != l)
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telnet->output_cb(telnet, buffer + l, i - l, user_data);
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l = i + 1;
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/* send escape */
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libtelnet_send_command(telnet, LIBTELNET_IAC, user_data);
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}
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}
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/* send whatever portion of buffer is left */
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if (i != l)
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telnet->output_cb(telnet, buffer + l, i - l, user_data);
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}
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/* send sub-request */
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void libtelnet_send_subrequest(struct libtelnet_t *telnet, unsigned char type,
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unsigned char *buffer, size_t size, void *user_data) {
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libtelnet_send_command(telnet, SB, user_data);
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libtelnet_send_data(telnet, &type, 1, user_data);
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libtelnet_send_data(telnet, buffer, size, user_data);
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libtelnet_send_command(telnet, SE, user_data);
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}
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@ -0,0 +1,111 @@
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/*
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* The author or authors of this code dedicate any and all copyright interest
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* in this code to the public domain. We make this dedication for the benefit
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* of the public at large and to the detriment of our heirs and successors. We
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* intend this dedication to be an overt act of relinquishment in perpetuity of
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* all present and future rights to this code under copyright law.
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*/
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/* sub request buffer size increment (defualt 4K) */
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#define LIBTELNET_BUFFER_SIZE (4 * 1024)
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/* sub request buffer size (default 16K) */
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#define LIBTELNET_BUFFER_SIZE_MAX (16 * 1024)
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/* telnet special values */
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#define LIBTELNET_IAC 255
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#define LIBTELNET_DONT 254
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#define LIBTELNET_DO 253
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#define LIBTELNET_WONT 252
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#define LIBTELNET_WILL 251
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#define LIBTELNET_SB 250
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#define LIBTELNET_SE 240
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/* telnet options */
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#define LIBTELNET_OPTION_BINARY 0
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#define LIBTELNET_OPTION_ECHO 1
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#define LIBTELNET_OPTION_NAWS 31
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#define LIBTELNET_OPTION_ZMP 93
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/* telnet states */
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enum libtelnet_state_t {
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LIBTELNET_STATE_TEXT = 0,
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LIBTELNET_STATE_IAC,
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LIBTELNET_STATE_DO,
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LIBTELNET_STATE_DONT,
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LIBTELNET_STATE_WILL,
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LIBTELNET_STATE_WONT,
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LIBTELNET_STATE_SB,
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LIBTELNET_STATE_SB_IAC,
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};
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/* error codes */
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enum libtelnet_error_t {
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LIBTELNET_ERROR_OK = 0,
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LIBTELNET_ERROR_OVERFLOW, /* input exceeds buffer size */
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LIBTELNET_ERROR_PROTOCOL, /* invalid sequence of special bytes */
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LIBTELNET_ERROR_UNKNOWN, /* some crazy unexplainable unknown error */
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};
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/* callback prototypes */
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typedef (void)(*libtelnet_input)(struct libtelnet_t *telnet, unsigned char
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byte, void *user_data);
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typedef (void)(*libtelnet_output)(struct libtelnet_t *telnet, unsigned char
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byte, void *user_data);
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typedef (void)(*libtelnet_command)(struct libtelnet_t *telnet, unsigned char
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cmd, void *user_data);
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typedef (void)(*libtelnet_negotiate)(struct libtelnet_t *telnet, unsigned char
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cmd, unsigned char opt, void *user_data);
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typedef (void)(*libtelnet_subrequest)(struct libtelnet_t *telnet, unsigned char
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cmd, unsigned char type, unsigned char *data, size_t size,
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void *user_data);
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typedef (void)(*libtelnet_error)(struct libtelnet_t *telnet,
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enum libtelnet_error_t error, void *user_data);
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/* state tracker */
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struct libtelnet_t {
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/* current state */
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enum libtelnet_state_t state;
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/* sub-request buffer */
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char *buffer;
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/* current size of the buffer */
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size_t size;
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/* length of data in the buffer */
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size_t length;
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/* callbacks */
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libtelnet_input input_cb;
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libtelnet_output output_cb;
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libtelnet_command command_cb;
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libtelnet_negotiate negotiate_cb;
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libtelnet_subrequest subrequest_cb;
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};
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/* initialize a telnet state tracker */
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void libtelnet_init(struct libtelnet_t *telnet);
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/* free up any memory allocated by a state tracker */
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void libtelnet_close(struct libtelnet_t *telnet);
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/* push a single byte into the state tracker */
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void libtelnet_push_byte(struct libtelnet_t *telnet, unsigned char byte,
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void *user_data);
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/* push a byte buffer into the state tracker */
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void libtelnet_push_buffer(struct libtelnet_t *telnet, unsigned char *buffer,
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size_t size, void *user_data);
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/* send an iac command */
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void libtelnet_send_command(struct libtelnet_t *telnet, unsigned char cmd,
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void *user_data);
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/* send negotiation */
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void libtelnet_send_negotiate(struct libtelnet_t *telnet, unsigned char cmd,
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unsigned char opt, void *user_data);
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/* send non-command data (escapes IAC bytes) */
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void libtelnet_send_data(struct libtelnet_t *telnet, unsigned char *buffer,
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size_t size, void *user_data);
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/* send sub-request */
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void libtelnet_send_subrequest(struct libtelnet_t *telnet, unsigned char type,
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unsigned char *buffer, size_t size, void *user_data);
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