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libtelnet.c
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libtelnet.c
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/*
* libtelnet - TELNET protocol handling library
*
* Sean Middleditch
* sean@sourcemud.org
*
* The author or authors of this code dedicate any and all copyright interest
* in this code to the public domain. We make this dedication for the benefit
* of the public at large and to the detriment of our heirs and successors. We
* intend this dedication to be an overt act of relinquishment in perpetuity of
* all present and future rights to this code under copyright law.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdarg.h>
/* Win32 compatibility */
#if defined(_WIN32)
# define vsnprintf _vsnprintf
# define __func__ __FUNCTION__
# define ZLIB_WINAPI 1
# if defined(_MSC_VER)
/* va_copy() is directly supported starting in Visual Studio 2013
* https://msdn.microsoft.com/en-us/library/kb57fad8(v=vs.110).aspx
* https://msdn.microsoft.com/en-us/library/kb57fad8(v=vs.120).aspx
*/
# if _MSC_VER <= 1700
# define va_copy(dest, src) (dest = src)
# endif
# endif
#endif
#if defined(HAVE_ZLIB)
# include <zlib.h>
#endif
#include "libtelnet.h"
/* inlinable functions */
#if defined(__GNUC__) || __STDC_VERSION__ >= 199901L
# define INLINE __inline__
#else
# define INLINE
#endif
/* helper for Q-method option tracking */
#define Q_US(q) ((q).state & 0x0F)
#define Q_HIM(q) (((q).state & 0xF0) >> 4)
#define Q_MAKE(us,him) ((us) | ((him) << 4))
/* helper for the negotiation routines */
#define NEGOTIATE_EVENT(telnet,cmd,opt) \
ev.type = (cmd); \
ev.neg.telopt = (opt); \
(telnet)->eh((telnet), &ev, (telnet)->ud);
/* telnet state codes */
enum telnet_state_t {
TELNET_STATE_DATA = 0,
TELNET_STATE_EOL,
TELNET_STATE_IAC,
TELNET_STATE_WILL,
TELNET_STATE_WONT,
TELNET_STATE_DO,
TELNET_STATE_DONT,
TELNET_STATE_SB,
TELNET_STATE_SB_DATA,
TELNET_STATE_SB_DATA_IAC
};
typedef enum telnet_state_t telnet_state_t;
/* telnet state tracker */
struct telnet_t {
/* user data */
void *ud;
/* telopt support table */
const telnet_telopt_t *telopts;
/* event handler */
telnet_event_handler_t eh;
#if defined(HAVE_ZLIB)
/* zlib (mccp2) compression */
z_stream *z;
#endif
/* RFC1143 option negotiation states */
struct telnet_rfc1143_t *q;
/* sub-request buffer */
char *buffer;
/* current size of the buffer */
size_t buffer_size;
/* current buffer write position (also length of buffer data) */
size_t buffer_pos;
/* current state */
enum telnet_state_t state;
/* option flags */
unsigned char flags;
/* current subnegotiation telopt */
unsigned char sb_telopt;
/* length of RFC1143 queue */
unsigned int q_size;
/* number of entries in RFC1143 queue */
unsigned int q_cnt;
};
/* RFC1143 option negotiation state */
typedef struct telnet_rfc1143_t {
unsigned char telopt;
unsigned char state;
} telnet_rfc1143_t;
/* RFC1143 state names */
#define Q_NO 0
#define Q_YES 1
#define Q_WANTNO 2
#define Q_WANTYES 3
#define Q_WANTNO_OP 4
#define Q_WANTYES_OP 5
/* telnet NVT EOL sequences */
static const char CRLF[] = { '\r', '\n' };
static const char CRNUL[] = { '\r', '\0' };
/* buffer sizes */
static const size_t _buffer_sizes[] = { 0, 512, 2048, 8192, 16384, };
static const size_t _buffer_sizes_count = sizeof(_buffer_sizes) /
sizeof(_buffer_sizes[0]);
/* RFC1143 option negotiation state table allocation quantum */
#define Q_BUFFER_GROWTH_QUANTUM 4
/* error generation function */
static telnet_error_t _error(telnet_t *telnet, unsigned line,
const char* func, telnet_error_t err, int fatal, const char *fmt,
...) {
telnet_event_t ev;
char buffer[512];
va_list va;
/* format informational text */
va_start(va, fmt);
vsnprintf(buffer, sizeof(buffer), fmt, va);
va_end(va);
/* send error event to the user */
ev.type = fatal ? TELNET_EV_ERROR : TELNET_EV_WARNING;
ev.error.file = __FILE__;
ev.error.func = func;
ev.error.line = line;
ev.error.msg = buffer;
telnet->eh(telnet, &ev, telnet->ud);
return err;
}
#if defined(HAVE_ZLIB)
/* initialize the zlib box for a telnet box; if deflate is non-zero, it
* initializes zlib for delating (compression), otherwise for inflating
* (decompression). returns TELNET_EOK on success, something else on
* failure.
*/
telnet_error_t _init_zlib(telnet_t *telnet, int deflate, int err_fatal) {
z_stream *z;
int rs;
/* if compression is already enabled, fail loudly */
if (telnet->z != 0)
return _error(telnet, __LINE__, __func__, TELNET_EBADVAL,
err_fatal, "cannot initialize compression twice");
/* allocate zstream box */
if ((z= (z_stream *)calloc(1, sizeof(z_stream))) == 0)
return _error(telnet, __LINE__, __func__, TELNET_ENOMEM, err_fatal,
"malloc() failed: %s", strerror(errno));
/* initialize */
if (deflate) {
if ((rs = deflateInit(z, Z_DEFAULT_COMPRESSION)) != Z_OK) {
free(z);
return _error(telnet, __LINE__, __func__, TELNET_ECOMPRESS,
err_fatal, "deflateInit() failed: %s", zError(rs));
}
telnet->flags |= TELNET_PFLAG_DEFLATE;
} else {
if ((rs = inflateInit(z)) != Z_OK) {
free(z);
return _error(telnet, __LINE__, __func__, TELNET_ECOMPRESS,
err_fatal, "inflateInit() failed: %s", zError(rs));
}
telnet->flags &= ~TELNET_PFLAG_DEFLATE;
}
telnet->z = z;
return TELNET_EOK;
}
#endif /* defined(HAVE_ZLIB) */
/* push bytes out, compressing them first if need be */
static void _send(telnet_t *telnet, const char *buffer,
size_t size) {
telnet_event_t ev;
#if defined(HAVE_ZLIB)
/* if we have a deflate (compression) zlib box, use it */
if (telnet->z != 0 && telnet->flags & TELNET_PFLAG_DEFLATE) {
char deflate_buffer[1024];
int rs;
/* initialize z state */
telnet->z->next_in = (unsigned char *)buffer;
telnet->z->avail_in = (unsigned int)size;
telnet->z->next_out = (unsigned char *)deflate_buffer;
telnet->z->avail_out = sizeof(deflate_buffer);
/* deflate until buffer exhausted and all output is produced */
while (telnet->z->avail_in > 0 || telnet->z->avail_out == 0) {
/* compress */
if ((rs = deflate(telnet->z, Z_SYNC_FLUSH)) != Z_OK) {
_error(telnet, __LINE__, __func__, TELNET_ECOMPRESS, 1,
"deflate() failed: %s", zError(rs));
deflateEnd(telnet->z);
free(telnet->z);
telnet->z = 0;
break;
}
/* send event */
ev.type = TELNET_EV_SEND;
ev.data.buffer = deflate_buffer;
ev.data.size = sizeof(deflate_buffer) - telnet->z->avail_out;
telnet->eh(telnet, &ev, telnet->ud);
/* prepare output buffer for next run */
telnet->z->next_out = (unsigned char *)deflate_buffer;
telnet->z->avail_out = sizeof(deflate_buffer);
}
/* do not continue with remaining code */
return;
}
#endif /* defined(HAVE_ZLIB) */
ev.type = TELNET_EV_SEND;
ev.data.buffer = buffer;
ev.data.size = size;
telnet->eh(telnet, &ev, telnet->ud);
}
/* to send bags of unsigned chars */
#define _sendu(t, d, s) _send((t), (const char*)(d), (s))
/* check if we support a particular telopt; if us is non-zero, we
* check if we (local) supports it, otherwise we check if he (remote)
* supports it. return non-zero if supported, zero if not supported.
*/
static INLINE int _check_telopt(telnet_t *telnet, unsigned char telopt,
int us) {
int i;
/* if we have no telopts table, we obviously don't support it */
if (telnet->telopts == 0)
return 0;
/* loop until found or end marker (us and him both 0) */
for (i = 0; telnet->telopts[i].telopt != -1; ++i) {
if (telnet->telopts[i].telopt == telopt) {
if (us && telnet->telopts[i].us == TELNET_WILL)
return 1;
else if (!us && telnet->telopts[i].him == TELNET_DO)
return 1;
else
return 0;
}
}
/* not found, so not supported */
return 0;
}
/* retrieve RFC1143 option state */
static INLINE telnet_rfc1143_t _get_rfc1143(telnet_t *telnet,
unsigned char telopt) {
telnet_rfc1143_t empty;
int i;
/* search for entry */
for (i = 0; i != telnet->q_cnt; ++i) {
if (telnet->q[i].telopt == telopt) {
return telnet->q[i];
}
}
/* not found, return empty value */
empty.telopt = telopt;
empty.state = 0;
return empty;
}
/* save RFC1143 option state */
static INLINE void _set_rfc1143(telnet_t *telnet, unsigned char telopt,
char us, char him) {
telnet_rfc1143_t *qtmp;
int i;
/* search for entry */
for (i = 0; i != telnet->q_cnt; ++i) {
if (telnet->q[i].telopt == telopt) {
telnet->q[i].state = Q_MAKE(us,him);
if (telopt != TELNET_TELOPT_BINARY)
return;
telnet->flags &= ~(TELNET_FLAG_TRANSMIT_BINARY |
TELNET_FLAG_RECEIVE_BINARY);
if (us == Q_YES)
telnet->flags |= TELNET_FLAG_TRANSMIT_BINARY;
if (him == Q_YES)
telnet->flags |= TELNET_FLAG_RECEIVE_BINARY;
return;
}
}
/* we're going to need to track state for it, so grow the queue
* by 4 (four) elements and put the telopt into it; bail on allocation
* error. we go by four because it seems like a reasonable guess as
* to the number of enabled options for most simple code, and it
* allows for an acceptable number of reallocations for complex code.
*/
/* Did we reach the end of the table? */
if (telnet->q_cnt >= telnet->q_size) {
/* Expand the size */
if ((qtmp = (telnet_rfc1143_t *)realloc(telnet->q,
sizeof(telnet_rfc1143_t) *
(telnet->q_size + Q_BUFFER_GROWTH_QUANTUM))) == 0) {
_error(telnet, __LINE__, __func__, TELNET_ENOMEM, 0,
"realloc() failed: %s", strerror(errno));
return;
}
memset(&qtmp[telnet->q_size], 0, sizeof(telnet_rfc1143_t) *
Q_BUFFER_GROWTH_QUANTUM);
telnet->q = qtmp;
telnet->q_size += Q_BUFFER_GROWTH_QUANTUM;
}
/* Add entry to end of table */
telnet->q[telnet->q_cnt].telopt = telopt;
telnet->q[telnet->q_cnt].state = Q_MAKE(us, him);
++telnet->q_cnt;
}
/* send negotiation bytes */
static INLINE void _send_negotiate(telnet_t *telnet, unsigned char cmd,
unsigned char telopt) {
unsigned char bytes[3];
bytes[0] = TELNET_IAC;
bytes[1] = cmd;
bytes[2] = telopt;
_sendu(telnet, bytes, 3);
}
/* negotiation handling magic for RFC1143 */
static void _negotiate(telnet_t *telnet, unsigned char telopt) {
telnet_event_t ev;
telnet_rfc1143_t q;
/* in PROXY mode, just pass it thru and do nothing */
if (telnet->flags & TELNET_FLAG_PROXY) {
switch ((int)telnet->state) {
case TELNET_STATE_WILL:
NEGOTIATE_EVENT(telnet, TELNET_EV_WILL, telopt);
break;
case TELNET_STATE_WONT:
NEGOTIATE_EVENT(telnet, TELNET_EV_WONT, telopt);
break;
case TELNET_STATE_DO:
NEGOTIATE_EVENT(telnet, TELNET_EV_DO, telopt);
break;
case TELNET_STATE_DONT:
NEGOTIATE_EVENT(telnet, TELNET_EV_DONT, telopt);
break;
}
return;
}
/* lookup the current state of the option */
q = _get_rfc1143(telnet, telopt);
/* start processing... */
switch ((int)telnet->state) {
/* request to enable option on remote end or confirm DO */
case TELNET_STATE_WILL:
switch (Q_HIM(q)) {
case Q_NO:
if (_check_telopt(telnet, telopt, 0)) {
_set_rfc1143(telnet, telopt, Q_US(q), Q_YES);
_send_negotiate(telnet, TELNET_DO, telopt);
NEGOTIATE_EVENT(telnet, TELNET_EV_WILL, telopt);
} else
_send_negotiate(telnet, TELNET_DONT, telopt);
break;
case Q_WANTNO:
_set_rfc1143(telnet, telopt, Q_US(q), Q_NO);
NEGOTIATE_EVENT(telnet, TELNET_EV_WONT, telopt);
_error(telnet, __LINE__, __func__, TELNET_EPROTOCOL, 0,
"DONT answered by WILL");
break;
case Q_WANTNO_OP:
_set_rfc1143(telnet, telopt, Q_US(q), Q_YES);
NEGOTIATE_EVENT(telnet, TELNET_EV_WILL, telopt);
_error(telnet, __LINE__, __func__, TELNET_EPROTOCOL, 0,
"DONT answered by WILL");
break;
case Q_WANTYES:
_set_rfc1143(telnet, telopt, Q_US(q), Q_YES);
NEGOTIATE_EVENT(telnet, TELNET_EV_WILL, telopt);
break;
case Q_WANTYES_OP:
_set_rfc1143(telnet, telopt, Q_US(q), Q_WANTNO);
_send_negotiate(telnet, TELNET_DONT, telopt);
NEGOTIATE_EVENT(telnet, TELNET_EV_WILL, telopt);
break;
}
break;
/* request to disable option on remote end, confirm DONT, reject DO */
case TELNET_STATE_WONT:
switch (Q_HIM(q)) {
case Q_YES:
_set_rfc1143(telnet, telopt, Q_US(q), Q_NO);
_send_negotiate(telnet, TELNET_DONT, telopt);
NEGOTIATE_EVENT(telnet, TELNET_EV_WONT, telopt);
break;
case Q_WANTNO:
_set_rfc1143(telnet, telopt, Q_US(q), Q_NO);
NEGOTIATE_EVENT(telnet, TELNET_EV_WONT, telopt);
break;
case Q_WANTNO_OP:
_set_rfc1143(telnet, telopt, Q_US(q), Q_WANTYES);
NEGOTIATE_EVENT(telnet, TELNET_EV_DO, telopt);
break;
case Q_WANTYES:
case Q_WANTYES_OP:
_set_rfc1143(telnet, telopt, Q_US(q), Q_NO);
break;
}
break;
/* request to enable option on local end or confirm WILL */
case TELNET_STATE_DO:
switch (Q_US(q)) {
case Q_NO:
if (_check_telopt(telnet, telopt, 1)) {
_set_rfc1143(telnet, telopt, Q_YES, Q_HIM(q));
_send_negotiate(telnet, TELNET_WILL, telopt);
NEGOTIATE_EVENT(telnet, TELNET_EV_DO, telopt);
} else
_send_negotiate(telnet, TELNET_WONT, telopt);
break;
case Q_WANTNO:
_set_rfc1143(telnet, telopt, Q_NO, Q_HIM(q));
NEGOTIATE_EVENT(telnet, TELNET_EV_DONT, telopt);
_error(telnet, __LINE__, __func__, TELNET_EPROTOCOL, 0,
"WONT answered by DO");
break;
case Q_WANTNO_OP:
_set_rfc1143(telnet, telopt, Q_YES, Q_HIM(q));
NEGOTIATE_EVENT(telnet, TELNET_EV_DO, telopt);
_error(telnet, __LINE__, __func__, TELNET_EPROTOCOL, 0,
"WONT answered by DO");
break;
case Q_WANTYES:
_set_rfc1143(telnet, telopt, Q_YES, Q_HIM(q));
NEGOTIATE_EVENT(telnet, TELNET_EV_DO, telopt);
break;
case Q_WANTYES_OP:
_set_rfc1143(telnet, telopt, Q_WANTNO, Q_HIM(q));
_send_negotiate(telnet, TELNET_WONT, telopt);
NEGOTIATE_EVENT(telnet, TELNET_EV_DO, telopt);
break;
}
break;
/* request to disable option on local end, confirm WONT, reject WILL */
case TELNET_STATE_DONT:
switch (Q_US(q)) {
case Q_YES:
_set_rfc1143(telnet, telopt, Q_NO, Q_HIM(q));
_send_negotiate(telnet, TELNET_WONT, telopt);
NEGOTIATE_EVENT(telnet, TELNET_EV_DONT, telopt);
break;
case Q_WANTNO:
_set_rfc1143(telnet, telopt, Q_NO, Q_HIM(q));
NEGOTIATE_EVENT(telnet, TELNET_EV_WONT, telopt);
break;
case Q_WANTNO_OP:
_set_rfc1143(telnet, telopt, Q_WANTYES, Q_HIM(q));
_send_negotiate(telnet, TELNET_WILL, telopt);
NEGOTIATE_EVENT(telnet, TELNET_EV_WILL, telopt);
break;
case Q_WANTYES:
case Q_WANTYES_OP:
_set_rfc1143(telnet, telopt, Q_NO, Q_HIM(q));
break;
}
break;
}
}
/* process an ENVIRON/NEW-ENVIRON subnegotiation buffer
*
* the algorithm and approach used here is kind of a hack,
* but it reduces the number of memory allocations we have
* to make.
*
* we copy the bytes back into the buffer, starting at the very
* beginning, which makes it easy to handle the ENVIRON ESC
* escape mechanism as well as ensure the variable name and
* value strings are NUL-terminated, all while fitting inside
* of the original buffer.
*/
static int _environ_telnet(telnet_t *telnet, unsigned char type,
char* buffer, size_t size) {
telnet_event_t ev;
struct telnet_environ_t *values = 0;
char *c, *last, *out;
size_t index, count;
/* if we have no data, just pass it through */
if (size == 0) {
return 0;
}
/* first byte must be a valid command */
if ((unsigned)buffer[0] != TELNET_ENVIRON_SEND &&
(unsigned)buffer[0] != TELNET_ENVIRON_IS &&
(unsigned)buffer[0] != TELNET_ENVIRON_INFO) {
_error(telnet, __LINE__, __func__, TELNET_EPROTOCOL, 0,
"telopt %d subneg has invalid command", type);
return 0;
}
/* store ENVIRON command */
ev.environ.cmd = buffer[0];
/* if we have no arguments, send an event with no data end return */
if (size == 1) {
/* no list of variables given */
ev.environ.values = 0;
ev.environ.size = 0;
/* invoke event with our arguments */
ev.type = TELNET_EV_ENVIRON;
telnet->eh(telnet, &ev, telnet->ud);
return 1;
}
/* very second byte must be VAR or USERVAR, if present */
if ((unsigned)buffer[1] != TELNET_ENVIRON_VAR &&
(unsigned)buffer[1] != TELNET_ENVIRON_USERVAR) {
_error(telnet, __LINE__, __func__, TELNET_EPROTOCOL, 0,
"telopt %d subneg missing variable type", type);
return 0;
}
/* ensure last byte is not an escape byte (makes parsing later easier) */
if ((unsigned)buffer[size - 1] == TELNET_ENVIRON_ESC) {
_error(telnet, __LINE__, __func__, TELNET_EPROTOCOL, 0,
"telopt %d subneg ends with ESC", type);
return 0;
}
/* count arguments; each valid entry starts with VAR or USERVAR */
count = 0;
for (c = buffer + 1; c < buffer + size; ++c) {
if (*c == TELNET_ENVIRON_VAR || *c == TELNET_ENVIRON_USERVAR) {
++count;
} else if (*c == TELNET_ENVIRON_ESC) {
/* skip the next byte */
++c;
}
}
/* allocate argument array, bail on error */
if ((values = (struct telnet_environ_t *)calloc(count,
sizeof(struct telnet_environ_t))) == 0) {
_error(telnet, __LINE__, __func__, TELNET_ENOMEM, 0,
"calloc() failed: %s", strerror(errno));
return 0;
}
/* parse argument array strings */
out = buffer;
c = buffer + 1;
for (index = 0; index != count; ++index) {
/* remember the variable type (will be VAR or USERVAR) */
values[index].type = *c++;
/* scan until we find an end-marker, and buffer up unescaped
* bytes into our buffer */
last = out;
while (c < buffer + size) {
/* stop at the next variable or at the value */
if ((unsigned)*c == TELNET_ENVIRON_VAR ||
(unsigned)*c == TELNET_ENVIRON_VALUE ||
(unsigned)*c == TELNET_ENVIRON_USERVAR) {
break;
}
/* buffer next byte (taking into account ESC) */
if (*c == TELNET_ENVIRON_ESC) {
++c;
}
*out++ = *c++;
}
*out++ = '\0';
/* store the variable name we have just received */
values[index].var = last;
values[index].value = "";
/* if we got a value, find the next end marker and
* store the value; otherwise, store empty string */
if (c < buffer + size && *c == TELNET_ENVIRON_VALUE) {
++c;
last = out;
while (c < buffer + size) {
/* stop when we find the start of the next variable */
if ((unsigned)*c == TELNET_ENVIRON_VAR ||
(unsigned)*c == TELNET_ENVIRON_USERVAR) {
break;
}
/* buffer next byte (taking into account ESC) */
if (*c == TELNET_ENVIRON_ESC) {
++c;
}
*out++ = *c++;
}
*out++ = '\0';
/* store the variable value */
values[index].value = last;
}
}
/* pass values array and count to event */
ev.environ.values = values;
ev.environ.size = count;
/* invoke event with our arguments */
ev.type = TELNET_EV_ENVIRON;
telnet->eh(telnet, &ev, telnet->ud);
/* clean up */
free(values);
return 1;
}
/* process an MSSP subnegotiation buffer */
static int _mssp_telnet(telnet_t *telnet, char* buffer, size_t size) {
telnet_event_t ev;
struct telnet_environ_t *values;
char *var = 0;
char *c, *last, *out;
size_t i, count;
unsigned char next_type;
/* if we have no data, just pass it through */
if (size == 0) {
return 0;
}
/* first byte must be a VAR */
if ((unsigned)buffer[0] != TELNET_MSSP_VAR) {
_error(telnet, __LINE__, __func__, TELNET_EPROTOCOL, 0,
"MSSP subnegotiation has invalid data");
return 0;
}
/* count the arguments, any part that starts with VALUE */
for (count = 0, i = 0; i != size; ++i) {
if ((unsigned)buffer[i] == TELNET_MSSP_VAL) {
++count;
}
}
/* allocate argument array, bail on error */
if ((values = (struct telnet_environ_t *)calloc(count,
sizeof(struct telnet_environ_t))) == 0) {
_error(telnet, __LINE__, __func__, TELNET_ENOMEM, 0,
"calloc() failed: %s", strerror(errno));
return 0;
}
ev.mssp.values = values;
ev.mssp.size = count;
/* allocate strings in argument array */
out = last = buffer;
next_type = buffer[0];
for (i = 0, c = buffer + 1; c < buffer + size;) {
/* search for end marker */
while (c < buffer + size && (unsigned)*c != TELNET_MSSP_VAR &&
(unsigned)*c != TELNET_MSSP_VAL) {
*out++ = *c++;
}
*out++ = '\0';
/* if it's a variable name, just store the name for now */
if (next_type == TELNET_MSSP_VAR) {
var = last;
} else if (next_type == TELNET_MSSP_VAL && var != 0) {
values[i].var = var;
values[i].value = last;
++i;
} else {
_error(telnet, __LINE__, __func__, TELNET_EPROTOCOL, 0,
"invalid MSSP subnegotiation data");
free(values);
return 0;
}
/* remember our next type and increment c for next loop run */
last = out;
next_type = *c++;
}
/* invoke event with our arguments */
ev.type = TELNET_EV_MSSP;
telnet->eh(telnet, &ev, telnet->ud);
/* clean up */
free(values);
return 0;
}
/* parse ZMP command subnegotiation buffers */
static int _zmp_telnet(telnet_t *telnet, const char* buffer, size_t size) {
telnet_event_t ev;
char **argv;
const char *c;
size_t i, argc;
/* make sure this is a valid ZMP buffer */
if (size == 0 || buffer[size - 1] != 0) {
_error(telnet, __LINE__, __func__, TELNET_EPROTOCOL, 0,
"incomplete ZMP frame");
return 0;
}
/* count arguments */
for (argc = 0, c = buffer; c != buffer + size; ++argc)
c += strlen(c) + 1;
/* allocate argument array, bail on error */
if ((argv = (char **)calloc(argc, sizeof(char *))) == 0) {
_error(telnet, __LINE__, __func__, TELNET_ENOMEM, 0,
"calloc() failed: %s", strerror(errno));
return 0;
}
/* populate argument array */
for (i = 0, c = buffer; i != argc; ++i) {
argv[i] = (char *)c;
c += strlen(c) + 1;
}
/* invoke event with our arguments */
ev.type = TELNET_EV_ZMP;
ev.zmp.argv = (const char**)argv;
ev.zmp.argc = argc;
telnet->eh(telnet, &ev, telnet->ud);
/* clean up */
free(argv);
return 0;
}
/* parse TERMINAL-TYPE command subnegotiation buffers */
static int _ttype_telnet(telnet_t *telnet, const char* buffer, size_t size) {
telnet_event_t ev;
/* make sure request is not empty */
if (size == 0) {
_error(telnet, __LINE__, __func__, TELNET_EPROTOCOL, 0,
"incomplete TERMINAL-TYPE request");
return 0;
}
/* make sure request has valid command type */
if (buffer[0] != TELNET_TTYPE_IS &&
buffer[0] != TELNET_TTYPE_SEND) {
_error(telnet, __LINE__, __func__, TELNET_EPROTOCOL, 0,
"TERMINAL-TYPE request has invalid type");
return 0;
}
/* send proper event */
if (buffer[0] == TELNET_TTYPE_IS) {
char *name;
/* allocate space for name */
if ((name = (char *)malloc(size)) == 0) {
_error(telnet, __LINE__, __func__, TELNET_ENOMEM, 0,
"malloc() failed: %s", strerror(errno));
return 0;
}
memcpy(name, buffer + 1, size - 1);
name[size - 1] = '\0';
ev.type = TELNET_EV_TTYPE;
ev.ttype.cmd = TELNET_TTYPE_IS;
ev.ttype.name = name;
telnet->eh(telnet, &ev, telnet->ud);
/* clean up */
free(name);
} else {
ev.type = TELNET_EV_TTYPE;
ev.ttype.cmd = TELNET_TTYPE_SEND;
ev.ttype.name = 0;
telnet->eh(telnet, &ev, telnet->ud);
}
return 0;
}
/* process a subnegotiation buffer; return non-zero if the current buffer
* must be aborted and reprocessed due to COMPRESS2 being activated
*/
static int _subnegotiate(telnet_t *telnet) {
telnet_event_t ev;
/* standard subnegotiation event */
ev.type = TELNET_EV_SUBNEGOTIATION;
ev.sub.telopt = telnet->sb_telopt;
ev.sub.buffer = telnet->buffer;
ev.sub.size = telnet->buffer_pos;
telnet->eh(telnet, &ev, telnet->ud);
switch (telnet->sb_telopt) {
#if defined(HAVE_ZLIB)
/* received COMPRESS2 begin marker, setup our zlib box and
* start handling the compressed stream if it's not already.
*/
case TELNET_TELOPT_COMPRESS2:
if (telnet->sb_telopt == TELNET_TELOPT_COMPRESS2) {
if (_init_zlib(telnet, 0, 1) != TELNET_EOK)
return 0;
/* notify app that compression was enabled */
ev.type = TELNET_EV_COMPRESS;
ev.compress.state = 1;
telnet->eh(telnet, &ev, telnet->ud);
return 1;
}
return 0;
#endif /* defined(HAVE_ZLIB) */
/* specially handled subnegotiation telopt types */
case TELNET_TELOPT_ZMP:
return _zmp_telnet(telnet, telnet->buffer, telnet->buffer_pos);
case TELNET_TELOPT_TTYPE:
return _ttype_telnet(telnet, telnet->buffer, telnet->buffer_pos);
case TELNET_TELOPT_ENVIRON:
case TELNET_TELOPT_NEW_ENVIRON:
return _environ_telnet(telnet, telnet->sb_telopt, telnet->buffer,
telnet->buffer_pos);
case TELNET_TELOPT_MSSP:
return _mssp_telnet(telnet, telnet->buffer, telnet->buffer_pos);
default:
return 0;
}
}
/* initialize a telnet state tracker */
telnet_t *telnet_init(const telnet_telopt_t *telopts,
telnet_event_handler_t eh, unsigned char flags, void *user_data) {
/* allocate structure */
struct telnet_t *telnet = (telnet_t*)calloc(1, sizeof(telnet_t));
if (telnet == 0)
return 0;
/* initialize data */
telnet->ud = user_data;
telnet->telopts = telopts;
telnet->eh = eh;
telnet->flags = flags;
return telnet;
}
/* free up any memory allocated by a state tracker */
void telnet_free(telnet_t *telnet) {
/* free sub-request buffer */
if (telnet->buffer != 0) {
free(telnet->buffer);
telnet->buffer = 0;
telnet->buffer_size = 0;
telnet->buffer_pos = 0;
}
#if defined(HAVE_ZLIB)
/* free zlib box */
if (telnet->z != 0) {
if (telnet->flags & TELNET_PFLAG_DEFLATE)
deflateEnd(telnet->z);
else
inflateEnd(telnet->z);
free(telnet->z);
telnet->z = 0;
}
#endif /* defined(HAVE_ZLIB) */
/* free RFC1143 queue */
if (telnet->q) {
free(telnet->q);
telnet->q = NULL;
telnet->q_size = 0;
telnet->q_cnt = 0;
}
/* free the telnet structure itself */
free(telnet);
}
/* push a byte into the telnet buffer */
static telnet_error_t _buffer_byte(telnet_t *telnet,
unsigned char byte) {
char *new_buffer;
size_t i;
/* check if we're out of room */
if (telnet->buffer_pos == telnet->buffer_size) {
/* find the next buffer size */
for (i = 0; i != _buffer_sizes_count; ++i) {
if (_buffer_sizes[i] == telnet->buffer_size) {
break;
}
}
/* overflow -- can't grow any more */
if (i >= _buffer_sizes_count - 1) {
_error(telnet, __LINE__, __func__, TELNET_EOVERFLOW, 0,
"subnegotiation buffer size limit reached");
return TELNET_EOVERFLOW;
}
/* (re)allocate buffer */
new_buffer = (char *)realloc(telnet->buffer, _buffer_sizes[i + 1]);
if (new_buffer == 0) {
_error(telnet, __LINE__, __func__, TELNET_ENOMEM, 0,
"realloc() failed");
return TELNET_ENOMEM;
}
telnet->buffer = new_buffer;
telnet->buffer_size = _buffer_sizes[i + 1];
}
/* push the byte, all set */
telnet->buffer[telnet->buffer_pos++] = byte;
return TELNET_EOK;
}
static void _process(telnet_t *telnet, const char *buffer, size_t size) {
telnet_event_t ev;
unsigned char byte;
size_t i, start;
for (i = start = 0; i != size; ++i) {
byte = buffer[i];
switch (telnet->state) {
/* regular data */
case TELNET_STATE_DATA:
/* on an IAC byte, pass through all pending bytes and
* switch states */
if (byte == TELNET_IAC) {
if (i != start) {
ev.type = TELNET_EV_DATA;
ev.data.buffer = buffer + start;
ev.data.size = i - start;
telnet->eh(telnet, &ev, telnet->ud);
}
telnet->state = TELNET_STATE_IAC;
} else if (byte == '\r' &&
(telnet->flags & TELNET_FLAG_NVT_EOL) &&
!(telnet->flags & TELNET_FLAG_RECEIVE_BINARY)) {
if (i != start) {
ev.type = TELNET_EV_DATA;
ev.data.buffer = buffer + start;
ev.data.size = i - start;
telnet->eh(telnet, &ev, telnet->ud);