| /* |
| * 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. |
| */ |
| |
| #include <malloc.h> |
| #include <string.h> |
| #include <stdio.h> |
| #include <errno.h> |
| #include <string.h> |
| #include <stdarg.h> |
| |
| #ifdef HAVE_ZLIB |
| #include "zlib.h" |
| #endif |
| |
| #include "libtelnet.h" |
| |
| /* buffer sizes */ |
| static const unsigned int _buffer_sizes[] = { |
| 0, |
| 512, |
| 2048, |
| 8192, |
| 16384, |
| }; |
| static const unsigned int _buffer_sizes_count = |
| sizeof(_buffer_sizes) / sizeof(_buffer_sizes[0]); |
| |
| /* event dispatch helper */ |
| static void _event(struct libtelnet_t *telnet, |
| enum libtelnet_event_type_t type, unsigned char command, |
| unsigned char telopt, unsigned char *buffer, unsigned int size) { |
| struct libtelnet_event_t ev; |
| ev.type = type; |
| ev.command = command; |
| ev.telopt = telopt; |
| ev.buffer = buffer; |
| ev.size = size; |
| |
| telnet->eh(telnet, &ev, telnet->ud); |
| } |
| |
| /* error generation function */ |
| static void _error(struct libtelnet_t *telnet, unsigned line, const char* func, |
| enum libtelnet_error_t err, int fatal, const char *fmt, ...) { |
| char buffer[512]; |
| va_list va; |
| |
| /* format error intro */ |
| snprintf(buffer, sizeof(buffer), "%s:%u in %s: ", |
| __FILE__, line, func); |
| |
| va_start(va, fmt); |
| vsnprintf(buffer + strlen(buffer), sizeof(buffer) - strlen(buffer), |
| fmt, va); |
| va_end(va); |
| |
| _event(telnet, fatal ? LIBTELNET_EV_ERROR : LIBTELNET_EV_WARNING, err, |
| 0, (unsigned char *)buffer, strlen(buffer)); |
| } |
| |
| /* initialize the zlib box for a telnet box; if deflate is non-zero, it |
| * initializes zlib for delating (compression), otherwise for inflating |
| * (decompression) |
| */ |
| z_stream *_init_zlib(struct libtelnet_t *telnet, int deflate, int err_fatal) { |
| z_stream *zlib; |
| int rs; |
| |
| /* allocate zstream box */ |
| if ((zlib = (z_stream *)calloc(1, sizeof(z_stream))) |
| == 0) { |
| _error(telnet, __LINE__, __func__, LIBTELNET_ENOMEM, err_fatal, |
| "malloc() failed: %s", strerror(errno)); |
| return 0; |
| } |
| |
| /* initialize */ |
| if (deflate) { |
| if ((rs = deflateInit(zlib, Z_DEFAULT_COMPRESSION)) != Z_OK) { |
| free(zlib); |
| _error(telnet, __LINE__, __func__, LIBTELNET_ECOMPRESS, err_fatal, |
| "deflateInit() failed: %s", zError(rs)); |
| return 0; |
| } |
| } else { |
| if ((rs = inflateInit(zlib)) != Z_OK) { |
| free(zlib); |
| _error(telnet, __LINE__, __func__, LIBTELNET_ECOMPRESS, err_fatal, |
| "inflateInit() failed: %s", zError(rs)); |
| return 0; |
| } |
| } |
| |
| return zlib; |
| } |
| |
| /* initialize a telnet state tracker */ |
| void libtelnet_init(struct libtelnet_t *telnet, libtelnet_event_handler_t eh, |
| enum libtelnet_mode_t mode, void *user_data) { |
| memset(telnet, 0, sizeof(struct libtelnet_t)); |
| telnet->ud = user_data; |
| telnet->eh = eh; |
| telnet->mode = mode; |
| } |
| |
| /* free up any memory allocated by a state tracker */ |
| void libtelnet_free(struct libtelnet_t *telnet) { |
| /* free sub-request buffer */ |
| if (telnet->buffer != 0) { |
| free(telnet->buffer); |
| telnet->buffer = 0; |
| telnet->size = 0; |
| telnet->length = 0; |
| } |
| |
| /* free zlib box(es) */ |
| if (telnet->z_inflate != 0) { |
| inflateEnd(telnet->z_inflate); |
| free(telnet->z_inflate); |
| telnet->z_inflate = 0; |
| } |
| if (telnet->z_deflate != 0) { |
| deflateEnd(telnet->z_deflate); |
| free(telnet->z_deflate); |
| telnet->z_deflate = 0; |
| } |
| } |
| |
| /* push a byte into the telnet buffer */ |
| static enum libtelnet_error_t _buffer_byte(struct libtelnet_t *telnet, |
| unsigned char byte) { |
| unsigned char *new_buffer; |
| int i; |
| |
| /* check if we're out of room */ |
| if (telnet->length == telnet->size) { |
| /* find the next buffer size */ |
| for (i = 0; i != _buffer_sizes_count; ++i) { |
| if (_buffer_sizes[i] == telnet->size) |
| break; |
| } |
| |
| /* overflow -- can't grow any more */ |
| if (i >= _buffer_sizes_count - 1) { |
| _error(telnet, __LINE__, __func__, LIBTELNET_EOVERFLOW, 0, |
| "subnegotiation buffer size limit reached"); |
| libtelnet_free(telnet); |
| return LIBTELNET_EOVERFLOW; |
| } |
| |
| /* (re)allocate buffer */ |
| new_buffer = (unsigned char *)realloc(telnet->buffer, |
| _buffer_sizes[i + 1]); |
| if (new_buffer == 0) { |
| _error(telnet, __LINE__, __func__, LIBTELNET_ENOMEM, 0, |
| "realloc() failed"); |
| libtelnet_free(telnet); |
| return LIBTELNET_ENOMEM; |
| } |
| |
| telnet->buffer = new_buffer; |
| telnet->size = _buffer_sizes[i + 1]; |
| } |
| |
| /* push the byte, all set */ |
| telnet->buffer[telnet->length++] = byte; |
| return LIBTELNET_EOK; |
| } |
| |
| static void _process(struct libtelnet_t *telnet, unsigned char *buffer, |
| unsigned int size) { |
| unsigned char byte; |
| unsigned int i, start; |
| for (i = start = 0; i != size; ++i) { |
| byte = buffer[i]; |
| switch (telnet->state) { |
| /* regular data */ |
| case LIBTELNET_STATE_DATA: |
| /* on an IAC byte, pass through all pending bytes and |
| * switch states */ |
| if (byte == LIBTELNET_IAC) { |
| if (i != start) |
| _event(telnet, LIBTELNET_EV_DATA, 0, 0, &buffer[start], |
| i - start); |
| telnet->state = LIBTELNET_STATE_IAC; |
| } |
| break; |
| |
| /* IAC command */ |
| case LIBTELNET_STATE_IAC: |
| switch (byte) { |
| /* subnegotiation */ |
| case LIBTELNET_SB: |
| telnet->state = LIBTELNET_STATE_SB; |
| break; |
| /* negotiation commands */ |
| case LIBTELNET_WILL: |
| telnet->state = LIBTELNET_STATE_WILL; |
| break; |
| case LIBTELNET_WONT: |
| telnet->state = LIBTELNET_STATE_WONT; |
| break; |
| case LIBTELNET_DO: |
| telnet->state = LIBTELNET_STATE_DO; |
| break; |
| case LIBTELNET_DONT: |
| telnet->state = LIBTELNET_STATE_DONT; |
| break; |
| /* IAC escaping */ |
| case LIBTELNET_IAC: |
| _event(telnet, LIBTELNET_EV_DATA, 0, 0, &byte, 1); |
| start = i + 1; |
| telnet->state = LIBTELNET_STATE_DATA; |
| break; |
| /* some other command */ |
| default: |
| _event(telnet, LIBTELNET_EV_IAC, byte, 0, 0, 0); |
| start = i + 1; |
| telnet->state = LIBTELNET_STATE_DATA; |
| } |
| break; |
| |
| /* negotiation commands */ |
| case LIBTELNET_STATE_DO: |
| _event(telnet, LIBTELNET_EV_NEGOTIATE, LIBTELNET_DO, byte, 0, 0); |
| start = i + 1; |
| telnet->state = LIBTELNET_STATE_DATA; |
| break; |
| case LIBTELNET_STATE_DONT: |
| _event(telnet, LIBTELNET_EV_NEGOTIATE, LIBTELNET_DONT, byte, 0, 0); |
| start = i + 1; |
| telnet->state = LIBTELNET_STATE_DATA; |
| break; |
| case LIBTELNET_STATE_WILL: |
| _event(telnet, LIBTELNET_EV_NEGOTIATE, LIBTELNET_WILL, byte, 0, 0); |
| start = i + 1; |
| telnet->state = LIBTELNET_STATE_DATA; |
| break; |
| case LIBTELNET_STATE_WONT: |
| _event(telnet, LIBTELNET_EV_NEGOTIATE, LIBTELNET_WONT, byte, 0, 0); |
| start = i + 1; |
| telnet->state = LIBTELNET_STATE_DATA; |
| break; |
| |
| /* subnegotiation -- determine subnegotiation telopt */ |
| case LIBTELNET_STATE_SB: |
| telnet->sb_telopt = byte; |
| telnet->length = 0; |
| telnet->state = LIBTELNET_STATE_SB_DATA; |
| break; |
| |
| /* subnegotiation -- buffer bytes until end request */ |
| case LIBTELNET_STATE_SB_DATA: |
| /* IAC command in subnegotiation -- either IAC SE or IAC IAC */ |
| if (byte == LIBTELNET_IAC) { |
| telnet->state = LIBTELNET_STATE_SB_DATA_IAC; |
| /* buffer the byte, or bail if we can't */ |
| } else if (_buffer_byte(telnet, byte) != LIBTELNET_EOK) { |
| start = i + 1; |
| telnet->state = LIBTELNET_STATE_DATA; |
| } |
| break; |
| |
| /* IAC escaping inside a subnegotiation */ |
| case LIBTELNET_STATE_SB_DATA_IAC: |
| switch (byte) { |
| /* end subnegotiation */ |
| case LIBTELNET_SE: |
| /* return to default state */ |
| start = i + 1; |
| telnet->state = LIBTELNET_STATE_DATA; |
| |
| /* invoke callback */ |
| _event(telnet, LIBTELNET_EV_SUBNEGOTIATION, 0, |
| telnet->sb_telopt, telnet->buffer, telnet->length); |
| |
| #ifdef HAVE_ZLIB |
| /* if we are a client or a proxy and just received the |
| * COMPRESS2 begin marker, setup our zlib box and start |
| * handling the compressed stream if it's not already. |
| */ |
| if (telnet->sb_telopt == LIBTELNET_TELOPT_COMPRESS2 && |
| telnet->z_inflate == 0 && |
| (telnet->mode == LIBTELNET_MODE_CLIENT || |
| telnet->mode == LIBTELNET_MODE_PROXY)) { |
| |
| if ((telnet->z_inflate = _init_zlib(telnet, 0, 1)) == 0) |
| break; |
| |
| /* notify app that compression was enabled */ |
| _event(telnet, LIBTELNET_EV_COMPRESS, 1, 0, 0, 0); |
| |
| /* any remaining bytes in the buffer are compressed. |
| * we have to re-invoke libtelnet_push to get those |
| * bytes inflated and abort trying to process the |
| * remaining compressed bytes in the current _process |
| * buffer argument |
| */ |
| libtelnet_push(telnet, &buffer[start], size - start); |
| return; |
| } |
| #endif /* HAVE_ZLIB */ |
| |
| break; |
| /* escaped IAC byte */ |
| case LIBTELNET_IAC: |
| /* push IAC into buffer */ |
| if (_buffer_byte(telnet, LIBTELNET_IAC) != |
| LIBTELNET_EOK) { |
| start = i + 1; |
| telnet->state = LIBTELNET_STATE_DATA; |
| } else { |
| telnet->state = LIBTELNET_STATE_SB_DATA; |
| } |
| break; |
| /* something else -- protocol error */ |
| default: |
| _error(telnet, __LINE__, __func__, LIBTELNET_EPROTOCOL, 0, |
| "unexpected byte after IAC inside SB: %d", |
| byte); |
| start = i + 1; |
| telnet->state = LIBTELNET_STATE_DATA; |
| break; |
| } |
| break; |
| } |
| } |
| |
| /* pass through any remaining bytes */ |
| if (telnet->state == LIBTELNET_STATE_DATA && i != start) |
| _event(telnet, LIBTELNET_EV_DATA, 0, 0, buffer + start, i - start); |
| } |
| |
| /* push a bytes into the state tracker */ |
| void libtelnet_push(struct libtelnet_t *telnet, unsigned char *buffer, |
| unsigned int size) { |
| #ifdef HAVE_ZLIB |
| /* if we have an inflate (decompression) zlib stream, use it */ |
| if (telnet->z_inflate != 0) { |
| unsigned char inflate_buffer[4096]; |
| int rs; |
| |
| /* initialize zlib state */ |
| telnet->z_inflate->next_in = buffer; |
| telnet->z_inflate->avail_in = size; |
| telnet->z_inflate->next_out = inflate_buffer; |
| telnet->z_inflate->avail_out = sizeof(inflate_buffer); |
| |
| /* inflate until buffer exhausted and all output is produced */ |
| while (telnet->z_inflate->avail_in > 0 || telnet->z_inflate->avail_out == 0) { |
| /* reset output buffer */ |
| |
| /* decompress */ |
| rs = inflate(telnet->z_inflate, Z_SYNC_FLUSH); |
| |
| /* process the decompressed bytes on success */ |
| if (rs == Z_OK || rs == Z_STREAM_END) |
| _process(telnet, inflate_buffer, sizeof(inflate_buffer) - |
| telnet->z_inflate->avail_out); |
| else |
| _error(telnet, __LINE__, __func__, LIBTELNET_ECOMPRESS, 1, |
| "inflate() failed: %s", zError(rs)); |
| |
| /* prepare output buffer for next run */ |
| telnet->z_inflate->next_out = inflate_buffer; |
| telnet->z_inflate->avail_out = sizeof(inflate_buffer); |
| |
| /* on error (or on end of stream) disable further inflation */ |
| if (rs != Z_OK) { |
| _event(telnet, LIBTELNET_EV_COMPRESS, 0, 0, 0, 0); |
| |
| inflateEnd(telnet->z_inflate); |
| free(telnet->z_inflate); |
| telnet->z_inflate = 0; |
| break; |
| } |
| } |
| |
| /* COMPRESS2 is not negotiated, just process */ |
| } else |
| #endif /* HAVE_ZLIB */ |
| _process(telnet, buffer, size); |
| } |
| |
| static void _send(struct libtelnet_t *telnet, unsigned char *buffer, |
| unsigned int size) { |
| #ifdef HAVE_ZLIB |
| /* if we have a deflate (compression) zlib box, use it */ |
| if (telnet->z_deflate != 0) { |
| unsigned char deflate_buffer[1024]; |
| int rs; |
| |
| /* initialize z_deflate state */ |
| telnet->z_deflate->next_in = buffer; |
| telnet->z_deflate->avail_in = size; |
| telnet->z_deflate->next_out = deflate_buffer; |
| telnet->z_deflate->avail_out = sizeof(deflate_buffer); |
| |
| /* deflate until buffer exhausted and all output is produced */ |
| while (telnet->z_deflate->avail_in > 0 || telnet->z_deflate->avail_out == 0) { |
| /* compress */ |
| if ((rs = deflate(telnet->z_deflate, Z_SYNC_FLUSH)) != Z_OK) { |
| _error(telnet, __LINE__, __func__, LIBTELNET_ECOMPRESS, 1, |
| "deflate() failed: %s", zError(rs)); |
| deflateEnd(telnet->z_deflate); |
| free(telnet->z_deflate); |
| telnet->z_deflate = 0; |
| break; |
| } |
| |
| _event(telnet, LIBTELNET_EV_SEND, 0, 0, deflate_buffer, |
| sizeof(deflate_buffer) - telnet->z_deflate->avail_out); |
| |
| /* prepare output buffer for next run */ |
| telnet->z_deflate->next_out = deflate_buffer; |
| telnet->z_deflate->avail_out = sizeof(deflate_buffer); |
| } |
| |
| /* COMPRESS2 is not negotiated, just send */ |
| } else |
| #endif /* HAVE_ZLIB */ |
| _event(telnet, LIBTELNET_EV_SEND, 0, 0, buffer, size); |
| } |
| |
| /* send an iac command */ |
| void libtelnet_send_command(struct libtelnet_t *telnet, unsigned char cmd) { |
| unsigned char bytes[2] = { LIBTELNET_IAC, cmd }; |
| _send(telnet, bytes, 2); |
| } |
| |
| /* send negotiation */ |
| void libtelnet_send_negotiate(struct libtelnet_t *telnet, unsigned char cmd, |
| unsigned char opt) { |
| unsigned char bytes[3] = { LIBTELNET_IAC, cmd, opt }; |
| _send(telnet, bytes, 3); |
| } |
| |
| /* send non-command data (escapes IAC bytes) */ |
| void libtelnet_send_data(struct libtelnet_t *telnet, unsigned char *buffer, |
| unsigned int size) { |
| unsigned int i, l; |
| for (l = i = 0; i != size; ++i) { |
| /* dump prior portion of text, send escaped bytes */ |
| if (buffer[i] == LIBTELNET_IAC) { |
| /* dump prior text if any */ |
| if (i != l) |
| _send(telnet, buffer + l, i - l); |
| l = i + 1; |
| |
| /* send escape */ |
| libtelnet_send_command(telnet, LIBTELNET_IAC); |
| } |
| } |
| |
| /* send whatever portion of buffer is left */ |
| if (i != l) |
| _send(telnet, buffer + l, i - l); |
| } |
| |
| /* send sub-request */ |
| void libtelnet_send_subnegotiation(struct libtelnet_t *telnet, |
| unsigned char opt, unsigned char *buffer, unsigned int size) { |
| libtelnet_send_command(telnet, LIBTELNET_SB); |
| libtelnet_send_data(telnet, &opt, 1); |
| libtelnet_send_data(telnet, buffer, size); |
| libtelnet_send_command(telnet, LIBTELNET_SE); |
| |
| #ifdef HAVE_ZLIB |
| /* if we're a proxy and we just sent the COMPRESS2 marker, we must |
| * make sure all further data is compressed if not already. |
| */ |
| if (telnet->mode == LIBTELNET_MODE_PROXY && |
| telnet->z_deflate == 0 && |
| opt == LIBTELNET_TELOPT_COMPRESS2) { |
| |
| if ((telnet->z_deflate = _init_zlib(telnet, 1, 1)) == 0) |
| return; |
| |
| /* notify app that compression was enabled */ |
| _event(telnet, LIBTELNET_EV_COMPRESS, 1, 0, 0, 0); |
| } |
| #endif /* HAVE_ZLIB */ |
| } |
| |
| void libtelnet_begin_compress2(struct libtelnet_t *telnet) { |
| #ifdef HAVE_ZLIB |
| z_stream *zlib; |
| |
| /* don't do this if we've already got a compression stream */ |
| if (telnet->z_deflate != 0) { |
| _error(telnet, __LINE__, __func__, LIBTELNET_EBADVAL, 0, |
| "compression already enabled"); |
| return; |
| } |
| |
| /* only supported by servers */ |
| if (telnet->mode != LIBTELNET_MODE_SERVER) { |
| _error(telnet, __LINE__, __func__, LIBTELNET_EBADVAL, 0, |
| "only supported in SERVER mode"); |
| return; |
| } |
| |
| /* attempt to create output stream first, bail if we can't */ |
| if ((zlib = _init_zlib(telnet, 1, 0)) == 0) |
| return; |
| |
| /* send compression marker */ |
| libtelnet_send_subnegotiation(telnet, LIBTELNET_TELOPT_COMPRESS2, 0, 0); |
| |
| /* set our deflate stream */ |
| telnet->z_deflate = zlib; |
| #endif /* HAVE_ZLIB */ |
| } |