/** * FreeRDP: A Remote Desktop Protocol Implementation * Implements Microsoft Point to Point Compression (MPPC) protocol * * Copyright 2012 Laxmikant Rashinkar * Copyright 2012 Jay Sorg * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include #include #include #include #include #include #define MPPC_ENC_DEBUG 0 /* local defines */ #define RDP_40_HIST_BUF_LEN (1024 * 8) /* RDP 4.0 uses 8K history buf */ #define RDP_50_HIST_BUF_LEN (1024 * 64) /* RDP 5.0 uses 64K history buf */ #define CRC_INIT 0xFFFF #define CRC(crcval, newchar) crcval = (crcval >> 8) ^ crc_table[(crcval ^ newchar) & 0x00ff] /* CRC16 defs */ static const UINT16 crc_table[256] = { 0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf, 0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7, 0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e, 0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876, 0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd, 0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5, 0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c, 0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974, 0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb, 0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3, 0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a, 0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72, 0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9, 0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1, 0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738, 0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70, 0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7, 0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff, 0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036, 0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e, 0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5, 0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd, 0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134, 0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c, 0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3, 0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb, 0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232, 0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a, 0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1, 0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9, 0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330, 0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78 }; /***************************************************************************** insert 2 bits into outputBuffer ******************************************************************************/ #define insert_2_bits(_data) \ do \ { \ if ((bits_left >= 3) && (bits_left <= 8)) \ { \ i = bits_left - 2; \ outputBuffer[opb_index] |= _data << i; \ bits_left = i; \ } \ else \ { \ i = 2 - bits_left; \ j = 8 - i; \ outputBuffer[opb_index++] |= _data >> i; \ outputBuffer[opb_index] |= _data << j; \ bits_left = j; \ } \ } while (0) /***************************************************************************** insert 3 bits into outputBuffer ******************************************************************************/ #define insert_3_bits(_data) \ do \ { \ if ((bits_left >= 4) && (bits_left <= 8)) \ { \ i = bits_left - 3; \ outputBuffer[opb_index] |= _data << i; \ bits_left = i; \ } \ else \ { \ i = 3 - bits_left; \ j = 8 - i; \ outputBuffer[opb_index++] |= _data >> i; \ outputBuffer[opb_index] |= _data << j; \ bits_left = j; \ } \ } while (0) /***************************************************************************** insert 4 bits into outputBuffer ******************************************************************************/ #define insert_4_bits(_data) \ do \ { \ if ((bits_left >= 5) && (bits_left <= 8)) \ { \ i = bits_left - 4; \ outputBuffer[opb_index] |= _data << i; \ bits_left = i; \ } \ else \ { \ i = 4 - bits_left; \ j = 8 - i; \ outputBuffer[opb_index++] |= _data >> i; \ outputBuffer[opb_index] |= _data << j; \ bits_left = j; \ } \ } while (0) /***************************************************************************** insert 5 bits into outputBuffer ******************************************************************************/ #define insert_5_bits(_data) \ do \ { \ if ((bits_left >= 6) && (bits_left <= 8)) \ { \ i = bits_left - 5; \ outputBuffer[opb_index] |= _data << i; \ bits_left = i; \ } \ else \ { \ i = 5 - bits_left; \ j = 8 - i; \ outputBuffer[opb_index++] |= _data >> i; \ outputBuffer[opb_index] |= _data << j; \ bits_left = j; \ } \ } while (0) /***************************************************************************** insert 6 bits into outputBuffer ******************************************************************************/ #define insert_6_bits(_data) \ do \ { \ if ((bits_left >= 7) && (bits_left <= 8)) \ { \ i = bits_left - 6; \ outputBuffer[opb_index] |= (_data << i); \ bits_left = i; \ } \ else \ { \ i = 6 - bits_left; \ j = 8 - i; \ outputBuffer[opb_index++] |= (_data >> i); \ outputBuffer[opb_index] |= (_data << j); \ bits_left = j; \ } \ } while (0) /***************************************************************************** insert 7 bits into outputBuffer ******************************************************************************/ #define insert_7_bits(_data) \ do \ { \ if (bits_left == 8) \ { \ outputBuffer[opb_index] |= _data << 1; \ bits_left = 1; \ } \ else \ { \ i = 7 - bits_left; \ j = 8 - i; \ outputBuffer[opb_index++] |= _data >> i; \ outputBuffer[opb_index] |= _data << j; \ bits_left = j; \ } \ } while (0) /***************************************************************************** insert 8 bits into outputBuffer ******************************************************************************/ #define insert_8_bits(_data) \ do \ { \ if (bits_left == 8) \ { \ outputBuffer[opb_index++] |= _data; \ bits_left = 8; \ } \ else \ { \ i = 8 - bits_left; \ j = 8 - i; \ outputBuffer[opb_index++] |= _data >> i; \ outputBuffer[opb_index] |= _data << j; \ bits_left = j; \ } \ } while (0) /***************************************************************************** insert 9 bits into outputBuffer ******************************************************************************/ #define insert_9_bits(_data16) \ do \ { \ i = 9 - bits_left; \ j = 8 - i; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index] |= (char) (_data16 << j); \ bits_left = j; \ if (bits_left == 0) \ { \ opb_index++; \ bits_left = 8; \ } \ } while (0) /***************************************************************************** insert 10 bits into outputBuffer ******************************************************************************/ #define insert_10_bits(_data16) \ do \ { \ i = 10 - bits_left; \ if ((bits_left >= 3) && (bits_left <= 8)) \ { \ j = 8 - i; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index] |= (char) (_data16 << j); \ bits_left = j; \ } \ else \ { \ j = i - 8; \ k = 8 - j; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index++] |= (char) (_data16 >> j); \ outputBuffer[opb_index] |= (char) (_data16 << k); \ bits_left = k; \ } \ } while (0) /***************************************************************************** insert 11 bits into outputBuffer ******************************************************************************/ #define insert_11_bits(_data16) \ do \ { \ i = 11 - bits_left; \ if ((bits_left >= 4) && (bits_left <= 8)) \ { \ j = 8 - i; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index] |= (char) (_data16 << j); \ bits_left = j; \ } \ else \ { \ j = i - 8; \ k = 8 - j; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index++] |= (char) (_data16 >> j); \ outputBuffer[opb_index] |= (char) (_data16 << k); \ bits_left = k; \ } \ } while (0) /***************************************************************************** insert 12 bits into outputBuffer ******************************************************************************/ #define insert_12_bits(_data16) \ do \ { \ i = 12 - bits_left; \ if ((bits_left >= 5) && (bits_left <= 8)) \ { \ j = 8 - i; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index] |= (char) (_data16 << j); \ bits_left = j; \ } \ else \ { \ j = i - 8; \ k = 8 - j; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index++] |= (char) (_data16 >> j); \ outputBuffer[opb_index] |= (char) (_data16 << k); \ bits_left = k; \ } \ } while (0) /***************************************************************************** insert 13 bits into outputBuffer ******************************************************************************/ #define insert_13_bits(_data16) \ do \ { \ i = 13 - bits_left; \ if ((bits_left >= 6) && (bits_left <= 8)) \ { \ j = 8 - i; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index] |= (char) (_data16 << j); \ bits_left = j; \ } \ else \ { \ j = i - 8; \ k = 8 - j; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index++] |= (char) (_data16 >> j); \ outputBuffer[opb_index] |= (char) (_data16 << k); \ bits_left = k; \ } \ } while (0) /***************************************************************************** insert 14 bits into outputBuffer ******************************************************************************/ #define insert_14_bits(_data16) \ do \ { \ i = 14 - bits_left; \ if ((bits_left >= 7) && (bits_left <= 8)) \ { \ j = 8 - i; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index] |= (char) (_data16 << j); \ bits_left = j; \ } \ else \ { \ j = i - 8; \ k = 8 - j; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index++] |= (char) (_data16 >> j); \ outputBuffer[opb_index] |= (char) (_data16 << k); \ bits_left = k; \ } \ } while (0) /***************************************************************************** insert 15 bits into outputBuffer ******************************************************************************/ #define insert_15_bits(_data16) \ do \ { \ i = 15 - bits_left; \ if (bits_left == 8) \ { \ j = 8 - i; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index] |= (char) (_data16 << j); \ bits_left = j; \ } \ else \ { \ j = i - 8; \ k = 8 - j; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index++] |= (char) (_data16 >> j); \ outputBuffer[opb_index] |= (char) (_data16 << k); \ bits_left = k; \ } \ } while (0) /***************************************************************************** insert 16 bits into outputBuffer ******************************************************************************/ #define insert_16_bits(_data16) \ do \ { \ i = 16 - bits_left; \ j = i - 8; \ k = 8 - j; \ outputBuffer[opb_index++] |= (char) (_data16 >> i); \ outputBuffer[opb_index++] |= (char) (_data16 >> j); \ outputBuffer[opb_index] |= (char) (_data16 << k); \ bits_left = k; \ } while (0) #if MPPC_ENC_DEBUG #define DLOG(_args) printf _args #else #define DLOG(_args) do { } while (0) #endif /** * Initialize mppc_enc structure * * @param protocol_type PROTO_RDP_40 or PROTO_RDP_50 * * @return struct rdp_mppc_enc* or nil on failure */ struct rdp_mppc_enc* mppc_enc_new(int protocol_type) { struct rdp_mppc_enc* enc; enc = xnew(struct rdp_mppc_enc); if (enc == NULL) return NULL; switch (protocol_type) { case PROTO_RDP_40: enc->protocol_type = PROTO_RDP_40; enc->buf_len = RDP_40_HIST_BUF_LEN; break; case PROTO_RDP_50: enc->protocol_type = PROTO_RDP_50; enc->buf_len = RDP_50_HIST_BUF_LEN; break; default: free(enc); return NULL; } enc->first_pkt = 1; enc->historyBuffer = (char*) xzalloc(enc->buf_len); if (enc->historyBuffer == NULL) { free(enc); return NULL; } enc->outputBufferPlus = (char*) xzalloc(enc->buf_len + 64); if (enc->outputBufferPlus == NULL) { free(enc->historyBuffer); free(enc); return NULL; } enc->outputBuffer = enc->outputBufferPlus + 64; enc->hash_table = (UINT16*) xzalloc(enc->buf_len * 2); if (enc->hash_table == NULL) { free(enc->historyBuffer); free(enc->outputBufferPlus); free(enc); return NULL; } return enc; } /** * deinit mppc_enc structure * * @param enc struct to be deinited */ void mppc_enc_free(struct rdp_mppc_enc* enc) { if (enc == NULL) return; free(enc->historyBuffer); free(enc->outputBufferPlus); free(enc->hash_table); free(enc); } /** * encode (compress) data * * @param enc encoder state info * @param srcData uncompressed data * @param len length of srcData * * @return TRUE on success, FALSE on failure */ BOOL compress_rdp(struct rdp_mppc_enc* enc, BYTE* srcData, int len) { if ((enc == NULL) || (srcData == NULL) || (len <= 0) || (len > enc->buf_len)) return FALSE; switch (enc->protocol_type) { case PROTO_RDP_40: return compress_rdp_4(enc, srcData, len); break; case PROTO_RDP_50: return compress_rdp_5(enc, srcData, len); break; } return FALSE; } /** * encode (compress) data using RDP 4.0 protocol * * @param enc encoder state info * @param srcData uncompressed data * @param len length of srcData * * @return TRUE on success, FALSE on failure */ BOOL compress_rdp_4(struct rdp_mppc_enc* enc, BYTE* srcData, int len) { /* RDP 4.0 encoding not yet implemented */ return FALSE; } /** * encode (compress) data using RDP 5.0 protocol using hash table * * @param enc encoder state info * @param srcData uncompressed data * @param len length of srcData * * @return TRUE on success, FALSE on failure */ BOOL compress_rdp_5(struct rdp_mppc_enc* enc, BYTE* srcData, int len) { char* outputBuffer; /* points to enc->outputBuffer */ char* hptr_end; /* points to end of history data */ char* historyPointer; /* points to first byte of srcData in historyBuffer */ char* hbuf_start; /* points to start of history buffer */ char* cptr1; char* cptr2; int opb_index; /* index into outputBuffer */ int bits_left; /* unused bits in current byte in outputBuffer */ UINT32 copy_offset; /* pattern match starts here... */ UINT32 lom; /* ...and matches this many bytes */ int last_crc_index; /* don't compute CRC beyond this index */ UINT16 *hash_table; /* hash table for pattern matching */ UINT32 i; UINT32 j; UINT32 k; UINT32 x; BYTE data; UINT16 data16; UINT32 historyOffset; UINT16 crc; UINT32 ctr; UINT32 saved_ctr; UINT32 data_end; BYTE byte_val; crc = 0; opb_index = 0; bits_left = 8; copy_offset = 0; hash_table = enc->hash_table; hbuf_start = enc->historyBuffer; outputBuffer = enc->outputBuffer; memset(outputBuffer, 0, len); enc->flags = PACKET_COMPR_TYPE_64K; if (enc->first_pkt) { enc->first_pkt = 0; enc->flagsHold |= PACKET_AT_FRONT; } if ((enc->historyOffset + len) > enc->buf_len) { /* historyBuffer cannot hold srcData - rewind it */ enc->historyOffset = 0; enc->flagsHold |= PACKET_AT_FRONT; memset(hash_table, 0, enc->buf_len * 2); } /* point to next free byte in historyBuffer */ historyOffset = enc->historyOffset; /* add / append new data to historyBuffer */ memcpy(&(enc->historyBuffer[historyOffset]), srcData, len); /* point to start of data to be compressed */ historyPointer = &(enc->historyBuffer[historyOffset]); ctr = copy_offset = lom = 0; /* if we are at start of history buffer, do not attempt to compress */ /* first 2 bytes,because minimum LoM is 3 */ if (historyOffset == 0) { /* encode first two bytes are literals */ for (x = 0; x < 2; x++) { data = *(historyPointer + x); DLOG(("%.2x ", (unsigned char) data)); if (data & 0x80) { /* insert encoded literal */ insert_2_bits(0x02); data &= 0x7f; insert_7_bits(data); } else { /* insert literal */ insert_8_bits(data); } } /* store hash for first two entries in historyBuffer */ crc = CRC_INIT; byte_val = enc->historyBuffer[0]; CRC(crc, byte_val); byte_val = enc->historyBuffer[1]; CRC(crc, byte_val); byte_val = enc->historyBuffer[2]; CRC(crc, byte_val); hash_table[crc] = 0; crc = CRC_INIT; byte_val = enc->historyBuffer[1]; CRC(crc, byte_val); byte_val = enc->historyBuffer[2]; CRC(crc, byte_val); byte_val = enc->historyBuffer[3]; CRC(crc, byte_val); hash_table[crc] = 1; /* first two bytes have already been processed */ ctr = 2; } enc->historyOffset += len; /* point to last byte in new data */ hptr_end = &(enc->historyBuffer[enc->historyOffset - 1]); /* do not compute CRC beyond this */ last_crc_index = enc->historyOffset - 3; /* do not search for pattern match beyond this */ data_end = len - 2; /* start compressing data */ while (ctr < data_end) { cptr1 = historyPointer + ctr; crc = CRC_INIT; byte_val = *cptr1; CRC(crc, byte_val); byte_val = *(cptr1 + 1); CRC(crc, byte_val); byte_val = *(cptr1 + 2); CRC(crc, byte_val); /* cptr2 points to start of pattern match */ cptr2 = hbuf_start + hash_table[crc]; copy_offset = cptr1 - cptr2; /* save current entry */ hash_table[crc] = cptr1 - hbuf_start; /* double check that we have a pattern match */ if ((*cptr1 != *cptr2) || (*(cptr1 + 1) != *(cptr2 + 1)) || (*(cptr1 + 2) != *(cptr2 + 2))) { /* no match found; encode literal byte */ data = *cptr1; DLOG(("%.2x ", (unsigned char) data)); if (data < 0x80) { /* literal byte < 0x80 */ insert_8_bits(data); } else { /* literal byte >= 0x80 */ insert_2_bits(0x02); data &= 0x7f; insert_7_bits(data); } ctr++; continue; } /* we have a match - compute Length of Match */ cptr1 += 3; cptr2 += 3; lom = 3; while ((cptr1 <= hptr_end) && (*(cptr1++) == *(cptr2++))) { lom++; } saved_ctr = ctr + lom; DLOG(("<%d: %ld,%d> ", (historyPointer + ctr) - hbuf_start, copy_offset, lom)); /* compute CRC for matching segment and store in hash table */ cptr1 = historyPointer + ctr; if (cptr1 + lom > hbuf_start + last_crc_index) { /* we have gone beyond last_crc_index - go back */ j = last_crc_index - (cptr1 - hbuf_start); } else { j = lom - 1; } ctr++; for (i = 0; i < j; i++) { cptr1 = historyPointer + ctr; /* compute CRC on triplet */ crc = CRC_INIT; byte_val = *(cptr1++); CRC(crc, byte_val); byte_val = *(cptr1++); CRC(crc, byte_val); byte_val = *(cptr1++); CRC(crc, byte_val); /* save current entry */ hash_table[crc] = (cptr1 - 3) - hbuf_start; /* point to next triplet */ ctr++; } ctr = saved_ctr; /* encode copy_offset and insert into output buffer */ if ((copy_offset >= 0) && (copy_offset <= 63)) { /* insert binary header */ data = 0x1f; insert_5_bits(data); /* insert 6 bits of copy_offset */ data = (char) (copy_offset & 0x3f); insert_6_bits(data); } else if ((copy_offset >= 64) && (copy_offset <= 319)) { /* insert binary header */ data = 0x1e; insert_5_bits(data); /* insert 8 bits of copy offset */ data = (char) (copy_offset - 64); insert_8_bits(data); } else if ((copy_offset >= 320) && (copy_offset <= 2367)) { /* insert binary header */ data = 0x0e; insert_4_bits(data); /* insert 11 bits of copy offset */ data16 = copy_offset - 320;; insert_11_bits(data16); } else { /* copy_offset is 2368+ */ /* insert binary header */ data = 0x06; insert_3_bits(data); /* insert 16 bits of copy offset */ data16 = copy_offset - 2368;; insert_16_bits(data16); } /* encode length of match and insert into output buffer */ if (lom == 3) { /* binary header is 'zero'; since outputBuffer is zero */ /* filled, all we have to do is update bits_left */ bits_left--; if (bits_left == 0) { opb_index++; bits_left = 8; } } else if ((lom >= 4) && (lom <= 7)) { /* insert binary header */ data = 0x02; insert_2_bits(data); /* insert lower 2 bits of LoM */ data = (char) (lom - 4); insert_2_bits(data); } else if ((lom >= 8) && (lom <= 15)) { /* insert binary header */ data = 0x06; insert_3_bits(data); /* insert lower 3 bits of LoM */ data = (char) (lom - 8); insert_3_bits(data); } else if ((lom >= 16) && (lom <= 31)) { /* insert binary header */ data = 0x0e; insert_4_bits(data); /* insert lower 4 bits of LoM */ data = (char) (lom - 16); insert_4_bits(data); } else if ((lom >= 32) && (lom <= 63)) { /* insert binary header */ data = 0x1e; insert_5_bits(data); /* insert lower 5 bits of LoM */ data = (char) (lom - 32); insert_5_bits(data); } else if ((lom >= 64) && (lom <= 127)) { /* insert binary header */ data = 0x3e; insert_6_bits(data); /* insert lower 6 bits of LoM */ data = (char) (lom - 64); insert_6_bits(data); } else if ((lom >= 128) && (lom <= 255)) { /* insert binary header */ data = 0x7e; insert_7_bits(data); /* insert lower 7 bits of LoM */ data = (char) (lom - 128); insert_7_bits(data); } else if ((lom >= 256) && (lom <= 511)) { /* insert binary header */ data = 0xfe; insert_8_bits(data); /* insert lower 8 bits of LoM */ data = (char) (lom - 256); insert_8_bits(data); } else if ((lom >= 512) && (lom <= 1023)) { /* insert binary header */ data16 = 0x1fe; insert_9_bits(data16); /* insert lower 9 bits of LoM */ data16 = lom - 512; insert_9_bits(data16); } else if ((lom >= 1024) && (lom <= 2047)) { /* insert binary header */ data16 = 0x3fe; insert_10_bits(data16); /* insert 10 lower bits of LoM */ data16 = lom - 1024; insert_10_bits(data16); } else if ((lom >= 2048) && (lom <= 4095)) { /* insert binary header */ data16 = 0x7fe; insert_11_bits(data16); /* insert 11 lower bits of LoM */ data16 = lom - 2048; insert_11_bits(data16); } else if ((lom >= 4096) && (lom <= 8191)) { /* insert binary header */ data16 = 0xffe; insert_12_bits(data16); /* insert 12 lower bits of LoM */ data16 = lom - 4096; insert_12_bits(data16); } else if ((lom >= 8192) && (lom <= 16383)) { /* insert binary header */ data16 = 0x1ffe; insert_13_bits(data16); /* insert 13 lower bits of LoM */ data16 = lom - 8192; insert_13_bits(data16); } else if ((lom >= 16384) && (lom <= 32767)) { /* insert binary header */ data16 = 0x3ffe; insert_14_bits(data16); /* insert 14 lower bits of LoM */ data16 = lom - 16384; insert_14_bits(data16); } else if ((lom >= 32768) && (lom <= 65535)) { /* insert binary header */ data16 = 0x7ffe; insert_15_bits(data16); /* insert 15 lower bits of LoM */ data16 = lom - 32768; insert_15_bits(data16); } } /* end while (ctr < data_end) */ /* add remaining data to the output */ while (len - ctr > 0) { data = srcData[ctr]; DLOG(("%.2x ", (unsigned char) data)); if (data < 0x80) { /* literal byte < 0x80 */ insert_8_bits(data); } else { /* literal byte >= 0x80 */ insert_2_bits(0x02); data &= 0x7f; insert_7_bits(data); } ctr++; } /* if bits_left == 8, opb_index has already been incremented */ if ((bits_left == 8) && (opb_index > len)) { /* compressed data longer than uncompressed data */ /* give up */ enc->historyOffset = 0; memset(hash_table, 0, enc->buf_len * 2); enc->flagsHold |= PACKET_FLUSHED; enc->first_pkt = 1; return TRUE; } else if (opb_index + 1 > len) { /* compressed data longer than uncompressed data */ /* give up */ enc->historyOffset = 0; memset(hash_table, 0, enc->buf_len * 2); enc->flagsHold |= PACKET_FLUSHED; enc->first_pkt = 1; return TRUE; } /* if bits_left != 8, increment opb_index, which is zero indexed */ if (bits_left != 8) { opb_index++; } if (opb_index > len) { /* give up */ enc->historyOffset = 0; memset(hash_table, 0, enc->buf_len * 2); enc->flagsHold |= PACKET_FLUSHED; enc->first_pkt = 1; return TRUE; } enc->flags |= PACKET_COMPRESSED; enc->bytes_in_opb = opb_index; enc->flags |= enc->flagsHold; enc->flagsHold = 0; DLOG(("\n")); return TRUE; }