From 6d79387715ee12197d6de41a1044b00ba78b2dcd Mon Sep 17 00:00:00 2001 From: Max Lv Date: Wed, 16 Sep 2015 20:36:18 +0800 Subject: [PATCH] use crc16 --- src/encrypt.c | 87 +++++++++++++++++++++++++++++++++------------------ src/server.c | 10 +++--- 2 files changed, 62 insertions(+), 35 deletions(-) diff --git a/src/encrypt.c b/src/encrypt.c index 27b1510e..b26407b5 100644 --- a/src/encrypt.c +++ b/src/encrypt.c @@ -66,6 +66,7 @@ #endif #include +#include #include "cache.h" #include "encrypt.h" @@ -1462,27 +1463,48 @@ int enc_init(const char *pass, const char *method) return m; } -/* - * Return CRC-8 of the data, using x^8 + x^2 + x + 1 polynomial. A table-based - * algorithm would be faster, but for only a few bytes it isn't worth the code - * size. - */ -uint8_t crc8(const void *vptr, int len) -{ - const uint8_t *data = vptr; - unsigned crc = 0; - int i, j; - - for (j = len; j; j--, data++) { - crc ^= (*data << 8); - for(i = 8; i; i--) { - if (crc & 0x8000) - crc ^= (0x1070 << 3); - crc <<= 1; - } - } +static const unsigned short crc16tab[256]= { + 0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7, + 0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef, + 0x1231,0x0210,0x3273,0x2252,0x52b5,0x4294,0x72f7,0x62d6, + 0x9339,0x8318,0xb37b,0xa35a,0xd3bd,0xc39c,0xf3ff,0xe3de, + 0x2462,0x3443,0x0420,0x1401,0x64e6,0x74c7,0x44a4,0x5485, + 0xa56a,0xb54b,0x8528,0x9509,0xe5ee,0xf5cf,0xc5ac,0xd58d, + 0x3653,0x2672,0x1611,0x0630,0x76d7,0x66f6,0x5695,0x46b4, + 0xb75b,0xa77a,0x9719,0x8738,0xf7df,0xe7fe,0xd79d,0xc7bc, + 0x48c4,0x58e5,0x6886,0x78a7,0x0840,0x1861,0x2802,0x3823, + 0xc9cc,0xd9ed,0xe98e,0xf9af,0x8948,0x9969,0xa90a,0xb92b, + 0x5af5,0x4ad4,0x7ab7,0x6a96,0x1a71,0x0a50,0x3a33,0x2a12, + 0xdbfd,0xcbdc,0xfbbf,0xeb9e,0x9b79,0x8b58,0xbb3b,0xab1a, + 0x6ca6,0x7c87,0x4ce4,0x5cc5,0x2c22,0x3c03,0x0c60,0x1c41, + 0xedae,0xfd8f,0xcdec,0xddcd,0xad2a,0xbd0b,0x8d68,0x9d49, + 0x7e97,0x6eb6,0x5ed5,0x4ef4,0x3e13,0x2e32,0x1e51,0x0e70, + 0xff9f,0xefbe,0xdfdd,0xcffc,0xbf1b,0xaf3a,0x9f59,0x8f78, + 0x9188,0x81a9,0xb1ca,0xa1eb,0xd10c,0xc12d,0xf14e,0xe16f, + 0x1080,0x00a1,0x30c2,0x20e3,0x5004,0x4025,0x7046,0x6067, + 0x83b9,0x9398,0xa3fb,0xb3da,0xc33d,0xd31c,0xe37f,0xf35e, + 0x02b1,0x1290,0x22f3,0x32d2,0x4235,0x5214,0x6277,0x7256, + 0xb5ea,0xa5cb,0x95a8,0x8589,0xf56e,0xe54f,0xd52c,0xc50d, + 0x34e2,0x24c3,0x14a0,0x0481,0x7466,0x6447,0x5424,0x4405, + 0xa7db,0xb7fa,0x8799,0x97b8,0xe75f,0xf77e,0xc71d,0xd73c, + 0x26d3,0x36f2,0x0691,0x16b0,0x6657,0x7676,0x4615,0x5634, + 0xd94c,0xc96d,0xf90e,0xe92f,0x99c8,0x89e9,0xb98a,0xa9ab, + 0x5844,0x4865,0x7806,0x6827,0x18c0,0x08e1,0x3882,0x28a3, + 0xcb7d,0xdb5c,0xeb3f,0xfb1e,0x8bf9,0x9bd8,0xabbb,0xbb9a, + 0x4a75,0x5a54,0x6a37,0x7a16,0x0af1,0x1ad0,0x2ab3,0x3a92, + 0xfd2e,0xed0f,0xdd6c,0xcd4d,0xbdaa,0xad8b,0x9de8,0x8dc9, + 0x7c26,0x6c07,0x5c64,0x4c45,0x3ca2,0x2c83,0x1ce0,0x0cc1, + 0xef1f,0xff3e,0xcf5d,0xdf7c,0xaf9b,0xbfba,0x8fd9,0x9ff8, + 0x6e17,0x7e36,0x4e55,0x5e74,0x2e93,0x3eb2,0x0ed1,0x1ef0 +}; - return (uint8_t)(crc >> 8); +uint16_t crc16(const void *buf, int len) +{ + register int counter; + register uint16_t crc = 0; + for( counter = 0; counter < len; counter++) + crc = (crc<<8) ^ crc16tab[((crc>>8) ^ *(char *)buf++)&0x00FF]; + return crc; } int ss_check_crc(char *buf, ssize_t *buf_len, char *crc_buf, ssize_t *crc_idx) @@ -1492,13 +1514,17 @@ int ss_check_crc(char *buf, ssize_t *buf_len, char *crc_buf, ssize_t *crc_idx) ssize_t cidx = *crc_idx; for (i = 0, j = 0; i < blen; i++) { - if (cidx == CRC_BUF_LEN) { - uint8_t c = crc8((const void*)crc_buf, CRC_BUF_LEN); - if (memcmp(&c, buf + i, 1) != 0) return 0; + crc_buf[cidx] = buf[i]; + cidx++; + if (cidx < CRC_BUF_LEN) { + buf[j] = buf[i]; + j++; + } + if (cidx == CRC_BUF_LEN + 1) { + uint16_t c = crc16((const void*)crc_buf, CRC_BUF_LEN); + c = htons(c); + if (memcmp(&c, crc_buf + CRC_BUF_LEN, 2) != 0) return 0; cidx = 0; - } else { - crc_buf[cidx] = buf[j] = buf[i]; - cidx++; j++; } } *buf_len = j; @@ -1511,16 +1537,17 @@ char *ss_gen_crc(char *buf, ssize_t *buf_len, char *crc_buf, ssize_t *crc_idx, i int i, j; ssize_t blen = *buf_len; ssize_t cidx = *crc_idx; - int size = max(blen / CRC_BUF_LEN + blen, buf_size); + int size = max(blen / CRC_BUF_LEN * 2 + blen, buf_size); if (buf_size < size) { buf = realloc(buf, size); } for (i = 0, j = 0; i < blen; i++, j++) { if (cidx == CRC_BUF_LEN) { - uint8_t c = crc8((const void*)crc_buf, CRC_BUF_LEN); - memmove(buf + j + 1, buf + j, blen - i); - memcpy(buf + j, &c, 1); + uint16_t c = crc16((const void*)crc_buf, CRC_BUF_LEN); + c = htons(c); + memmove(buf + j + 2, buf + j, blen - i); + memcpy(buf + j, &c, 2); j++; cidx = 0; } crc_buf[cidx] = buf[j]; diff --git a/src/server.c b/src/server.c index e4ae4415..963d36e8 100644 --- a/src/server.c +++ b/src/server.c @@ -541,11 +541,11 @@ static void server_recv_cb(EV_P_ ev_io *w, int revents) /* * Shadowsocks TCP Request Payload CRC (Optional, no CRC for response's payload): * - * +------+------+------+------+------+ - * | DATA | CRC8 | DATA | CRC8 | ... - * +------+------+------+------+------+ - * | 128 | 1 | 128 | 1 | ... - * +------+------+------+------+------+ + * +------+-------+------+-------+------+ + * | DATA | CRC16 | DATA | CRC16 | ... + * +------+-------+------+-------+------+ + * | 128 | 1 | 128 | 1 | ... + * +------+-------+------+-------+------+ */ int offset = 0;