CDT报文分次上传的合并

对于将一段报文进行分段上传，需要将它合并，并去除其中同步字之前的报文，

报文分段上传对于多个设备同时连接可能有影响

char* memstr(char* full_data, int full_data_len, char* substr) {
    if (full_data == NULL || full_data_len <= 0 || substr == NULL) 
        return NULL;
    if (*substr == '') 
        return NULL;
    int sublen = strlen(substr);
    int i;
    char* cur = full_data;
    int last_possible = full_data_len - sublen + 1;
    for (i = 0; i < last_possible; i++) {
        if (*cur == *substr) {
            if (memcmp(cur, substr, sublen) == 0) {
                return cur;
            }
        }
        cur++;
    }
    return NULL;
}

int MSGADD(unsigned char* recv_data, signed int recv_size, unsigned char** history_data, int historylen) {//将报文叠加起来
    if ((historylen) == 0) {
        historylen = recv_size;
        (*history_data) = chk_calloc(historylen, sizeof (ST_UCHAR));
        memcpy((*history_data), recv_data, (historylen));
    } else {
        ST_UCHAR *temprecv = chk_calloc(historylen + recv_size, sizeof (ST_UCHAR));
        memcpy(temprecv, (*history_data), (historylen));
        memcpy(temprecv + historylen, recv_data, recv_size);
        chk_free((*history_data));
        (*history_data) = temprecv;
        historylen = historylen + recv_size;
    }
    return historylen;
}
ST_INT MSG_superposition(ST_UCHAR *recv_data, ST_INT recv_size){
     static ST_UCHAR needle[7] = {0xeb, 0x90, 0xeb, 0x90, 0xeb, 0x90, ''};
    static ST_UCHAR *history_data = NULL;
    static int historylen = 0;
    ST_UCHAR *indexstr;
    historylen = MSGADD(recv_data, recv_size, &history_data, historylen);
    chk_free(recv_data);
    recv_data=NULL;
    recv_size = 0;if ((indexstr = memstr(history_data, historylen, needle)) == NULL)
        return -2;
    else if (indexstr != history_data) {//去除不正确报文
        int templen = indexstr - history_data;
        memcpy(history_data, history_data + templen, historylen - templen);
        historylen -= templen;
    } else {
        if ((indexstr = memstr(indexstr + 6, historylen - (indexstr - history_data + 6), needle)) == NULL)
            return -2;
        else {
            recv_size = indexstr - history_data;
            recv_data = chk_calloc(recv_size, sizeof (ST_UCHAR));
            memcpy(recv_data, history_data, recv_size);
            memcpy(history_data, history_data + recv_size, historylen - recv_size);
            historylen -= recv_size;
        }
    }

　　return recv_size;

　　//printf("revvdata: ");
　　//printdata(recv_data, recv_size);

}