//保存tracker的url地址到链表
int save_tracker_list()
{
//先查看有没有备用的tracker的URL,有的话直接从announce-list之后开始查找并添加到链表
long long pos = -1;//记录在metafile_buf中的缓冲区的位置
int len = 0; //记录字符串的长度
char tempUrl[512];
memset(tempUrl,0,sizeof(tempUrl));
if(find_buf("d8:announce",&pos) == 1){
if(find_buf("13:announce-list",&pos) == 1){
pos += strlen("13:announce-list");
pos += 2; //跳过2个l
while(metafile_buf[pos] != 'e')
{
len = 0;
while(isdigit(metafile_buf[pos]))
{
len = len*10 + metafile_buf[pos] - '0';
pos++;
}
pos++; //pass :
int i;
for(i = 0;i < len;i++){
tempUrl[i] = metafile_buf[pos++];
}
tempUrl[i+1] = '\0';
//质保存http的url
if(memcmp(tempUrl,"http",4) == 0){
add_tracker_list(tempUrl);
}
pos++; //pass e
if(metafile_buf[pos] == 'l'){
pos++; //pass l
}
}
}else{
//没有备用的tracker的url
pos += strlen("d8:announce");
while(isdigit(metafile_buf[pos]))
{
len = len *10 + metafile_buf[pos] - '0';
pos++;
}
pos++;//滤过:
int i;
for(i = 0;i < len;i++){
tempUrl[i] = metafile_buf[pos++];
}
tempUrl[i+1] = '\0';
//添加到链表节点
add_tracker_list(tempUrl);
}
}else{
printf("parse metafile fail %s:%d\n",__FILE__,__LINE__);
return -1;
}
return 0;
}
//获取pieces的hash值，保存到缓冲区中
int get_pieces_hash()
{
//先获取hash值的字符串长度
pieces_hash_length = 0;
long long pos;
if(find_buf("6:pieces",&pos) == 1)
{
pos += strlen("6:pieces");
while(metafile_buf[pos] != ':') //数字以：结束
{
pieces_hash_length = pieces_hash_length*10 + (metafile_buf[pos++] - '0');
}
#ifdef DEBUG
printf("pieces hash = %lld\n",pieces_hash_length);
#endif
pieces_hash = (char *)malloc(pieces_hash_length+1);
if(pieces_hash == NULL){
printf("malloc fial %s:%d \n",__FILE__,__LINE__);
return -1;
}
memset(pieces_hash,0,sizeof(pieces_hash));
pos++; //pass :
long i;
for(i = 0;i < pieces_hash_length ;i++){
pieces_hash[i] = metafile_buf[pos++];
}
pieces_hash[i] = '\0';
}
return 0;
}
//判断是否为多文件
int is_multi_file()
{
long long i;
if(find_buf("5:files",&i) == 1)
{
ismulti_file = 1;
}
#ifdef DEBUG
//printf("multi file = %d\n",ismulti_file);
#endif
return ismulti_file;
}
//获取每个piece的长度
int get_piece_length()
{
long long pos;
piece_length = 0;
if(find_buf("12:piece length",&pos) == 1){
pos += strlen("12:piece length");
pos++; //pass i
while(isdigit(metafile_buf[pos])&&(metafile_buf[pos] != 'e'))
{
piece_length = piece_length *10 + (metafile_buf[pos++] - '0');
}
}else{
printf("get piece_length fail %s:%d\n",__FILE__,__LINE__);
return -1;
}
return 0;
}
/*
* alloc_node()
* Allocate a new node
*
* Somewhat complicated because the file's storage structure is stored
* at the front of the file. We read in the first sector, then extend
* the buffered block out to the indicated size.
*/
static struct openfile *
alloc_node(daddr_t d)
{
struct buf *b;
struct fs_file *fs;
ulong len, fslen;
struct openfile *o;
/*
* Get buf, address first sector as an fs_file
*/
b = find_buf(d, 1, ABC_FILL);
fs = index_buf(b, 0, 1);
ASSERT(fs->fs_nblk > 0, "alloc_node: zero");
ASSERT(fs->fs_blks[0].a_start == d, "alloc_node: mismatch");
/*
* Extend the buf if necessary
*/
len = fs->fs_blks[0].a_len;
fslen = fs->fs_len;
if (len > 1) {
if (len > EXTSIZ) {
len = EXTSIZ;
}
if (resize_buf(d, (uint)len, 1)) {
return(0);
}
}
/*
* Create a new openfile and return it
*/
o = malloc(sizeof(struct openfile));
if (o == 0) {
return(0);
}
o->o_file = d;
o->o_len = len;
o->o_hiwrite = fslen;
o->o_refs = 1;
o->o_flags = 0;
return(o);
}
/* Select old buffer or create a new one. Defaults to previously
* used buffer.
*/
f_selbuffer()
{ register char *ans;
register struct buffer *b;
if((b = last_buf) == cur_buf) /* If default same as current, */
if(!(b = sel_mbuf(b))) /* try to pick a more useful one. */
b = sel_nbuf(cur_buf);
ans = ask("Select buffer (%s): ",b->b_name);
if (ans == 0) /* he aborted */
return;
if (*ans != '\0') /* Null string => use last buff */
{ b = find_buf (ans); /* Else find/create one */
if (b == 0)
b = make_buf (ans);
}
sel_buf(b);
chkfree(ans);
}
int get_next_line(int const fd, char **line)
{
static t_list *tree;
t_buf *buf;
t_list *cur;
char *tmpline;
if (line == NULL)
return (-1);
cur = find_buf(tree, fd);
if (cur == NULL && (cur = bufnew(&tree, fd)) == NULL)
return (-1);
buf = cur->content;
if ((tmpline = read_til_next_line(fd, buf)) == NULL)
if (buf->size == 0)
return (0);
else
return (-1);
else
{
*line = tmpline;
return (1);
}
}
// 计算info_hash的值
int cal_info_hash()
{
//找到4:info后面的字典d的结束标记e
long long begin,end,pos;
int push_pop = 0; //用于标记，找到d对应的e
//查找4:info
if(find_buf("4:info",&pos) == 1){
pos += strlen("4:info");
begin = pos; //记录info关键字对应值的开始位置
do{
if(metafile_buf[pos] == 'd'){ //字典开头
push_pop++;
pos++;
}
else if(isdigit(metafile_buf[pos]))
{
int i = 0;
//如果是数字，说明后面跟一个字符串 5:files 跳过：和字符串
while(isdigit(metafile_buf[pos])){
i = i * 10 + (metafile_buf[pos++] - '0');
}
pos++; //pass:
pos += i;
//printf("***%c\n",metafile_buf[pos]);
}
else if(metafile_buf[pos] == 'l') //列表开头
{
push_pop++;
pos++;
}
else if(metafile_buf[pos] == 'i' && isdigit(metafile_buf[pos+1])) //说明是数字
{
push_pop++;
pos++; //pass:i
while(isdigit(metafile_buf[pos])){
//跳过i和e之间的数字
pos++;
}
// printf("***%c\n",metafile_buf[pos]);
// printf("push_pop = %d\n",push_pop);
}
else if(metafile_buf[pos == 'e']){ //如果是e push_pop-1
push_pop--;
pos++;
}
}while(push_pop > 0);
//退出循环pos指向e的下一个字符
end = pos -1;
#ifdef DEBUG
printf("begin = %c,end = %c,pos = %c\n",metafile_buf[begin],metafile_buf[end],metafile_buf[pos]);
#endif
//计算info 对应信息的hash值,保存到info_hash中，用于连接tracker和peer
memset(info_hash,0,sizeof(info_hash));
SHA1_CTX context;
SHA1Init(&context);
SHA1Update(&context, (unsigned char *)&metafile_buf[begin], end - begin + 1);
SHA1Final(info_hash,&context);
#ifdef DEBUG
printf("info_hash: ");
int j = 0;
for(;j<20;j++){
printf("%.2x",info_hash[j]);
}
printf("\n");
#endif
}else{
printf("get info_hash fail %s:%d\n",__FILE__,__LINE__);
return -1;
}
return 0;
}
//获取文件名和文件大小，如果是多文件获取的是目录名
int get_filepath_name()
{
char filename[1024];
long long pos;
unsigned long long len = 0;//保存路径名的长度
unsigned long long len2 = 0;
filesize = 0;
memset(filename,0,sizeof(filename));
//获得目录名
memset(dirname,0,sizeof(dirname));
if(find_buf("4:name",&pos) == 1)
{
pos += strlen("4:name");
while(isdigit(metafile_buf[pos]))
{
len = len*10 + (metafile_buf[pos++] - '0');
}
pos++; //pass :
int i;
for(i = 0;i < len;i++)
{
dirname[i] = metafile_buf[pos++];
}
dirname[i] = '\0';
//判断是否为多问文件
if(is_multi_file() == 0){
//不是多文件,获取文件长度
if(find_buf("6:length",&pos) == 1){
pos += strlen("6:length");
pos++; //跳过i
while(metafile_buf[pos] != 'e' && isdigit(metafile_buf[pos]))
{
filesize = filesize * 10 + (metafile_buf[pos++] - '0');
}
#ifdef DEBUG
printf("single filesize = %lld\n",filesize);
#endif
}
}else{
//多文件模式 filesize 为所有文件大小之和
if(find_buf("5:files",&pos) == 1){
pos += strlen("5:files");
pos++; //pass l
pos++; //pass d
while(metafile_buf[pos] != 'e')
{
len = 0;
len2 = 0;
memset(filename,0,sizeof(filename));
//现获取文件长度
pos += strlen("6:length");
pos++; // pass i
while(isdigit(metafile_buf[pos]) && metafile_buf[pos] != 'e')
{
len = len *10 + (metafile_buf[pos++] - '0');
}
pos++; //pass e
//获取文件路径path
pos += strlen("4:path");
pos++; //pass l
while(isdigit(metafile_buf[pos])){
len2 = len2 *10 + (metafile_buf[pos++] - '0');
}
pos++; //pass :
int i;
for(i = 0; i < len2;i++)
{
filename[i] = metafile_buf[pos++];
}
filename[i] = '\0';
pos += 2;
if(metafile_buf[pos] == 'd')
{
pos++;
}
filesize += len;
//添加到Files链表中
add_toFiles(filename,len);
}
}
}
}
return 0;
}