写基于socket下载 使用epoll多任务

[zwy1114860564]

我在写基于socket下载的程序， 使用epoll实现多个任务非阻塞同时下载。测试了一些文件都还好，不过在测试

引用

./multi_download http://sw.bos.baidu.com/sw-search-sp/software/7811f6cde4b/QQ_8.3.18038.0_setup.exe

的时候卡在了100%（死循环）， 我查看了一下文件，这个QQ文件不完整。不知道怎么调试，还望哪位大神指明一些方向和步骤。最好成功下载文件，然后写写步骤，“受人以渔”嘛。

#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <stdarg.h>
#include <sys/epoll.h> 

#define	MAXLINE	4096			/* max line length */

#define MAX_RECV_SIZE    1440

#define bool int
#define false 0
#define true 1

const int EXIT_FAILURE = 1;
char req_addr[256] = "";
char req_file[1024] = "";
char req_serv[256] = "";
char filename[256] = "";
char buf_send[4*1024] = "";
char buf_recv[10][10*1024];

int fds[10];
int sockfds[10];
int flags[10];
int nbytes[10];
int filesizes[10];
int cursizes[10];
// 映射sockfd到文件, 用于socket关闭时，重新打开一个socket, sockfd < 1024
int sockfds_map_indexs[1024];

static void
err_doit(int errnoflag, const char *fmt, va_list ap)
{
	int		errno_save;
	char	buf[MAXLINE];

	errno_save = errno;		/* value caller might want printed */
	vsprintf(buf, fmt, ap);
	if (errnoflag)
		sprintf(buf+strlen(buf), ": %s", strerror(errno_save));
	strcat(buf, "\n");
	fflush(stdout);		/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(stderr);		/* SunOS 4.1.* doesn't grok NULL argument */
	return;
}

void
/* $f err_sys $ */
err_sys(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, fmt, ap);
	va_end(ap);
	exit(1);
}


void Close(int fd)
{
	if (close(fd) == -1){
		err_sys("close error!");
	}
}

void
Setsockopt(int fd, int level, int optname, const void *optval, socklen_t optlen)
{
	if (setsockopt(fd, level, optname, optval, optlen) < 0)
		err_sys("setsockopt error");
}

void Send(int fd, const void *ptr, size_t nbytes, int flags)
{
	if (send(fd, ptr, nbytes, flags) != (ssize_t)nbytes)
		err_sys("send error");
}

int tcp_connect(const char *host, const char *serv)
{
	int				sockfd, n;
	struct addrinfo	hints, *res, *ressave;

	struct timeval tv;
	tv.tv_sec = 0;
	tv.tv_usec = 500;

	bzero(&hints, sizeof(struct addrinfo));
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;

	if ( (n = getaddrinfo(host, serv, &hints, &res)) != 0)
		err_sys("tcp_connect error for %s, %s: %s",
				 host, serv, gai_strerror(n));

	ressave = res;
	do {
		sockfd = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
		if (sockfd < 0)
			continue;	/* ignore this one */
		Setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
		if (connect(sockfd, res->ai_addr, res->ai_addrlen) == 0)
			break;		/* success */

		Close(sockfd);	/* ignore this one */
	} while ( (res = res->ai_next) != NULL);

	if (res == NULL)	/* errno set from final connect() */
		err_sys("tcp_connect error for %s, %s", host, serv);
	freeaddrinfo(ressave);

	return(sockfd);
}
/* end tcp_connect */

/*
 * We place the wrapper function here, not in wraplib.c, because some
 * XTI programs need to include wraplib.c, and it also defines
 * a Tcp_connect() function.
 */

int
Tcp_connect(const char *host, const char *serv)
{
	return(tcp_connect(host, serv));
}



void Writen(int fd, char *buff, int nbytes){
	int done = 0, index = 0;
	while(nbytes > 0){
		done = write(fd, buff + index, nbytes);
		if(done < 0)
			err_sys("write error!\n");
		index += done;
		nbytes -= done;
	}
}

int url_parser(char *url){
	char *ptr = NULL;
	char *pcolon = NULL;

	int len = 0;
	ptr = strstr(url, "http://");
	if(NULL != ptr)
		url = ptr + strlen("http://");

	ptr = strchr(url, '/');
	len = strlen(url);

	memset(req_addr, 0x0, sizeof(req_addr));
	memset(req_serv, 0x0, sizeof(req_serv));

	pcolon = strchr(url, ':');
	if(NULL == pcolon || strchr(ptr+1, '/') - pcolon < 0)
	{	
		strncpy(req_addr, url, ptr - url);
		sprintf(req_serv, "80");
	}
	else
	{
		strncpy(req_addr, url, pcolon - url);
		strncpy(req_serv, pcolon + 1, ptr - pcolon - 1);
	}

	memset(req_file, 0x0, sizeof(req_file));
	strcpy(req_file, ptr);

	int i = len - 1;
	for(; i >= 0; --i){
		if('/' == url[i]){
			strcpy(filename, url + i + 1);
			break;
		}
			
	}
	return 0;
}

void set_download_http_head(char *req_addr, char *req_file, char *range)
{
    char buf[64];
    memset(buf_send,0x0, sizeof(buf_send));         
    sprintf(buf_send, "GET %s",req_file);

    
    //HTTP/1.1\r\n 前面需要一个空格
    strcat(buf_send," HTTP/1.1\r\n");
    strcat(buf_send, "Host: ");
    strcat(buf_send, req_addr);
    //strcat(g_buf_send, ":");
    //strcat(g_buf_send, PORT);
    
    sprintf(buf, "\r\nRange: bytes=%s",range);
   	strcat(buf_send,buf);
    //strcat(buf_send, "\r\nKeep-Alive: 200");
    strcat(buf_send,"\r\nConnection: Keep-Alive\r\n\r\n");
}

//获取Content-Range
int get_value_of_content_range(char *revbuf)
{
    char *p1 = NULL, *p2 = NULL;
    int HTTP_Body = 0;//内容体长度

    p1 = strstr(revbuf,"Content-Range");
    if(p1 == NULL)
        return -1;
    else
    {
        p2 = strchr(p1, '/');
        HTTP_Body = atoi(p2+1);
        return HTTP_Body;
    }

}


void setnonblocking(int sockfd)
{
    int opts;
    opts = fcntl(sockfd,F_GETFL);
    if(opts<0)
    	err_sys("fcntl(sock,GETFL)");
    opts = opts|O_NONBLOCK;
    if(fcntl(sockfd,F_SETFL,opts)<0)
    	err_sys("error : fcntl(sock,SETFL,opts)"); 
}


void download_files(int vc, char ** ve)
{
	#define MAX_EVENTS 10
    struct epoll_event ev, events[MAX_EVENTS];
    int nfds, epollfd, cursize;
    int nbyte, index, count = 0;
    char *p = NULL;
    bool flag = true;
    char range[6];

    epollfd = epoll_create(10);
    if (epollfd == -1)
    	err_sys("epoll_create");

    // 因为这里是直接使用main函数的头， 0表示的文件名
    int i = 1;
	for(; i < vc; ++i)
	{
		url_parser(ve[i]);
		sockfds[i] = Tcp_connect(req_addr, req_serv);

		if((fds[i]=open(filename,O_WRONLY|O_CREAT|O_APPEND,S_IRUSR|S_IWUSR))==-1)
        	err_sys("Open %s Error：%s\n",filename,strerror(errno));
        // 设置非阻塞
        setnonblocking(sockfds[i]);
        // 设置映射
        sockfds_map_indexs[sockfds[i]] = i;

    	off_t cursize;
    	cursize = lseek(fds[i], 0, SEEK_END);

		memset(range, 0x0, sizeof(range));
		sprintf(range,"%d-", cursize);

		set_download_http_head(req_addr, req_file, range);

		Send(sockfds[i], buf_send, strlen(buf_send), 0);

		ev.events = EPOLLIN | EPOLLET;
        ev.data.fd = sockfds[i];

        if (epoll_ctl(epollfd, EPOLL_CTL_ADD, sockfds[i],
            &ev) == -1)
            	err_sys("epoll_ctl: conn_sock");

        flags[i] = false;
        memset(buf_recv[i], 0x0, sizeof(buf_recv[i]));
	}

	for(;;)
	{
		nfds = epoll_wait(epollfd, events, MAX_EVENTS, -1);

		if (nfds == -1)
        	err_sys("epoll_pwait");

        int i = 0;
        for(; i < nfds; ++i)
        {
        	index = sockfds_map_indexs[ events[i].data.fd ];
        	flag = true;
        	while(flag)
        	{
        		nbyte = recv(events[i].data.fd, buf_recv[index] + nbytes[index], sizeof(buf_recv[index]) - nbytes[index], 0);

        		if(nbyte < 0)
        		{
        			epoll_ctl(epollfd, EPOLL_CTL_DEL, events[i].data.fd, &ev);
                    close(events[i].data.fd);

                    url_parser(ve[index]);
                    sockfds[index] = Tcp_connect(req_addr, req_serv);

                    memset(range, 0x0, sizeof(range));
					sprintf(range,"%d-", cursizes[index]);

					set_download_http_head(req_addr, req_file, range);

					Send(sockfds[index], buf_send, strlen(buf_send), 0);

					ev.events = EPOLLIN | EPOLLET;
        			ev.data.fd = sockfds[index];

        			if (epoll_ctl(epollfd, EPOLL_CTL_ADD, sockfds[index],
            			&ev) == -1)
            				err_sys("epoll_ctl: conn_sock");
                    flag = false;
        		}
        		else if(0 == nbyte)
        		{
        			epoll_ctl(epollfd, EPOLL_CTL_DEL, events[i].data.fd, &ev);
        			close(events[i].data.fd);
        			close(fds[index]);
        			printf("one download success\n");
        			flag = false;
        		}
        		else
        		{
        			nbytes[index] += nbyte;

        			if(sizeof(buf_recv[index]) != nbytes[index])
        				flag = false;

        			if(false == flags[index])
        			{
        				p = strstr(buf_recv[index], "\r\n\r\n");
	        			if(NULL != p)
						{
							flags[index] = true;
							filesizes[index] = get_value_of_content_range(buf_recv[index]);
							Writen(fds[index], p+4, nbytes[index] - (p - buf_recv[index]) - 4);
							cursizes[index] += nbytes[index] - (p - buf_recv[index]) - 4;
							nbytes[index] = 0;
							memset(buf_recv[index], 0x0, sizeof(buf_recv[index]));
						}
        			}
        			else
        			{
        				Writen(fds[index], buf_recv[index], nbyte);
        				cursizes[index] += nbyte;
        				printf("%s download %.f%%\n", ve[index], cursizes[index] * 100.0 / filesizes[index]); 
        				nbytes[index] = 0;
        				memset(buf_recv[index], 0x0, sizeof(buf_recv[index]));
        				if(cursizes[index] == filesizes[index])
        					break;
        			}
        		}
        	}
        	if(cursizes[index] == filesizes[index])
        	{
    		    epoll_ctl(epollfd, EPOLL_CTL_DEL, events[i].data.fd, &ev);
    			close(events[i].data.fd);
    			close(fds[index]);
    			++count;
    			printf("%s download success\n", ve[index]);   			
        	}
        }

        if(count == vc - 1)
        {
        	printf("%d file download succeed \n", count);
        	break;
        }
	}

}



int main(int argc, char ** argv)
{
	download_files(argc, argv);
	return 0;
}

问题主要是在download_file这个函数里面。