解決回射伺服器的粘包問題

tcp傳送的是流所以可能產生下圖幾種粘包問題

傳過來的可能是 m1包加m2包

m1包加m2包前半部分

m1包後半部分加m2包

粘包產生的原因：

解決方案：

本質上是要在應用層維護訊息與訊息的邊界

定長包包尾加\r\n(ftp)

包頭加上包體長度

更複雜的應用層協議

1、我們可以封裝2個函式 readn 和 writen 確定讀和寫的長度

server

#include #include #include #include #include #include #include #include #include #define err_exit(m) do while(0)

struct packet;
ssize_t readn(int fd,void *buf,size_t count)
else if(nread==0)
return count-nleft;
/*nread>0*/
bufp+=nread;
nleft-=nread;
} return count;
}ssize_t writen(int fd,const void*buf,size_t count)
else if(nwritten==0)
continue;
bufp+=nwritten;
nleft-=nwritten;
}return count;
}void do_service(int conn)
n=ntohl(recvbuf.len);
ret=readn(conn,recvbuf.buf,n);
if(ret==-1)
err_exit("read");
else if(retclient：
#include #include #include #include #include #include #include #include #include #define err_exit(m) do while(0)
struct packet;
ssize_t readn(int fd,void *buf,size_t count)
else if(nread==0)
return count-nleft;
/*nread>0*/
bufp+=nread;
nleft-=nread;
} return count;
}ssize_t writen(int fd,const void*buf,size_t count)
else if(nwritten==0)
continue;
bufp+=nwritten;
nleft-=nwritten;
}return count;
}void do_service(int conn)
n=ntohl(recvbuf.len);
ret=readn(conn,recvbuf.buf,n);
if(ret==-1)
err_exit("read");
else if(ret2、包尾加\r\n  readline函式
server：
#include #include #include #include #include #include #include #include #include #define err_exit(m) do while(0)
ssize_t readn(int fd,void *buf,size_t count)
else if(nread==0)
return count-nleft;
/*nread>0*/
bufp+=nread;
nleft-=nread;
} return count;
}ssize_t writen(int fd,const void*buf,size_t count)
else if(nwritten==0)
continue;
bufp+=nwritten;
nleft-=nwritten;
}return count;
}ssize_t recv_peek(int sockfd,void *buf,size_t len)
}ssize_t readline(int sockfd,void *buf,size_t maxline)
return -1;
}void do_service(int conn)
fputs(recvbuf,stdout);
writen(conn,recvbuf,strlen(recvbuf));
}}int main(void)
else 
close(conn);
} return 0;
}

#include #include #include #include #include #include #include #include #include #define err_exit(m) do while(0)

size_t readn(int fd,void *buf,size_t count)
else if(nread==0)
return count-nleft;
/*nread>0*/
bufp+=nread;
nleft-=nread;
}return count;
}ssize_t writen(int fd,const void*buf,size_t count)
else if(nwritten==0)
continue;
bufp+=nwritten;
nleft-=nwritten;
}return count;
}ssize_t recv_peek(int sockfd,void *buf,size_t len)
}ssize_t readline(int sockfd,void *buf,size_t maxline)
return -1;
}int main(void);
char recvbuf[1024]=;
while(fgets(sendbuf,sizeof(sendbuf),stdin)!=null)
fputs(recvbuf,stdout);
memset(sendbuf,0,sizeof(sendbuf));
memset(recvbuf,0,sizeof(recvbuf));
} close(sock);
return 0;
}

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