網路程式設計 hw8

觀念題

第一題

請說明，當socket設定blocking mode與non-blocking mode之後，會有何差異？
- 在攔阻模式下
  - recv()函數會等待資料收到才會進到下一行
  - accept()函數會等待客戶連線才會進到下一行
- 在非攔阻模式下
  - recv()函數不會等待收到資料，當沒收到，會回傳-1
  - accept()函數不會等待客戶連線，當沒連線，會回傳-1
  - ~~感覺上非攔阻模式就像急性子~~
請說明，影片裏第一個程式的範例裏，由blocking mode改為non-blocking mode，請問結果有何不同？
- 以下為執行結果
  - blocking mode
  - non-blocking mode
- 差別
  - blocking mode
    - 在blocking mode下，recv會一直等待，直到接收到資料
  - non-blocking mode
    - 在non-blocking mode，recv不會等待，沒收到就直接回傳-1

實作題

第二題

TCP或UDP都可改為非攔阻，請將上例中non-blocking mode的client與server，由TCP改為UDP。

程式碼

Sever






















































#include <stdio.h>
#include <string.h>
#include <winsock.h>

#define MAXLINE 1024    /* 字串緩衝區長度 */

int main()
{
    SOCKET	serv_sd, cli_sd;        /* socket 描述子 */
    int   	cli_len, n,i;
    char  	str[MAXLINE];

    struct 	sockaddr_in   	serv, cli;
    WSADATA wsadata;

    WSAStartup(0x101, &wsadata); //呼叫 WSAStartup() 註冊 WinSock DLL 的使用

    serv_sd=socket(AF_INET, SOCK_DGRAM, 0);// 開啟 UDP socket

    //指定 socket 的 IP 位址和 port number
    serv.sin_family      = AF_INET;
    serv.sin_addr.s_addr = 0;
    serv.sin_port        = htons(5678);	// 指定 IPPORT_ECHO 為 echo port

    bind(serv_sd, (LPSOCKADDR) &serv, sizeof(serv));


    cli_len = sizeof(cli);

    u_long iMode=1;
    ioctlsocket(serv_sd,FIONBIO,&iMode);

    while (1) {
        n=recvfrom(serv_sd, str, MAXLINE, 0, (LPSOCKADDR) &cli, &cli_len);
        str[n]='\0';

        if (n > 0 )
            printf("Recv: %s\n",str);    	// 顯示從 client 傳來的字串		

        Sleep(1000);

        int nError=WSAGetLastError();
        if(nError!=WSAEWOULDBLOCK && nError!=0){
            printf("Disconnected! error code:%d\n",nError);
            closesocket(cli_sd);
            break;
        }       
    }

    //結束 WinSock DLL 的使用
    closesocket(serv_sd);
    closesocket(cli_sd);
    WSACleanup();
}

Python





















import socket
import time

"""
    Server Information
        IP: 127.0.0.1
        PORT: 1234
"""
IP, PORT = "127.0.0.1", 1234

# create UDP socket
server = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
server.bind((IP, PORT))
server.setblocking(False)

while True:
    try:
        data, addr = server.recvfrom(1024)
        print(f"Received: {data.decode()} from {addr}")
    except:
pass

Client















































#include <stdio.h>
#include <string.h>
#include <winsock.h>

#define MAXLINE 1024

int main(int argc, char** argv) {  
   SOCKET        	sd;     
   struct sockaddr_in serv;
   char  		str[1024]="How are you?",str1[1024];
   WSADATA 		wsadata;
   int n,i;

   WSAStartup(0x101,(LPWSADATA) &wsadata); // 呼叫 WSAStartup() 註冊 WinSock DLL 的使用

   sd=socket(AF_INET, SOCK_DGRAM, 0); //開啟一個 UDP socket.

   serv.sin_family       = AF_INET;
   serv.sin_addr.s_addr  = inet_addr("127.0.0.1");
   serv.sin_port         = htons(5678);

   connect(sd, (LPSOCKADDR) &serv, sizeof(serv)); // 連接至 echo server
   printf("Client has connectted to Server.\n"); 
   printf("Waiting 10 secs on purpose...\n");
   Sleep(10000); // 建立連線後，刻意停頓， 觀察 recv()是否block 

    for (;;){  //每隔3秒，週期送出 

        Sleep(3000);   
        send(sd, str, strlen(str)+1, 0);

            int nError=WSAGetLastError();
            if(nError!=WSAEWOULDBLOCK && nError!=0)
            {
                printf("Winsock error code:%d\n",nError);
                printf("Disconnected!");
                // Close our socket entirely
                closesocket(sd);
                break;
            }	   
       printf("Send every 3 secs: %s\n" ,str);    
}
   closesocket(sd); //關閉TCP socket   
   WSACleanup();  // 結束 WinSock DLL 的使用

   return 0;
}

Python
























import socket
import time

"""
    Server Information
        IP: 127.0.0.1
        PORT: 1234
"""
IP, PORT = "127.0.0.1", 1234

# create UDP socket
sd = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sd.connect((IP, PORT))
sd.setblocking(False)
print("Wait for 10 secs...")
time.sleep(10)

while True:
    try:
        sd.send(b"Hello World!")
        print("Send every 3 secs: Hello World!")
        time.sleep(3)
    except:
        pass

執行結果

備註

在Python中非阻攔模式需要用try/except

try: 
    sd.resv()
except:
    pass

第三題

程式碼

Sever






































































#include <stdio.h>
#include <winsock.h>

int main(){
    FILE *fin, *fout;
    fin = fopen("def.txt", "r");
    fout = fopen("server.txt","w");

    SOCKET sd,clnt_sd;
    WSADATA wsadata;
    struct sockaddr_in serv,clnt;
    int i,n;
    char str[2048]="";

    WSAStartup(0x101,&wsadata);
    sd = socket(AF_INET, SOCK_STREAM, 0);
    serv.sin_family = AF_INET;
    serv.sin_port = htons(1234);
    serv.sin_addr.s_addr = inet_addr("127.0.0.1");

    bind(sd, (struct sockaddr *) &serv, sizeof(serv));

    listen(sd,5);
    int clnt_len=sizeof(clnt);
    printf("Server waits.\n");
    clnt_sd =  accept(sd, (struct sockaddr *)  &clnt,&clnt_len );
    printf("Client is connected.\n");

    u_long mode = 1;
    ioctlsocket(clnt_sd,FIONBIO,&mode);

    while(1){
        char* c_line = NULL;
        size_t len = 0;
        int status = getline(&c_line,&len,fin);
        if (status != EOF) {
            send(clnt_sd,c_line, strlen(c_line)+1,0);	
            printf("Send: %s\n",c_line);
        }
        else{
            send(clnt_sd,"END", 4,0);	
            printf("Send: END\n");
        }
        free(c_line);
        memset(str,0,sizeof(str));
        n = recv(clnt_sd,str, sizeof(str), 0);
        if (n > 0){
            str[n] = '\0';
            printf("Receive: %s\n",str);
            if (strcmp(str, "END\0") == 0 && status == EOF) {
                break;
            }
            else if (strcmp(str, "END\0") == 0) {
                continue;
            }

            fprintf(fout,"%s",str);
        }
        else if (n == 0){
            break;
        }
        Sleep(100);
    }
    closesocket(sd);
    closesocket(clnt_sd);
    fclose(fin);
    fclose(fout);
    WSACleanup();

}

Python
























































import socket
import time

"""
    File 
        Input: def.txt
        Output: server.txt
"""
fin = open("def.txt", "r")
fout = open("server.txt", "w")

"""
    Server Information
        IP: 127.0.0.1
        PORT: 1234
"""
IP,PORT = "127.0.0.1", 1234


# crete a server socket
serverSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
serverSocket.bind((IP,PORT))
serverSocket.listen(5)

# Accept the client connection
clientSocket, address = serverSocket.accept()

# Set Non Blocking
clientSocket.setblocking(False)
serverSocket.setblocking(False)



EOF = False
while True:
    try:
        data = clientSocket.recv(1024).decode()
        print(f"Client: {data}")
        if EOF and data == "END": break
        elif EOF: continue
        fout.write(data)
    except :
        pass
    try:
        data = fin.readline()
        if not data: raise EOFError
        clientSocket.send(data.encode())
        print(f"Server: {data}")
    except EOFError:
        clientSocket.send(b'END')
        print(f"Server: END")
        EOF = True
    time.sleep(1)
# Close the connection
clientSocket.close()
serverSocket.close()

Client































































#include <stdio.h>
#include <winsock.h>

int main(){
    FILE *fin, *fout;
    fin = fopen("abc.txt", "r");
    fout = fopen("client.txt","w");

    SOCKET sd;
    WSADATA wsadata;
    struct sockaddr_in serv;
    int i,n;
    char str[2048]="";

    WSAStartup(0x101,&wsadata);
    sd = socket(AF_INET, SOCK_STREAM, 0);

    serv.sin_family = AF_INET;
    serv.sin_port = htons(1234);
    serv.sin_addr.s_addr = inet_addr("127.0.0.1");

    connect(sd, (struct sockaddr *)  &serv,sizeof(serv) );
    printf("Connect to server.\n");
    u_long mode = 1;
    ioctlsocket(sd,FIONBIO,&mode);

    while(1){
        char* c_line = NULL;
        size_t len = 0;
        int status = getline(&c_line,&len,fin);
        if (status != EOF) {
            send(sd,c_line, strlen(c_line)+1,0);	
            printf("Send: %s\n",c_line);
        }
        else{
            send(sd,"END", 4,0);	
            printf("Send: END\n");
        }
        memset(str,0,sizeof(str));
        n = recv(sd,str, sizeof(str), 0);
        if (n > 0) {
            str[n] = '\0';
            printf("Receive: %s\n",str);
            if (strcmp(str, "END\0") == 0 && status == EOF) {
                break;
            }
            else if (strcmp(str, "END\0") == 0) {
                continue;
            }
            fprintf(fout,"%s",str);

        }
        else if (n == 0){
            break;
        }
        Sleep(100);
    }
    closesocket(sd);
    fclose(fin);
    fclose(fout);
    WSACleanup();

}

Python



















































import socket
import time

"""
    File 
        Input: abc.txt
        Output: client.txt
"""
fin = open("abc.txt", "r")
fout = open("client.txt", "w")

"""
    Client Information
        IP: 127.0.0.1
        PORT: 1234
"""
IP,PORT = "127.0.0.1", 1234

# Create a client socket
clientSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
clientSocket.connect((IP,PORT))

# Set Non Blocking
clientSocket.setblocking(False)

EOF = False
while True:
    try:
        data = clientSocket.recv(1024).decode()
        print(f"Server: {data}")
        if EOF and data == "END": break
        elif EOF: continue
        fout.write(data)
    except:
        pass
    try:
        data = fin.readline()
        if not data: raise EOFError
        clientSocket.send(data.encode())
        print(f"Client: {data}")
    except EOFError:   
        EOF = True
        print(f"Client: END")
        clientSocket.send(b'END')
    time.sleep(1)
fin.close()
fout.close()
# Close the connection
clientSocket.close()
fout.close()
fin.close()

執行結果
備註
- 為了知道雙方都已經傳送完畢，因此作了以下動作
  - 自己輸入完成，EOF的指標會傳出True，並傳END給Server
  - 當收到END時要判斷自己是否也EOF

第四題

程式碼

Sever

C++






































































#include <iostream>
#include <string>
#include <winsock.h>
#include <vector>
#include <time.h>
using namespace std;

int main(){

    SOCKET sd;
    vector<SOCKET> clnt_sd;
    u_long mode = 1;
    WSADATA wsadata;
    struct sockaddr_in serv,clnt1,clnt2;
    int i,n;
    char str[2048];

    WSAStartup(0x101,&wsadata);
    sd = socket(AF_INET, SOCK_STREAM, 0);
    serv.sin_family = AF_INET;
    serv.sin_port = htons(1234);
    serv.sin_addr.s_addr = inet_addr("127.0.0.1");

    bind(sd, (struct sockaddr *) &serv, sizeof(serv));
    listen(sd,5);

    int clnt_len1=sizeof(clnt1);
    int clnt_len2=sizeof(clnt2);
    printf("Server waits.\n");

    time_t start, end;
    end = time(NULL);
    start = time(NULL);

    SOCKET clnt = accept(sd, (struct sockaddr *)  &clnt1,&clnt_len1 );
    printf("Client connected.\n");
    ioctlsocket(clnt,FIONBIO,&mode);
    clnt_sd.push_back(clnt);

    clnt = accept(sd, (struct sockaddr *)  &clnt1,&clnt_len1 );
    printf("Client connected.\n");
    ioctlsocket(clnt,FIONBIO,&mode);
    clnt_sd.push_back(clnt);


    while(1){
        for (int i = 0; i<clnt_sd.size(); i++){
            // Receive from client
            n = recv(clnt_sd[i],str, 2048, 0);
            if (n>0){
                printf("(%i) %s\n",i+1,str);
                for (int j=0; j<clnt_sd.size(); j++){
                    if (i==j) continue;
                    // Send to other clients
                    send(clnt_sd[j],str, strlen(str)+1,0);
                }
            }
            else if (n == 0){
                // Client disconnected
                goto end;
            }
        }
    }
    end:
    closesocket(sd);
    for (int i=0; i<clnt_sd.size(); i++)
        closesocket(clnt_sd[i]);
    WSACleanup();

}

Python

















































import socket
import time

"""
    Server Information
        IP: 127.0.0.1
        PORT: 1234
"""
IP,PORT = "127.0.0.1", 1234

# crete a server socket
serverSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
serverSocket.bind((IP,PORT))
serverSocket.listen(5)
serverSocket.setblocking(False)

# crete client socket
clientSocket = []
# Waiting for connteing (5 seconds)
start,end = time.time(),time.time()
while end-start < 5:
    try:
        conn, addr = serverSocket.accept()
        print(f"Connect to {addr}")
        conn.setblocking(False)
        clientSocket.append(conn)
    except:
        pass
    end = time.time()
time.sleep(5)
breaked = False
while True: 
    for i, client in enumerate(clientSocket):
        try:
            data = client.recv(1024).decode()
            print(f"({i}) {data}")
            for j,sock in enumerate(clientSocket):
                if j == i: continue
                n = sock.send(data.encode())
                if n == 0: 
                    breaked = True
                    break
            if breaked: break
        except:
            pass
    if breaked: break

for i in clientSocket:
    i.close()

Client




























































































#include <stdio.h>
#include <winsock.h>
#include <time.h>

int main(){
    FILE *fin, *fout;

    SOCKET sd;
    WSADATA wsadata;
    struct sockaddr_in serv;
    int i,n;	

    WSAStartup(0x101,&wsadata);
    sd = socket(AF_INET, SOCK_STREAM, 0);

    serv.sin_family = AF_INET;
    serv.sin_port = htons(1234);
    serv.sin_addr.s_addr = inet_addr("127.0.0.1");

    connect(sd, (struct sockaddr *)  &serv,sizeof(serv) );
    printf("Connect to server.\n");

    char fileName[1024];
    printf("Enter file name: ");
    scanf("%s", fileName, sizeof(fileName));
    fin = fopen(fileName, "r");
    if (fin == NULL){
        printf("File not found\n");
        return 1;
    }

    memset(fileName,0,sizeof(fileName));
    printf("Enter exports file name: ");
    scanf("%s", fileName, sizeof(fileName));
    fout = fopen(fileName, "w");
    if (fin == NULL){
        printf("File not found\n");
        return 1;
    }

    u_long mode = 1;
    ioctlsocket(sd,FIONBIO,&mode);

    Sleep(5000);

    while(1){
        char* c_line = NULL;
        size_t len = 0;
        int status = getline(&c_line,&len,fin); // Read line from file
        char buffer[2048] = "";
        if (status == EOF){
            // Send END to server
            int n = send(sd,"END", 3+1,0);
            if (n == SOCKET_ERROR){
                break;
            }
            printf("Send: %s\n","END");
        }
        else{
            // Send line to server
            send(sd,c_line, strlen(c_line)+1,0);
            printf("Send: %s\n",c_line);
        }
        free(c_line);
        n = recv(sd,buffer, 2048, 0);
        if (n>0){
            // Receive line from server
            buffer[n] = '\0';
            if (strcmp(buffer,"END") == 0 && status == EOF){
                printf("Received: %s\n",buffer);
                break;
            }
            else if (strcmp(buffer,"END") == 0){
                printf("Received: %s\n",buffer);
                continue;
            }
            else{
                printf("Received: %s\n",buffer);
                fprintf(fout,"%s",buffer);
            }
        }
        else if (n == 0){
            break;
        }
        Sleep(1000);
    }
    closesocket(sd);
    fclose(fin);
    fclose(fout);
    WSACleanup();

}

Python

















































import socket
import time

"""
    Server Information
        IP: 127.0.0.1
        PORT: 1234
"""
IP,PORT = "127.0.0.1", 1234

# crete a server socket
serverSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
serverSocket.bind((IP,PORT))
serverSocket.listen(5)
serverSocket.setblocking(False)

# crete client socket
clientSocket = []
# Waiting for connteing (5 seconds)
start,end = time.time(),time.time()
while end-start < 5:
    try:
        conn, addr = serverSocket.accept()
        print(f"Connect to {addr}")
        conn.setblocking(False)
        clientSocket.append(conn)
    except:
        pass
    end = time.time()
time.sleep(5)
breaked = False
while True: 
    for i, client in enumerate(clientSocket):
        try:
            data = client.recv(1024).decode()
            print(f"({i}) {data}")
            for j,sock in enumerate(clientSocket):
                if j == i: continue
                n = sock.send(data.encode())
                if n == 0: 
                    breaked = True
                    break
            if breaked: break
        except:
            pass
    if breaked: break

for i in clientSocket:
    i.close()

執行結果

第五題

程式碼

Sever

C++



























































#include <stdio.h>
#include <winsock.h>
#include <vector>
using namespace std;

int main(){
    SOCKET sd;
    vector<SOCKET> clientsd;
    WSADATA wsadata;
    struct sockaddr_in serv,clnt;
    int i,n;
    char str[100]="I love NP!";

    WSAStartup(0x101,&wsadata);
    sd = socket(AF_INET, SOCK_STREAM, 0);
    serv.sin_family = AF_INET;
    serv.sin_port = htons(1234);
    serv.sin_addr.s_addr = inet_addr("127.0.0.1");

    bind(sd, (struct sockaddr *) &serv, sizeof(serv));

    listen(sd,5);
    int clnt_len=sizeof(clnt);
    printf("Server waits.\n");
    SOCKET clnt_sd =  accept(sd, (struct sockaddr *)  &clnt,&clnt_len );
    printf("Client is connected.\n");	
    clientsd.push_back(clnt_sd);

    u_long mode = 1;
    ioctlsocket(sd,FIONBIO,&mode);

    while(1){
        clnt_sd =  accept(sd, (struct sockaddr *)  &clnt,&clnt_len );
        if (clnt_sd != INVALID_SOCKET){
            clientsd.push_back(clnt_sd);
        }
        vector<int> disconnect;
        for (int i = 0; i<clientsd.size();i++){
            int n = send(clientsd[i],str, strlen(str)+1,0);
            if (n <= 0){
                disconnect.push_back(i);
                printf("Client %d is disconnected.\n",i);
            }
        }
        for (auto i:disconnect){
            closesocket(clientsd[i]);
            clientsd.erase(clientsd.begin()+i);
        }
        printf("(server send): %s\n",str);
        Sleep(1000);
    }
    closesocket(sd);
    for (int i = 0; i<clientsd.size();i++){
        closesocket(clientsd[i]);
    }
    WSACleanup();
    system("pause");

}

Python
















































import socket
import time

"""
    The Data I want to send to the clinet
"""
DATA = "Something Smell"
FREQ = 1

"""
    Server Information
        IP: 127.0.0.1
        PORT: 1234
"""

IP,PORT = "127.0.0.1", 1234
# crete server socket
serverSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
serverSocket.bind((IP,PORT))
serverSocket.listen(5)

# A list for client socket
clientSocket = []
sd,addr = serverSocket.accept()
clientSocket.append(sd)
print(f"Client {addr} connected")
serverSocket.setblocking(False)

while True:
    try:
        sd, addr = serverSocket.accept()
        clientSocket.append(sd)
        print(f"Client {addr} connected")
    except:
        pass
    disconnect = []
    for i,conn in enumerate(clientSocket):
        try:
            conn.send(DATA.encode())
        except ConnectionResetError:
            disconnect.append(i)
    for i in disconnect:
        clientSocket[i].close()
        clientSocket.pop(i)
        print(f"Client {i} disconnected")
    time.sleep(FREQ)
for i in clientSocket:
    i.close()

Client

C++





























#include <stdio.h>
#include <winsock.h>

int main(){
    SOCKET sd;
    WSADATA wsadata;
    struct sockaddr_in serv;
    int i,n;
    char str[100]="I love NP!";

    WSAStartup(0x101,&wsadata);
    sd = socket(AF_INET, SOCK_STREAM, 0);

    serv.sin_family = AF_INET;
    serv.sin_port = htons(1234);
    serv.sin_addr.s_addr = inet_addr("127.0.0.1");

    connect(sd, (struct sockaddr *)  &serv,sizeof(serv) );
    printf("Connect to server.\n");

    while(1){
        n = recv(sd,str, 100, 0);
        if(n <= 0) break;
        printf("(from server): %s\n",str);
    }
    closesocket(sd);
    WSACleanup();

}

Python

















import socket

"""
    Server Information
        IP: 127.0.0.1
        PORT: 1234
"""
IP,PORT = "127.0.0.1", 1234
# crete a socket connet to server
sd = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sd.connect((IP,PORT))
print(f"Connect to server {IP}:{PORT}")

while True:
    data = sd.recv(1024).decode()
    print(f"Server: {data}")
sd.close()

執行結果
備註
- 當Server因為對方關閉連線，並將該連線踢出list中

心得

這周作業交了non blocking mode，感覺他像是一個有不耐煩的人，沒收到就直接回傳-1，雖然更有彈性了，但是要找霸哥 aka bug，就很困難。

這周作業感覺變難做了，感覺要考慮很多情況，而且加上非阻攔模式下有夠難debug，我發現錯誤時一直拿wireshark，發明這個的人真電。

在寫作業其實有遇到一個小問題，我以為Python也要像C那樣去看recv回傳的結果，結果會報錯，原來要改成try/except，雖然小麻煩，但我覺得比C易讀很多。

附錄

檔案的連結

網路程式設計 hw8

觀念題

第一題

實作題

第二題

第三題

第四題

第五題

心得

附錄

Read more

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