C＃指定客戶端端口

Question

我有一個關於異步socket編程下面的代碼：

public void ServerBeginAceept(ushort ServerPort) 
    { 
     try 
     { 
      ServerSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); 

      IPEndPoint ipEndPoint = new IPEndPoint(IPAddress.Any, ServerPort); 
      ServerSocket.Bind(ipEndPoint); 
      ServerSocket.Listen(MAX_CONNECTIONS); 
      IAsyncResult result = ServerSocket.BeginAccept(new AsyncCallback(ServerEndAccept), ServerSocket); 
     } 
    } 


    public void ServerEndAccept(IAsyncResult iar) 
    { 
     try 
     { 
      ServerSocket = (Socket)iar.AsyncState; 
      CommSocket = ServerSocket.EndAccept(iar); 
     } 
    } 

    public void ClientBeginConnect(string ServerIP, ushort ServerPort) 
    { 
     try 
     { 
      CommSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); 
      IPEndPoint ipEndPoint = new IPEndPoint(IPAddress.Parse(ServerIP), ServerPort); 
      IAsyncResult result = CommSocket.BeginConnect(ipEndPoint, new AsyncCallback(ClientEndConnect), CommSocket); 

     } 
    } 


    public void ClientEndConnect(IAsyncResult iar) 
    { 
     try 
     { 
      CommSocket = (Socket)iar.AsyncState; 
      CommSocket.EndConnect(iar); 

      OnNetworkEvents eventArgs = new OnNetworkEvents(true, "Connected: " + CommSocket.RemoteEndPoint.ToString(), string.Empty); 
      OnUpdateNetworkStatusMessage(this, eventArgs); 
     } 
    } 

那麼有沒有錯代碼（我已經簡化它，它在這裏呈現爲我的工作證明它不尋找作業的幫助！）

我的問題是：我如何從指定的客戶端端口與服務器通信？這裏的代碼是所有基於服務器的端口，並且這很有效。但是我想實現與客戶端的特定端口進行通信的代碼，而不僅僅是服務器隨機生成的代碼。

謝謝你的時間。

Answer 1

爲什麼你想要使用特定的端口？

客戶端端口是根據設計隨機選擇的，因爲只有一個套接字在它沒有在該套接字上偵聽時可以打開一個端口。

例如，如果您始終在HTTP連接的客戶端上使用端口80，則該計算機上只有一個套接字可以一次連接到端口80。這意味着HTTP連接不能並行。

Answer 2

不確定C＃，但這裏有一個可行的解決方案。在C：

 /*dl_senderprog.c - debian linux send to server a client, datagram*/ 

/*********************************************************************** 


140203 lets see if we can bind to a port 

ts7500:/var/www/jon/uvir_sensor_lab/source/socket# 
ts7500:/var/www/jon/uvir_sensor_lab/source/socket# vi senderprog_bind.c 
ts7500:/var/www/jon/uvir_sensor_lab/source/socket# gcc -g senderprog_bind.c -o senderprog_bind 
ts7500:/var/www/jon/uvir_sensor_lab/source/socket# ./senderprog_bind 
Sender:Client-Usage: ./senderprog_bind <hostname> <message> 
ts7500:/var/www/jon/uvir_sensor_lab/source/socket# 
ts7500:/var/www/jon/uvir_sensor_lab/source/socket# 
ts7500:/var/www/jon/uvir_sensor_lab/source/socket# ./senderprog_bind 10.0.1.26 "dot,33,22" 
MY IP address:10.0.1.242: on port: 1043 
Sender: Client-gethostname() is OK... 
Sender: Client-socket() sockfd is OK... 
Sender: Using port: 14950 
Sender: Client-sendto() is OK... 
Sender: sent 9 bytes to 10.0.1.26 
Sender: Client-sockfd successfully closed! 
ts7500:/var/www/jon/uvir_sensor_lab/source/socket# 
ts7500:/var/www/jon/uvir_sensor_lab/source/socket# 
ts7500:/var/www/jon/uvir_sensor_lab/source/socket# # it worked!!!!! 
ts7500:/var/www/jon/uvir_sensor_lab/source/socket# 



***********************************************************************/ 




#include <stdio.h> 
#include <stdlib.h> 
#include <unistd.h> 
#include <errno.h> 
#include <string.h> 
#include <sys/types.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <arpa/inet.h> 
#include <netdb.h> 

#include <sys/ioctl.h> 
#include <net/if.h> 





/* the port users will be connecting to 14950 is the port on the windows machine 
    that I have the server running on */ 
#define TOPORT 14950 
#define MYPORT 1043 

void my_ip(char *myniccard, char *myipaddr) { 
     int fd; 
     struct ifreq ifr; 

     myipaddr[0]=0; 

     fd = socket(AF_INET, SOCK_DGRAM, 0); 

     /* I want to get an IPv4 IP address */ 
     ifr.ifr_addr.sa_family = AF_INET; 

     /* I want IP address attached to "eth0" */ 
     //strncpy(ifr.ifr_name, "eth0", IFNAMSIZ-1); 
     strncpy(ifr.ifr_name, myniccard, IFNAMSIZ-1); 

     ioctl(fd, SIOCGIFADDR, &ifr); 

     close(fd); 

     /* display result */ 
     sprintf(myipaddr,"%s" 
     , inet_ntoa(((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr)); 
     printf("MY IP address:%s: on port: %d\n", myipaddr, MYPORT); 

     } // my_ip 


int main(int argc, char *argv[ ]) 
{ 
int sockfd; 
/* connectors address information */ 
struct sockaddr_in their_addr; 
struct sockaddr_in localaddr; 
char myipaddressm[22]; //buffer for ip address 
char *myniccardm ="eth0"; // check with ipconfig for correct ethernet port 

struct hostent *he; 
int numbytes; 

if (argc != 3) { 
     fprintf(stderr, "Sender:Client-Usage: %s <hostname> <message>\n", argv[0]); 
     exit(1); 
     } 

my_ip(myniccardm, myipaddressm); 


/* get the host info */ 
if ((he = gethostbyname(argv[1])) == NULL) { 
     perror("Sender: Client-gethostbyname() error lol!"); 
     exit(1); 
     } 
    else 
     printf("Sender: Client-gethostname() is OK...\n"); 

if((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) { 
     perror("Sender: Client-socket() error lol!"); 
     exit(1); 
     } 
    else 
     printf("Sender: Client-socket() sockfd is OK...\n"); 


// Bind to a specific network interface 
// (this is unusual, as you normally do not want a specific 
// port for the client, but we have a specific server in 
// this case that will not accept connects unless its on 
// a specific port) 
localaddr.sin_family = AF_INET; 
localaddr.sin_addr.s_addr = inet_addr(myipaddressm); 
localaddr.sin_port = htons(MYPORT); // Any local port will do 
bind(sockfd, (struct sockaddr *)&localaddr, sizeof(localaddr)); 



/* host byte order */ 
their_addr.sin_family = AF_INET; 
/* short, network byte order */ 
printf("Sender: Using port: %d\n",TOPORT); 
their_addr.sin_port = htons(TOPORT); 
their_addr.sin_addr = *((struct in_addr *)he->h_addr); 
/* zero the rest of the struct */ 
memset(&(their_addr.sin_zero), '\0', 8); 

if((numbytes = sendto(sockfd, argv[2], 
         strlen(argv[2]), 
         0, 
         (struct sockaddr *)&their_addr, 
         sizeof(struct sockaddr))) == -1) { 
     perror("Sender: Client-sendto() error lol!"); 
     exit(1); 
     } 
    else 
     printf("Sender: Client-sendto() is OK...\n"); 

printf("Sender: sent %d bytes to %s\n", numbytes, inet_ntoa(their_addr.sin_addr)); 

if (close(sockfd) != 0) 
     printf("Sender: Client-sockfd closing is failed!\n"); 
    else 
     printf("Sender: Client-sockfd successfully closed!\n"); 
return 0; 

}//main 


/*******************************************EOF***********************/