基于UDP套接字的局域网聊天室

需要实现功能如下：

1.服务器端功能如下：

广播通知客服端登录/退出

接受客服端发来的消息，广播给所有用户

广播系统消息

2.客服端功能如下：

接收服务器发来的消息并显示

发送消息给服务器端

 

实现代码如下：

1.服务器端代码：

 

#include
#include
#include
#include
#include
#include
#include

#define R 1
#define U 2
#define B 3

#define N 64

typedef struct
{
 int type;
 char name[16];
 char text[N];
} MESG;

typedef struct sockaddr SA;

typedef struct _node_
{
 struct sockaddr_in cliaddr;
 struct _node_ *next;
} linknode, *linklist;

linklist CreateEmptyLinklist()
{
 linklist h;

 h = (linklist)malloc(sizeof(linknode));
 h->next = NULL;

 return h;
}

void AddUser(int sockfd, linklist h, struct sockaddr_in peeraddr, MESG buf)
{
 linklist p;

 printf("AddUser()\n");
 p = (linklist)malloc(sizeof(linknode));
 p->cliaddr = peeraddr;
 p->next = h->next;
 h->next = p;

 p = p->next;
 sprintf(buf.text, "%s is online\n", buf.name);
 strcpy(buf.name, "system");
 while (p != NULL)
 {
  sendto(sockfd, &buf, sizeof(buf), 0, (SA *)&p->cliaddr, sizeof(peeraddr));
  p = p->next;
 }

 strcpy(buf.text, "Welcome to Farsight Chat Room\n");
 sendto(sockfd, &buf, sizeof(buf), 0, (SA *)&peeraddr, sizeof(peeraddr));

 return;
}

void DelUser(int sockfd, linklist h, struct sockaddr_in peeraddr, MESG buf)
{
 linklist p = h->next;

 printf("DelUser()\n");
 sprintf(buf.text, "%s is offline\n", buf.name);
 strcpy(buf.name, "system");
 while (p != NULL)
 {
  if ((p->cliaddr.sin_addr.s_addr == peeraddr.sin_addr.s_addr) &&
   (p->cliaddr.sin_port == peeraddr.sin_port))
  {
   h->next = p->next;
   free(p);
  }
  else
  {
   sendto(sockfd, &buf, sizeof(buf), 0, (SA *)&p->cliaddr, sizeof(peeraddr));
   h = h->next;
  }
  p = h->next;
 }
 strcpy(buf.text, "See you next time\n");
 sendto(sockfd, &buf, sizeof(buf), 0, (SA *)&peeraddr, sizeof(peeraddr));

 return;
}

void Broadcast(int sockfd, linklist h, MESG buf)
{
 h = h->next;

 while (h != NULL)
 {
  sendto(sockfd, &buf, sizeof(buf), 0, (SA *)&h->cliaddr, sizeof(h->cliaddr));
  h = h->next;
 }

 return;
}

int main(int argc, char *argv[])
{
 int sockfd;
 MESG buf;
 struct sockaddr_in myaddr, peeraddr;
 socklen_t peerlen;
 linklist h;

 if (argc < 3)
 {
  printf("Usage : %s \n", argv[0]);
  exit(-1);
 }

 if ((sockfd = socket(PF_INET, SOCK_DGRAM, 0)) < 0)
 {
  perror("fail to socket");
  exit(-1);
 }

 bzero(&myaddr, sizeof(myaddr));
 myaddr.sin_family = PF_INET;
 myaddr.sin_port = htons(atoi(argv[2]));
 myaddr.sin_addr.s_addr = inet_addr(argv[1]);

 if (bind(sockfd, (SA *)&myaddr, sizeof(myaddr)) < 0)
 {
  perror("fail to bind");
  exit(-1);
 }

 h = CreateEmptyLinklist();

 while ( 1 )
 {
  peerlen = sizeof(peeraddr);
  recvfrom(sockfd, &buf, sizeof(buf), 0, (SA *)&peeraddr, &peerlen);
  switch ( buf.type )
  {
  case R:
   AddUser(sockfd, h, peeraddr, buf);
   break;
  case U:
   DelUser(sockfd, h, peeraddr, buf);
   break;
  case B:
   Broadcast(sockfd, h, buf);
   break;
  }
 }

 return 0;
}

2.客服端代码如下：

#include
#include
#include
#include
#include
#include
#include
#include

#define R 1
#define U 2
#define B 3

#define N 64

typedef struct
{
 int type;
 char name[16];
 char text[N];
} MESG;

typedef struct sockaddr SA;

/*
typedef struct _node_
{
 struct sockaddr_in cliaddr;
 struct _node_ *next;
} linknode, *linklist;
*/

int main(int argc, char *argv[])
{
 int sockfd;
 MESG buf;
 struct sockaddr_in servaddr;

 if (argc < 3)
 {
  printf("Usage : %s \n", argv[0]);
  exit(-1);
 }

 printf("please input your login name : ");
 fgets(buf.name, 16, stdin);
 buf.name[strlen(buf.name)-1] = '\0';

 bzero(&servaddr, sizeof(servaddr));
 servaddr.sin_family = PF_INET;
 servaddr.sin_port = htons(atoi(argv[2]));
 servaddr.sin_addr.s_addr = inet_addr(argv[1]);

 if ((sockfd = socket(PF_INET, SOCK_DGRAM, 0)) < 0)
 {
  perror("fail to socket");
  exit(-1);
 }

 // XXX: register
 buf.type = R;
 sendto(sockfd, &buf, sizeof(buf), 0, (SA *)&servaddr, sizeof(servaddr));

 pid_t pid;

 if ((pid = fork()) == 0)  // child process
 {
  while ( 1 )
  {
   recvfrom(sockfd, &buf, sizeof(buf), 0, NULL, NULL);
   printf("[%s] %s", buf.name, buf.text);
  }
 }
 else   // parent process
 {
  buf.type = B;
  while ( 1 )
  {
   printf(" ");
   fgets(buf.text, N, stdin);
   if (strncmp(buf.text, "quit", 4) == 0)
   {
    buf.type = U;
    sendto(sockfd, &buf, sizeof(buf), 0, (SA *)&servaddr,sizeof(servaddr));
    usleep(100000);
    kill(pid, SIGKILL);
    exit(0);
   }
   sendto(sockfd, &buf, sizeof(buf), 0, (SA *)&servaddr,sizeof(servaddr));
  }
 } 

 return 0;
}