实验4

 1 #include<stdio.h>
 2 #include<string.h>
 3 #include<unistd.h>
 4 #include<sys/types.h>
 5 #include<sys/socket.h>
 6 #include<stdlib.h>
 7 #include<netinet/in.h>
 8 #include<arpa/inet.h>
 9 #define PORT 1234
10 #define MAXDATASIZE 100
11 main()
12 {
13     int sockfd;
14     struct sockaddr_in server;
15     struct sockaddr_in client;
16     socklen_t len;
17     int num;
18     char buf[MAXDATASIZE];
19     if((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
20     {
21         perror("Creating socket failed");
22         exit(1);
23     }
24     bzero(&server,sizeof(server));
25     server.sin_family=AF_INET;
26     server.sin_port=htons(PORT);
27     server.sin_addr.s_addr = htonl(INADDR_ANY);
28     if(bind(sockfd, (struct sockaddr *)&server, sizeof(server)) == -1)
29     {
30         perror("Bind() error.");
31         exit(1);
32     }
33     len=sizeof(client);
34     while(1)
35     {
36         num = recvfrom(sockfd,buf,MAXDATASIZE,0,(struct sockaddr *)&client,&len);
37         if ( num<0)
38         {
39             perror("recvfrom() error\n");
40             exit(1);
41         }
42         buf[num] = ‘\0‘;
43         printf("You got a message <%s> from cient.\nIt‘s ip is %s, port is %d.\n",buf,inet_ntoa(client.sin_addr),htons(client.sin_port));
44         sendto(sockfd,"Welcome\n",8,0,(struct sockaddr *)&client,len);
45         if(!strcmp(buf,"bye"))
46             break;
47     }
48     close(sockfd);
49 }

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include<unistd.h>
 4 #include<string.h>
 5 #include<sys/types.h>
 6 #include<sys/socket.h>
 7 #include<netinet/in.h>
 8 #include<netdb.h>
 9 #define PORT 1234
10 #define MAXDATASIZE 100
11 int main(int argc, char *argv[])
12 {
13     int sockfd, num;
14     char buf[MAXDATASIZE];
15     struct hostent *he;
16     struct sockaddr_in server,peer;
17     if (argc !=3)
18     {
19         printf("Usage: %s <IP Address> <message>\n",argv[0]);
20         exit(1);
21     }
22     if ((he=gethostbyname(argv[1]))==NULL)
23     {
24         printf("gethostname() error\n");
25         exit(1);
26     }
27     if ((sockfd=socket(AF_INET, SOCK_DGRAM, 0))==-1)
28     {
29         printf("socket() error\n");
30         exit(1);
31     }
32     bzero(&server,sizeof(server));
33     server.sin_family = AF_INET;
34     server.sin_port = htons(PORT);
35     server.sin_addr =* ((struct in_addr *)he->h_addr);
36     sendto(sockfd, argv[2], strlen(argv[2]), 0 , (struct sockaddr *)&server, sizeof(server));
37     socklen_t len;
38     len=sizeof(server);
39     while(1)
40     {
41         if((num=recvfrom(sockfd,buf,MAXDATASIZE,0,(struct sockaddr *)&peer,&len)) == -1)
42         {
43             printf("recvfrom() error\n");
44             exit(1);
45         }
46         if(len !=sizeof(server) || memcmp((const void *)&server, (const void *) &peer,len) !=0)
47         {
48             printf("Rcecive message from other server.\n");
49             continue;
50         }
51         buf[num]=‘\0‘;
52         printf("Server Message: %s",buf);
53         break;
54     }
55     close(sockfd);
56 }