网络编程udp入门

Posted 2020-10-30 kagi

老师布置的作业

echo4_server.c

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include<string.h>
 4 #include<unistd.h>
 5 #include<arpa/inet.h>
 6 #include<sys/socket.h>
 7 
 8 #define BUF_SIZE 10 //一次最大传输大小
 9 void error_handling(char *message); //异常
10 
11 int main(int argc,char** argv)
12 {
13     int serv_sock,n;
14     char message[BUF_SIZE*8+3],message1[BUF_SIZE+3]; 
15     int str_len;
16     socklen_t clnt_adr_sz;
17     struct sockaddr_in serv_adr,clnt_adr;
18     if(argc!=2){
19         printf("Usage : %s <port>\\n",argv[0]);
20         exit(1);
21     }
22     serv_sock=socket(PF_INET,SOCK_DGRAM,0);
23     if(serv_sock == -1){
24         error_handling("UDP socket creattion error");
25     }
26 
27     memset(&serv_adr,0,sizeof(serv_adr));
28     serv_adr.sin_family=AF_INET;
29     serv_adr.sin_addr.s_addr=htonl(INADDR_ANY);
30     serv_adr.sin_port=htons(atoi(argv[1]));
31 
32     if(bind(serv_sock,(struct sockaddr*)&serv_adr,sizeof(serv_adr))==-1)
33         error_handling("bind() error");
34 
35     while(1){
36         clnt_adr_sz=sizeof(clnt_adr);
37         str_len=recvfrom(serv_sock,message,BUF_SIZE+3,0,(struct sockaddr*)&clnt_adr,&clnt_adr_sz);
38         message[str_len]=0;
39         if(message[0]==0){
40             n=message[1];
41             message[0]=message[1]=message[2]=\'1\';
42             message[3]=0;
43             for(int i=0;i<n;i++){
44                 str_len=recvfrom(serv_sock,&message1,BUF_SIZE*2,0,(struct sockaddr*)&clnt_adr,&clnt_adr_sz);
45                 message1[str_len]=0;
46                 strcat(message,&message1[3]);
47             }
48         }
49         if(strlen(&message[3])-1<=BUF_SIZE){
50             message[0]=1;
51             message[2]=strlen(&message[3]);
52             sendto(serv_sock,message,strlen(&message[3])+3,0,(struct sockaddr*)&clnt_adr,clnt_adr_sz);
53         }
54         else{
55             message[0]=0;
56             message[1]=strlen(&message[3])/BUF_SIZE;
57             if(strlen(&message[3])%BUF_SIZE!=0)
58                 message[1]+=1;
59             sendto(serv_sock,message,2,0,(struct sockaddr*)&clnt_adr,clnt_adr_sz);
60             for(int i=0;i*BUF_SIZE<strlen(&message[3]);i++){
61                 message[i*BUF_SIZE]=2;
62                 message[i*BUF_SIZE+1]=i+1;
63                 message[i*BUF_SIZE+2]=BUF_SIZE;
64                 if((i+1)*BUF_SIZE>strlen(&message[3]))
65                 message[i*BUF_SIZE+2]=strlen(&message[3])-i*BUF_SIZE;
66                 sendto(serv_sock,&message[i*BUF_SIZE],message[i*BUF_SIZE+2]+3,0,(struct sockaddr*)&clnt_adr,clnt_adr_sz);
67             }
68         }
69     }
70     close(serv_sock);
71     return 0;
72 }
73 
74 void error_handling(char *message)
75 {
76     fputs(message,stderr);
77     fputc(\'\\n\',stderr);
78     exit(1);
79 }

 

echo4_client.c

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include<string.h>
 4 #include<unistd.h>
 5 #include<arpa/inet.h>
 6 #include<sys/socket.h>
 7 
 8 #define BUF_SIZE 10
 9 
10 void error_handling(char *message);
11 
12 int main(int argc,char** argv)
13 {
14     int sock;
15     char message[BUF_SIZE*8+3],message1[BUF_SIZE+3];
16     int str_len,n;
17     socklen_t adr_sz;
18 
19     struct sockaddr_in serv_adr,from_adr;
20     if(argc!=3){
21         printf("Usage : %s <IP> <port>\\n",argv[0]);
22         exit(1);
23     }
24 
25     sock=socket(PF_INET,SOCK_DGRAM,0);
26     if(sock==-1)
27         error_handling("sock() error");
28     memset(&serv_adr,0,sizeof(serv_adr));
29     serv_adr.sin_family=AF_INET;
30     serv_adr.sin_addr.s_addr=inet_addr(argv[1]);
31     serv_adr.sin_port=htons(atoi(argv[2]));
32 
33     while(1){
34         int m_len;
35         fputs("Insert message(q to quit): ",stdout);
36         fgets(&message[3],sizeof(message)-3,stdin);
37         if(!strcmp(&message[3],"q\\n")||!strcmp(&message[3],"Q\\n"))break;
38         if(strlen(&message[3])-1<=BUF_SIZE){
39             message[0]=1;
40             message[2]=strlen(&message[3]);
41             sendto(sock,message,strlen(&message[3])+3,0,(struct sockaddr*)&serv_adr,sizeof(serv_adr));
42         }
43         else{
44             message[0]=0;
45             message[1]=strlen(&message[3])/BUF_SIZE;
46             if(strlen(&message[3])%BUF_SIZE!=0)
47                 message[1]+=1;
48             sendto(sock,message,2,0,(struct sockaddr*)&serv_adr,sizeof(serv_adr));
49             for(int i=0;i*BUF_SIZE+1<strlen(&message[3]);i++){
50                 message[i*BUF_SIZE]=2;
51                 message[i*BUF_SIZE+1]=i+1;
52                 message[i*BUF_SIZE+2]=BUF_SIZE;
53                 if((i+1)*BUF_SIZE>=strlen(&message[3]))
54                 message[i*BUF_SIZE+2]=strlen(&message[3])-1-i*BUF_SIZE;
55                 sendto(sock,&message[i*BUF_SIZE],message[i*BUF_SIZE+2]+3,0,(struct sockaddr*)&serv_adr,sizeof(serv_adr));
56             }
57         }
58 
59         str_len=recvfrom(sock,message,BUF_SIZE+3,0,(struct sockaddr*)&from_adr,&adr_sz);
60         message[str_len]=0;
61         if(message[0]==0){
62             n=message[1];
63             message[0]=message[1]=message[2]=\'1\';
64             message[3]=0;
65             for(int i=0;i<n;i++){
66                 str_len=recvfrom(sock,&message1,BUF_SIZE*2,0,(struct sockaddr*)&from_adr,&adr_sz);
67                 message1[str_len]=0;
68                 strcat(message,&message1[3]);
69                 //
printf("%d,%d,%d,%s\\n",message1[0],message1[1],message1[2],&message1[3]);
70             }
71         }
72         printf("Message from server : %s \\n",&message[3]);
73     }
74     close(sock);
75     return 0;
76 }
77 
78 void error_handling(char *message)
79 {
80     fputs(message,stderr);
81     fputc(\'\\n\',stderr);
82     exit(1);
83 }