网络编程udp入门

约定不等于承诺〃 2021-09-30 14:58 375阅读 0赞

![1309874-20180411225333611-643118699.png][]

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 }

转载于:https://www.cnblogs.com/kagari/p/8799292.html

[1309874-20180411225333611-643118699.png]: /images/20210724/a76b7a5cdc034d1db6e300a1d5d576c8.png