chap6 code

uecho_server

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <arpa/inet.h>

#include <sys/socket.h>

#define BUF_SIZE 30

void error_handling(char *message);

int main(int argc, char *argv[])

{

int serv_sock;

char message[BUF_SIZE];

int str_len;

socklen_t clnt_adr_sz;

struct sockaddr_in serv_adr, clnt_adr;

if(argc!=2){

printf("Usage : %s <port>\n", argv[0]);

exit(1);

}

serv_sock=socket(PF_INET, SOCK_DGRAM, 0);

if(serv_sock==-1)

error_handling("UDP socket creation error");

memset(&serv_adr, 0, sizeof(serv_adr));

serv_adr.sin_family=AF_INET;

serv_adr.sin_addr.s_addr=htonl(INADDR_ANY);

serv_adr.sin_port=htons(atoi(argv[1]));

if(bind(serv_sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr))==-1)

error_handling("bind() error");

while(1) 

{

clnt_adr_sz=sizeof(clnt_adr);

str_len=recvfrom(serv_sock, message, BUF_SIZE, 0, 

(struct sockaddr*)&clnt_adr, &clnt_adr_sz);

sendto(serv_sock, message, str_len, 0, 

(struct sockaddr*)&clnt_adr, clnt_adr_sz);

}

close(serv_sock);

return 0;

}

void error_handling(char *message)

{

fputs(message, stderr);

fputc('\n', stderr);

exit(1);

}

uecho_client

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <arpa/inet.h>

#include <sys/socket.h>

#define BUF_SIZE 30

void error_handling(char *message);

int main(int argc, char *argv[])

{

int sock;

char message[BUF_SIZE];

int str_len;

socklen_t adr_sz;

struct sockaddr_in serv_adr, from_adr;

if(argc!=3){

printf("Usage : %s <IP> <port>\n", argv[0]);

exit(1);

}

sock=socket(PF_INET, SOCK_DGRAM, 0);   

if(sock==-1)

error_handling("socket() error");

memset(&serv_adr, 0, sizeof(serv_adr));

serv_adr.sin_family=AF_INET;

serv_adr.sin_addr.s_addr=inet_addr(argv[1]);

serv_adr.sin_port=htons(atoi(argv[2]));

while(1)

{

fputs("Insert message(q to quit): ", stdout);

fgets(message, sizeof(message), stdin);     

if(!strcmp(message,"q\n") || !strcmp(message,"Q\n"))

break;

sendto(sock, message, strlen(message), 0, 

(struct sockaddr*)&serv_adr, sizeof(serv_adr));

adr_sz=sizeof(from_adr);

str_len=recvfrom(sock, message, BUF_SIZE, 0, 

(struct sockaddr*)&from_adr, &adr_sz);

message[str_len]=0;

printf("Message from server: %s", message);

}

close(sock);

return 0;

}

void error_handling(char *message)

{

fputs(message, stderr);

fputc('\n', stderr);

exit(1);

}