/*---------------------------------------------------------------------------------------------- 
ÆÄÀϸí : myecho.c 
±â ´É : echo ¼­ºñ½º¸¦ ¿ä±¸ÇÏ´Â TCP(¿¬°áÇü) Ŭ¶óÀ̾ðÆ® 
ÄÄÆÄÀÏ : cc -o myecho myecho.c -lsocket -lnsl 
½ÇÇ࿹ : myecho 203.252.65.3 
----------------------------------------------------------------------------------------------*/ 
#include <stdio.h> 
#include <sys/types.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <unistd.h> 
#define BUF_LEN 128 

int main(int argc, char *argv[]) { 
int s, n, len_in, len_out; 
struct sockaddr_in server_addr; 
char *haddr; 
char buf[BUF_LEN+1];
if(argc != 2) { 
printf("usage: %s ip_address\n", argv[0]); 
return -1; 
} 
haddr = argv[1]; 
if((s = socket(PF_INET, SOCK_STREAM, 0)) < 0) { 
printf("can't create socket\n"); 
return -1; 
} if((s = socket(PF_INET, SOCK_STREAM, 0)) < 0) { 
printf("can't create socket\n"); 
return -1; 
} 

/* echo ¼­¹öÀÇ ¼ÒÄÏÁÖ¼Ò ±¸Á¶Ã¼ ÀÛ¼º */	
bzero((char *)&server_addr, sizeof(server_addr)); 
server_addr.sin_family = AF_INET; 
server_addr.sin_addr.s_addr = inet_addr(haddr); 
server_addr.sin_port = htonl(7); 


/* ¿¬°á¿äû */	
if(connect(s, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) { 
printf("can't connect.\n"); 
return -1; 
} 

/* Å°º¸µå ÀÔ·ÂÀ» ¹ÞÀ½ */	
printf("Input any string : ");


if (fgets(buf, BUF_LEN, stdin)) { 
buf[BUF_LEN] = '\0'; 
len_out = strlen(buf); 
} else { 
printf("fgets error\n"); 
return -1; 
} 

/* echo ¼­¹ö·Î ¸Þ½ÃÁö ¼Û½Å */	
if (write(s, buf, len_out) < 0) { 
printf("write error\n"); 
return -1; 
} 
/* ¼ö½ÅµÈ echo ¸Þ½ÃÁö È­¸éÃâ·Â */	
printf("Echoed string : "); 
for(len_in=0,n = 0; len_in < len_out; len_in += n) { 
if((n = read(s, &buf[len_in], len_out - len_in)) < 0) { 
printf("read error\n"); 
return -1; 
} 
} 
printf("%s", buf); 
close(s); 
}