converting host to ip by sockaddr_in gethostname etc
i need help converting hostname to ip and inserting to sockaddr_in->sin_addr to be able assign to char. For example i input: localhost and it gives me 127.0.0.1
I found code, but i dont know why it gives me wrong numbers
//---
#include <sys/types.h>
#include <netinet/in.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <time.h>
#include <sys/fcntl.h>
#include <netdb.h>
//---
///CZY WPISANO HOST
struct in_addr inaddr;
inaddr.s_addr = inet_addr(argv[1]);
if( inaddr.s_addr == INADDR_NONE) //if sHost is name and not IP
{
struct hostent* phostent = gethostbyname( argv[1]);
if( phostent == 0)
bail("gethostbyname()");
if( sizeof(inaddr) != phostent->h_length)
bail("problem z inaddr"); // error something wrong,
puts(argv[1]);
inaddr.s_addr = *((unsigned long*) phostent->h_addr);
//strdup( inet_ntoa(inaddr));
sr开发者_如何学Pythonvr_addr = inet_ntoa(adr_srvr.sin_addr);
puts(srvr_addr);
}
I also wrote own code but i dont know how transfer from sockaddr to sockaddr_in data:
///CZY WPISANO HOST
if(argv[1][0]>=(char)'a' && argv[1][0]<=(char)'Z')
{
struct hostent *hent;
hent = gethostbyname(argv[1]);
adr_srvr.sin_addr = (struct in_addr*)hent->h_addr_list;
}
adr_srvr is a char* type
I really need help, thanks!
Try something like this:
struct hostent *he;
struct sockaddr_in server;
int socket;
const char hostname[] = "localhost";
/* resolve hostname */
if ( (he = gethostbyname(hostname) ) == NULL ) {
exit(1); /* error */
}
/* copy the network address to sockaddr_in structure */
memcpy(&server.sin_addr, he->h_addr_list[0], he->h_length);
server.sin_family = AF_INET;
server.sin_port = htons(1337);
/* and now you can connect */
if ( connect(socket, (struct sockaddr *)&server, sizeof(server) ) {
exit(1); /* error */
}
I wrote this code straight from my memory so I cannot guarantee that it works but I am pretty sure it should be OK.
This shell script compiles correct C code, which I believe will do what you want it to:
rm -f 1; cat > 1.c <<EOD; gcc -Wall -Werror 1.c -o 1; ./1
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
void
do_one(char *the_name,int port_number)
{
int my_socket;
char **pointer_pointer;
char answer[INET_ADDRSTRLEN];
struct hostent *returned_host;
struct sockaddr_in outgoing_address;
printf("==========\n");
printf("destination : %s:%d\n",the_name,port_number);
returned_host=gethostbyname(the_name);
if(returned_host==NULL)
{
fprintf(stderr,"error %d\n",h_errno);
return;
}
printf("host's official name: %s\n",returned_host->h_name);
for(pointer_pointer=returned_host->h_aliases;
*pointer_pointer;
pointer_pointer++
)
{
printf("alias : %s\n",*pointer_pointer);
}
for(pointer_pointer=returned_host->h_addr_list;
*pointer_pointer;
pointer_pointer++
)
{
inet_ntop(AF_INET,(void *)*pointer_pointer,answer,sizeof(answer));
printf("IP address : %s\n",answer);
my_socket=socket(AF_INET,SOCK_STREAM,0);
if(my_socket<0)
{
perror("socket()");
return;
}
memset(&outgoing_address,0,sizeof(outgoing_address));
outgoing_address.sin_family=AF_INET;
outgoing_address.sin_port=htons(port_number);
memmove(&outgoing_address.sin_addr,
*pointer_pointer,
sizeof(&outgoing_address.sin_addr)
);
if(connect(my_socket,(struct sockaddr*)&outgoing_address,sizeof(outgoing_address)))
{
perror("connect()");
return ;
}
printf("connection established on file descriptor %d\n",my_socket);
}
} /* do_one() */
int
main(void)
{
do_one("localhost",80);
do_one("localhost",81);
do_one("127.0.0.1",80);
do_one("tiger",80);
do_one("www.google.com",80);
return 0;
} /* main() */
EOD
The output I got was this:
==========
destination : localhost:80
host's official name: localhost
IP address : 127.0.0.1
connection established on file descriptor 3
==========
destination : localhost:81
host's official name: localhost
IP address : 127.0.0.1
connect(): Connection refused
==========
destination : 127.0.0.1:80
host's official name: 127.0.0.1
IP address : 127.0.0.1
connection established on file descriptor 5
==========
destination : tiger:80
host's official name: tiger.x441afea5.org
alias : tiger
IP address : 10.0.0.1
connection established on file descriptor 6
==========
destination : www.google.com:80
host's official name: www.l.google.com
alias : www.google.com
IP address : 74.125.229.50
connection established on file descriptor 7
IP address : 74.125.229.52
connection established on file descriptor 8
IP address : 74.125.229.48
connection established on file descriptor 9
IP address : 74.125.229.49
connection established on file descriptor 10
IP address : 74.125.229.51
connection established on file descriptor 11
Hope this helps.
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