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// Using getaddrinfo() to get IPv4 address for
// hostname (argv[1]) and service (argv[2]).
//
// The print_XXX() functions are from Stevens
// and Rago.
//
// P. Kearns, February 2009
#include <netdb.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
void
print_family(struct addrinfo *aip)
{
printf(" family ");
switch (aip->ai_family) {
case AF_INET:
printf("inet");
break;
case AF_INET6:
printf("inet6");
break;
case AF_UNIX:
printf("unix");
break;
case AF_UNSPEC:
printf("unspecified");
break;
default:
printf("unknown");
}
}
void
print_type(struct addrinfo *aip)
{
printf(" type ");
switch (aip->ai_socktype) {
case SOCK_STREAM:
printf("stream");
break;
case SOCK_DGRAM:
printf("datagram");
break;
case SOCK_SEQPACKET:
printf("seqpacket");
break;
case SOCK_RAW:
printf("raw");
break;
default:
printf("unknown (%d)", aip->ai_socktype);
}
}
void
print_protocol(struct addrinfo *aip)
{
printf(" protocol ");
switch (aip->ai_protocol) {
case 0:
printf("default");
break;
case IPPROTO_TCP:
printf("TCP");
break;
case IPPROTO_UDP:
printf("UDP");
break;
case IPPROTO_RAW:
printf("raw");
break;
default:
printf("unknown (%d)", aip->ai_protocol);
}
}
void
print_flags(struct addrinfo *aip)
{
printf("flags");
if (aip->ai_flags == 0) {
printf(" 0");
} else {
if (aip->ai_flags & AI_PASSIVE)
printf(" passive");
if (aip->ai_flags & AI_CANONNAME)
printf(" canon");
if (aip->ai_flags & AI_NUMERICHOST)
printf(" numhost");
#if defined(AI_NUMERICSERV)
if (aip->ai_flags & AI_NUMERICSERV)
printf(" numserv");
#endif
#if defined(AI_V4MAPPED)
if (aip->ai_flags & AI_V4MAPPED)
printf(" v4mapped");
#endif
#if defined(AI_ALL)
if (aip->ai_flags & AI_ALL)
printf(" all");
#endif
}
}
int main(int argc,char **argv)
{
struct addrinfo *addrlist, *aptr, hints;
struct sockaddr_in *saddrptr;
const char * p; char addrbuffer[INET_ADDRSTRLEN]; int ecode;
if(argc != 3) {
fprintf(stderr, "usage: getaddrs node service\n");
exit(1);
}
// Want IPv4 lookup only.
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_INET;
hints.ai_socktype = 0;
hints.ai_flags = AI_CANONNAME;
hints.ai_protocol = 0;
hints.ai_canonname = NULL;
hints.ai_addr = NULL;
hints.ai_next = NULL;
// Do the lookup.
ecode = getaddrinfo(argv[1], argv[2], &hints, &addrlist);
if (ecode != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(ecode));
exit(1);
}
// Scan the list of results.
for (aptr = addrlist; aptr != NULL; aptr = aptr->ai_next) {
print_flags(aptr); print_family(aptr);
print_type(aptr); print_protocol(aptr);
if (aptr->ai_family == AF_INET){
printf("\tName: %s\n", aptr->ai_canonname?aptr->ai_canonname:"none");
// Get at filled-in sockaddr_in hanging off the addrinfo.
saddrptr = (struct sockaddr_in *) aptr->ai_addr;
p = inet_ntop(AF_INET, &saddrptr->sin_addr.s_addr, addrbuffer, INET_ADDRSTRLEN);
if (!p) {
perror("inet_ntop");
exit(1);
}
printf("IP Address: %s\n", p?p:"unknown");
printf("Port: %d\n", ntohs(saddrptr->sin_port));
}
}
// Give back result structs (not really impt here).
freeaddrinfo(addrlist);
exit(0);
}
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