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@ximik777
Created October 30, 2015 12:09
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static gethostbyname with libcares
#include <ares.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdarg.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
// gcc -static ares.c -lcares -o ares
static void state_cb(void *data, int s, int read, int write) {
printf("Change state fd %d read:%d write:%d\n", s, read, write);
}
static void callback(void *arg, int status, int timeouts, struct hostent *host) {
if (!host || status != ARES_SUCCESS) {
printf("Failed to lookup %s\n", ares_strerror(status));
return;
}
char buff[INET_ADDRSTRLEN];
inet_ntop(host->h_addrtype, host->h_addr_list[0], buff, sizeof(buff));
memcpy(arg, buff, strlen(buff));
}
static void wait_ares(ares_channel channel) {
for (; ;) {
struct timeval *tvp, tv;
fd_set read_fds, write_fds;
int nfds;
FD_ZERO(&read_fds);
FD_ZERO(&write_fds);
nfds = ares_fds(channel, &read_fds, &write_fds);
if (nfds == 0) {
break;
}
tvp = ares_timeout(channel, NULL, &tv);
select(nfds, &read_fds, &write_fds, NULL, tvp);
ares_process(channel, &read_fds, &write_fds);
}
}
int mygethostbyname(char *host, char *ip) {
ares_channel channel;
int status;
struct ares_options options;
int optmask = 0;
status = ares_library_init(ARES_LIB_INIT_ALL);
if (status != ARES_SUCCESS) {
printf("ares_library_init: %s\n", ares_strerror(status));
return 0;
}
//options.sock_state_cb_data;
options.sock_state_cb = state_cb;
optmask |= ARES_OPT_SOCK_STATE_CB;
status = ares_init_options(&channel, &options, optmask);
if (status != ARES_SUCCESS) {
printf("ares_init_options: %s\n", ares_strerror(status));
return 0;
}
ares_gethostbyname(channel, host, AF_INET, callback, ip);
wait_ares(channel);
ares_destroy(channel);
ares_library_cleanup();
ip[strlen(ip)] = 0;
return 0;
}
int main() {
char *host = "google.com";
char ip[16];
getipbyhost(host, ip);
printf("IP [%s]\n", ip);
return 0;
}
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