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#include <stdio.h>
#include <stdarg.h>
#include <stdbool.h>
#include <string.h>
#include <net/if.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
int sockprintf(int s, const char *fmt, ...) {
int n;
char buf[8192] = {0};
va_list vl;
va_start(vl, fmt);
n = vsnprintf(buf, sizeof(buf), fmt, vl);
va_end(vl);
return send(s, buf, n, 0);
}
bool validate_ipv4(const char *ip) {
return inet_aton(ip, NULL) ? true : false;
}
bool validate_ip(const char *ip) {
struct in_addr addr4;
struct in6_addr addr6;
return inet_pton(AF_INET, ip, &addr4) == 1 || inet_pton(AF_INET6, ip, &addr6) == 1;
}
// get the interface assigned to the default route. this is a sensible
// default for most deployments, but not perfect.
char *get_default_iface(void) {
static char iface[IFNAMSIZ] = {0};
FILE *fp = fopen("/proc/net/route", "r");
if (!fp) {
return NULL;
}
char line[256];
fgets(line, sizeof(line), fp); // skip header line
while (fgets(line, sizeof(line), fp)) {
char iface_name[IFNAMSIZ];
unsigned long dest;
if (sscanf(line, "%s %lx", iface_name, &dest) == 2) {
if (dest == 0) { // default route
strncpy(iface, iface_name, IFNAMSIZ - 1);
fclose(fp);
return iface;
}
}
}
fclose(fp);
return NULL;
}
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