인터넷에 돌아다니는 코드 막 붙여 넣었음. 코드 정리가 필요함;;;
출처: https://kldp.org/node/42683
http://www.qnx.com/developers/docs/6.5.0/index.jsp?topic=%2Fcom.qnx.doc.neutrino_lib_ref%2Fi%2Fifaddrs.html
http://pencil1031.tistory.com/69
http://stackoverflow.com/questions/1779715/how-to-get-mac-address-of-your-machine-using-a-c-program
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <ifaddrs.h>
#include <net/if.h>
#include <netdb.h>
#include <netinet/in.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#define dpt() printf( "[dmsg] [file:%s, line:%d] \n", __FILE__, __LINE__ )
#include <stdlib.h>
#include <arpa/inet.h>
#include <sys/ioctl.h>
#define BUFSIZE 8192
struct route_info
{
struct in_addr dstAddr;
struct in_addr srcAddr;
struct in_addr gateWay;
char ifName[IF_NAMESIZE];
};
int readNlSock(int sockFd, char *bufPtr, size_t buf_size, int seqNum, int pId)
{
struct nlmsghdr *nlHdr;
int readLen = 0, msgLen = 0;
do
{
/* Recieve response from the kernel */
if((readLen = recv(sockFd, bufPtr, buf_size - msgLen, 0)) < 0)
{
perror("SOCK READ: ");
return -1;
}
nlHdr = (struct nlmsghdr *)bufPtr;
/* Check if the header is valid */
if((NLMSG_OK(nlHdr, readLen) == 0) || (nlHdr->nlmsg_type == NLMSG_ERROR))
{
perror("Error in recieved packet");
return -1;
}
/* Check if the its the last message */
if(nlHdr->nlmsg_type == NLMSG_DONE)
{
break;
}
else
{
/* Else move the pointer to buffer appropriately */
bufPtr += readLen;
msgLen += readLen;
}
/* Check if its a multi part message */
if((nlHdr->nlmsg_flags & NLM_F_MULTI) == 0)
{
/* return if its not */
break;
}
}
while((nlHdr->nlmsg_seq != seqNum) || (nlHdr->nlmsg_pid != pId));
return msgLen;
}
/* parse the route info returned */
int parseRoutes(struct nlmsghdr *nlHdr, struct route_info *rtInfo)
{
struct rtmsg *rtMsg;
struct rtattr *rtAttr;
int rtLen;
rtMsg = (struct rtmsg *)NLMSG_DATA(nlHdr);
/* If the route is not for AF_INET or does not belong to main routing table then return. */
if((rtMsg->rtm_family != AF_INET) || (rtMsg->rtm_table != RT_TABLE_MAIN))
return -1;
/* get the rtattr field */
rtAttr = (struct rtattr *)RTM_RTA(rtMsg);
rtLen = RTM_PAYLOAD(nlHdr);
for(; RTA_OK(rtAttr,rtLen); rtAttr = RTA_NEXT(rtAttr,rtLen))
{
switch(rtAttr->rta_type)
{
case RTA_OIF:
if_indextoname(*(int *)RTA_DATA(rtAttr), rtInfo->ifName);
break;
case RTA_GATEWAY:
memcpy(&rtInfo->gateWay, RTA_DATA(rtAttr), sizeof(rtInfo->gateWay));
break;
case RTA_PREFSRC:
memcpy(&rtInfo->srcAddr, RTA_DATA(rtAttr), sizeof(rtInfo->srcAddr));
break;
case RTA_DST:
memcpy(&rtInfo->dstAddr, RTA_DATA(rtAttr), sizeof(rtInfo->dstAddr));
break;
}
}
return 0;
}
// meat
int get_gatewayip(char *gatewayip, socklen_t size)
{
int found_gatewayip = 0;
struct nlmsghdr *nlMsg;
struct rtmsg *rtMsg;
struct route_info route_info;
char msgBuf[BUFSIZE]; // pretty large buffer
int sock, len, msgSeq = 0;
/* Create Socket */
if((sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)) < 0)
{
perror("Socket Creation: ");
return(-1);
}
/* Initialize the buffer */
memset(msgBuf, 0, sizeof(msgBuf));
/* point the header and the msg structure pointers into the buffer */
nlMsg = (struct nlmsghdr *)msgBuf;
rtMsg = (struct rtmsg *)NLMSG_DATA(nlMsg);
/* Fill in the nlmsg header*/
nlMsg->nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg)); // Length of message.
nlMsg->nlmsg_type = RTM_GETROUTE; // Get the routes from kernel routing table .
nlMsg->nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST; // The message is a request for dump.
nlMsg->nlmsg_seq = msgSeq++; // Sequence of the message packet.
nlMsg->nlmsg_pid = getpid(); // PID of process sending the request.
/* Send the request */
if(send(sock, nlMsg, nlMsg->nlmsg_len, 0) < 0)
{
printf("Write To Socket Failed...\n");
return -1;
}
/* Read the response */
if((len = readNlSock(sock, msgBuf, sizeof(msgBuf), msgSeq, getpid())) < 0)
{
printf("Read From Socket Failed...\n");
return -1;
}
/* Parse and print the response */
for(; NLMSG_OK(nlMsg,len); nlMsg = NLMSG_NEXT(nlMsg,len))
{
memset(&route_info, 0, sizeof(route_info));
if ( parseRoutes(nlMsg, &route_info) < 0 )
continue; // don't check route_info if it has not been set up
// Check if default gateway
if (strstr((char *)inet_ntoa(route_info.dstAddr), "0.0.0.0"))
{
// copy it over
inet_ntop(AF_INET, &route_info.gateWay, gatewayip, size);
found_gatewayip = 1;
break;
}
}
close(sock);
return found_gatewayip;
}
static int
create_sock (const char *nic)
{
struct sockaddr_nl addr;
int sock;
memset (&addr, 0, sizeof (addr));
addr.nl_family = AF_NETLINK;
addr.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | RTMGRP_IPV6_IFADDR;
sock = socket (PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
if (sock < 0)
{
printf ("failed to open NETLINK_ROUTE socket for %s - %s(%d)",
nic, strerror (errno), errno);
return -1;
}
if (bind (sock, (struct sockaddr *)&addr, sizeof(addr)) < 0)
{
printf ( "failed to bind NETLINK_ROUTE socket for %s - %s(%d)",
nic, strerror (errno), errno);
close (sock);
return -1;
}
return sock;
}
static int
ip_changed (int sock,
const char *nic)
{
struct nlmsghdr *nlh;
char buffer[4096];
int len;
int idx;
int found;
len = recv (sock, buffer, sizeof (buffer), 0);
if (len <= 0)
{
printf ( "NETLINK_ROUTE socket recv() failedn");
return -1;
}
found = 0;
idx = if_nametoindex (nic);
for (nlh = (struct nlmsghdr *)buffer;
NLMSG_OK (nlh, len);
nlh = NLMSG_NEXT (nlh, len))
{
if (nlh->nlmsg_type == NLMSG_DONE)
break;
if (nlh->nlmsg_type == NLMSG_ERROR)
continue;
if (!(NLMSG_OK (nlh, len)))
continue;
switch (nlh->nlmsg_type)
{
case RTM_NEWADDR:
{
struct ifaddrmsg *ifa = (struct ifaddrmsg *)NLMSG_DATA (nlh);
if (ifa->ifa_index == idx)
found = 1;
}
break;
case RTM_NEWLINK:
{
struct ifinfomsg *ifi = (struct ifinfomsg *)NLMSG_DATA (nlh);
if (ifi->ifi_index == idx)
found = 1;
}
break;
default:
break;
}
}
return found;
}
static int
get_nic_addr (const char *nic,
struct ifaddrs *ifaddr,
int wanted_family,
char *host,
int host_len,
int *active)
{
struct ifaddrs *ifa;
char test[100];
for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next)
{
int family;
int s;
if (ifa->ifa_addr == NULL)
continue;
if (strcmp (ifa->ifa_name, nic))
continue;
/* Skip unwanted families. */
family = ifa->ifa_addr->sa_family;
if (family != wanted_family)
continue;
*active = (ifa->ifa_flags & IFF_RUNNING) ? 1 : 0;
s = getnameinfo (ifa->ifa_addr,
family == AF_INET ? sizeof (struct sockaddr_in) :
sizeof (struct sockaddr_in6),
host,
host_len,
NULL,
0,
NI_NUMERICHOST);
if (s != 0)
{
printf ( "failed to getnameinfo() for '%s - %s(%d)",
ifa->ifa_name, strerror (errno), errno);
continue;
}
memset(test, 0, 100);
s = getnameinfo (ifa->ifa_netmask,
family == AF_INET ? sizeof (struct sockaddr_in) :
sizeof (struct sockaddr_in6),
test,
100,
NULL,
0,
NI_NUMERICHOST);
printf("netmask:%s\n",test);
memset(test, 0, 100);
s = getnameinfo (ifa->ifa_dstaddr,
family == AF_INET ? sizeof (struct sockaddr_in) :
sizeof (struct sockaddr_in6),
test,
100,
NULL,
0,
NI_NUMERICHOST);
printf("ifa_dstaddr:%s\n",test);
/* Get the address of only the first network interface card. */
return 1;
}
return 0;
}
static void
print_ip (const char *nic)
{
struct ifaddrs *ifaddr;
char addr[NI_MAXHOST];
int active;
if (getifaddrs (&ifaddr) == -1)
{
printf ( "failed to getifaddrs() - %s(%d)", strerror (errno), errno);
return;
}
if (!get_nic_addr (nic, ifaddr, AF_INET, addr, sizeof (addr), &active))
if (!get_nic_addr (nic, ifaddr, AF_INET6, addr, sizeof (addr), &active))
{
strcpy (addr, "127.0.0.1");
active = 0;
}
freeifaddrs (ifaddr);
printf ( "%s is %s (link %s)n", nic, addr, active ? "active" : "inactive");
}
int
main (void)
{
char *nic = "eth0";
int sock;
char gw[100];
struct ifreq ifr;
struct ifconf ifc;
char buf[1024];
int success = 0;
sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
if (sock == -1) { /* handle error*/ };
ifc.ifc_len = sizeof(buf);
ifc.ifc_buf = buf;
if (ioctl(sock, SIOCGIFCONF, &ifc) == -1) { /* handle error */ }
struct ifreq* it = ifc.ifc_req;
const struct ifreq* const end = it + (ifc.ifc_len / sizeof(struct ifreq));
for (; it != end; ++it) {
strcpy(ifr.ifr_name, it->ifr_name);
if (ioctl(sock, SIOCGIFFLAGS, &ifr) == 0) {
if (! (ifr.ifr_flags & IFF_LOOPBACK)) { // don't count loopback
if (ioctl(sock, SIOCGIFHWADDR, &ifr) == 0) {
success = 1;
break;
}
}
}
else { /* handle error */ }
}
unsigned char mac_address[6];
if (success) memcpy(mac_address, ifr.ifr_hwaddr.sa_data, 6);
printf("mac_address:%02x\n",mac_address[0]);
printf("mac_address:%02x\n",mac_address[1]);
printf("mac_address:%02x\n",mac_address[2]);
printf("mac_address:%02x\n",mac_address[3]);
printf("mac_address:%02x\n",mac_address[4]);
printf("mac_address:%02x\n",mac_address[5]);
print_ip (nic);
dpt();
sock = create_sock (nic);
if (sock < 0)
return -1;
memset(gw, 0, 100);
get_gatewayip(gw,100);
printf("gw:%s\n",gw);
dpt();
while (1)
{
int ret;
ret = ip_changed (sock, nic);
if (ret < 0)
return -1;
if (ret)
print_ip (nic);
}
close (sock);
return 0;
}
