VijayaLakshmi Seshadri wrote:
Hi all
Iam trying to implement "route add " using netlink. The changes are
not reflected in the routing table. I have given my code and screen
shots of the routing tables.
Can anybody tell me is there any mistake iam making in defining the
fields .
or any other mistake iam commiting
thanxs
viji
//////////////////////////////////// CODE
//////////////////////////////////////////////////////
#include <asm/types.h>
#include <netinet/ether.h>
#include <netinet/in.h>
#include <net/if.h>
#include <stdio.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <sys/types.h>
#define BUFSIZE 192
struct route_info{
u_int dstAddr;
u_int srcAddr;
u_int gateWay;
char ifName[IF_NAMESIZE];
};
void fillRoute (struct route_info *rinfo, const char* dstAddr,
const char* srcAddr, const char* gateway, const char*
ifName)
{
/* Convert from the standrad numbers and dots notation
to binary data */
inet_aton("192.168.51.0", (struct in_addr *)&rinfo->dstAddr);
inet_aton("192.168.51.90", (struct in_addr *)&rinfo->gateWay);
}
int addAttr (struct nlmsghdr *nlhdr, int maxlen, int type,
void *data, int alen)
{
struct rtattr *rta;
int len = RTA_LENGTH(alen);
if (NLMSG_ALIGN(nlhdr->nlmsg_len) + len > maxlen)
return -1;
rta = (struct rtattr*)((char *)nlhdr +
NLMSG_ALIGN(nlhdr->nlmsg_len));
rta->rta_type = type;
rta->rta_len = len;
memcpy(RTA_DATA(rta), data, alen);
nlhdr->nlmsg_len = NLMSG_ALIGN(nlhdr->nlmsg_len) + len;
return 0;
}
int main()
{
struct nlmsghdr *nlMsg;
struct rtmsg *rtMsg;
char dstAddr[30] ;
char srcAddr[30] ;
char gateway[30] ;
char ifName[30];
char msgBuf[BUFSIZE];
struct route_info rinfo;
int sock, len, msgSeq = 0;
int val, i;
/* Create Socket */
if((sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE)) < 0)
perror("Socket Creation: ");
/* Initialize the buffer */
memset(msgBuf, 0, BUFSIZE);
/* 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 ofmessage.
nlMsg->nlmsg_type = RTM_NEWROUTE; // Get
the routes from kernel routing table .
nlMsg->nlmsg_flags = NLM_F_CREATE ; // 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.
rtMsg->rtm_family = AF_INET;
rtMsg->rtm_table = RT_TABLE_UNSPEC;
rtMsg->rtm_dst_len = 16;
rtMsg->rtm_src_len = 16;
rtMsg->rtm_scope = RT_SCOPE_UNIVERSE;
rtMsg->rtm_type = RTN_UNICAST;
rtMsg->rtm_protocol = RTPROT_UNSPEC;
rtMsg->rtm_flags = RTM_F_NOTIFY;
fillRoute (&rinfo, dstAddr, srcAddr, gateway, ifName);
addAttr (nlMsg, BUFSIZE, RTA_DST,
&rinfo.dstAddr, 4);
addAttr (nlMsg, BUFSIZE, RTA_GATEWAY,
&rinfo.gateWay, 4);
/* Send the request */
if((val = send(sock, nlMsg, nlMsg->nlmsg_len,0 )) < 0){
printf("Write To Socket Failed...\n");
return -1;
}
printf (" No of Bytes sent %d \n", val);
printf (" Value that is sent \n " );
for (i =0 ; i < val ; i ++)
printf ("%u", msgBuf[i]);
printf ("\n");
close(sock);
return 0;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
OUTPUT
[root@vijdom]gcc netlink_addroute.c -o addroute
[root@vijdom]# ./addroute
No of Bytes sent 44
Value that is sent
4400024004000042949672398800216160000101008010429496723242949672085108050429496723242949672085190
//////////////////////////////////////////////////////////////////////////////////////////////////////////
SCREEN SHOTS
*Routing table before execution of program*
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref
Use Iface
192.168.51.0 * 255.255.255.0 U 0 0
0 eth0
169.254.0.0 * 255.255.0.0 U 0 0
0 eth0
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default embedded 0.0.0.0 UG 0 0
0 eth0
*Routing table after the execution of program
*Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref
Use Iface
192.168.51.0 * 255.255.255.0 U 0 0
0 eth0
169.254.0.0 * 255.255.0.0 U 0 0
0 eth0
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default embedded 0.0.0.0 UG 0 0
0 eth0
------------------------------------------------------------------------
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I have a similar network 4 /24 ip classess splitet in 7 regions. rhus i
have to do routing. For this i use:::
/sbin/ip route add class via ip for
eatch region.
ex::: /sbin/ip route add 89.34.23.0/26 via 81.181.180.21
89.34.23.0/26 > region ip address
81.181.180.21 > router ip
This i what i use....
looking forward to learning about netlink,
Good luck,
Adorean Alexandru Raul
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