* [LARTC] Re: problem in Route add using netlink
@ 2006-07-31 7:03 Jarek Poplawski
2006-07-31 7:24 ` Jarek Poplawski
0 siblings, 1 reply; 2+ messages in thread
From: Jarek Poplawski @ 2006-07-31 7:03 UTC (permalink / raw)
To: lartc
On 25-07-2006 16:59, 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
I had some free time at the weekend - it's probably to late and I
hope you've found this bugs yet, but maybe someone else (like me)
will be looking here some day with similar problem, so here is
what I've found.
Jarek P
>
> //////////////////////////////////// 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);
> }
Of corse you always have to be sure to have the valid route to
192.168.51.90 on the testing box...
> 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
// the flag is needed here
nlMsg->nlmsg_flags = NLM_F_CREATE | NLM_F_REQUEST;
> 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;
// this should be address' lenghts in bits so:
rtMsg->rtm_dst_len = 32;
rtMsg->rtm_src_len = 32;
> 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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2006-07-31 7:03 [LARTC] Re: problem in Route add using netlink Jarek Poplawski
2006-07-31 7:24 ` Jarek Poplawski
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