* Tom?? Macek <Pine.LNX.4.61.0506182042540.29813@xxxxxxxxxxxxxxxxxxxxx>
2005-06-18 20:55
> The 'rtm_dst_len = 16' should mean the mask of the route I'm looking for,
> correct?
Yes.
> The whole code before sending the packet is below:
>
>
> /* Create Socket */
> if((sock = socket(PF_NETLINK, SOCK_DGRAM, 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);
> rtMsg->rtm_family = AF_INET;
> rtMsg->rtm_dst_len = 16;
>
> /* 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_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.
>
> char *cp;
> unsigned int xx[4]; int i = 0;
> unsigned char *ap = (unsigned char *)xx;
> for (cp = argv[1], i = 0; *cp; cp++) {
> if (*cp <= '9' && *cp >= '0') {
> ap[i] = 10*ap[i] + (*cp-'0');
> continue;
> }
> if (*cp == '.' && ++i <= 3)
> continue;
> return -1;
> }
>
> NetlinkAddAttr(nlMsg, sizeof(nlMsg), RTA_DST, &xx, 4);
This looks good but your NetlinkAddAttr is bogus, it should
be something like this:
int nl_msg_append_tlv(struct nlmsghdr *n, int type, void *data, size_t len)
{
int tlen;
struct rtattr *rta;
tlen = NLMSG_ALIGN(n->nlmsg_len) + RTA_LENGTH(NLMSG_ALIGN(len));
rta = (struct rtattr *) NLMSG_TAIL(n);
rta->rta_type = type;
rta->rta_len = RTA_LENGTH(NLMSG_ALIGN(len));
memcpy(RTA_DATA(rta), data, len);
n->nlmsg_len = tlen;
return 0;
}
Your code is missing various alignment requirements. I can't tell
whether this is the last bug. I recommend you to read ip/iproute.c
in the iproute2 source or give libnl a second chance.
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