import of dnsmasq-2.21.tar.gz

src/netlink.c

@@ -0,0 +1,153 @@
+/* dnsmasq is Copyright (c) 2000-2005 Simon Kelley
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 dated June, 1991.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+*/
+
+/* Author's email: simon@thekelleys.org.uk */
+
+#include "dnsmasq.h"
+
+#ifdef HAVE_RTNETLINK
+
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+
+int netlink_init(void)
+{
+  struct sockaddr_nl addr;
+  int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+  
+  if (sock < 0)
+    return -1; /* no kernel support */
+
+  addr.nl_family = AF_NETLINK;
+  addr.nl_pad = 0;
+  addr.nl_pid = getpid();
+  addr.nl_groups = 0;
+  
+  if (bind(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0)
+    die("cannot bind netlink socket: %s", NULL);
+  
+  return sock;
+}
+
+
+/* We borrow the DNS packet buffer here. (The DHCP one already has a packet in it)
+   Since it's used only within this routine, that's fine, just remember 
+   that calling icmp_echo() will trash it */
+int netlink_process(struct daemon *daemon, int index, struct in_addr relay, 
+		    struct in_addr primary, struct dhcp_context **retp)
+{
+  struct sockaddr_nl addr;
+  struct nlmsghdr *h;
+  int len, found_primary = 0;
+  struct dhcp_context *ret = NULL;
+  static unsigned int seq = 0;
+
+  struct {
+    struct nlmsghdr nlh;
+    struct rtgenmsg g; 
+  } req;
+
+  if (daemon->netlinkfd == -1)
+    return 0;
+
+  addr.nl_family = AF_NETLINK;
+  addr.nl_pad = 0;
+  addr.nl_groups = 0;
+  addr.nl_pid = 0; /* address to kernel */
+
+  req.nlh.nlmsg_len = sizeof(req);
+  req.nlh.nlmsg_type = RTM_GETADDR;
+  req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST;
+  req.nlh.nlmsg_pid = 0;
+  req.nlh.nlmsg_seq = ++seq;
+  req.g.rtgen_family = AF_INET; 
+
+  /* Don't block in recvfrom if send fails */
+  while((len = sendto(daemon->netlinkfd, (void *)&req, sizeof(req), 0, 
+		      (struct sockaddr *)&addr, sizeof(addr))) == -1 && retry_send());
+
+  if (len == -1)
+    {
+      /* if RTnetlink not configured in the kernel, don't keep trying. */
+      if (errno == ECONNREFUSED)
+	{
+	  close(daemon->netlinkfd);
+	  daemon->netlinkfd = -1;
+	}
+      return 0;
+    }
+
+ get_next:
+  while((len = recvfrom(daemon->netlinkfd, daemon->packet, daemon->packet_buff_sz, 
+			MSG_WAITALL, NULL, 0)) == -1 && retry_send());
+ 
+  if (len == -1)
+    return 0;
+  
+  h = (struct nlmsghdr *)daemon->packet;
+
+  while (NLMSG_OK(h, (unsigned int)len))
+    {
+          
+      if (h->nlmsg_seq != seq)
+	goto get_next;
+	
+      if (h->nlmsg_type == NLMSG_DONE)
+	break;
+
+      if (h->nlmsg_type == NLMSG_ERROR)
+	return 0;
+      
+      if (h->nlmsg_type == RTM_NEWADDR)
+	{
+	  struct ifaddrmsg *ifa = NLMSG_DATA(h);
+	  
+	  if (ifa->ifa_index == index && ifa->ifa_family == AF_INET)
+	    {
+	      struct rtattr *rta = IFA_RTA(ifa);
+	      unsigned int len1 = h->nlmsg_len - NLMSG_LENGTH(sizeof(*ifa));
+	      struct in_addr netmask, addr, broadcast;
+	      
+	      netmask.s_addr = htonl(0xffffffff << (32 - ifa->ifa_prefixlen));
+	      addr.s_addr = 0;
+	      broadcast.s_addr = 0;
+	      
+	      while (RTA_OK(rta, len1))
+		{
+		  if (rta->rta_type == IFA_LOCAL)
+		    addr = *((struct in_addr *)(rta+1));
+		  else if (rta->rta_type == IFA_BROADCAST)
+		    broadcast = *((struct in_addr *)(rta+1));
+		  
+		  rta = RTA_NEXT(rta, len1);
+		}
+	      
+	      if (addr.s_addr && broadcast.s_addr)
+		{
+		  ret = complete_context(daemon, addr, ret, netmask, broadcast, relay, primary);	
+		  if (addr.s_addr == primary.s_addr)
+		    found_primary = 1;
+		}
+	    }
+	}
+
+      h = NLMSG_NEXT(h, len);
+    }
+
+  *retp = ret;
+
+  return found_primary;
+}
+
+#endif
+
+