src/patches/dnsmasq/0060-dhcp-set-outbound-interface-via-cmsg-in-unicast-repl.patch

   1 From 65c721200023ef0023114459a8d12f8b0a24cfd8 Mon Sep 17 00:00:00 2001
   2 From: Lung-Pin Chang <changlp@cs.nctu.edu.tw>
   3 Date: Thu, 19 Mar 2015 23:22:21 +0000
   4 Subject: [PATCH 60/87] dhcp: set outbound interface via cmsg in unicast reply
   5
   6   If multiple routes to the same network exist, Linux blindly picks
   7   the first interface (route) based on destination address, which might not be
   8   the one we're actually offering leases. Rather than relying on this,
   9   always set the interface for outgoing unicast DHCP packets.
  10 ---
  11  src/dhcp.c | 45 +++++++++++++++++++++++++--------------------
  12  1 file changed, 25 insertions(+), 20 deletions(-)
  13
  14 diff --git a/src/dhcp.c b/src/dhcp.c
  15 index 5c3089ab94ff..f1f43f8d8f90 100644
  16 --- a/src/dhcp.c
  17 +++ b/src/dhcp.c
  18 @@ -376,10 +376,9 @@ void dhcp_packet(time_t now, int pxe_fd)
  19         }
  20      }
  21  #if defined(HAVE_LINUX_NETWORK)
  22 -  else if ((ntohs(mess->flags) & 0x8000) || mess->hlen == 0 ||
  23 -          mess->hlen > sizeof(ifr.ifr_addr.sa_data) || mess->htype == 0)
  24 +  else
  25      {
  26 -      /* broadcast to 255.255.255.255 (or mac address invalid) */
  27 +      /* fill cmsg for outbound interface (both broadcast & unicast) */
  28        struct in_pktinfo *pkt;
  29        msg.msg_control = control_u.control;
  30        msg.msg_controllen = sizeof(control_u);
  31 @@ -389,23 +388,29 @@ void dhcp_packet(time_t now, int pxe_fd)
  32        pkt->ipi_spec_dst.s_addr = 0;
  33        msg.msg_controllen = cmptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
  34        cmptr->cmsg_level = IPPROTO_IP;
  35 -      cmptr->cmsg_type = IP_PKTINFO;
  36 -      dest.sin_addr.s_addr = INADDR_BROADCAST;
  37 -      dest.sin_port = htons(daemon->dhcp_client_port);
  38 -    }
  39 -  else
  40 -    {
  41 -      /* unicast to unconfigured client. Inject mac address direct into ARP cache.
  42 -        struct sockaddr limits size to 14 bytes. */
  43 -      dest.sin_addr = mess->yiaddr;
  44 -      dest.sin_port = htons(daemon->dhcp_client_port);
  45 -      memcpy(&arp_req.arp_pa, &dest, sizeof(struct sockaddr_in));
  46 -      arp_req.arp_ha.sa_family = mess->htype;
  47 -      memcpy(arp_req.arp_ha.sa_data, mess->chaddr, mess->hlen);
  48 -      /* interface name already copied in */
  49 -      arp_req.arp_flags = ATF_COM;
  50 -      if (ioctl(daemon->dhcpfd, SIOCSARP, &arp_req) == -1)
  51 -       my_syslog(MS_DHCP | LOG_ERR, _("ARP-cache injection failed: %s"), strerror(errno));
  52 +      cmptr->cmsg_type = IP_PKTINFO;
  53 +
  54 +      if ((ntohs(mess->flags) & 0x8000) || mess->hlen == 0 ||
  55 +         mess->hlen > sizeof(ifr.ifr_addr.sa_data) || mess->htype == 0)
  56 +        {
  57 +          /* broadcast to 255.255.255.255 (or mac address invalid) */
  58 +          dest.sin_addr.s_addr = INADDR_BROADCAST;
  59 +          dest.sin_port = htons(daemon->dhcp_client_port);
  60 +        }
  61 +      else
  62 +        {
  63 +          /* unicast to unconfigured client. Inject mac address direct into ARP cache.
  64 +          struct sockaddr limits size to 14 bytes. */
  65 +          dest.sin_addr = mess->yiaddr;
  66 +          dest.sin_port = htons(daemon->dhcp_client_port);
  67 +          memcpy(&arp_req.arp_pa, &dest, sizeof(struct sockaddr_in));
  68 +          arp_req.arp_ha.sa_family = mess->htype;
  69 +          memcpy(arp_req.arp_ha.sa_data, mess->chaddr, mess->hlen);
  70 +          /* interface name already copied in */
  71 +          arp_req.arp_flags = ATF_COM;
  72 +          if (ioctl(daemon->dhcpfd, SIOCSARP, &arp_req) == -1)
  73 +            my_syslog(MS_DHCP | LOG_ERR, _("ARP-cache injection failed: %s"), strerror(errno));
  74 +        }
  75      }
  76  #elif defined(HAVE_SOLARIS_NETWORK)
  77    else if ((ntohs(mess->flags) & 0x8000) || mess->hlen != ETHER_ADDR_LEN || mess->htype != ARPHRD_ETHER)
  78 --
  79 2.1.0
  80