BIND 10 #3188: socket creator support for raw sockets

[BIND 10 Development]

#3188: socket creator support for raw sockets
-------------------------------------+-------------------------------------
                   Reporter:  shane  |                 Owner:
                       Type:         |                Status:  new
  enhancement                        |             Milestone:  Next-Sprint-
                   Priority:         |  Proposed
  medium                             |              Keywords:
                  Component:         |             Sensitive:  0
  Unclassified                       |           Sub-Project:  Core
               CVSS Scoring:         |  Estimated Difficulty:  0
            Defect Severity:  N/A    |           Total Hours:  0
Feature Depending on Ticket:         |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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 The DHCP team needs to have support for raw sockets in the socket creator.

 Currently this is done directly in the code (iface_mgr_linux.cc):

 {{{#!cpp
     fd_ = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
     if (fd_ < 0) {
         isc_throw(Unexpected, "Failed to create NETLINK socket.");
     }

     if (setsockopt(fd_, SOL_SOCKET, SO_SNDBUF, &SNDBUF_SIZE,
 sizeof(SNDBUF_SIZE)) < 0) {
         isc_throw(Unexpected, "Failed to set send buffer in NETLINK
 socket.");
     }

     if (setsockopt(fd_, SOL_SOCKET, SO_RCVBUF, &RCVBUF_SIZE,
 sizeof(RCVBUF_SIZE)) < 0) {
         isc_throw(Unexpected, "Failed to set receive buffer in NETLINK
 socket.");
     }

     local_.nl_family = AF_NETLINK;
     local_.nl_groups = 0;

     if (bind(fd_, convertSockAddr(&local_), sizeof(local_)) < 0) {
         isc_throw(Unexpected, "Failed to bind netlink socket.");
     }
 }}}

 Or in pkt_filter_lpf:

 {{{#!cpp
     int sock = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
     if (sock < 0) {
         isc_throw(SocketConfigError, "Failed to create raw LPF socket");
     }

     // Create socket filter program. This program will only allow incoming
 UDP
     // traffic which arrives on the specific (DHCP) port). It will also
 filter
     // out all fragmented packets.
     struct sock_fprog filter_program;
     memset(&filter_program, 0, sizeof(filter_program));

     filter_program.filter = dhcp_sock_filter;
     filter_program.len = sizeof(dhcp_sock_filter) / sizeof(struct
 sock_filter);
     // Override the default port value.
     dhcp_sock_filter[8].k = port;
     // Apply the filter.
     if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter_program,
                    sizeof(filter_program)) < 0) {
         close(sock);
         isc_throw(SocketConfigError, "Failed to install packet filtering
 program"
                   << " on the socket " << sock);
     }

     struct sockaddr_ll sa;
     memset(&sa, 0, sizeof(sockaddr_ll));
     sa.sll_family = AF_PACKET;
     sa.sll_ifindex = iface.getIndex();

     // For raw sockets we construct IP headers on our own, so we don't
 bind
     // socket to IP address but to the interface. We will later use the
     // Linux Packet Filtering to filter out these packets that we are
     // interested in.
     if (bind(sock, reinterpret_cast<const struct sockaddr*>(&sa),
              sizeof(sa)) < 0) {
         close(sock);
         isc_throw(SocketConfigError, "Failed to bind LPF socket '" << sock
                   << "' to interface '" << iface.getName() << "'");
     }

     return (sock);
 }}}

 This may be a simple change to the protocol (described in
 src/bin/socketcreator/README). The current command consists of:

 * 'S' 'U|T' '4|6' port address: Asks it to create a port.

 Probably we want to add something like:

 * 'R' 'N|L' ifindex: Asks it to create a raw port for either netlink or
 LPF (with the specified interface index).

-- 
Ticket URL: <http://bind10.isc.org/ticket/3188>
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