udhcpc: in comments, explain the kind of raw socket we create

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index ee19f55780cbec654901890159ba27db38fdb218..bdb1e2b9b0ed7e8127911a0aa8a528af29797a17 100644 (file)
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -979,6 +979,10 @@ static int udhcp_raw_socket(int ifindex)
        log1("Opening raw socket on ifindex %d", ifindex); //log2?
 
        fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
+       /* ^^^^^
+        * SOCK_DGRAM: remove link-layer headers on input (SOCK_RAW keeps them)
+        * ETH_P_IP: want to receive only packets with IPv4 eth type
+        */
        log1("Got raw socket fd"); //log2?
 
        sock.sll_family = AF_PACKET;
@@ -1005,8 +1009,6 @@ static int udhcp_raw_socket(int ifindex)
                 *
                 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
                 * License: GPL v2.
-                *
-                * TODO: make conditional?
                 */
                static const struct sock_filter filter_instr[] = {
                        /* load 9th byte (protocol) */