Contents of /trunk/mkinitrd-magellan/busybox/networking/udhcp/clientsocket.c
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Fri Apr 24 18:33:46 2009 UTC (15 years, 1 month ago) by niro
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Fri Apr 24 18:33:46 2009 UTC (15 years, 1 month ago) by niro
File MIME type: text/plain
File size: 3710 byte(s)
-updated to busybox-1.13.4
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * clientsocket.c -- DHCP client socket creation |
4 | * |
5 | * udhcp client |
6 | * |
7 | * Russ Dill <Russ.Dill@asu.edu> July 2001 |
8 | * |
9 | * This program is free software; you can redistribute it and/or modify |
10 | * it under the terms of the GNU General Public License as published by |
11 | * the Free Software Foundation; either version 2 of the License, or |
12 | * (at your option) any later version. |
13 | * |
14 | * This program is distributed in the hope that it will be useful, |
15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
17 | * GNU General Public License for more details. |
18 | * |
19 | * You should have received a copy of the GNU General Public License |
20 | * along with this program; if not, write to the Free Software |
21 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
22 | */ |
23 | |
24 | #include <features.h> |
25 | #include <asm/types.h> |
26 | #if (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1) || defined(_NEWLIB_VERSION) |
27 | #include <netpacket/packet.h> |
28 | #include <net/ethernet.h> |
29 | #else |
30 | #include <linux/if_packet.h> |
31 | #include <linux/if_ether.h> |
32 | #endif |
33 | #include <linux/filter.h> |
34 | |
35 | #include "common.h" |
36 | #include "dhcpd.h" |
37 | #include "dhcpc.h" |
38 | |
39 | int FAST_FUNC udhcp_raw_socket(int ifindex) |
40 | { |
41 | int fd; |
42 | struct sockaddr_ll sock; |
43 | |
44 | /* |
45 | * Comment: |
46 | * |
47 | * I've selected not to see LL header, so BPF doesn't see it, too. |
48 | * The filter may also pass non-IP and non-ARP packets, but we do |
49 | * a more complete check when receiving the message in userspace. |
50 | * |
51 | * and filter shamelessly stolen from: |
52 | * |
53 | * http://www.flamewarmaster.de/software/dhcpclient/ |
54 | * |
55 | * There are a few other interesting ideas on that page (look under |
56 | * "Motivation"). Use of netlink events is most interesting. Think |
57 | * of various network servers listening for events and reconfiguring. |
58 | * That would obsolete sending HUP signals and/or make use of restarts. |
59 | * |
60 | * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>. |
61 | * License: GPL v2. |
62 | * |
63 | * TODO: make conditional? |
64 | */ |
65 | #define SERVER_AND_CLIENT_PORTS ((67 << 16) + 68) |
66 | static const struct sock_filter filter_instr[] = { |
67 | /* check for udp */ |
68 | BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9), |
69 | BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 2, 0), /* L5, L1, is UDP? */ |
70 | /* ugly check for arp on ethernet-like and IPv4 */ |
71 | BPF_STMT(BPF_LD|BPF_W|BPF_ABS, 2), /* L1: */ |
72 | BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 0x08000604, 3, 4), /* L3, L4 */ |
73 | /* skip IP header */ |
74 | BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0), /* L5: */ |
75 | /* check udp source and destination ports */ |
76 | BPF_STMT(BPF_LD|BPF_W|BPF_IND, 0), |
77 | BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, SERVER_AND_CLIENT_PORTS, 0, 1), /* L3, L4 */ |
78 | /* returns */ |
79 | BPF_STMT(BPF_RET|BPF_K, 0x0fffffff ), /* L3: pass */ |
80 | BPF_STMT(BPF_RET|BPF_K, 0), /* L4: reject */ |
81 | }; |
82 | static const struct sock_fprog filter_prog = { |
83 | .len = sizeof(filter_instr) / sizeof(filter_instr[0]), |
84 | /* casting const away: */ |
85 | .filter = (struct sock_filter *) filter_instr, |
86 | }; |
87 | |
88 | DEBUG("opening raw socket on ifindex %d", ifindex); |
89 | |
90 | fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP)); |
91 | DEBUG("got raw socket fd %d", fd); |
92 | |
93 | if (SERVER_PORT == 67 && CLIENT_PORT == 68) { |
94 | /* Use only if standard ports are in use */ |
95 | /* Ignoring error (kernel may lack support for this) */ |
96 | if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog, |
97 | sizeof(filter_prog)) >= 0) |
98 | DEBUG("attached filter to raw socket fd %d", fd); |
99 | } |
100 | |
101 | sock.sll_family = AF_PACKET; |
102 | sock.sll_protocol = htons(ETH_P_IP); |
103 | sock.sll_ifindex = ifindex; |
104 | xbind(fd, (struct sockaddr *) &sock, sizeof(sock)); |
105 | DEBUG("bound to raw socket fd %d", fd); |
106 | |
107 | return fd; |
108 | } |