1 /***********************************************************************
2 *
3 * if.c
4 *
5 * Implementation of user-space PPPoE redirector for Linux.
6 *
7 * Functions for opening a raw socket and reading/writing raw Ethernet frames.
8 *
9 * Copyright (C) 2000 by Roaring Penguin Software Inc.
10 *
11 * This program may be distributed according to the terms of the GNU
12 * General Public License, version 2 or (at your option) any later version.
13 *
14 ***********************************************************************/
15
16 static char const RCSID[] =
17 "$Id: if.c,v 1.2 2008/06/09 08:34:23 paulus Exp $";
18
19 #define _GNU_SOURCE 1
20 #include "pppoe.h"
21 #include "pppd/pppd.h"
22
23 #ifdef HAVE_UNISTD_H
24 #include <unistd.h>
25 #endif
26
27 #ifdef HAVE_NETPACKET_PACKET_H
28 #include <netpacket/packet.h>
29 #elif defined(HAVE_LINUX_IF_PACKET_H)
30 #include <linux/if_packet.h>
31 #endif
32
33 #ifdef HAVE_NET_ETHERNET_H
34 #include <net/ethernet.h>
35 #endif
36
37 #ifdef HAVE_ASM_TYPES_H
38 #include <asm/types.h>
39 #endif
40
41 #ifdef HAVE_SYS_IOCTL_H
42 #include <sys/ioctl.h>
43 #endif
44
45 #include <errno.h>
46 #include <stdlib.h>
47 #include <string.h>
48
49 #ifdef HAVE_NET_IF_ARP_H
50 #include <net/if_arp.h>
51 #endif
52
53 /* Initialize frame types to RFC 2516 values. Some broken peers apparently
54 use different frame types... sigh... */
55
56 UINT16_t Eth_PPPOE_Discovery = ETH_PPPOE_DISCOVERY;
57 UINT16_t Eth_PPPOE_Session = ETH_PPPOE_SESSION;
58
59 /**********************************************************************
60 *%FUNCTION: etherType
61 *%ARGUMENTS:
62 * packet -- a received PPPoE packet
63 *%RETURNS:
64 * ethernet packet type (see /usr/include/net/ethertypes.h)
65 *%DESCRIPTION:
66 * Checks the ethernet packet header to determine its type.
67 * We should only be receveing DISCOVERY and SESSION types if the BPF
68 * is set up correctly. Logs an error if an unexpected type is received.
69 * Note that the ethernet type names come from "pppoe.h" and the packet
70 * packet structure names use the LINUX dialect to maintain consistency
71 * with the rest of this file. See the BSD section of "pppoe.h" for
72 * translations of the data structure names.
73 ***********************************************************************/
74 UINT16_t
etherType(PPPoEPacket * packet)75 etherType(PPPoEPacket *packet)
76 {
77 UINT16_t type = (UINT16_t) ntohs(packet->ethHdr.h_proto);
78 if (type != Eth_PPPOE_Discovery && type != Eth_PPPOE_Session) {
79 error("Invalid ether type 0x%x", type);
80 }
81 return type;
82 }
83
84 /**********************************************************************
85 *%FUNCTION: openInterface
86 *%ARGUMENTS:
87 * ifname -- name of interface
88 * type -- Ethernet frame type
89 * hwaddr -- if non-NULL, set to the hardware address
90 *%RETURNS:
91 * A raw socket for talking to the Ethernet card. Exits on error.
92 *%DESCRIPTION:
93 * Opens a raw Ethernet socket
94 ***********************************************************************/
95 int
openInterface(char const * ifname,UINT16_t type,unsigned char * hwaddr)96 openInterface(char const *ifname, UINT16_t type, unsigned char *hwaddr)
97 {
98 int optval=1;
99 int fd;
100 struct ifreq ifr;
101 int domain, stype;
102
103 #ifdef HAVE_STRUCT_SOCKADDR_LL
104 struct sockaddr_ll sa;
105 #else
106 struct sockaddr sa;
107 #endif
108
109 memset(&sa, 0, sizeof(sa));
110
111 #ifdef HAVE_STRUCT_SOCKADDR_LL
112 domain = PF_PACKET;
113 stype = SOCK_RAW;
114 #else
115 domain = PF_INET;
116 stype = SOCK_PACKET;
117 #endif
118
119 if ((fd = socket(domain, stype, htons(type))) < 0) {
120 /* Give a more helpful message for the common error case */
121 if (errno == EPERM) {
122 fatal("Cannot create raw socket -- pppoe must be run as root.");
123 }
124 error("Can't open socket for pppoe: %m");
125 return -1;
126 }
127
128 if (setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &optval, sizeof(optval)) < 0) {
129 error("Can't set socket options for pppoe: %m");
130 close(fd);
131 return -1;
132 }
133
134 /* Fill in hardware address */
135 if (hwaddr) {
136 strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
137 if (ioctl(fd, SIOCGIFHWADDR, &ifr) < 0) {
138 error("Can't get hardware address for %s: %m", ifname);
139 close(fd);
140 return -1;
141 }
142 memcpy(hwaddr, ifr.ifr_hwaddr.sa_data, ETH_ALEN);
143 #ifdef ARPHRD_ETHER
144 if (ifr.ifr_hwaddr.sa_family != ARPHRD_ETHER) {
145 warn("Interface %.16s is not Ethernet", ifname);
146 }
147 #endif
148 if (NOT_UNICAST(hwaddr)) {
149 fatal("Can't use interface %.16s: it has broadcast/multicast MAC address",
150 ifname);
151 }
152 }
153
154 /* Sanity check on MTU */
155 strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
156 if (ioctl(fd, SIOCGIFMTU, &ifr) < 0) {
157 error("Can't get MTU for %s: %m", ifname);
158 } else if (ifr.ifr_mtu < ETH_DATA_LEN) {
159 error("Interface %.16s has MTU of %d -- should be at least %d.",
160 ifname, ifr.ifr_mtu, ETH_DATA_LEN);
161 error("This may cause serious connection problems.");
162 }
163
164 #ifdef HAVE_STRUCT_SOCKADDR_LL
165 /* Get interface index */
166 sa.sll_family = AF_PACKET;
167 sa.sll_protocol = htons(type);
168
169 strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
170 if (ioctl(fd, SIOCGIFINDEX, &ifr) < 0) {
171 error("Could not get interface index for %s: %m", ifname);
172 close(fd);
173 return -1;
174 }
175 sa.sll_ifindex = ifr.ifr_ifindex;
176
177 #else
178 strcpy(sa.sa_data, ifname);
179 #endif
180
181 /* We're only interested in packets on specified interface */
182 if (bind(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0) {
183 error("Failed to bind to interface %s: %m", ifname);
184 close(fd);
185 return -1;
186 }
187
188 return fd;
189 }
190
191
192 /***********************************************************************
193 *%FUNCTION: sendPacket
194 *%ARGUMENTS:
195 * sock -- socket to send to
196 * pkt -- the packet to transmit
197 * size -- size of packet (in bytes)
198 *%RETURNS:
199 * 0 on success; -1 on failure
200 *%DESCRIPTION:
201 * Transmits a packet
202 ***********************************************************************/
203 int
sendPacket(PPPoEConnection * conn,int sock,PPPoEPacket * pkt,int size)204 sendPacket(PPPoEConnection *conn, int sock, PPPoEPacket *pkt, int size)
205 {
206 int err;
207
208 if (debug)
209 pppoe_log_packet("Send ", pkt);
210 #if defined(HAVE_STRUCT_SOCKADDR_LL)
211 err = send(sock, pkt, size, 0);
212 #else
213 struct sockaddr sa;
214
215 strcpy(sa.sa_data, conn->ifName);
216 err = sendto(sock, pkt, size, 0, &sa, sizeof(sa));
217 #endif
218 if (err < 0) {
219 error("error sending pppoe packet: %m");
220 return -1;
221 }
222 return 0;
223 }
224
225 /***********************************************************************
226 *%FUNCTION: receivePacket
227 *%ARGUMENTS:
228 * sock -- socket to read from
229 * pkt -- place to store the received packet
230 * size -- set to size of packet in bytes
231 *%RETURNS:
232 * >= 0 if all OK; < 0 if error
233 *%DESCRIPTION:
234 * Receives a packet
235 ***********************************************************************/
236 int
receivePacket(int sock,PPPoEPacket * pkt,int * size)237 receivePacket(int sock, PPPoEPacket *pkt, int *size)
238 {
239 if ((*size = recv(sock, pkt, sizeof(PPPoEPacket), 0)) < 0) {
240 error("error receiving pppoe packet: %m");
241 return -1;
242 }
243 if (debug)
244 pppoe_log_packet("Recv ", pkt);
245 return 0;
246 }
247