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* WPA Supplicant - Layer2 packet handling with libpcap/libdnet and WinPcap
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* Copyright (c) 2003-2006, Jouni Malinen <jkmaline@cc.hut.fi>
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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* Alternatively, this software may be distributed under the terms of BSD
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* See README and COPYING for more details.
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#ifndef CONFIG_NATIVE_WINDOWS
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#include <sys/ioctl.h>
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#endif /* CONFIG_NATIVE_WINDOWS */
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#ifndef CONFIG_WINPCAP
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#endif /* CONFIG_WINPCAP */
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#include "l2_packet.h"
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static const u8 pae_group_addr[ETH_ALEN] =
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{ 0x01, 0x80, 0xc2, 0x00, 0x00, 0x03 };
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struct l2_packet_data {
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unsigned int num_fast_poll;
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#else /* CONFIG_WINPCAP */
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#endif /* CONFIG_WINPCAP */
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u8 own_addr[ETH_ALEN];
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void (*rx_callback)(void *ctx, const u8 *src_addr,
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const u8 *buf, size_t len);
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void *rx_callback_ctx;
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int l2_hdr; /* whether to include layer 2 (Ethernet) header in calls
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int l2_packet_get_own_addr(struct l2_packet_data *l2, u8 *addr)
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os_memcpy(addr, l2->own_addr, ETH_ALEN);
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#ifndef CONFIG_WINPCAP
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static int l2_packet_init_libdnet(struct l2_packet_data *l2)
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l2->eth = eth_open(l2->ifname);
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printf("Failed to open interface '%s'.\n", l2->ifname);
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if (eth_get(l2->eth, &own_addr) < 0) {
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printf("Failed to get own hw address from interface '%s'.\n",
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os_memcpy(l2->own_addr, own_addr.data, ETH_ALEN);
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#endif /* CONFIG_WINPCAP */
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int l2_packet_send(struct l2_packet_data *l2, const u8 *dst_addr, u16 proto,
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const u8 *buf, size_t len)
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struct l2_ethhdr *eth;
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ret = pcap_sendpacket(l2->pcap, buf, len);
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#else /* CONFIG_WINPCAP */
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ret = eth_send(l2->eth, buf, len);
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#endif /* CONFIG_WINPCAP */
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size_t mlen = sizeof(*eth) + len;
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eth = os_malloc(mlen);
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os_memcpy(eth->h_dest, dst_addr, ETH_ALEN);
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os_memcpy(eth->h_source, l2->own_addr, ETH_ALEN);
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eth->h_proto = htons(proto);
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os_memcpy(eth + 1, buf, len);
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#ifdef CONFIG_WINPCAP
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ret = pcap_sendpacket(l2->pcap, (u8 *) eth, mlen);
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#else /* CONFIG_WINPCAP */
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ret = eth_send(l2->eth, (u8 *) eth, mlen);
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#endif /* CONFIG_WINPCAP */
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#ifndef CONFIG_WINPCAP
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static void l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx)
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struct l2_packet_data *l2 = eloop_ctx;
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pcap_t *pcap = sock_ctx;
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struct pcap_pkthdr hdr;
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const u_char *packet;
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struct l2_ethhdr *ethhdr;
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packet = pcap_next(pcap, &hdr);
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if (packet == NULL || hdr.caplen < sizeof(*ethhdr))
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ethhdr = (struct l2_ethhdr *) packet;
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buf = (unsigned char *) ethhdr;
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buf = (unsigned char *) (ethhdr + 1);
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len = hdr.caplen - sizeof(*ethhdr);
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l2->rx_callback(l2->rx_callback_ctx, ethhdr->h_source, buf, len);
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#endif /* CONFIG_WINPCAP */
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#ifdef CONFIG_WINPCAP
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static void l2_packet_receive_cb(u_char *user, const struct pcap_pkthdr *hdr,
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const u_char *pkt_data)
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struct l2_packet_data *l2 = (struct l2_packet_data *) user;
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struct l2_ethhdr *ethhdr;
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if (pkt_data == NULL || hdr->caplen < sizeof(*ethhdr))
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ethhdr = (struct l2_ethhdr *) pkt_data;
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buf = (unsigned char *) ethhdr;
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buf = (unsigned char *) (ethhdr + 1);
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len = hdr->caplen - sizeof(*ethhdr);
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l2->rx_callback(l2->rx_callback_ctx, ethhdr->h_source, buf, len);
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* Use shorter poll interval for 3 seconds to reduce latency during key
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l2->num_fast_poll = 3 * 50;
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static void l2_packet_receive_timeout(void *eloop_ctx, void *timeout_ctx)
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struct l2_packet_data *l2 = eloop_ctx;
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pcap_t *pcap = timeout_ctx;
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if (l2->num_fast_poll > 0) {
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/* Register new timeout before calling l2_packet_receive() since
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* receive handler may free this l2_packet instance (which will
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* cancel this timeout). */
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eloop_register_timeout(0, timeout, l2_packet_receive_timeout,
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pcap_dispatch(pcap, 10, l2_packet_receive_cb, (u_char *) l2);
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#endif /* CONFIG_WINPCAP */
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static int l2_packet_init_libpcap(struct l2_packet_data *l2,
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unsigned short protocol)
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bpf_u_int32 pcap_maskp, pcap_netp;
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char pcap_filter[200], pcap_err[PCAP_ERRBUF_SIZE];
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struct bpf_program pcap_fp;
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#ifdef CONFIG_WINPCAP
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os_snprintf(ifname, sizeof(ifname), "\\Device\\NPF_%s", l2->ifname);
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pcap_lookupnet(ifname, &pcap_netp, &pcap_maskp, pcap_err);
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l2->pcap = pcap_open_live(ifname, 2500, 0, 10, pcap_err);
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if (l2->pcap == NULL) {
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fprintf(stderr, "pcap_open_live: %s\n", pcap_err);
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fprintf(stderr, "ifname='%s'\n", ifname);
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if (pcap_setnonblock(l2->pcap, 1, pcap_err) < 0)
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fprintf(stderr, "pcap_setnonblock: %s\n",
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pcap_geterr(l2->pcap));
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#else /* CONFIG_WINPCAP */
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pcap_lookupnet(l2->ifname, &pcap_netp, &pcap_maskp, pcap_err);
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l2->pcap = pcap_open_live(l2->ifname, 2500, 0, 10, pcap_err);
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if (l2->pcap == NULL) {
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fprintf(stderr, "pcap_open_live: %s\n", pcap_err);
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fprintf(stderr, "ifname='%s'\n", l2->ifname);
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if (pcap_datalink(l2->pcap) != DLT_EN10MB &&
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pcap_set_datalink(l2->pcap, DLT_EN10MB) < 0) {
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fprintf(stderr, "pcap_set_datalinke(DLT_EN10MB): %s\n",
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pcap_geterr(l2->pcap));
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#endif /* CONFIG_WINPCAP */
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os_snprintf(pcap_filter, sizeof(pcap_filter),
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"not ether src " MACSTR " and "
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"( ether dst " MACSTR " or ether dst " MACSTR " ) and "
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MAC2STR(l2->own_addr), /* do not receive own packets */
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MAC2STR(l2->own_addr), MAC2STR(pae_group_addr),
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if (pcap_compile(l2->pcap, &pcap_fp, pcap_filter, 1, pcap_netp) < 0) {
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fprintf(stderr, "pcap_compile: %s\n", pcap_geterr(l2->pcap));
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if (pcap_setfilter(l2->pcap, &pcap_fp) < 0) {
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fprintf(stderr, "pcap_setfilter: %s\n", pcap_geterr(l2->pcap));
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pcap_freecode(&pcap_fp);
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* When libpcap uses BPF we must enable "immediate mode" to
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* receive frames right away; otherwise the system may
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* buffer them for us.
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if (ioctl(pcap_fileno(l2->pcap), BIOCIMMEDIATE, &on) < 0) {
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fprintf(stderr, "%s: cannot enable immediate mode on "
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"interface %s: %s\n",
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__func__, l2->ifname, strerror(errno));
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/* XXX should we fail? */
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#endif /* BIOCIMMEDIATE */
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#ifdef CONFIG_WINPCAP
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eloop_register_timeout(0, 100000, l2_packet_receive_timeout,
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#else /* CONFIG_WINPCAP */
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eloop_register_read_sock(pcap_get_selectable_fd(l2->pcap),
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l2_packet_receive, l2, l2->pcap);
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#endif /* CONFIG_WINPCAP */
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struct l2_packet_data * l2_packet_init(
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const char *ifname, const u8 *own_addr, unsigned short protocol,
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void (*rx_callback)(void *ctx, const u8 *src_addr,
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const u8 *buf, size_t len),
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void *rx_callback_ctx, int l2_hdr)
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struct l2_packet_data *l2;
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l2 = os_zalloc(sizeof(struct l2_packet_data));
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os_strlcpy(l2->ifname, ifname, sizeof(l2->ifname));
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l2->rx_callback = rx_callback;
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l2->rx_callback_ctx = rx_callback_ctx;
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#ifdef CONFIG_WINPCAP
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os_memcpy(l2->own_addr, own_addr, ETH_ALEN);
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#else /* CONFIG_WINPCAP */
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if (l2_packet_init_libdnet(l2))
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#endif /* CONFIG_WINPCAP */
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if (l2_packet_init_libpcap(l2, protocol)) {
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#ifndef CONFIG_WINPCAP
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#endif /* CONFIG_WINPCAP */
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void l2_packet_deinit(struct l2_packet_data *l2)
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#ifdef CONFIG_WINPCAP
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eloop_cancel_timeout(l2_packet_receive_timeout, l2, l2->pcap);
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#else /* CONFIG_WINPCAP */
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eloop_unregister_read_sock(pcap_get_selectable_fd(l2->pcap));
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#endif /* CONFIG_WINPCAP */
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pcap_close(l2->pcap);
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int l2_packet_get_ip_addr(struct l2_packet_data *l2, char *buf, size_t len)
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pcap_if_t *devs, *dev;
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struct pcap_addr *addr;
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struct sockaddr_in *saddr;
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char err[PCAP_ERRBUF_SIZE + 1];
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if (pcap_findalldevs(&devs, err) < 0) {
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wpa_printf(MSG_DEBUG, "pcap_findalldevs: %s\n", err);
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for (dev = devs; dev && !found; dev = dev->next) {
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if (os_strcmp(dev->name, l2->ifname) != 0)
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addr = dev->addresses;
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saddr = (struct sockaddr_in *) addr->addr;
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if (saddr && saddr->sin_family == AF_INET) {
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os_strlcpy(buf, inet_ntoa(saddr->sin_addr),
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pcap_freealldevs(devs);
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return found ? 0 : -1;
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void l2_packet_notify_auth_start(struct l2_packet_data *l2)
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#ifdef CONFIG_WINPCAP
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* Use shorter poll interval for 3 seconds to reduce latency during key
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l2->num_fast_poll = 3 * 50;
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eloop_cancel_timeout(l2_packet_receive_timeout, l2, l2->pcap);
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eloop_register_timeout(0, 10000, l2_packet_receive_timeout,
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#endif /* CONFIG_WINPCAP */
added
removed
l2_packet_pcap.c
