l2_packet_freebsd.c

Go to the documentation of this file.

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <pcap.h>

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "common.h"
#include "eloop.h"
#include "l2_packet.h"


struct l2_packet_data {
        pcap_t *pcap;
        char ifname[100];
        u8 own_addr[ETH_ALEN];
        void (*rx_callback)(void *ctx, const u8 *src_addr,
                            const u8 *buf, size_t len);
        void *rx_callback_ctx;
        int l2_hdr; /* whether to include layer 2 (Ethernet) header data
                     * buffers */
};


int l2_packet_get_own_addr(struct l2_packet_data *l2, u8 *addr)
{
        memcpy(addr, l2->own_addr, ETH_ALEN);
        return 0;
}


int l2_packet_send(struct l2_packet_data *l2, const u8 *dst_addr, u16 proto,
                   const u8 *buf, size_t len)
{
        if (!l2->l2_hdr) {
                int ret;
                struct l2_ethhdr *eth = malloc(sizeof(*eth) + len);
                if (eth == NULL)
                        return -1;
                memcpy(eth->h_dest, dst_addr, ETH_ALEN);
                memcpy(eth->h_source, l2->own_addr, ETH_ALEN);
                eth->h_proto = htons(proto);
                memcpy(eth + 1, buf, len);
                ret = pcap_inject(l2->pcap, (u8 *) eth, len + sizeof(*eth));
                free(eth);
                return ret;
        } else
                return pcap_inject(l2->pcap, buf, len);
}


static void l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx)
{
        struct l2_packet_data *l2 = eloop_ctx;
        pcap_t *pcap = sock_ctx;
        struct pcap_pkthdr hdr;
        const u_char *packet;
        struct l2_ethhdr *ethhdr;
        unsigned char *buf;
        size_t len;

        packet = pcap_next(pcap, &hdr);

        if (packet == NULL || hdr.caplen < sizeof(*ethhdr))
                return;

        ethhdr = (struct l2_ethhdr *) packet;
        if (l2->l2_hdr) {
                buf = (unsigned char *) ethhdr;
                len = hdr.caplen;
        } else {
                buf = (unsigned char *) (ethhdr + 1);
                len = hdr.caplen - sizeof(*ethhdr);
        }
        l2->rx_callback(l2->rx_callback_ctx, ethhdr->h_source, buf, len);
}


static int l2_packet_init_libpcap(struct l2_packet_data *l2,
                                  unsigned short protocol)
{
        bpf_u_int32 pcap_maskp, pcap_netp;
        char pcap_filter[100], pcap_err[PCAP_ERRBUF_SIZE];
        struct bpf_program pcap_fp;

        pcap_lookupnet(l2->ifname, &pcap_netp, &pcap_maskp, pcap_err);
        l2->pcap = pcap_open_live(l2->ifname, 2500, 0, 10, pcap_err);
        if (l2->pcap == NULL) {
                fprintf(stderr, "pcap_open_live: %s\n", pcap_err);
                fprintf(stderr, "ifname='%s'\n", l2->ifname);
                return -1;
        }
        if (pcap_datalink(l2->pcap) != DLT_EN10MB &&
            pcap_set_datalink(l2->pcap, DLT_EN10MB) < 0) {
                fprintf(stderr, "pcap_set_datalinke(DLT_EN10MB): %s\n",
                        pcap_geterr(l2->pcap));
                return -1;
        }
        snprintf(pcap_filter, sizeof(pcap_filter),
                 "ether dst " MACSTR " and ether proto 0x%x",
                 MAC2STR(l2->own_addr), protocol);
        if (pcap_compile(l2->pcap, &pcap_fp, pcap_filter, 1, pcap_netp) < 0) {
                fprintf(stderr, "pcap_compile: %s\n", pcap_geterr(l2->pcap));
                return -1;
        }

        if (pcap_setfilter(l2->pcap, &pcap_fp) < 0) {
                fprintf(stderr, "pcap_setfilter: %s\n", pcap_geterr(l2->pcap));
                return -1;
        }

        pcap_freecode(&pcap_fp);
        /*
         * When libpcap uses BPF we must enable "immediate mode" to
         * receive frames right away; otherwise the system may
         * buffer them for us.
         */
        {
                unsigned int on = 1;
                if (ioctl(pcap_fileno(l2->pcap), BIOCIMMEDIATE, &on) < 0) {
                        fprintf(stderr, "%s: cannot enable immediate mode on "
                                "interface %s: %s\n",
                                __func__, l2->ifname, strerror(errno));
                        /* XXX should we fail? */
                }
        }

        eloop_register_read_sock(pcap_get_selectable_fd(l2->pcap),
                                 l2_packet_receive, l2, l2->pcap);

        return 0;
}


static int eth_get(const char *device, u8 ea[ETH_ALEN])
{
        struct if_msghdr *ifm;
        struct sockaddr_dl *sdl;
        u_char *p, *buf;
        size_t len;
        int mib[] = { CTL_NET, AF_ROUTE, 0, AF_LINK, NET_RT_IFLIST, 0 };

        if (sysctl(mib, 6, NULL, &len, NULL, 0) < 0)
                return -1;
        if ((buf = malloc(len)) == NULL)
                return -1;
        if (sysctl(mib, 6, buf, &len, NULL, 0) < 0) {
                free(buf);
                return -1;
        }
        for (p = buf; p < buf + len; p += ifm->ifm_msglen) {
                ifm = (struct if_msghdr *)p;
                sdl = (struct sockaddr_dl *)(ifm + 1);
                if (ifm->ifm_type != RTM_IFINFO ||
                    (ifm->ifm_addrs & RTA_IFP) == 0)
                        continue;
                if (sdl->sdl_family != AF_LINK || sdl->sdl_nlen == 0 ||
                    memcmp(sdl->sdl_data, device, sdl->sdl_nlen) != 0)
                        continue;
                memcpy(ea, LLADDR(sdl), sdl->sdl_alen);
                break;
        }
        free(buf);

        if (p >= buf + len) {
                errno = ESRCH;
                return -1;
        }
        return 0;
}


struct l2_packet_data * l2_packet_init(
        const char *ifname, const u8 *own_addr, unsigned short protocol,
        void (*rx_callback)(void *ctx, const u8 *src_addr,
                            const u8 *buf, size_t len),
        void *rx_callback_ctx, int l2_hdr)
{
        struct l2_packet_data *l2;

        l2 = malloc(sizeof(struct l2_packet_data));
        if (l2 == NULL)
                return NULL;
        memset(l2, 0, sizeof(*l2));
        strncpy(l2->ifname, ifname, sizeof(l2->ifname));
        l2->rx_callback = rx_callback;
        l2->rx_callback_ctx = rx_callback_ctx;
        l2->l2_hdr = l2_hdr;

        if (eth_get(l2->ifname, l2->own_addr) < 0) {
                fprintf(stderr, "Failed to get link-level address for "
                        "interface '%s'.\n", l2->ifname);
                free(l2);
                return NULL;
        }

        if (l2_packet_init_libpcap(l2, protocol)) {
                free(l2);
                return NULL;
        }

        return l2;
}


void l2_packet_deinit(struct l2_packet_data *l2)
{
        if (l2 != NULL) {
                if (l2->pcap)
                        pcap_close(l2->pcap);
                free(l2);
        }
}


int l2_packet_get_ip_addr(struct l2_packet_data *l2, char *buf, size_t len)
{
        pcap_if_t *devs, *dev;
        struct pcap_addr *addr;
        struct sockaddr_in *saddr;
        int found = 0;
        char err[PCAP_ERRBUF_SIZE + 1];

        if (pcap_findalldevs(&devs, err) < 0) {
                wpa_printf(MSG_DEBUG, "pcap_findalldevs: %s\n", err);
                return -1;
        }

        for (dev = devs; dev && !found; dev = dev->next) {
                if (strcmp(dev->name, l2->ifname) != 0)
                        continue;

                addr = dev->addresses;
                while (addr) {
                        saddr = (struct sockaddr_in *) addr->addr;
                        if (saddr && saddr->sin_family == AF_INET) {
                                snprintf(buf, len, "%s",
                                         inet_ntoa(saddr->sin_addr));
                                found = 1;
                                break;
                        }
                        addr = addr->next;
                }
        }

        pcap_freealldevs(devs);

        return found ? 0 : -1;
}


void l2_packet_notify_auth_start(struct l2_packet_data *l2)
{
}

---