packets/packet_osx_bpf.c

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#include "packet_osx_bpf.h"
#ifdef _OSX_

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <time.h>
#include <net/bpf.h>
#include <errno.h>
#include <err.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>

#define DEBUG

#define FATAL           1
#define NONFATAL        0

extern GlobalVars       Globals;

/***********************************************
* Open up a bpf
***********************************************/
static int
bpf_open()
{
        int     fd;
        int     n = 0;
        char    device[sizeof "/dev/bpf0000000000"];

        /* Go through all the minors and find one that isn't in use. */
        do {
                (void) snprintf(device, sizeof device, "/dev/bpf%d", n++);
                fd = open(device, O_RDWR);
        } while (fd < 0 && errno == EBUSY);

        if (fd < 0) {
                err(FATAL, "%s: %s", device, strerror(errno));
                /* NOTREACHED */
        }
        return fd;
}

/*********************************************
* Get the MTU of interface named "name"
*********************************************/
int GetIfrMTU(char *name) {
    int fd;
    struct ifreq ifr;
    int retval;

    retval = -1;
    fd = socket(AF_INET, SOCK_DGRAM, 0);
    if ( fd < 0) {
        printf("Couldn't create socket for MTU\n");
        return -1;
    }

    strncpy(ifr.ifr_name, name, sizeof(ifr.ifr_name));
    if (ioctl(fd, SIOCGIFMTU, &ifr) == 0)
        retval = ifr.ifr_metric;
    else
        printf("ioctl(SIOCGIFMTU)");    
    close(fd);
        return retval;
}


/*********************************************
* Open an interface OSX BPF's
**********************************************/
int OpenInterfaceOSXBPF(int InterfaceID){
        int                     fd;
        struct                  ifreq ifr;
        u_int                   dlt;
        int                     immediate;
        int                             promisc;
        int                             link;
        struct timeval  timeout;
        InterfaceRec*   Interface;

#ifdef DEBUGPATH
        printf("In OpenInterfaceOSXBPF\n");
#endif

        Interface=&Globals.Interfaces[InterfaceID];

#ifdef DEBUG
        printf("Opening interface %s\n", Interface->Name);
#endif

        fd = bpf_open();

        (void) strncpy(ifr.ifr_name, Interface->Name, sizeof ifr.ifr_name);
        if (ioctl(fd, BIOCSETIF, (caddr_t) & ifr) < 0) {
                err(FATAL, "BIOCSETIF: %s", strerror(errno));
                /* NOTREACHED */
        }
        /* Check that the data link layer is an Ethernet; this code won't work
         * with anything else. */
        if (ioctl(fd, BIOCGDLT, (caddr_t) & dlt) < 0) {
                err(FATAL, "BIOCGDLT: %s", strerror(errno));
                /* NOTREACHED */
        }
        if (dlt != DLT_EN10MB) {
                err(FATAL, "%s is not an ethernet", Interface->Name);
                /* NOTREACHED */
        }
        /*turn off automatic filling of the mac address*/
        link=1;
        if (ioctl(fd, BIOCSHDRCMPLT, &link) < 0){
                printf("Couldn't turn off auto mac address\n");
                exit(0);
        }
        /* Switch the interface into promisc mode*/
        promisc=1;
        if (ioctl(fd, BIOCPROMISC, &promisc) < 0) {
                printf("Couldn't enter promisc mode\n");
                exit(1);
        }
        if (dlt != DLT_EN10MB) {
                err(FATAL, "%s is not an ethernet", Interface->Name);
                /* NOTREACHED */
        }       
        
        /* Set immediate mode so packets are processed as they arrive. */
        immediate = 1;
        if (ioctl(fd, BIOCIMMEDIATE, &immediate) < 0) {
                err(FATAL, "BIOCIMMEDIATE: %s", strerror(errno));
                /* NOTREACHED */
        }

        /* Set immediate mode so packets are processed as they arrive. */
        timeout.tv_sec=0;
        timeout.tv_usec=1;
        if (ioctl(fd, BIOCSRTIMEOUT, &timeout) < 0) {
                err(FATAL, "BIOCSRTIMEOUT: %s", strerror(errno));
                /* NOTREACHED */
        }


        /* Set immediate mode so packets are processed as they arrive. */
        immediate = 0;
        if (ioctl(fd, BIOCIMMEDIATE, &immediate) < 0) {
                err(FATAL, "BIOCIMMEDIATE: %s", strerror(errno));
                /* NOTREACHED */
        }

        Interface->FD=fd;
        Interface->MTU=GetIfrMTU(Interface->Name);
        if (Interface->MTU==-1) Interface->MTU=1500;

        Interface->IsPollable=TRUE;

        return TRUE;
}

/**********************************************
* Read a packet off of the bpf
* TODO: Get rid of the malloc
**********************************************/
int ReadPacketOSXBPF(int InterfaceID){
        int                     bufsize1, cc;
        u_char                  *buf1, *bp, *ep;
        
        InterfaceRec*   interface;
        PacketRec*              p;
        int             PacketSlot;

#ifdef DEBUGPATH
        printf("In ReadPacketOSXBPF\n");
#endif
        
        interface=&Globals.Interfaces[InterfaceID];
        
        /*Get the sizes of the buffers*/
        if (ioctl(interface->FD, BIOCGBLEN, (caddr_t) & bufsize1) < 0) {
                err(FATAL, "BIOCGBLEN: %s", strerror(errno));
                /* NOTREACHED */
        }
#ifdef DEBUG1   
        printf("Buffer size1 is %i\n",bufsize1);
#endif
                 
        buf1 = (u_char *) malloc((unsigned) bufsize1);
        if (buf1 == 0) {
                err(FATAL, "malloc: %s", strerror(errno));
                /* NOTREACHED */
        }
                
        again:
        cc = read(interface->FD, (char *) buf1, bufsize1);
#ifdef DEBUG1                           
        printf("Read %i bytes from the bpf\n",cc);
#endif                                  

        if (cc==0){
                free(buf1);
                return TRUE;
        }

        /* Don't choke when we get ptraced */
        if (cc < 0 && errno == EINTR)
                goto again;
        if (cc < 0) {
                if (errno == EINVAL &&
                (lseek(interface->FD, 0, SEEK_CUR) + bufsize1) < 0) {
                                (void) lseek(interface->FD, 0, 0);
                                goto again;
                }
                err(FATAL, "read: %s", strerror(errno));
                
                /* NOTREACHED */
        }
        
        /* Loop through the packet(s) */
#define bhp ((struct bpf_hdr *)bp)
        bp = buf1;
        ep = bp + cc;
        while (bp < ep) {
                register int caplen, hdrlen;

                caplen = bhp->bh_caplen;
                hdrlen = bhp->bh_hdrlen;
                
#ifdef DEBUG
                printf("This packet is %u bytes\n",bhp->bh_caplen);
#endif  
                /*Get a new packet*/
                PacketSlot=GetEmptyPacket();
                if (PacketSlot==PACKET_NONE) return FALSE;
                p=&Globals.Packets[PacketSlot];
                p->InterfaceNum=InterfaceID;

                /*fill it in*/
                p->PacketLen=bhp->bh_caplen;                                    
                p->tv.tv_sec=bhp->bh_tstamp.tv_sec;
                p->tv.tv_usec=bhp->bh_tstamp.tv_usec;
                memcpy(p->RawPacket, bp+18, p->PacketLen);
                
                /*send it off*/
                if (!AddPacketToPending(PacketSlot)){
                        printf("Coulnd't add packet to pending queue\n");
                        ReturnEmptyPacket(PacketSlot);
                        free(buf1);
                        return FALSE;
                }
                bp += BPF_WORDALIGN(hdrlen + caplen);
        }

        free(buf1);     
        return TRUE;
}

/***************************************************
* Send a packet off to the bpf
****************************************************/
int WritePacketOSXBPF(int InterfaceID, unsigned char* Packet, int PacketLen){
        InterfaceRec*   interface;
        int                     cc;
        
#ifdef DEBUGPATH
        printf("In WritePacketOSXBPF\n");
#endif

        interface=&Globals.Interfaces[InterfaceID];

#ifdef DEBUG
        printf("Writing packet OBX to interface %s\n",interface->Name);
#endif
        
        cc=write(interface->FD, Packet, PacketLen);
        if (cc!=PacketLen){
#ifdef DEBUG
                printf("write_packet: Failed to write packet ot interface %s\n",interface->Name);
#endif
                return FALSE;
        }

        return TRUE;
}

/**********************************************
* The thread func
**********************************************/
void* OSXBPFLoopFunc(void* v){
        int                             InterfaceID;

#ifdef DEBUGPATH
        printf("In OSXBPFLoopFunc\n");
#endif

        InterfaceID=(int)v;
        while (!Globals.Done){
                ReadPacketOSXBPF(InterfaceID);
        }
        
        return NULL;
}

/**********************************************
* Start a thread to continuously read
**********************************************/
int LoopThreadOSXBPF(int InterfaceID){
#ifdef DEBUGPATH
        printf("In loopThreadOSXBPF\n");
#endif

#ifndef HAS_THREADS
        return FALSE;
#else

#ifdef DEBUG
        printf("Starting Thread for interface %s\n",Globals.Interfaces[InterfaceID].Name);
#endif

        Globals.Interfaces[InterfaceID].ThreadID=pthread_create(
                &Globals.Interfaces[InterfaceID].Thread,
                NULL,
                OSXBPFLoopFunc,
                (void*)InterfaceID
        );
        
        return (!Globals.Interfaces[InterfaceID].ThreadID);     
#endif  
}

#endif /*if OSX*/

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