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/*
* Copyright (C) 2010 by Darren Reed.
*
* See the IPFILTER.LICENCE file for details on licencing.
*
* $Id$
*/
#define IPF_TFTP_PROXY
void ipf_p_tftp_main_load __P((void));
void ipf_p_tftp_main_unload __P((void));
int ipf_p_tftp_new __P((void *, fr_info_t *, ap_session_t *, nat_t *));
int ipf_p_tftp_out __P((void *, fr_info_t *, ap_session_t *, nat_t *));
int ipf_p_tftp_in __P((void *, fr_info_t *, ap_session_t *, nat_t *));
int ipf_p_tftp_client __P((fr_info_t *, ap_session_t *, nat_t *));
int ipf_p_tftp_server __P((fr_info_t *, ap_session_t *, nat_t *));
int ipf_p_tftp_backchannel __P((fr_info_t *, ap_session_t *, nat_t *));
static frentry_t tftpfr;
int tftp_proxy_init = 0;
typedef struct tftpinfo {
nat_t *ti_datanat;
ipstate_t *ti_datastate;
int ti_lastcmd;
int ti_nextblk;
int ti_lastblk;
int ti_lasterror;
char ti_filename[80];
} tftpinfo_t;
#define TFTP_CMD_READ 1
#define TFTP_CMD_WRITE 2
#define TFTP_CMD_DATA 3
#define TFTP_CMD_ACK 4
#define TFTP_CMD_ERROR 5
/*
* TFTP application proxy initialization.
*/
void
ipf_p_tftp_main_load()
{
bzero((char *)&tftpfr, sizeof(tftpfr));
tftpfr.fr_ref = 1;
tftpfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
MUTEX_INIT(&tftpfr.fr_lock, "TFTP proxy rule lock");
tftp_proxy_init = 1;
}
void
ipf_p_tftp_main_unload()
{
if (tftp_proxy_init == 1) {
MUTEX_DESTROY(&tftpfr.fr_lock);
tftp_proxy_init = 0;
}
}
int
ipf_p_tftp_out(arg, fin, aps, nat)
void *arg;
fr_info_t *fin;
ap_session_t *aps;
nat_t *nat;
{
if (nat->nat_dir == NAT_OUTBOUND)
return ipf_p_tftp_client(fin, aps, nat);
return ipf_p_tftp_server(fin, aps, nat);
}
int
ipf_p_tftp_in(arg, fin, aps, nat)
void *arg;
fr_info_t *fin;
ap_session_t *aps;
nat_t *nat;
{
if (nat->nat_dir == NAT_INBOUND)
return ipf_p_tftp_client(fin, aps, nat);
return ipf_p_tftp_server(fin, aps, nat);
}
int
ipf_p_tftp_new(arg, fin, aps, nat)
void *arg;
fr_info_t *fin;
ap_session_t *aps;
nat_t *nat;
{
udphdr_t *udp;
tftpinfo_t *ti;
KMALLOC(ti, tftpinfo_t *);
if (ti == NULL)
return -1;
aps->aps_data = ti;
aps->aps_psiz = sizeof(*ti);
ti->ti_lastcmd = 0;
nat = nat; /* LINT */
fin = fin; /* LINT */
udp = (udphdr_t *)fin->fin_dp;
aps->aps_sport = udp->uh_sport;
aps->aps_dport = udp->uh_dport;
return 0;
}
/*
* Setup for a new TFTP proxy.
*/
int
ipf_p_tftp_backchannel(fin, aps, nat)
fr_info_t *fin;
ap_session_t *aps;
nat_t *nat;
{
ipf_main_softc_t *softc = fin->fin_main_soft;
#ifdef USE_MUTEXES
ipf_nat_softc_t *softn = softc->ipf_nat_soft;
#endif
struct in_addr swip,swip2;
tftpinfo_t *ti;
udphdr_t *udp;
fr_info_t fi;
nat_t *nat2;
ti = aps->aps_data;
udp = (udphdr_t *)fin->fin_dp;
/*
* Add skeleton NAT entry for connection which will come back the
* other way.
*/
bcopy((char *)fin, (char *)&fi, sizeof(fi));
fi.fin_flx |= FI_IGNORE;
fi.fin_data[1] = 0;
if (nat->nat_dir == NAT_OUTBOUND)
nat2 = ipf_nat_outlookup(&fi, NAT_SEARCH|IPN_UDP,
nat->nat_pr[0], nat->nat_osrcip,
nat->nat_odstip);
else
nat2 = ipf_nat_inlookup(&fi, NAT_SEARCH|IPN_UDP,
nat->nat_pr[0], nat->nat_nsrcip,
nat->nat_odstip);
if (nat2 == NULL) {
u_short slen;
int nflags;
ip_t *ip;
ip = fin->fin_ip;
slen = ip->ip_len;
ip->ip_len = htons(fin->fin_hlen + sizeof(*udp));
bzero((char *)udp, sizeof(*udp));
udp->uh_sport = htons(fi.fin_data[0]);
udp->uh_dport = 0; /* XXX - don't specify remote port */
udp->uh_ulen = 0;
udp->uh_sum = 0;
fi.fin_dp = (char *)udp;
fi.fin_fr = &tftpfr;
fi.fin_dlen = sizeof(*udp);
fi.fin_plen = fi.fin_hlen + sizeof(*udp);
fi.fin_flx &= FI_LOWTTL|FI_FRAG|FI_TCPUDP|FI_OPTIONS|FI_IGNORE;
nflags = NAT_SLAVE|IPN_UDP|SI_W_DPORT;
swip = ip->ip_src;
swip2 = ip->ip_dst;
fi.fin_fi.fi_saddr = nat->nat_osrcaddr;
ip->ip_src = nat->nat_osrcip;
fi.fin_fi.fi_daddr = nat->nat_odstaddr;
ip->ip_dst = nat->nat_odstip;
if (nat->nat_dir == NAT_INBOUND)
nflags |= NAT_NOTRULEPORT;
MUTEX_ENTER(&softn->ipf_nat_new);
nat2 = ipf_nat_add(&fi, nat->nat_ptr, &ti->ti_datanat,
nflags, nat->nat_dir);
MUTEX_EXIT(&softn->ipf_nat_new);
if (nat2 != NULL) {
(void) ipf_nat_proto(&fi, nat2, IPN_UDP);
ipf_nat_update(&fi, nat2);
fi.fin_ifp = NULL;
if (ipf_state_add(softc, &fi, &ti->ti_datastate,
SI_W_DPORT) != 0) {
ipf_nat_setpending(softc, nat2);
}
}
ip->ip_len = slen;
ip->ip_src = swip;
ip->ip_dst = swip2;
return 0;
}
return -1;
}
int
ipf_p_tftp_client(fin, aps, nat)
fr_info_t *fin;
ap_session_t *aps;
nat_t *nat;
{
u_char *msg, *s, *t;
tftpinfo_t *ti;
u_short opcode;
udphdr_t *udp;
int len;
if (fin->fin_dlen < 4)
return 0;
ti = aps->aps_data;
msg = fin->fin_dp;
msg += sizeof(udphdr_t);
opcode = (msg[0] << 8) | msg[1];
switch (opcode)
{
case TFTP_CMD_READ :
case TFTP_CMD_WRITE :
if (fin->fin_out != 0)
return -1;
len = fin->fin_dlen - sizeof(*udp) - 2;
if (len > sizeof(ti->ti_filename) - 1)
len = sizeof(ti->ti_filename) - 1;
s = msg + 2;
for (t = (u_char *)ti->ti_filename; (len > 0); len--, s++) {
*t++ = *s;
if (*s == '\0')
break;
}
break;
default :
return -1;
}
ti = aps->aps_data;
ti->ti_lastcmd = opcode;
return 0;
}
int
ipf_p_tftp_server(fin, aps, nat)
fr_info_t *fin;
ap_session_t *aps;
nat_t *nat;
{
tftpinfo_t *ti;
u_short opcode;
u_short arg;
u_char *msg;
if (fin->fin_dlen < 4)
return 0;
ti = aps->aps_data;
msg = fin->fin_dp;
msg += sizeof(udphdr_t);
arg = (msg[2] << 8) | msg[3];
opcode = (msg[0] << 8) | msg[1];
switch (opcode)
{
case TFTP_CMD_ACK :
/* This proxy should not see any ACKS for DATA blocks */
if (fin->fin_out != 1)
return -1;
if ((arg == 0) &&
(ti->ti_lastcmd == TFTP_CMD_READ ||
ti->ti_lastcmd == TFTP_CMD_WRITE))
ipf_p_tftp_backchannel(fin, aps, nat);
ti->ti_lastblk = arg;
break;
case TFTP_CMD_ERROR :
if (fin->fin_out != 1)
return -1;
ti->ti_lasterror = arg;
break;
default :
return -1;
}
ti->ti_lastcmd = opcode;
return 0;
}