269 lines
5.9 KiB
C
269 lines
5.9 KiB
C
/* $NetBSD: ip_ftp_pxy.c,v 1.9 1998/07/12 15:27:46 veego Exp $ */
|
|
|
|
/*
|
|
* Simple FTP transparent proxy for in-kernel use. For use with the NAT
|
|
* code.
|
|
*/
|
|
|
|
#define isdigit(x) ((x) >= '0' && (x) <= '9')
|
|
|
|
#define IPF_FTP_PROXY
|
|
|
|
#define IPF_MINPORTLEN 18
|
|
#define IPF_MAXPORTLEN 30
|
|
|
|
|
|
int ippr_ftp_init __P((fr_info_t *, ip_t *, tcphdr_t *,
|
|
ap_session_t *, nat_t *));
|
|
int ippr_ftp_in __P((fr_info_t *, ip_t *, tcphdr_t *,
|
|
ap_session_t *, nat_t *));
|
|
int ippr_ftp_out __P((fr_info_t *, ip_t *, tcphdr_t *,
|
|
ap_session_t *, nat_t *));
|
|
u_short ipf_ftp_atoi __P((char **));
|
|
|
|
|
|
int ippr_ftp_init __P((fr_info_t *, ip_t *, tcphdr_t *, ap_session_t *,
|
|
nat_t *));
|
|
int ippr_ftp_in __P((fr_info_t *, ip_t *, tcphdr_t *, ap_session_t *,
|
|
nat_t *));
|
|
int ippr_ftp_out __P((fr_info_t *, ip_t *, tcphdr_t *, ap_session_t *,
|
|
nat_t *));
|
|
|
|
u_short ipf_ftp_atoi __P((char **));
|
|
|
|
|
|
|
|
/*
|
|
* FTP application proxy initialization.
|
|
*/
|
|
int ippr_ftp_init(fin, ip, tcp, aps, nat)
|
|
fr_info_t *fin;
|
|
ip_t *ip;
|
|
tcphdr_t *tcp;
|
|
ap_session_t *aps;
|
|
nat_t *nat;
|
|
{
|
|
aps->aps_sport = tcp->th_sport;
|
|
aps->aps_dport = tcp->th_dport;
|
|
return 0;
|
|
}
|
|
|
|
|
|
int ippr_ftp_in(fin, ip, tcp, aps, nat)
|
|
fr_info_t *fin;
|
|
ip_t *ip;
|
|
tcphdr_t *tcp;
|
|
ap_session_t *aps;
|
|
nat_t *nat;
|
|
{
|
|
u_32_t sum1, sum2;
|
|
short sel;
|
|
|
|
if (tcp->th_sport == aps->aps_dport) {
|
|
sum2 = (u_32_t)ntohl(tcp->th_ack);
|
|
sel = aps->aps_sel;
|
|
if ((aps->aps_after[!sel] > aps->aps_after[sel]) &&
|
|
(sum2 > aps->aps_after[!sel])) {
|
|
sel = aps->aps_sel = !sel; /* switch to other set */
|
|
}
|
|
if (aps->aps_seqoff[sel] && (sum2 > aps->aps_after[sel])) {
|
|
sum1 = (u_32_t)aps->aps_seqoff[sel];
|
|
tcp->th_ack = htonl(sum2 - sum1);
|
|
return 2;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*
|
|
* ipf_ftp_atoi - implement a version of atoi which processes numbers in
|
|
* pairs separated by commas (which are expected to be in the range 0 - 255),
|
|
* returning a 16 bit number combining either side of the , as the MSB and
|
|
* LSB.
|
|
*/
|
|
u_short ipf_ftp_atoi(ptr)
|
|
char **ptr;
|
|
{
|
|
register char *s = *ptr, c;
|
|
register u_char i = 0, j = 0;
|
|
|
|
while ((c = *s++) && isdigit(c)) {
|
|
i *= 10;
|
|
i += c - '0';
|
|
}
|
|
if (c != ',') {
|
|
*ptr = NULL;
|
|
return 0;
|
|
}
|
|
while ((c = *s++) && isdigit(c)) {
|
|
j *= 10;
|
|
j += c - '0';
|
|
}
|
|
*ptr = s;
|
|
return (i << 8) | j;
|
|
}
|
|
|
|
|
|
int ippr_ftp_out(fin, ip, tcp, aps, nat)
|
|
fr_info_t *fin;
|
|
ip_t *ip;
|
|
tcphdr_t *tcp;
|
|
ap_session_t *aps;
|
|
nat_t *nat;
|
|
{
|
|
register u_32_t sum1, sum2;
|
|
char newbuf[IPF_MAXPORTLEN+1];
|
|
char portbuf[IPF_MAXPORTLEN+1], *s;
|
|
int ch = 0, off = (ip->ip_hl << 2) + (tcp->th_off << 2);
|
|
u_int a1, a2, a3, a4;
|
|
u_short a5, a6;
|
|
int olen, dlen, nlen = 0, inc = 0;
|
|
tcphdr_t tcph, *tcp2 = &tcph;
|
|
void *savep;
|
|
nat_t *ipn;
|
|
struct in_addr swip;
|
|
mb_t *m = *(mb_t **)fin->fin_mp;
|
|
|
|
#if SOLARIS
|
|
mb_t *m1;
|
|
|
|
m = fin->fin_qfm;
|
|
|
|
dlen = msgdsize(m) - off;
|
|
bzero(portbuf, sizeof(portbuf));
|
|
copyout_mblk(m, off, MIN(sizeof(portbuf), dlen), portbuf);
|
|
#else
|
|
dlen = mbufchainlen(m) - off;
|
|
bzero(portbuf, sizeof(portbuf));
|
|
m_copydata(m, off, MIN(sizeof(portbuf), dlen), portbuf);
|
|
#endif
|
|
portbuf[IPF_MAXPORTLEN] = '\0';
|
|
|
|
if ((dlen < IPF_MINPORTLEN) || strncmp(portbuf, "PORT ", 5))
|
|
goto adjust_seqack;
|
|
|
|
/*
|
|
* Skip the PORT command + space
|
|
*/
|
|
s = portbuf + 5;
|
|
/*
|
|
* Pick out the address components, two at a time.
|
|
*/
|
|
(void) ipf_ftp_atoi(&s);
|
|
if (!s)
|
|
goto adjust_seqack;
|
|
(void) ipf_ftp_atoi(&s);
|
|
if (!s)
|
|
goto adjust_seqack;
|
|
a5 = ipf_ftp_atoi(&s);
|
|
if (!s)
|
|
goto adjust_seqack;
|
|
/*
|
|
* check for CR-LF at the end.
|
|
*/
|
|
if (*s != '\n' || *(s - 1) != '\r')
|
|
goto adjust_seqack;
|
|
a6 = a5 & 0xff;
|
|
a5 >>= 8;
|
|
/*
|
|
* Calculate new address parts for PORT command
|
|
*/
|
|
a1 = ntohl(ip->ip_src.s_addr);
|
|
a2 = (a1 >> 16) & 0xff;
|
|
a3 = (a1 >> 8) & 0xff;
|
|
a4 = a1 & 0xff;
|
|
a1 >>= 24;
|
|
olen = s - portbuf + 1;
|
|
(void) sprintf(newbuf, "PORT %d,%d,%d,%d,%d,%d\r\n",
|
|
a1, a2, a3, a4, a5, a6);
|
|
nlen = strlen(newbuf);
|
|
inc = nlen - olen;
|
|
#if SOLARIS
|
|
for (m1 = m; m1->b_cont; m1 = m1->b_cont)
|
|
;
|
|
if (inc > 0) {
|
|
mblk_t *nm;
|
|
|
|
/* alloc enough to keep same trailer space for lower driver */
|
|
nm = allocb(nlen + m1->b_datap->db_lim - m1->b_wptr, BPRI_MED);
|
|
PANIC((!nm),("ippr_ftp_out: allocb failed"));
|
|
|
|
nm->b_band = m1->b_band;
|
|
nm->b_wptr += nlen;
|
|
|
|
m1->b_wptr -= olen;
|
|
PANIC((m1->b_wptr < m1->b_rptr),("ippr_ftp_out: cannot handle fragmented data block"));
|
|
|
|
linkb(m1, nm);
|
|
} else {
|
|
m1->b_wptr += inc;
|
|
}
|
|
copyin_mblk(m, off, nlen, newbuf);
|
|
#else
|
|
if (inc < 0)
|
|
m_adj(m, inc);
|
|
/* the mbuf chain will be extended if necessary by m_copyback() */
|
|
m_copyback(m, off, nlen, newbuf);
|
|
#endif
|
|
if (inc) {
|
|
#if SOLARIS || defined(__sgi)
|
|
sum1 = ip->ip_len;
|
|
sum2 = ip->ip_len + inc;
|
|
|
|
/* Because ~1 == -2, We really need ~1 == -1 */
|
|
if (sum1 > sum2)
|
|
sum2--;
|
|
sum2 -= sum1;
|
|
sum2 = (sum2 & 0xffff) + (sum2 >> 16);
|
|
|
|
fix_outcksum(&ip->ip_sum, sum2);
|
|
#endif
|
|
ip->ip_len += inc;
|
|
}
|
|
ch = 1;
|
|
|
|
/*
|
|
* Add skeleton NAT entry for connection which will come back the
|
|
* other way.
|
|
*/
|
|
savep = fin->fin_dp;
|
|
fin->fin_dp = (char *)tcp2;
|
|
bzero((char *)tcp2, sizeof(*tcp2));
|
|
tcp2->th_sport = htons(a5 << 8 | a6);
|
|
tcp2->th_dport = htons(20);
|
|
swip = ip->ip_src;
|
|
ip->ip_src = nat->nat_inip;
|
|
if ((ipn = nat_new(nat->nat_ptr, ip, fin, IPN_TCP, NAT_OUTBOUND)))
|
|
ipn->nat_age = fr_defnatage;
|
|
(void) fr_addstate(ip, fin, FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE);
|
|
ip->ip_src = swip;
|
|
fin->fin_dp = (char *)savep;
|
|
|
|
adjust_seqack:
|
|
if (tcp->th_dport == aps->aps_dport) {
|
|
sum2 = (u_32_t)ntohl(tcp->th_seq);
|
|
off = aps->aps_sel;
|
|
if ((aps->aps_after[!off] > aps->aps_after[off]) &&
|
|
(sum2 > aps->aps_after[!off])) {
|
|
off = aps->aps_sel = !off; /* switch to other set */
|
|
}
|
|
if (aps->aps_seqoff[off]) {
|
|
sum1 = (u_32_t)aps->aps_after[off] -
|
|
aps->aps_seqoff[off];
|
|
if (sum2 > sum1) {
|
|
sum1 = (u_32_t)aps->aps_seqoff[off];
|
|
sum2 += sum1;
|
|
tcp->th_seq = htonl(sum2);
|
|
ch = 1;
|
|
}
|
|
}
|
|
|
|
if (inc && (sum2 > aps->aps_after[!off])) {
|
|
aps->aps_after[!off] = sum2 + nlen - 1;
|
|
aps->aps_seqoff[!off] = aps->aps_seqoff[off] + inc;
|
|
}
|
|
}
|
|
return ch ? 2 : 0;
|
|
}
|