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/*
* Simple FTP transparent proxy for in-kernel.
*/
#define isdigit(x) ((x) >= '0' && (x) <= '9')
#define IPF_FTP_PROXY
#define IPF_MINPORTLEN 18
#define IPF_MAXPORTLEN 30
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;
{
int ch = 0;
u_long sum1, sum2;
if (tcp->th_dport != aps->aps_dport) {
sum2 = (u_long)ntohl(tcp->th_ack);
if (aps->aps_seqoff && (sum2 > aps->aps_after)) {
sum1 = (u_long)aps->aps_seqoff;
tcp->th_ack = htonl(sum2 - sum1);
return 2;
}
}
return 0;
}
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_long sum1, sum2, sumd;
char newbuf[IPF_MAXPORTLEN+1];
char portbuf[IPF_MAXPORTLEN+1], *s, c;
int ch = 0, off = (ip->ip_hl << 2) + (tcp->th_off << 2), len;
u_int a1, a2, a3, a4;
u_short a5, a6;
int olen, dlen, nlen, inc = 0, blen;
tcphdr_t tcph, *tcp2 = &tcph;
void *savep;
nat_t *ipn;
struct in_addr swip;
#if SOLARIS
mblk_t *m1, *m = *(mblk_t **)fin->fin_mp;
dlen = m->b_wptr - m->b_rptr - off;
blen = m->b_datap->db_lim - m->b_datap->db_base;
bzero(portbuf, sizeof(portbuf));
copyout_mblk(m, off, portbuf, MIN(sizeof(portbuf), dlen));
#else
struct mbuf *m1, *m = *(struct mbuf **)fin->fin_mp;
dlen = m->m_len - off;
# if BSD >= 199306
blen = (MLEN - m->m_len) - (m->m_data - m->m_dat);
# else
blen = (MLEN - m->m_len) - m->m_off;
# endif
if (blen < 0)
panic("blen < 0 - size of mblk/mbuf wrong");
bzero(portbuf, sizeof(portbuf));
m_copydata(m, off, MIN(sizeof(portbuf), dlen), portbuf);
#endif
portbuf[IPF_MAXPORTLEN] = '\0';
len = MIN(32, dlen);
if ((len < 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 (tcp->th_seq > aps->aps_after) {
aps->aps_after = ntohl(tcp->th_seq) + dlen;
aps->aps_seqoff += inc;
}
#if SOLARIS
if (inc && dlen)
if ((inc < 0) || (blen >= dlen)) {
bcopy(m->b_rptr + off,
m->b_rptr + off + aps->aps_seqoff, dlen);
}
for (m1 = m; m1->b_cont; m1 = m1->b_cont)
;
m1->b_wptr += inc;
copyin_mblk(m, off, newbuf, strlen(newbuf));
#else
if (inc && dlen)
if ((inc < 0) || (blen >= dlen)) {
bcopy((char *)ip + off,
(char *)ip + off + aps->aps_seqoff, dlen);
}
m->m_len += inc;
m_copyback(m, off, nlen, newbuf);
#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;
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;
ip->ip_src = swip;
fin->fin_dp = (char *)savep;
adjust_seqack:
if (tcp->th_dport == aps->aps_dport) {
sum2 = (u_long)ntohl(tcp->th_seq);
if (aps->aps_seqoff && (sum2 > aps->aps_after)) {
sum1 = (u_long)aps->aps_seqoff;
tcp->th_seq = htonl(sum2 + sum1);
ch = 1;
}
}
return ch ? 2 : 0;
}
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