bsd/netinet/ip_ftp_pxy.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Simple FTP transparent proxy for in-kernel use.  For use with the NAT
  24  * code.
  25  */
  26
  27
  28 #define isdigit(x)      ((x) >= '0' && (x) <= '9')
  29
  30 #define IPF_FTP_PROXY
  31
  32 #define IPF_MINPORTLEN  18
  33 #define IPF_MAXPORTLEN  30
  34
  35
  36 int ippr_ftp_init __P((fr_info_t *, ip_t *, tcphdr_t *,
  37                        ap_session_t *, nat_t *));
  38 int ippr_ftp_in __P((fr_info_t *, ip_t *, tcphdr_t *,
  39                        ap_session_t *, nat_t *));
  40 int ippr_ftp_out __P((fr_info_t *, ip_t *, tcphdr_t *,
  41                        ap_session_t *, nat_t *));
  42 u_short ipf_ftp_atoi __P((char **));
  43
  44
  45 /*
  46  * FTP application proxy initialization.
  47  */
  48 int ippr_ftp_init(fin, ip, tcp, aps, nat)
  49 fr_info_t *fin;
  50 ip_t *ip;
  51 tcphdr_t *tcp;
  52 ap_session_t *aps;
  53 nat_t *nat;
  54 {
  55         aps->aps_sport = tcp->th_sport;
  56         aps->aps_dport = tcp->th_dport;
  57         return 0;
  58 }
  59
  60
  61 int ippr_ftp_in(fin, ip, tcp, aps, nat)
  62 fr_info_t *fin;
  63 ip_t *ip;
  64 tcphdr_t *tcp;
  65 ap_session_t *aps;
  66 nat_t *nat;
  67 {
  68         u_32_t  sum1, sum2;
  69         short sel;
  70
  71         if (tcp->th_sport == aps->aps_dport) {
  72                 sum2 = (u_32_t)ntohl(tcp->th_ack);
  73                 sel = aps->aps_sel;
  74                 if ((aps->aps_after[!sel] > aps->aps_after[sel]) &&
  75                         (sum2 > aps->aps_after[!sel])) {
  76                         sel = aps->aps_sel = !sel; /* switch to other set */
  77                 }
  78                 if (aps->aps_seqoff[sel] && (sum2 > aps->aps_after[sel])) {
  79                         sum1 = (u_32_t)aps->aps_seqoff[sel];
  80                         tcp->th_ack = htonl(sum2 - sum1);
  81                         return 2;
  82                 }
  83         }
  84         return 0;
  85 }
  86
  87
  88 /*
  89  * ipf_ftp_atoi - implement a version of atoi which processes numbers in
  90  * pairs separated by commas (which are expected to be in the range 0 - 255),
  91  * returning a 16 bit number combining either side of the , as the MSB and
  92  * LSB.
  93  */
  94 u_short ipf_ftp_atoi(ptr)
  95 char **ptr;
  96 {
  97         register char *s = *ptr, c;
  98         register u_char i = 0, j = 0;
  99
 100         while ((c = *s++) && isdigit(c)) {
 101                 i *= 10;
 102                 i += c - '0';
 103         }
 104         if (c != ',') {
 105                 *ptr = NULL;
 106                 return 0;
 107         }
 108         while ((c = *s++) && isdigit(c)) {
 109                 j *= 10;
 110                 j += c - '0';
 111         }
 112         *ptr = s;
 113         return (i << 8) | j;
 114 }
 115
 116
 117 int ippr_ftp_out(fin, ip, tcp, aps, nat)
 118 fr_info_t *fin;
 119 ip_t *ip;
 120 tcphdr_t *tcp;
 121 ap_session_t *aps;
 122 nat_t *nat;
 123 {
 124         register u_32_t sum1, sum2;
 125         char    newbuf[IPF_MAXPORTLEN+1];
 126         char    portbuf[IPF_MAXPORTLEN+1], *s;
 127         int     ch = 0, off = (ip->ip_hl << 2) + (tcp->th_off << 2);
 128         u_int   a1, a2, a3, a4;
 129         u_short a5, a6;
 130         int     olen, dlen, nlen = 0, inc = 0;
 131         tcphdr_t tcph, *tcp2 = &tcph;
 132         void    *savep;
 133         nat_t   *ipn;
 134         struct  in_addr swip;
 135         mb_t *m = *(mb_t **)fin->fin_mp;
 136
 137 #if     SOLARIS
 138         mb_t *m1;
 139
 140         /* skip any leading M_PROTOs */
 141         while(m && (MTYPE(m) != M_DATA))
 142                 m = m->b_cont;
 143         PANIC((!m),("ippr_ftp_out: no M_DATA"));
 144
 145         dlen = msgdsize(m) - off;
 146         bzero(portbuf, sizeof(portbuf));
 147         copyout_mblk(m, off, MIN(sizeof(portbuf), dlen), portbuf);
 148 #else
 149         dlen = mbufchainlen(m) - off;
 150         bzero(portbuf, sizeof(portbuf));
 151         m_copydata(m, off, MIN(sizeof(portbuf), dlen), portbuf);
 152 #endif
 153         portbuf[IPF_MAXPORTLEN] = '\0';
 154
 155         if ((dlen < IPF_MINPORTLEN) || strncmp(portbuf, "PORT ", 5))
 156                 goto adjust_seqack;
 157
 158         /*
 159          * Skip the PORT command + space
 160          */
 161         s = portbuf + 5;
 162         /*
 163          * Pick out the address components, two at a time.
 164          */
 165         (void) ipf_ftp_atoi(&s);
 166         if (!s)
 167                 goto adjust_seqack;
 168         (void) ipf_ftp_atoi(&s);
 169         if (!s)
 170                 goto adjust_seqack;
 171         a5 = ipf_ftp_atoi(&s);
 172         if (!s)
 173                 goto adjust_seqack;
 174         /*
 175          * check for CR-LF at the end.
 176          */
 177         if (*s != '\n' || *(s - 1) != '\r')
 178                 goto adjust_seqack;
 179         a6 = a5 & 0xff;
 180         a5 >>= 8;
 181         /*
 182          * Calculate new address parts for PORT command
 183          */
 184         a1 = ntohl(ip->ip_src.s_addr);
 185         a2 = (a1 >> 16) & 0xff;
 186         a3 = (a1 >> 8) & 0xff;
 187         a4 = a1 & 0xff;
 188         a1 >>= 24;
 189         olen = s - portbuf + 1;
 190         (void) snprintf(newbuf, sizeof(newbuf), "PORT %d,%d,%d,%d,%d,%d\r\n",
 191                 a1, a2, a3, a4, a5, a6);
 192         nlen = strlen(newbuf);
 193         inc = nlen - olen;
 194 #if SOLARIS
 195         for (m1 = m; m1->b_cont; m1 = m1->b_cont)
 196                 ;
 197         if (inc > 0) {
 198                 mblk_t *nm;
 199
 200                 /* alloc enough to keep same trailer space for lower driver */
 201                 nm = allocb(nlen + m1->b_datap->db_lim - m1->b_wptr, BPRI_MED);
 202                 PANIC((!nm),("ippr_ftp_out: allocb failed"));
 203
 204                 nm->b_band = m1->b_band;
 205                 nm->b_wptr += nlen;
 206
 207                 m1->b_wptr -= olen;
 208                 PANIC((m1->b_wptr < m1->b_rptr),("ippr_ftp_out: cannot handle fragmented data block"));
 209
 210                 linkb(m1, nm);
 211         } else {
 212                 m1->b_wptr += inc;
 213         }
 214         copyin_mblk(m, off, nlen, newbuf);
 215 #else
 216         if (inc < 0)
 217                 m_adj(m, inc);
 218         /* the mbuf chain will be extended if necessary by m_copyback() */
 219         m_copyback(m, off, nlen, newbuf);
 220 #endif
 221         if (inc) {
 222 #if SOLARIS || defined(__sgi)
 223                 sum1 = ip->ip_len;
 224                 sum2 = ip->ip_len + inc;
 225
 226                 /* Because ~1 == -2, We really need ~1 == -1 */
 227                 if (sum1 > sum2)
 228                         sum2--;
 229                 sum2 -= sum1;
 230                 sum2 = (sum2 & 0xffff) + (sum2 >> 16);
 231
 232                 fix_outcksum(&ip->ip_sum, sum2);
 233 #endif
 234                 ip->ip_len += inc;
 235         }
 236         ch = 1;
 237
 238         /*
 239          * Add skeleton NAT entry for connection which will come back the
 240          * other way.
 241          */
 242         savep = fin->fin_dp;
 243         fin->fin_dp = (char *)tcp2;
 244         bzero((char *)tcp2, sizeof(*tcp2));
 245         tcp2->th_sport = htons(a5 << 8 | a6);
 246         tcp2->th_dport = htons(20);
 247         swip = ip->ip_src;
 248         ip->ip_src = nat->nat_inip;
 249         if ((ipn = nat_new(nat->nat_ptr, ip, fin, IPN_TCP, NAT_OUTBOUND)))
 250                 ipn->nat_age = fr_defnatage;
 251         (void) fr_addstate(ip, fin, FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE);
 252         ip->ip_src = swip;
 253         fin->fin_dp = (char *)savep;
 254
 255 adjust_seqack:
 256         if (tcp->th_dport == aps->aps_dport) {
 257                 sum2 = (u_32_t)ntohl(tcp->th_seq);
 258                 off = aps->aps_sel;
 259                 if ((aps->aps_after[!off] > aps->aps_after[off]) &&
 260                         (sum2 > aps->aps_after[!off])) {
 261                         off = aps->aps_sel = !off; /* switch to other set */
 262                 }
 263                 if (aps->aps_seqoff[off]) {
 264                         sum1 = (u_32_t)aps->aps_after[off] -
 265                                aps->aps_seqoff[off];
 266                         if (sum2 > sum1) {
 267                                 sum1 = (u_32_t)aps->aps_seqoff[off];
 268                                 sum2 += sum1;
 269                                 tcp->th_seq = htonl(sum2);
 270                                 ch = 1;
 271                         }
 272                 }
 273
 274                 if (inc && (sum2 > aps->aps_after[!off])) {
 275                         aps->aps_after[!off] = sum2 + nlen - 1;
 276                         aps->aps_seqoff[!off] = aps->aps_seqoff[off] + inc;
 277                 }
 278         }
 279         return ch ? 2 : 0;
 280 }