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1.1 root 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: }
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