ipv4.cpp@ 17082

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1	/* $Id: ipv4.cpp 12821 2008-09-30 07:30:01Z vboxsync $ */
2	/** @file
3	* IPRT - IPv4 Checksum calculation and validation.
4	*/
5
6	/*
7	* Copyright (C) 2008 Sun Microsystems, Inc.
8	*
9	* This file is part of VirtualBox Open Source Edition (OSE), as
10	* available from http://www.virtualbox.org. This file is free software;
11	* you can redistribute it and/or modify it under the terms of the GNU
12	* General Public License (GPL) as published by the Free Software
13	* Foundation, in version 2 as it comes in the "COPYING" file of the
14	* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15	* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16	*
17	* The contents of this file may alternatively be used under the terms
18	* of the Common Development and Distribution License Version 1.0
19	* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
20	* VirtualBox OSE distribution, in which case the provisions of the
21	* CDDL are applicable instead of those of the GPL.
22	*
23	* You may elect to license modified versions of this file under the
24	* terms and conditions of either the GPL or the CDDL or both.
25	*
26	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
27	* Clara, CA 95054 USA or visit http://www.sun.com if you need
28	* additional information or have any questions.
29	*/
30
31	/*******************************************************************************
32	* Header Files *
33	*******************************************************************************/
34	#include <iprt/net.h>
35	#include <iprt/asm.h>
36	#include <iprt/assert.h>
37
38
39	/**
40	* Calculates the checksum of the IPv4 header.
41	*
42	* @returns Checksum (network endian).
43	* @param pIpHdr Pointer to the IPv4 header to checksum, network endian (big).
44	* Assumes the caller already checked the minimum size requirement.
45	*/
46	RTDECL(uint16_t) RTNetIPv4HdrChecksum(PCRTNETIPV4 pIpHdr)
47	{
48	uint16_t const paw = (uint16_t const )pIpHdr;
49	uint32_t u32Sum = paw[0] /* ip_hl */
50	+ paw[1] /* ip_len */
51	+ paw[2] /* ip_id */
52	+ paw[3] /* ip_off */
53	+ paw[4] /* ip_ttl */
54	/+ paw[5] == 0 / /* ip_sum */
55	+ paw[6] /* ip_src */
56	+ paw[7] /* ip_src:16 */
57	+ paw[8] /* ip_dst */
58	+ paw[9]; /* ip_dst:16 */
59	/* any options */
60	if (pIpHdr->ip_hl > 20 / 4)
61	{
62	/* this is a bit insane... (identical to the TCP header) */
63	switch (pIpHdr->ip_hl)
64	{
65	case 6: u32Sum += paw[10] + paw[11]; break;
66	case 7: u32Sum += paw[10] + paw[11] + paw[12] + paw[13]; break;
67	case 8: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15]; break;
68	case 9: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17]; break;
69	case 10: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19]; break;
70	case 11: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19] + paw[20] + paw[21]; break;
71	case 12: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19] + paw[20] + paw[21] + paw[22] + paw[23]; break;
72	case 13: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19] + paw[20] + paw[21] + paw[22] + paw[23] + paw[24] + paw[25]; break;
73	case 14: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19] + paw[20] + paw[21] + paw[22] + paw[23] + paw[24] + paw[25] + paw[26] + paw[27]; break;
74	case 15: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19] + paw[20] + paw[21] + paw[22] + paw[23] + paw[24] + paw[25] + paw[26] + paw[27] + paw[28] + paw[29]; break;
75	default:
76	AssertFailed();
77	}
78	}
79
80	/* 16-bit one complement fun */
81	u32Sum = (u32Sum >> 16) + (u32Sum & 0xffff); /* hi + low words */
82	u32Sum += u32Sum >> 16; /* carry */
83	return (uint16_t)~u32Sum;
84	}
85
86
87	/**
88	* Verifies the header version, header size, packet size, and header checksum
89	* of the specified IPv4 header.
90	*
91	* @returns true if valid, false if invalid.
92	* @param pIpHdr Pointer to the IPv4 header to validate. Network endian (big).
93	* @param cbHdrMax The max header size, or the max size of what pIpHdr points
94	* to if you like. Note that an IPv4 header can be up to 60 bytes.
95	* @param cbPktMax The max IP packet size, IP header and payload. This doesn't have
96	* to be mapped following pIpHdr.
97	*/
98	RTDECL(bool) RTNetIPv4IsHdrValid(PCRTNETIPV4 pIpHdr, size_t cbHdrMax, size_t cbPktMax)
99	{
100	/*
101	* The header fields.
102	*/
103	Assert(cbPktMax >= cbHdrMax);
104	if (RT_UNLIKELY(cbHdrMax < RTNETIPV4_MIN_LEN))
105	return false;
106	if (RT_UNLIKELY(pIpHdr->ip_hl * 4 < RTNETIPV4_MIN_LEN))
107	return false;
108	if (RT_UNLIKELY((size_t)pIpHdr->ip_hl * 4 > cbHdrMax))
109	{
110	Assert((size_t)pIpHdr->ip_hl * 4 > cbPktMax); /* You'll hit this if you mapped/copy too little of the header! */
111	return false;
112	}
113	if (RT_UNLIKELY(pIpHdr->ip_v != 4))
114	return false;
115	if (RT_UNLIKELY(RT_BE2H_U16(pIpHdr->ip_len) > cbPktMax))
116	return false;
117
118	/*
119	* The header checksum.
120	*/
121	uint16_t u16Sum = RTNetIPv4HdrChecksum(pIpHdr);
122	if (RT_UNLIKELY(pIpHdr->ip_sum != u16Sum))
123	return false;
124	return true;
125	}
126
127
128	/**
129	* Calculates the checksum of a pseudo header given an IPv4 header [inlined].
130	*
131	* @returns 32-bit intermediary checksum value.
132	* @param pIpHdr The IP header (network endian (big)).
133	*/
134	DECLINLINE(uint32_t) rtNetIPv4PseudoChecksum(PCRTNETIPV4 pIpHdr)
135	{
136	uint16_t cbPayload = RT_BE2H_U16(pIpHdr->ip_len) - pIpHdr->ip_hl * 4;
137	uint32_t u32Sum = pIpHdr->ip_src.au16[0]
138	+ pIpHdr->ip_src.au16[1]
139	+ pIpHdr->ip_dst.au16[0]
140	+ pIpHdr->ip_dst.au16[1]
141	#ifdef RT_BIG_ENDIAN
142	+ pIpHdr->ip_p
143	#else
144	+ ((uint32_t)pIpHdr->ip_p << 8)
145	#endif
146	+ RT_H2BE_U16(cbPayload);
147	return u32Sum;
148	}
149
150
151	/**
152	* Calculates the checksum of a pseudo header given an IPv4 header.
153	*
154	* @returns 32-bit intermediary checksum value.
155	* @param pIpHdr The IP header (network endian (big)).
156	*/
157	RTDECL(uint32_t) RTNetIPv4PseudoChecksum(PCRTNETIPV4 pIpHdr)
158	{
159	return rtNetIPv4PseudoChecksum(pIpHdr);
160	}
161
162
163	/**
164	* Calculates the checksum of a pseudo header given the individual components.
165	*
166	* @returns 32-bit intermediary checksum value.
167	* @param SrcAddr The source address in host endian.
168	* @param DstAddr The destination address in host endian.
169	* @param bProtocol The protocol number.
170	* @param cbPkt The packet size (host endian of course) (no IPv4 header).
171	*/
172	RTDECL(uint32_t) RTNetIPv4PseudoChecksumBits(RTNETADDRIPV4 SrcAddr, RTNETADDRIPV4 DstAddr, uint8_t bProtocol, uint16_t cbPkt)
173	{
174	uint32_t u32Sum = RT_H2BE_U16(SrcAddr.au16[0])
175	+ RT_H2BE_U16(SrcAddr.au16[1])
176	+ RT_H2BE_U16(DstAddr.au16[0])
177	+ RT_H2BE_U16(DstAddr.au16[1])
178	#ifdef RT_BIG_ENDIAN
179	+ bProtocol
180	#else
181	+ ((uint32_t)bProtocol << 8)
182	#endif
183	+ RT_H2BE_U16(cbPkt);
184	return u32Sum;
185	}
186
187
188	/**
189	* Adds the checksum of the UDP header to the intermediate checksum value [inlined].
190	*
191	* @returns 32-bit intermediary checksum value.
192	* @param pUdpHdr Pointer to the UDP header to checksum, network endian (big).
193	* @param u32Sum The 32-bit intermediate checksum value.
194	*/
195	DECLINLINE(uint32_t) rtNetIPv4AddUDPChecksum(PCRTNETUDP pUdpHdr, uint32_t u32Sum)
196	{
197	u32Sum += pUdpHdr->uh_sport
198	+ pUdpHdr->uh_dport
199	/+ pUdpHdr->uh_sum = 0 /
200	+ pUdpHdr->uh_ulen;
201	return u32Sum;
202	}
203
204
205	/**
206	* Adds the checksum of the UDP header to the intermediate checksum value.
207	*
208	* @returns 32-bit intermediary checksum value.
209	* @param pUdpHdr Pointer to the UDP header to checksum, network endian (big).
210	* @param u32Sum The 32-bit intermediate checksum value.
211	*/
212	RTDECL(uint32_t) RTNetIPv4AddUDPChecksum(PCRTNETUDP pUdpHdr, uint32_t u32Sum)
213	{
214	return rtNetIPv4AddUDPChecksum(pUdpHdr, u32Sum);
215	}
216
217
218	/**
219	* Adds the checksum of the TCP header to the intermediate checksum value [inlined].
220	*
221	* @returns 32-bit intermediary checksum value.
222	* @param pUdpHdr Pointer to the TCP header to checksum, network endian (big).
223	* Assums the caller has already validate it and made sure the
224	* entire header is present.
225	* @param u32Sum The 32-bit intermediate checksum value.
226	*/
227	DECLINLINE(uint32_t) rtNetIPv4AddTCPChecksum(PCRTNETTCP pTcpHdr, uint32_t u32Sum)
228	{
229	uint16_t const paw = (uint16_t const )pTcpHdr;
230	u32Sum += paw[0] /* th_sport */
231	+ paw[1] /* th_dport */
232	+ paw[2] /* th_seq */
233	+ paw[3] /* th_seq:16 */
234	+ paw[4] /* th_ack */
235	+ paw[5] /* th_ack:16 */
236	+ paw[6] /* th_off, th_x2, th_flags */
237	+ paw[7] /* th_win */
238	/+ paw[8] == 0 / /* th_sum */
239	+ paw[9]; /* th_urp */
240	if (pTcpHdr->th_off > RTNETTCP_MIN_LEN / 4)
241	{
242	/* this is a bit insane... (identical to the IPv4 header) */
243	switch (pTcpHdr->th_off)
244	{
245	case 6: u32Sum += paw[10] + paw[11]; break;
246	case 7: u32Sum += paw[10] + paw[11] + paw[12] + paw[13]; break;
247	case 8: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15]; break;
248	case 9: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17]; break;
249	case 10: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19]; break;
250	case 11: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19] + paw[20] + paw[21]; break;
251	case 12: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19] + paw[20] + paw[21] + paw[22] + paw[23]; break;
252	case 13: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19] + paw[20] + paw[21] + paw[22] + paw[23] + paw[24] + paw[25]; break;
253	case 14: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19] + paw[20] + paw[21] + paw[22] + paw[23] + paw[24] + paw[25] + paw[26] + paw[27]; break;
254	case 15: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19] + paw[20] + paw[21] + paw[22] + paw[23] + paw[24] + paw[25] + paw[26] + paw[27] + paw[28] + paw[29]; break;
255	default:
256	AssertFailed();
257	}
258	}
259
260	return u32Sum;
261	}
262
263
264	/**
265	* Adds the checksum of the TCP header to the intermediate checksum value.
266	*
267	* @returns 32-bit intermediary checksum value.
268	* @param pUdpHdr Pointer to the TCP header to checksum, network endian (big).
269	* Assums the caller has already validate it and made sure the
270	* entire header is present.
271	* @param u32Sum The 32-bit intermediate checksum value.
272	*/
273	RTDECL(uint32_t) RTNetIPv4AddTCPChecksum(PCRTNETTCP pTcpHdr, uint32_t u32Sum)
274	{
275	return rtNetIPv4AddTCPChecksum(pTcpHdr, u32Sum);
276	}
277
278
279	/**
280	* Adds the checksum of the specified data segment to the intermediate checksum value [inlined].
281	*
282	* @returns 32-bit intermediary checksum value.
283	* @param pUdpHdr Pointer to the UDP header to checksum, network endian (big).
284	* @param u32Sum The 32-bit intermediate checksum value.
285	* @param pfOdd This is used to keep track of odd bits, initialize to false
286	* when starting to checksum the data (aka text) after a TCP
287	* or UDP header (data never start at an odd offset).
288	*/
289	DECLINLINE(uint32_t) rtNetIPv4AddDataChecksum(void const pvData, size_t cbData, uint32_t u32Sum, bool pfOdd)
290	{
291	if (*pfOdd)
292	{
293	#ifdef RT_BIG_ENDIAN
294	/* there was an odd byte in the previous chunk, add the lower byte. */
295	u32Sum += (uint8_t )pvData;
296	#else
297	/* there was an odd byte in the previous chunk, add the upper byte. */
298	u32Sum += (uint32_t)(uint8_t )pvData << 8;
299	#endif
300	/* skip the byte. */
301	cbData--;
302	if (!cbData)
303	return u32Sum;
304	pvData = (uint8_t const *)pvData + 1;
305	}
306
307	/* iterate the data. */
308	uint16_t const pw = (uint16_t const )pvData;
309	while (cbData > 1)
310	{
311	u32Sum += *pw;
312	pw++;
313	cbData -= 2;
314	}
315
316	/* handle odd byte. */
317	if (cbData)
318	{
319	#ifdef RT_BIG_ENDIAN
320	u32Sum += (uint32_t)(uint8_t )pw << 8;
321	#else
322	u32Sum += (uint8_t )pw;
323	#endif
324	*pfOdd = true;
325	}
326	else
327	*pfOdd = false;
328	return u32Sum;
329	}
330
331	/**
332	* Adds the checksum of the specified data segment to the intermediate checksum value.
333	*
334	* @returns 32-bit intermediary checksum value.
335	* @param pUdpHdr Pointer to the UDP header to checksum, network endian (big).
336	* @param u32Sum The 32-bit intermediate checksum value.
337	* @param pfOdd This is used to keep track of odd bits, initialize to false
338	* when starting to checksum the data (aka text) after a TCP
339	* or UDP header (data never start at an odd offset).
340	*/
341	RTDECL(uint32_t) RTNetIPv4AddDataChecksum(void const pvData, size_t cbData, uint32_t u32Sum, bool pfOdd)
342	{
343	return rtNetIPv4AddDataChecksum(pvData, cbData, u32Sum, pfOdd);
344	}
345
346
347	/**
348	* Finalizes a IPv4 checksum [inlined].
349	*
350	* @returns The checksum (network endian).
351	* @param u32Sum The 32-bit intermediate checksum value.
352	*/
353	DECLINLINE(uint16_t) rtNetIPv4FinalizeChecksum(uint32_t u32Sum)
354	{
355	/* 16-bit one complement fun */
356	u32Sum = (u32Sum >> 16) + (u32Sum & 0xffff); /* hi + low words */
357	u32Sum += u32Sum >> 16; /* carry */
358	return (uint16_t)~u32Sum;
359	}
360
361
362	/**
363	* Finalizes a IPv4 checksum.
364	*
365	* @returns The checksum (network endian).
366	* @param u32Sum The 32-bit intermediate checksum value.
367	*/
368	RTDECL(uint16_t) RTNetIPv4FinalizeChecksum(uint32_t u32Sum)
369	{
370	return rtNetIPv4FinalizeChecksum(u32Sum);
371	}
372
373
374	/**
375	* Calculates the checksum for the UDP header given the IP header,
376	* UDP header and payload.
377	*
378	* @returns The checksum (network endian).
379	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
380	* @param pUdpHdr Pointer to the UDP header, in network endian (big).
381	* @param pvData Pointer to the UDP payload. The size is taken from the
382	* UDP header and the caller is supposed to have validated
383	* this before calling.
384	*/
385	RTDECL(uint16_t) RTNetIPv4UDPChecksum(PCRTNETIPV4 pIpHdr, PCRTNETUDP pUdpHdr, void const *pvData)
386	{
387	uint32_t u32Sum = rtNetIPv4PseudoChecksum(pIpHdr);
388	u32Sum = rtNetIPv4AddUDPChecksum(pUdpHdr, u32Sum);
389	bool fOdd = false;
390	u32Sum = rtNetIPv4AddDataChecksum(pvData, RT_BE2H_U16(pUdpHdr->uh_ulen) - sizeof(*pUdpHdr), u32Sum, &fOdd);
391	return rtNetIPv4FinalizeChecksum(u32Sum);
392	}
393
394
395	/**
396	* Simple verficiation of an UDP packet size.
397	*
398	* @returns true if valid, false if invalid.
399	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
400	* This is assumed to be valid and the minimum size being mapped.
401	* @param pUdpHdr Pointer to the UDP header, in network endian (big).
402	* @param cbPktMax The max UDP packet size, UDP header and payload (data).
403	*/
404	DECLINLINE(bool) rtNetIPv4IsUDPSizeValid(PCRTNETIPV4 pIpHdr, PCRTNETUDP pUdpHdr, size_t cbPktMax)
405	{
406	/*
407	* Size validation.
408	*/
409	if (RT_UNLIKELY(cbPktMax < RTNETUDP_MIN_LEN))
410	return false;
411	size_t cb = RT_BE2H_U16(pUdpHdr->uh_ulen);
412	if (RT_UNLIKELY(cb > cbPktMax))
413	return false;
414	if (RT_UNLIKELY(cb > (size_t)(RT_BE2H_U16(pIpHdr->ip_len) - pIpHdr->ip_hl * 4)))
415	return false;
416	return true;
417	}
418
419
420	/**
421	* Simple verficiation of an UDP packet size.
422	*
423	* @returns true if valid, false if invalid.
424	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
425	* This is assumed to be valid and the minimum size being mapped.
426	* @param pUdpHdr Pointer to the UDP header, in network endian (big).
427	* @param cbPktMax The max UDP packet size, UDP header and payload (data).
428	*/
429	RTDECL(bool) RTNetIPv4IsUDPSizeValid(PCRTNETIPV4 pIpHdr, PCRTNETUDP pUdpHdr, size_t cbPktMax)
430	{
431	return rtNetIPv4IsUDPSizeValid(pIpHdr, pUdpHdr, cbPktMax);
432	}
433
434
435	/**
436	* Simple verficiation of an UDP packet (size + checksum).
437	*
438	* @returns true if valid, false if invalid.
439	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
440	* This is assumed to be valid and the minimum size being mapped.
441	* @param pUdpHdr Pointer to the UDP header, in network endian (big).
442	* @param pvData Pointer to the data, assuming it's one single segment
443	* and that cbPktMax - sizeof(RTNETUDP) is mapped here.
444	* @param cbPktMax The max UDP packet size, UDP header and payload (data).
445	*/
446	RTDECL(bool) RTNetIPv4IsUDPValid(PCRTNETIPV4 pIpHdr, PCRTNETUDP pUdpHdr, void const *pvData, size_t cbPktMax)
447	{
448	if (RT_UNLIKELY(!rtNetIPv4IsUDPSizeValid(pIpHdr, pUdpHdr, cbPktMax)))
449	return false;
450	if (pUdpHdr->uh_sum)
451	{
452	uint16_t u16Sum = RTNetIPv4UDPChecksum(pIpHdr, pUdpHdr, pvData);
453	if (RT_UNLIKELY(pUdpHdr->uh_sum != u16Sum))
454	return false;
455	}
456	return true;
457	}
458
459
460	/**
461	* Calculates the checksum for the TCP header given the IP header,
462	* TCP header and payload.
463	*
464	* @returns The checksum (network endian).
465	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
466	* @param pTcpHdr Pointer to the TCP header, in network endian (big).
467	* @param pvData Pointer to the TCP payload. The size is taken from the
468	* TCP header and the caller is supposed to have validated
469	* this before calling.
470	* If NULL then we assume the data follows immediately after
471	* the TCP header.
472	*/
473	RTDECL(uint16_t) RTNetIPv4TCPChecksum(PCRTNETIPV4 pIpHdr, PCRTNETTCP pTcpHdr, void const *pvData)
474	{
475	uint32_t u32Sum = rtNetIPv4PseudoChecksum(pIpHdr);
476	u32Sum = rtNetIPv4AddTCPChecksum(pTcpHdr, u32Sum);
477	bool fOdd = false;
478	size_t cbData = RT_BE2H_U16(pIpHdr->ip_len) - pIpHdr->ip_hl * 4 - pTcpHdr->th_off * 4;
479	u32Sum = rtNetIPv4AddDataChecksum(pvData ? pvData : (uint8_t const )pTcpHdr + pTcpHdr->th_off 4,
480	cbData, u32Sum, &fOdd);
481	return rtNetIPv4FinalizeChecksum(u32Sum);
482	}
483
484
485	/**
486	* Verficiation of a TCP header.
487	*
488	* @returns true if valid, false if invalid.
489	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
490	* This is assumed to be valid and the minimum size being mapped.
491	* @param pTcpHdr Pointer to the TCP header, in network endian (big).
492	* @param cbHdrMax The max TCP header size (what pTcpHdr points to).
493	* @param cbPktMax The max TCP packet size, TCP header and payload (data).
494	*/
495	DECLINLINE(bool) rtNetIPv4IsTCPSizeValid(PCRTNETIPV4 pIpHdr, PCRTNETTCP pTcpHdr, size_t cbHdrMax, size_t cbPktMax)
496	{
497	Assert(cbPktMax >= cbHdrMax);
498
499	/*
500	* Size validations.
501	*/
502	if (RT_UNLIKELY(cbPktMax < RTNETTCP_MIN_LEN))
503	return false;
504	size_t cbTcpHdr = pTcpHdr->th_off * 4;
505	if (RT_UNLIKELY(cbTcpHdr > cbHdrMax))
506	return false;
507	size_t cbTcp = RT_BE2H_U16(pIpHdr->ip_len) - pIpHdr->ip_hl * 4;
508	if (RT_UNLIKELY(cbTcp > cbPktMax))
509	return false;
510	return true;
511	}
512
513
514	/**
515	* Simple verficiation of an TCP packet size.
516	*
517	* @returns true if valid, false if invalid.
518	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
519	* This is assumed to be valid and the minimum size being mapped.
520	* @param pTcpHdr Pointer to the TCP header, in network endian (big).
521	* @param cbHdrMax The max TCP header size (what pTcpHdr points to).
522	* @param cbPktMax The max TCP packet size, TCP header and payload (data).
523	*/
524	RTDECL(bool) RTNetIPv4IsTCPSizeValid(PCRTNETIPV4 pIpHdr, PCRTNETTCP pTcpHdr, size_t cbHdrMax, size_t cbPktMax)
525	{
526	return rtNetIPv4IsTCPSizeValid(pIpHdr, pTcpHdr, cbHdrMax, cbPktMax);
527	}
528
529
530	/**
531	* Simple verficiation of an TCP packet (size + checksum).
532	*
533	* @returns true if valid, false if invalid.
534	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
535	* This is assumed to be valid and the minimum size being mapped.
536	* @param pTcpHdr Pointer to the TCP header, in network endian (big).
537	* @param cbHdrMax The max TCP header size (what pTcpHdr points to).
538	* @param pvData Pointer to the data, assuming it's one single segment
539	* and that cbPktMax - sizeof(RTNETTCP) is mapped here.
540	* If NULL then we assume the data follows immediately after
541	* the TCP header.
542	* @param cbPktMax The max TCP packet size, TCP header and payload (data).
543	*/
544	RTDECL(bool) RTNetIPv4IsTCPValid(PCRTNETIPV4 pIpHdr, PCRTNETTCP pTcpHdr, size_t cbHdrMax, void const *pvData, size_t cbPktMax)
545	{
546	if (RT_UNLIKELY(!rtNetIPv4IsTCPSizeValid(pIpHdr, pTcpHdr, cbHdrMax, cbPktMax)))
547	return false;
548	uint16_t u16Sum = RTNetIPv4TCPChecksum(pIpHdr, pTcpHdr, pvData);
549	if (RT_UNLIKELY(pTcpHdr->th_sum != u16Sum))
550	return false;
551	return true;
552	}
553
554
555	/**
556	* Minimal validation of a DHCP packet.
557	*
558	* This will fail on BOOTP packets (if sufficient data is supplied).
559	* It will not verify the source and destination ports, that's the
560	* caller's responsibility.
561	*
562	* This function will ASSUME that the hardware type is ethernet
563	* and use that for htype/hlen validation.
564	*
565	* @returns true if valid, false if invalid.
566	* @param pUdpHdr Pointer to the UDP header, in network endian (big).
567	* This is assumed to be valid and fully mapped.
568	* @param pDhcp Pointer to the DHCP packet.
569	* This might not be the entire thing, see cbDhcp.
570	* @param cbDhcp The number of valid bytes that pDhcp points to.
571	* @param pMsgType Where to store the message type (if found).
572	* This will be set to 0 if not found and on failure.
573	*/
574	RTDECL(bool) RTNetIPv4IsDHCPValid(PCRTNETUDP pUdpHdr, PCRTNETBOOTP pDhcp, size_t cbDhcp, uint8_t *pMsgType)
575	{
576	AssertPtrNull(pMsgType);
577	if (pMsgType)
578	*pMsgType = 0;
579
580	/*
581	* Validate all the header fields we're able to...
582	*/
583	if (cbDhcp < RT_OFFSETOF(RTNETBOOTP, bp_op) + sizeof(pDhcp->bp_op))
584	return true;
585	if (RT_UNLIKELY( pDhcp->bp_op != RTNETBOOTP_OP_REQUEST
586	&& pDhcp->bp_op != RTNETBOOTP_OP_REPLY))
587	return false;
588
589	if (cbDhcp < RT_OFFSETOF(RTNETBOOTP, bp_htype) + sizeof(pDhcp->bp_htype))
590	return true;
591	if (RT_UNLIKELY(pDhcp->bp_htype != RTNET_ARP_ETHER))
592	return false;
593
594	if (cbDhcp < RT_OFFSETOF(RTNETBOOTP, bp_hlen) + sizeof(pDhcp->bp_hlen))
595	return true;
596	if (RT_UNLIKELY(pDhcp->bp_hlen != sizeof(RTMAC)))
597	return false;
598
599	if (cbDhcp < RT_OFFSETOF(RTNETBOOTP, bp_flags) + sizeof(pDhcp->bp_flags))
600	return true;
601	if (RT_UNLIKELY(RT_BE2H_U16(pDhcp->bp_flags) & ~(RTNET_DHCP_FLAGS_NO_BROADCAST)))
602	return false;
603
604	/*
605	* Check the DHCP cookie and make sure it isn't followed by an END option
606	* (because that seems to be indicating that it's BOOTP and not DHCP).
607	*/
608	ssize_t cbLeft = (ssize_t)cbDhcp - RT_OFFSETOF(RTNETBOOTP, bp_vend.Dhcp.dhcp_cookie) + sizeof(pDhcp->bp_vend.Dhcp.dhcp_cookie);
609	if (cbLeft < 0)
610	return true;
611	if (RT_UNLIKELY(RT_BE2H_U32(pDhcp->bp_vend.Dhcp.dhcp_cookie) != RTNET_DHCP_COOKIE))
612	return false;
613	if (cbLeft < 1)
614	return true;
615	PCRTNETDHCPOPT pOpt = (PCRTNETDHCPOPT)&pDhcp->bp_vend.Dhcp.dhcp_opts[0];
616	if (pOpt->dhcp_opt == RTNET_DHCP_OPT_END)
617	return false;
618
619	/*
620	* Scan the options until we find the message type or run out of message.
621	*
622	* We're not strict about termination (END) for many reasons, however,
623	* we don't accept END without MSG_TYPE.
624	*/
625	uint8_t MsgType = 0;
626	while (cbLeft > 0)
627	{
628	if (pOpt->dhcp_opt == RTNET_DHCP_OPT_END)
629	{
630	/* Fail if no MSG_TYPE. */
631	if (!MsgType)
632	return false;
633	break;
634	}
635	if (pOpt->dhcp_opt == RTNET_DHCP_OPT_PAD)
636	{
637	pOpt = (PCRTNETDHCPOPT)((uint8_t const *)pOpt + 1);
638	cbLeft--;
639	}
640	else
641	{
642	switch (pOpt->dhcp_opt)
643	{
644	case RTNET_DHCP_OPT_MSG_TYPE:
645	{
646	if (cbLeft < 3)
647	return true;
648	MsgType = (const uint8_t )(pOpt + 1);
649	switch (MsgType)
650	{
651	case RTNET_DHCP_MT_DISCOVER:
652	case RTNET_DHCP_MT_OFFER:
653	case RTNET_DHCP_MT_REQUEST:
654	case RTNET_DHCP_MT_DECLINE:
655	case RTNET_DHCP_MT_ACK:
656	case RTNET_DHCP_MT_NAC:
657	case RTNET_DHCP_MT_RELEASE:
658	case RTNET_DHCP_MT_INFORM:
659	break;
660
661	default:
662	/* we don't know this message type, fail. */
663	return false;
664	}
665
666	/* Found a known message type, consider the job done. */
667	if (pMsgType)
668	*pMsgType = MsgType;
669	return true;
670	}
671	}
672
673	/* Skip the option. */
674	cbLeft -= pOpt->dhcp_len + sizeof(*pOpt);
675	pOpt = (PCRTNETDHCPOPT)((uint8_t const )pOpt + pOpt->dhcp_len + sizeof(pOpt));
676	}
677	}
678
679	return true;
680	}
681

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source: vbox/trunk/src/VBox/Runtime/common/checksum/ipv4.cpp@ 17082

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