ipv4.cpp@ 31376

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1	/* $Id: ipv4.cpp 28800 2010-04-27 08:22:32Z vboxsync $ */
2	/** @file
3	* IPRT - IPv4 Checksum calculation and validation.
4	*/
5
6	/*
7	* Copyright (C) 2008 Oracle Corporation
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
27
28	/*******************************************************************************
29	* Header Files *
30	*******************************************************************************/
31	#include <iprt/net.h>
32	#include "internal/iprt.h"
33
34	#include <iprt/asm.h>
35	#include <iprt/assert.h>
36
37
38	/**
39	* Calculates the checksum of the IPv4 header.
40	*
41	* @returns Checksum (network endian).
42	* @param pIpHdr Pointer to the IPv4 header to checksum, network endian (big).
43	* Assumes the caller already checked the minimum size requirement.
44	*/
45	RTDECL(uint16_t) RTNetIPv4HdrChecksum(PCRTNETIPV4 pIpHdr)
46	{
47	uint16_t const paw = (uint16_t const )pIpHdr;
48	uint32_t u32Sum = paw[0] /* ip_hl */
49	+ paw[1] /* ip_len */
50	+ paw[2] /* ip_id */
51	+ paw[3] /* ip_off */
52	+ paw[4] /* ip_ttl */
53	/+ paw[5] == 0 / /* ip_sum */
54	+ paw[6] /* ip_src */
55	+ paw[7] /* ip_src:16 */
56	+ paw[8] /* ip_dst */
57	+ paw[9]; /* ip_dst:16 */
58	/* any options */
59	if (pIpHdr->ip_hl > 20 / 4)
60	{
61	/* this is a bit insane... (identical to the TCP header) */
62	switch (pIpHdr->ip_hl)
63	{
64	case 6: u32Sum += paw[10] + paw[11]; break;
65	case 7: u32Sum += paw[10] + paw[11] + paw[12] + paw[13]; break;
66	case 8: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15]; break;
67	case 9: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17]; break;
68	case 10: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19]; break;
69	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;
70	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;
71	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;
72	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;
73	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;
74	default:
75	AssertFailed();
76	}
77	}
78
79	/* 16-bit one complement fun */
80	u32Sum = (u32Sum >> 16) + (u32Sum & 0xffff); /* hi + low words */
81	u32Sum += u32Sum >> 16; /* carry */
82	return (uint16_t)~u32Sum;
83	}
84	RT_EXPORT_SYMBOL(RTNetIPv4HdrChecksum);
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	* @param fChecksum Whether to validate the checksum (GSO).
98	*/
99	RTDECL(bool) RTNetIPv4IsHdrValid(PCRTNETIPV4 pIpHdr, size_t cbHdrMax, size_t cbPktMax, bool fChecksum)
100	{
101	/*
102	* The header fields.
103	*/
104	Assert(cbPktMax >= cbHdrMax);
105	if (RT_UNLIKELY(cbHdrMax < RTNETIPV4_MIN_LEN))
106	return false;
107	if (RT_UNLIKELY(pIpHdr->ip_hl * 4 < RTNETIPV4_MIN_LEN))
108	return false;
109	if (RT_UNLIKELY((size_t)pIpHdr->ip_hl * 4 > cbHdrMax))
110	{
111	Assert((size_t)pIpHdr->ip_hl * 4 > cbPktMax); /* You'll hit this if you mapped/copy too little of the header! */
112	return false;
113	}
114	if (RT_UNLIKELY(pIpHdr->ip_v != 4))
115	return false;
116	if (RT_UNLIKELY(RT_BE2H_U16(pIpHdr->ip_len) > cbPktMax))
117	return false;
118
119	/*
120	* The header checksum if requested.
121	*/
122	if (fChecksum)
123	{
124	uint16_t u16Sum = RTNetIPv4HdrChecksum(pIpHdr);
125	if (RT_UNLIKELY(pIpHdr->ip_sum != u16Sum))
126	return false;
127	}
128	return true;
129	}
130	RT_EXPORT_SYMBOL(RTNetIPv4IsHdrValid);
131
132
133	/**
134	* Calculates the checksum of a pseudo header given an IPv4 header [inlined].
135	*
136	* @returns 32-bit intermediary checksum value.
137	* @param pIpHdr The IP header (network endian (big)).
138	*/
139	DECLINLINE(uint32_t) rtNetIPv4PseudoChecksum(PCRTNETIPV4 pIpHdr)
140	{
141	uint16_t cbPayload = RT_BE2H_U16(pIpHdr->ip_len) - pIpHdr->ip_hl * 4;
142	uint32_t u32Sum = pIpHdr->ip_src.au16[0]
143	+ pIpHdr->ip_src.au16[1]
144	+ pIpHdr->ip_dst.au16[0]
145	+ pIpHdr->ip_dst.au16[1]
146	#ifdef RT_BIG_ENDIAN
147	+ pIpHdr->ip_p
148	#else
149	+ ((uint32_t)pIpHdr->ip_p << 8)
150	#endif
151	+ RT_H2BE_U16(cbPayload);
152	return u32Sum;
153	}
154
155
156	/**
157	* Calculates the checksum of a pseudo header given an IPv4 header.
158	*
159	* @returns 32-bit intermediary checksum value.
160	* @param pIpHdr The IP header (network endian (big)).
161	*/
162	RTDECL(uint32_t) RTNetIPv4PseudoChecksum(PCRTNETIPV4 pIpHdr)
163	{
164	return rtNetIPv4PseudoChecksum(pIpHdr);
165	}
166	RT_EXPORT_SYMBOL(RTNetIPv4PseudoChecksum);
167
168
169	/**
170	* Calculates the checksum of a pseudo header given the individual components.
171	*
172	* @returns 32-bit intermediary checksum value.
173	* @param SrcAddr The source address in host endian.
174	* @param DstAddr The destination address in host endian.
175	* @param bProtocol The protocol number.
176	* @param cbPkt The packet size (host endian of course) (no IPv4 header).
177	*/
178	RTDECL(uint32_t) RTNetIPv4PseudoChecksumBits(RTNETADDRIPV4 SrcAddr, RTNETADDRIPV4 DstAddr, uint8_t bProtocol, uint16_t cbPkt)
179	{
180	uint32_t u32Sum = RT_H2BE_U16(SrcAddr.au16[0])
181	+ RT_H2BE_U16(SrcAddr.au16[1])
182	+ RT_H2BE_U16(DstAddr.au16[0])
183	+ RT_H2BE_U16(DstAddr.au16[1])
184	#ifdef RT_BIG_ENDIAN
185	+ bProtocol
186	#else
187	+ ((uint32_t)bProtocol << 8)
188	#endif
189	+ RT_H2BE_U16(cbPkt);
190	return u32Sum;
191	}
192	RT_EXPORT_SYMBOL(RTNetIPv4PseudoChecksumBits);
193
194
195	/**
196	* Adds the checksum of the UDP header to the intermediate checksum value [inlined].
197	*
198	* @returns 32-bit intermediary checksum value.
199	* @param pUdpHdr Pointer to the UDP header to checksum, network endian (big).
200	* @param u32Sum The 32-bit intermediate checksum value.
201	*/
202	DECLINLINE(uint32_t) rtNetIPv4AddUDPChecksum(PCRTNETUDP pUdpHdr, uint32_t u32Sum)
203	{
204	u32Sum += pUdpHdr->uh_sport
205	+ pUdpHdr->uh_dport
206	/+ pUdpHdr->uh_sum = 0 /
207	+ pUdpHdr->uh_ulen;
208	return u32Sum;
209	}
210
211
212	/**
213	* Adds the checksum of the UDP header to the intermediate checksum value.
214	*
215	* @returns 32-bit intermediary checksum value.
216	* @param pUdpHdr Pointer to the UDP header to checksum, network endian (big).
217	* @param u32Sum The 32-bit intermediate checksum value.
218	*/
219	RTDECL(uint32_t) RTNetIPv4AddUDPChecksum(PCRTNETUDP pUdpHdr, uint32_t u32Sum)
220	{
221	return rtNetIPv4AddUDPChecksum(pUdpHdr, u32Sum);
222	}
223	RT_EXPORT_SYMBOL(RTNetIPv4AddUDPChecksum);
224
225
226	/**
227	* Adds the checksum of the TCP header to the intermediate checksum value [inlined].
228	*
229	* @returns 32-bit intermediary checksum value.
230	* @param pTcpHdr Pointer to the TCP header to checksum, network
231	* endian (big). Assums the caller has already validate
232	* it and made sure the entire header is present.
233	* @param u32Sum The 32-bit intermediate checksum value.
234	*/
235	DECLINLINE(uint32_t) rtNetIPv4AddTCPChecksum(PCRTNETTCP pTcpHdr, uint32_t u32Sum)
236	{
237	uint16_t const paw = (uint16_t const )pTcpHdr;
238	u32Sum += paw[0] /* th_sport */
239	+ paw[1] /* th_dport */
240	+ paw[2] /* th_seq */
241	+ paw[3] /* th_seq:16 */
242	+ paw[4] /* th_ack */
243	+ paw[5] /* th_ack:16 */
244	+ paw[6] /* th_off, th_x2, th_flags */
245	+ paw[7] /* th_win */
246	/+ paw[8] == 0 / /* th_sum */
247	+ paw[9]; /* th_urp */
248	if (pTcpHdr->th_off > RTNETTCP_MIN_LEN / 4)
249	{
250	/* this is a bit insane... (identical to the IPv4 header) */
251	switch (pTcpHdr->th_off)
252	{
253	case 6: u32Sum += paw[10] + paw[11]; break;
254	case 7: u32Sum += paw[10] + paw[11] + paw[12] + paw[13]; break;
255	case 8: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15]; break;
256	case 9: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17]; break;
257	case 10: u32Sum += paw[10] + paw[11] + paw[12] + paw[13] + paw[14] + paw[15] + paw[16] + paw[17] + paw[18] + paw[19]; break;
258	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;
259	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;
260	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;
261	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;
262	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;
263	default:
264	AssertFailed();
265	}
266	}
267
268	return u32Sum;
269	}
270
271
272	/**
273	* Adds the checksum of the TCP header to the intermediate checksum value.
274	*
275	* @returns 32-bit intermediary checksum value.
276	* @param pTcpHdr Pointer to the TCP header to checksum, network
277	* endian (big). Assums the caller has already validate
278	* it and made sure the entire header is present.
279	* @param u32Sum The 32-bit intermediate checksum value.
280	*/
281	RTDECL(uint32_t) RTNetIPv4AddTCPChecksum(PCRTNETTCP pTcpHdr, uint32_t u32Sum)
282	{
283	return rtNetIPv4AddTCPChecksum(pTcpHdr, u32Sum);
284	}
285	RT_EXPORT_SYMBOL(RTNetIPv4AddTCPChecksum);
286
287
288	/**
289	* Adds the checksum of the specified data segment to the intermediate checksum value [inlined].
290	*
291	* @returns 32-bit intermediary checksum value.
292	* @param pvData Pointer to the data that should be checksummed.
293	* @param cbData The number of bytes to checksum.
294	* @param u32Sum The 32-bit intermediate checksum value.
295	* @param pfOdd This is used to keep track of odd bits, initialize to false
296	* when starting to checksum the data (aka text) after a TCP
297	* or UDP header (data never start at an odd offset).
298	*/
299	DECLINLINE(uint32_t) rtNetIPv4AddDataChecksum(void const pvData, size_t cbData, uint32_t u32Sum, bool pfOdd)
300	{
301	if (*pfOdd)
302	{
303	#ifdef RT_BIG_ENDIAN
304	/* there was an odd byte in the previous chunk, add the lower byte. */
305	u32Sum += (uint8_t )pvData;
306	#else
307	/* there was an odd byte in the previous chunk, add the upper byte. */
308	u32Sum += (uint32_t)(uint8_t )pvData << 8;
309	#endif
310	/* skip the byte. */
311	cbData--;
312	if (!cbData)
313	return u32Sum;
314	pvData = (uint8_t const *)pvData + 1;
315	}
316
317	/* iterate the data. */
318	uint16_t const pw = (uint16_t const )pvData;
319	while (cbData > 1)
320	{
321	u32Sum += *pw;
322	pw++;
323	cbData -= 2;
324	}
325
326	/* handle odd byte. */
327	if (cbData)
328	{
329	#ifdef RT_BIG_ENDIAN
330	u32Sum += (uint32_t)(uint8_t )pw << 8;
331	#else
332	u32Sum += (uint8_t )pw;
333	#endif
334	*pfOdd = true;
335	}
336	else
337	*pfOdd = false;
338	return u32Sum;
339	}
340
341	/**
342	* Adds the checksum of the specified data segment to the intermediate checksum value.
343	*
344	* @returns 32-bit intermediary checksum value.
345	* @param pvData The data bits to checksum.
346	* @param cbData The number of bytes to checksum.
347	* @param u32Sum The 32-bit intermediate checksum value.
348	* @param pfOdd This is used to keep track of odd bits, initialize to false
349	* when starting to checksum the data (aka text) after a TCP
350	* or UDP header (data never start at an odd offset).
351	*/
352	RTDECL(uint32_t) RTNetIPv4AddDataChecksum(void const pvData, size_t cbData, uint32_t u32Sum, bool pfOdd)
353	{
354	return rtNetIPv4AddDataChecksum(pvData, cbData, u32Sum, pfOdd);
355	}
356	RT_EXPORT_SYMBOL(RTNetIPv4AddDataChecksum);
357
358
359	/**
360	* Finalizes a IPv4 checksum [inlined].
361	*
362	* @returns The checksum (network endian).
363	* @param u32Sum The 32-bit intermediate checksum value.
364	*/
365	DECLINLINE(uint16_t) rtNetIPv4FinalizeChecksum(uint32_t u32Sum)
366	{
367	/* 16-bit one complement fun */
368	u32Sum = (u32Sum >> 16) + (u32Sum & 0xffff); /* hi + low words */
369	u32Sum += u32Sum >> 16; /* carry */
370	return (uint16_t)~u32Sum;
371	}
372
373
374	/**
375	* Finalizes a IPv4 checksum.
376	*
377	* @returns The checksum (network endian).
378	* @param u32Sum The 32-bit intermediate checksum value.
379	*/
380	RTDECL(uint16_t) RTNetIPv4FinalizeChecksum(uint32_t u32Sum)
381	{
382	return rtNetIPv4FinalizeChecksum(u32Sum);
383	}
384	RT_EXPORT_SYMBOL(RTNetIPv4FinalizeChecksum);
385
386
387	/**
388	* Calculates the checksum for the UDP header given the UDP header w/ payload
389	* and the checksum of the pseudo header.
390	*
391	* @returns The checksum (network endian).
392	* @param u32Sum The checksum of the pseudo header. See
393	* RTNetIPv4PseudoChecksum and RTNetIPv6PseudoChecksum.
394	* @param pUdpHdr Pointer to the UDP header and the payload, in
395	* network endian (big). We use the uh_ulen field to
396	* figure out how much to checksum.
397	*/
398	RTDECL(uint16_t) RTNetUDPChecksum(uint32_t u32Sum, PCRTNETUDP pUdpHdr)
399	{
400	u32Sum = rtNetIPv4AddUDPChecksum(pUdpHdr, u32Sum);
401	bool fOdd = false;
402	u32Sum = rtNetIPv4AddDataChecksum(pUdpHdr + 1, RT_BE2H_U16(pUdpHdr->uh_ulen) - sizeof(*pUdpHdr), u32Sum, &fOdd);
403	return rtNetIPv4FinalizeChecksum(u32Sum);
404	}
405	RT_EXPORT_SYMBOL(RTNetUDPChecksum);
406
407
408	/**
409	* Calculates the checksum for the UDP header given the IP header,
410	* UDP header and payload.
411	*
412	* @returns The checksum (network endian).
413	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
414	* @param pUdpHdr Pointer to the UDP header, in network endian (big).
415	* @param pvData Pointer to the UDP payload. The size is taken from the
416	* UDP header and the caller is supposed to have validated
417	* this before calling.
418	*/
419	RTDECL(uint16_t) RTNetIPv4UDPChecksum(PCRTNETIPV4 pIpHdr, PCRTNETUDP pUdpHdr, void const *pvData)
420	{
421	uint32_t u32Sum = rtNetIPv4PseudoChecksum(pIpHdr);
422	u32Sum = rtNetIPv4AddUDPChecksum(pUdpHdr, u32Sum);
423	bool fOdd = false;
424	u32Sum = rtNetIPv4AddDataChecksum(pvData, RT_BE2H_U16(pUdpHdr->uh_ulen) - sizeof(*pUdpHdr), u32Sum, &fOdd);
425	return rtNetIPv4FinalizeChecksum(u32Sum);
426	}
427	RT_EXPORT_SYMBOL(RTNetIPv4UDPChecksum);
428
429
430	/**
431	* Simple verficiation of an UDP packet size.
432	*
433	* @returns true if valid, false if invalid.
434	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
435	* This is assumed to be valid and the minimum size being mapped.
436	* @param pUdpHdr Pointer to the UDP header, in network endian (big).
437	* @param cbPktMax The max UDP packet size, UDP header and payload (data).
438	*/
439	DECLINLINE(bool) rtNetIPv4IsUDPSizeValid(PCRTNETIPV4 pIpHdr, PCRTNETUDP pUdpHdr, size_t cbPktMax)
440	{
441	/*
442	* Size validation.
443	*/
444	if (RT_UNLIKELY(cbPktMax < RTNETUDP_MIN_LEN))
445	return false;
446	size_t cb = RT_BE2H_U16(pUdpHdr->uh_ulen);
447	if (RT_UNLIKELY(cb > cbPktMax))
448	return false;
449	if (RT_UNLIKELY(cb > (size_t)(RT_BE2H_U16(pIpHdr->ip_len) - pIpHdr->ip_hl * 4)))
450	return false;
451	return true;
452	}
453
454
455	/**
456	* Simple verficiation of an UDP packet size.
457	*
458	* @returns true if valid, false if invalid.
459	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
460	* This is assumed to be valid and the minimum size being mapped.
461	* @param pUdpHdr Pointer to the UDP header, in network endian (big).
462	* @param cbPktMax The max UDP packet size, UDP header and payload (data).
463	*/
464	RTDECL(bool) RTNetIPv4IsUDPSizeValid(PCRTNETIPV4 pIpHdr, PCRTNETUDP pUdpHdr, size_t cbPktMax)
465	{
466	return rtNetIPv4IsUDPSizeValid(pIpHdr, pUdpHdr, cbPktMax);
467	}
468	RT_EXPORT_SYMBOL(RTNetIPv4IsUDPSizeValid);
469
470
471	/**
472	* Simple verficiation of an UDP packet (size + checksum).
473	*
474	* @returns true if valid, false if invalid.
475	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
476	* This is assumed to be valid and the minimum size being mapped.
477	* @param pUdpHdr Pointer to the UDP header, in network endian (big).
478	* @param pvData Pointer to the data, assuming it's one single segment
479	* and that cbPktMax - sizeof(RTNETUDP) is mapped here.
480	* @param cbPktMax The max UDP packet size, UDP header and payload (data).
481	* @param fChecksum Whether to validate the checksum (GSO).
482	*/
483	RTDECL(bool) RTNetIPv4IsUDPValid(PCRTNETIPV4 pIpHdr, PCRTNETUDP pUdpHdr, void const *pvData, size_t cbPktMax, bool fChecksum)
484	{
485	if (RT_UNLIKELY(!rtNetIPv4IsUDPSizeValid(pIpHdr, pUdpHdr, cbPktMax)))
486	return false;
487	if (fChecksum && pUdpHdr->uh_sum)
488	{
489	uint16_t u16Sum = RTNetIPv4UDPChecksum(pIpHdr, pUdpHdr, pvData);
490	if (RT_UNLIKELY(pUdpHdr->uh_sum != u16Sum))
491	return false;
492	}
493	return true;
494	}
495	RT_EXPORT_SYMBOL(RTNetIPv4IsUDPValid);
496
497
498	/**
499	* Calculates the checksum for the TCP header given the IP header,
500	* TCP header and payload.
501	*
502	* @returns The checksum (network endian).
503	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
504	* @param pTcpHdr Pointer to the TCP header, in network endian (big).
505	* @param pvData Pointer to the TCP payload. The size is derived from
506	* the two headers and the caller is supposed to have
507	* validated this before calling. If NULL, we assume
508	* the data follows immediately after the TCP header.
509	*/
510	RTDECL(uint16_t) RTNetIPv4TCPChecksum(PCRTNETIPV4 pIpHdr, PCRTNETTCP pTcpHdr, void const *pvData)
511	{
512	uint32_t u32Sum = rtNetIPv4PseudoChecksum(pIpHdr);
513	u32Sum = rtNetIPv4AddTCPChecksum(pTcpHdr, u32Sum);
514	bool fOdd = false;
515	size_t cbData = RT_BE2H_U16(pIpHdr->ip_len) - pIpHdr->ip_hl * 4 - pTcpHdr->th_off * 4;
516	u32Sum = rtNetIPv4AddDataChecksum(pvData ? pvData : (uint8_t const )pTcpHdr + pTcpHdr->th_off 4,
517	cbData, u32Sum, &fOdd);
518	return rtNetIPv4FinalizeChecksum(u32Sum);
519	}
520	RT_EXPORT_SYMBOL(RTNetIPv4TCPChecksum);
521
522
523	/**
524	* Calculates the checksum for the TCP header given the TCP header, payload and
525	* the checksum of the pseudo header.
526	*
527	* This is not specific to IPv4.
528	*
529	* @returns The checksum (network endian).
530	* @param u32Sum The checksum of the pseudo header. See
531	* RTNetIPv4PseudoChecksum and RTNetIPv6PseudoChecksum.
532	* @param pTcpHdr Pointer to the TCP header, in network endian (big).
533	* @param pvData Pointer to the TCP payload.
534	* @param cbData The size of the TCP payload.
535	*/
536	RTDECL(uint16_t) RTNetTCPChecksum(uint32_t u32Sum, PCRTNETTCP pTcpHdr, void const *pvData, size_t cbData)
537	{
538	u32Sum = rtNetIPv4AddTCPChecksum(pTcpHdr, u32Sum);
539	bool fOdd = false;
540	u32Sum = rtNetIPv4AddDataChecksum(pvData, cbData, u32Sum, &fOdd);
541	return rtNetIPv4FinalizeChecksum(u32Sum);
542	}
543	RT_EXPORT_SYMBOL(RTNetTCPChecksum);
544
545
546	/**
547	* Verficiation of a TCP header.
548	*
549	* @returns true if valid, false if invalid.
550	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
551	* This is assumed to be valid and the minimum size being mapped.
552	* @param pTcpHdr Pointer to the TCP header, in network endian (big).
553	* @param cbHdrMax The max TCP header size (what pTcpHdr points to).
554	* @param cbPktMax The max TCP packet size, TCP header and payload (data).
555	*/
556	DECLINLINE(bool) rtNetIPv4IsTCPSizeValid(PCRTNETIPV4 pIpHdr, PCRTNETTCP pTcpHdr, size_t cbHdrMax, size_t cbPktMax)
557	{
558	Assert(cbPktMax >= cbHdrMax);
559
560	/*
561	* Size validations.
562	*/
563	if (RT_UNLIKELY(cbPktMax < RTNETTCP_MIN_LEN))
564	return false;
565	size_t cbTcpHdr = pTcpHdr->th_off * 4;
566	if (RT_UNLIKELY(cbTcpHdr > cbHdrMax))
567	return false;
568	size_t cbTcp = RT_BE2H_U16(pIpHdr->ip_len) - pIpHdr->ip_hl * 4;
569	if (RT_UNLIKELY(cbTcp > cbPktMax))
570	return false;
571	return true;
572	}
573
574
575	/**
576	* Simple verficiation of an TCP packet size.
577	*
578	* @returns true if valid, false if invalid.
579	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
580	* This is assumed to be valid and the minimum size being mapped.
581	* @param pTcpHdr Pointer to the TCP header, in network endian (big).
582	* @param cbHdrMax The max TCP header size (what pTcpHdr points to).
583	* @param cbPktMax The max TCP packet size, TCP header and payload (data).
584	*/
585	RTDECL(bool) RTNetIPv4IsTCPSizeValid(PCRTNETIPV4 pIpHdr, PCRTNETTCP pTcpHdr, size_t cbHdrMax, size_t cbPktMax)
586	{
587	return rtNetIPv4IsTCPSizeValid(pIpHdr, pTcpHdr, cbHdrMax, cbPktMax);
588	}
589	RT_EXPORT_SYMBOL(RTNetIPv4IsTCPSizeValid);
590
591
592	/**
593	* Simple verficiation of an TCP packet (size + checksum).
594	*
595	* @returns true if valid, false if invalid.
596	* @param pIpHdr Pointer to the IPv4 header, in network endian (big).
597	* This is assumed to be valid and the minimum size being mapped.
598	* @param pTcpHdr Pointer to the TCP header, in network endian (big).
599	* @param cbHdrMax The max TCP header size (what pTcpHdr points to).
600	* @param pvData Pointer to the data, assuming it's one single segment
601	* and that cbPktMax - sizeof(RTNETTCP) is mapped here.
602	* If NULL then we assume the data follows immediately after
603	* the TCP header.
604	* @param cbPktMax The max TCP packet size, TCP header and payload (data).
605	* @param fChecksum Whether to validate the checksum (GSO).
606	*/
607	RTDECL(bool) RTNetIPv4IsTCPValid(PCRTNETIPV4 pIpHdr, PCRTNETTCP pTcpHdr, size_t cbHdrMax, void const *pvData, size_t cbPktMax,
608	bool fChecksum)
609	{
610	if (RT_UNLIKELY(!rtNetIPv4IsTCPSizeValid(pIpHdr, pTcpHdr, cbHdrMax, cbPktMax)))
611	return false;
612	if (fChecksum)
613	{
614	uint16_t u16Sum = RTNetIPv4TCPChecksum(pIpHdr, pTcpHdr, pvData);
615	if (RT_UNLIKELY(pTcpHdr->th_sum != u16Sum))
616	return false;
617	}
618	return true;
619	}
620	RT_EXPORT_SYMBOL(RTNetIPv4IsTCPValid);
621
622
623	/**
624	* Minimal validation of a DHCP packet.
625	*
626	* This will fail on BOOTP packets (if sufficient data is supplied).
627	* It will not verify the source and destination ports, that's the
628	* caller's responsibility.
629	*
630	* This function will ASSUME that the hardware type is ethernet
631	* and use that for htype/hlen validation.
632	*
633	* @returns true if valid, false if invalid.
634	* @param pUdpHdr Pointer to the UDP header, in network endian (big).
635	* This is assumed to be valid and fully mapped.
636	* @param pDhcp Pointer to the DHCP packet.
637	* This might not be the entire thing, see cbDhcp.
638	* @param cbDhcp The number of valid bytes that pDhcp points to.
639	* @param pMsgType Where to store the message type (if found).
640	* This will be set to 0 if not found and on failure.
641	*/
642	RTDECL(bool) RTNetIPv4IsDHCPValid(PCRTNETUDP pUdpHdr, PCRTNETBOOTP pDhcp, size_t cbDhcp, uint8_t *pMsgType)
643	{
644	AssertPtrNull(pMsgType);
645	if (pMsgType)
646	*pMsgType = 0;
647
648	/*
649	* Validate all the header fields we're able to...
650	*/
651	if (cbDhcp < RT_OFFSETOF(RTNETBOOTP, bp_op) + sizeof(pDhcp->bp_op))
652	return true;
653	if (RT_UNLIKELY( pDhcp->bp_op != RTNETBOOTP_OP_REQUEST
654	&& pDhcp->bp_op != RTNETBOOTP_OP_REPLY))
655	return false;
656
657	if (cbDhcp < RT_OFFSETOF(RTNETBOOTP, bp_htype) + sizeof(pDhcp->bp_htype))
658	return true;
659	if (RT_UNLIKELY(pDhcp->bp_htype != RTNET_ARP_ETHER))
660	return false;
661
662	if (cbDhcp < RT_OFFSETOF(RTNETBOOTP, bp_hlen) + sizeof(pDhcp->bp_hlen))
663	return true;
664	if (RT_UNLIKELY(pDhcp->bp_hlen != sizeof(RTMAC)))
665	return false;
666
667	if (cbDhcp < RT_OFFSETOF(RTNETBOOTP, bp_flags) + sizeof(pDhcp->bp_flags))
668	return true;
669	if (RT_UNLIKELY(RT_BE2H_U16(pDhcp->bp_flags) & ~(RTNET_DHCP_FLAGS_NO_BROADCAST)))
670	return false;
671
672	/*
673	* Check the DHCP cookie and make sure it isn't followed by an END option
674	* (because that seems to be indicating that it's BOOTP and not DHCP).
675	*/
676	ssize_t cbLeft = (ssize_t)cbDhcp - RT_OFFSETOF(RTNETBOOTP, bp_vend.Dhcp.dhcp_cookie) + sizeof(pDhcp->bp_vend.Dhcp.dhcp_cookie);
677	if (cbLeft < 0)
678	return true;
679	if (RT_UNLIKELY(RT_BE2H_U32(pDhcp->bp_vend.Dhcp.dhcp_cookie) != RTNET_DHCP_COOKIE))
680	return false;
681	if (cbLeft < 1)
682	return true;
683	PCRTNETDHCPOPT pOpt = (PCRTNETDHCPOPT)&pDhcp->bp_vend.Dhcp.dhcp_opts[0];
684	if (pOpt->dhcp_opt == RTNET_DHCP_OPT_END)
685	return false;
686
687	/*
688	* Scan the options until we find the message type or run out of message.
689	*
690	* We're not strict about termination (END) for many reasons, however,
691	* we don't accept END without MSG_TYPE.
692	*/
693	uint8_t MsgType = 0;
694	while (cbLeft > 0)
695	{
696	if (pOpt->dhcp_opt == RTNET_DHCP_OPT_END)
697	{
698	/* Fail if no MSG_TYPE. */
699	if (!MsgType)
700	return false;
701	break;
702	}
703	if (pOpt->dhcp_opt == RTNET_DHCP_OPT_PAD)
704	{
705	pOpt = (PCRTNETDHCPOPT)((uint8_t const *)pOpt + 1);
706	cbLeft--;
707	}
708	else
709	{
710	switch (pOpt->dhcp_opt)
711	{
712	case RTNET_DHCP_OPT_MSG_TYPE:
713	{
714	if (cbLeft < 3)
715	return true;
716	MsgType = (const uint8_t )(pOpt + 1);
717	switch (MsgType)
718	{
719	case RTNET_DHCP_MT_DISCOVER:
720	case RTNET_DHCP_MT_OFFER:
721	case RTNET_DHCP_MT_REQUEST:
722	case RTNET_DHCP_MT_DECLINE:
723	case RTNET_DHCP_MT_ACK:
724	case RTNET_DHCP_MT_NAC:
725	case RTNET_DHCP_MT_RELEASE:
726	case RTNET_DHCP_MT_INFORM:
727	break;
728
729	default:
730	/* we don't know this message type, fail. */
731	return false;
732	}
733
734	/* Found a known message type, consider the job done. */
735	if (pMsgType)
736	*pMsgType = MsgType;
737	return true;
738	}
739	}
740
741	/* Skip the option. */
742	cbLeft -= pOpt->dhcp_len + sizeof(*pOpt);
743	pOpt = (PCRTNETDHCPOPT)((uint8_t const )pOpt + pOpt->dhcp_len + sizeof(pOpt));
744	}
745	}
746
747	return true;
748	}
749	RT_EXPORT_SYMBOL(RTNetIPv4IsDHCPValid);
750

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source: vbox/trunk/src/VBox/Runtime/common/checksum/ipv4.cpp@ 31376

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