Adding upstream version 7.0.6-dfsg.upstream/7.0.6-dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 724 insertions, 0 deletions

diff --git a/include/VBox/vmm/pdmnetinline.h b/include/VBox/vmm/pdmnetinline.h
new file mode 100644
index 00000000..0acd5fb9
--- /dev/null
+++ b/include/VBox/vmm/pdmnetinline.h
@@ -0,0 +1,724 @@
+/** @file
+ * PDM - Networking Helpers, Inlined Code. (DEV,++)
+ *
+ * This is all inlined because it's too tedious to create 2-3 libraries to
+ * contain it all (same bad excuse as for intnetinline.h).
+ */
+
+/*
+ * Copyright (C) 2010-2022 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+#ifndef VBOX_INCLUDED_vmm_pdmnetinline_h
+#define VBOX_INCLUDED_vmm_pdmnetinline_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+
+/*******************************************************************************
+*   Header Files                                                               *
+*******************************************************************************/
+#include <VBox/log.h>
+#include <VBox/types.h>
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/net.h>
+#include <iprt/string.h>
+
+
+/** @defgroup grp_pdm_net_inline    The PDM Networking Helper APIs
+ * @ingroup grp_pdm
+ * @{
+ */
+
+
+/**
+ * Checksum type.
+ */
+typedef enum PDMNETCSUMTYPE
+{
+    /** No checksum. */
+    PDMNETCSUMTYPE_NONE = 0,
+    /** Normal TCP checksum. */
+    PDMNETCSUMTYPE_COMPLETE,
+    /** Checksum on pseudo header (used with GSO). */
+    PDMNETCSUMTYPE_PSEUDO,
+    /** The usual 32-bit hack. */
+    PDMNETCSUMTYPE_32_BIT_HACK = 0x7fffffff
+} PDMNETCSUMTYPE;
+
+
+/**
+ * Validates the GSO context.
+ *
+ * @returns true if valid, false if not (not asserted or logged).
+ * @param   pGso                The GSO context.
+ * @param   cbGsoMax            The max size of the GSO context.
+ * @param   cbFrame             The max size of the GSO frame (use to validate
+ *                              the MSS).
+ */
+DECLINLINE(bool) PDMNetGsoIsValid(PCPDMNETWORKGSO pGso, size_t cbGsoMax, size_t cbFrame)
+{
+#define CHECK_COND_RETURN_FALSE(expr) if (RT_LIKELY(expr)) { /* likely */ } else return false
+    PDMNETWORKGSOTYPE enmType;
+
+    CHECK_COND_RETURN_FALSE(cbGsoMax >= sizeof(*pGso));
+
+    enmType = (PDMNETWORKGSOTYPE)pGso->u8Type;
+    CHECK_COND_RETURN_FALSE(enmType > PDMNETWORKGSOTYPE_INVALID && enmType < PDMNETWORKGSOTYPE_END);
+
+    /* all types requires both headers. */
+    CHECK_COND_RETURN_FALSE(pGso->offHdr1 >= sizeof(RTNETETHERHDR));
+    CHECK_COND_RETURN_FALSE(pGso->offHdr2 > pGso->offHdr1);
+    CHECK_COND_RETURN_FALSE(pGso->cbHdrsTotal > pGso->offHdr2);
+
+    /* min size of the 1st header(s). */
+    switch (enmType)
+    {
+        case PDMNETWORKGSOTYPE_IPV4_TCP:
+        case PDMNETWORKGSOTYPE_IPV4_UDP:
+            CHECK_COND_RETURN_FALSE((unsigned)pGso->offHdr2 - pGso->offHdr1 >= RTNETIPV4_MIN_LEN);
+            break;
+        case PDMNETWORKGSOTYPE_IPV6_TCP:
+        case PDMNETWORKGSOTYPE_IPV6_UDP:
+            CHECK_COND_RETURN_FALSE((unsigned)pGso->offHdr2 - pGso->offHdr1 >= RTNETIPV6_MIN_LEN);
+            break;
+        case PDMNETWORKGSOTYPE_IPV4_IPV6_TCP:
+        case PDMNETWORKGSOTYPE_IPV4_IPV6_UDP:
+            CHECK_COND_RETURN_FALSE((unsigned)pGso->offHdr2 - pGso->offHdr1 >= RTNETIPV4_MIN_LEN + RTNETIPV6_MIN_LEN);
+            break;
+        /* These two have been rejected above already, but we need to include them to avoid gcc warnings. */
+        case PDMNETWORKGSOTYPE_INVALID:
+        case PDMNETWORKGSOTYPE_END:
+            break;
+        /* No default case! Want gcc warnings. */
+    }
+
+    /* min size of the 2nd header. */
+    switch (enmType)
+    {
+        case PDMNETWORKGSOTYPE_IPV4_TCP:
+        case PDMNETWORKGSOTYPE_IPV6_TCP:
+        case PDMNETWORKGSOTYPE_IPV4_IPV6_TCP:
+            CHECK_COND_RETURN_FALSE((unsigned)pGso->cbHdrsTotal - pGso->offHdr2 >= RTNETTCP_MIN_LEN);
+            break;
+        case PDMNETWORKGSOTYPE_IPV4_UDP:
+        case PDMNETWORKGSOTYPE_IPV6_UDP:
+        case PDMNETWORKGSOTYPE_IPV4_IPV6_UDP:
+            CHECK_COND_RETURN_FALSE((unsigned)pGso->cbHdrsTotal - pGso->offHdr2 >= RTNETUDP_MIN_LEN);
+            break;
+        /* These two have been rejected above already, but we need to include them to avoid gcc warnings. */
+        case PDMNETWORKGSOTYPE_INVALID:
+        case PDMNETWORKGSOTYPE_END:
+            break;
+        /* No default case! Want gcc warnings. */
+    }
+
+    /* There must be at more than one segment. */
+    CHECK_COND_RETURN_FALSE(cbFrame > pGso->cbHdrsTotal);
+    CHECK_COND_RETURN_FALSE(cbFrame - pGso->cbHdrsTotal >= pGso->cbMaxSeg);
+
+    /* Make sure the segment size is enough to fit a UDP header. */
+    CHECK_COND_RETURN_FALSE(enmType != PDMNETWORKGSOTYPE_IPV4_UDP || pGso->cbMaxSeg >= RTNETUDP_MIN_LEN);
+
+    /* Make sure the segment size is not zero. */
+    CHECK_COND_RETURN_FALSE(pGso->cbMaxSeg > 0);
+
+    return true;
+#undef CHECK_COND_RETURN_FALSE
+}
+
+
+/**
+ * Returns the length of header for a particular segment/fragment.
+ *
+ * We cannot simply treat UDP header as a part of payload because we do not
+ * want to modify the payload but still need to modify the checksum field in
+ * UDP header. So we want to include UDP header when calculating the length
+ * of headers in the first segment getting it copied to a temporary buffer
+ * along with other headers.
+ *
+ * @returns Length of headers (including UDP header for the first fragment).
+ * @param   pGso                The GSO context.
+ * @param   iSeg                The segment index.
+ */
+DECLINLINE(uint8_t) pdmNetSegHdrLen(PCPDMNETWORKGSO pGso, uint32_t iSeg)
+{
+    return iSeg ? pGso->cbHdrsSeg : pGso->cbHdrsTotal;
+}
+
+/**
+ * Returns the length of payload for a particular segment/fragment.
+ *
+ * The first segment does not contain UDP header. The size of UDP header is
+ * determined as the difference between the total headers size and the size
+ * used during segmentation.
+ *
+ * @returns Length of payload (including UDP header for the first fragment).
+ * @param   pGso                The GSO context.
+ * @param   iSeg                The segment that we're carving out (0-based).
+ * @param   cSegs               The number of segments in the GSO frame.
+ * @param   cbFrame             The size of the GSO frame.
+ */
+DECLINLINE(uint32_t) pdmNetSegPayloadLen(PCPDMNETWORKGSO pGso, uint32_t iSeg, uint32_t cSegs, uint32_t cbFrame)
+{
+    if (iSeg + 1 == cSegs)
+        return cbFrame - iSeg * pGso->cbMaxSeg - pdmNetSegHdrLen(pGso, iSeg);
+    return pGso->cbMaxSeg - (iSeg ? 0 : pGso->cbHdrsTotal - pGso->cbHdrsSeg);
+}
+
+/**
+ * Calculates the number of segments a GSO frame will be segmented into.
+ *
+ * @returns Segment count.
+ * @param   pGso                The GSO context.
+ * @param   cbFrame             The GSO frame size (header proto + payload).
+ */
+DECLINLINE(uint32_t) PDMNetGsoCalcSegmentCount(PCPDMNETWORKGSO pGso, size_t cbFrame)
+{
+    size_t cbPayload;
+    Assert(PDMNetGsoIsValid(pGso, sizeof(*pGso), cbFrame));
+    cbPayload = cbFrame - pGso->cbHdrsSeg;
+    return (uint32_t)((cbPayload + pGso->cbMaxSeg - 1) / pGso->cbMaxSeg);
+}
+
+
+/**
+ * Used to find the IPv6 header when handling 4to6 tunneling.
+ *
+ * @returns Offset of the IPv6 header.
+ * @param   pbSegHdrs           The headers / frame start.
+ * @param   offIPv4Hdr          The offset of the IPv4 header.
+ */
+DECLINLINE(uint8_t) pgmNetGsoCalcIpv6Offset(uint8_t *pbSegHdrs, uint8_t offIPv4Hdr)
+{
+    PCRTNETIPV4 pIPv4Hdr = (PCRTNETIPV4)&pbSegHdrs[offIPv4Hdr];
+    return offIPv4Hdr + pIPv4Hdr->ip_hl * 4;
+}
+
+
+/**
+ * Update an UDP header after carving out a segment
+ *
+ * @param   u32PseudoSum        The pseudo checksum.
+ * @param   pbSegHdrs           Pointer to the header bytes / frame start.
+ * @param   offUdpHdr           The offset into @a pbSegHdrs of the UDP header.
+ * @param   pbPayload           Pointer to the payload bytes.
+ * @param   cbPayload           The amount of payload.
+ * @param   cbHdrs              The size of all the headers.
+ * @param   enmCsumType         Whether to checksum the payload, the pseudo
+ *                              header or nothing.
+ * @internal
+ */
+DECLINLINE(void) pdmNetGsoUpdateUdpHdr(uint32_t u32PseudoSum, uint8_t *pbSegHdrs, uint8_t offUdpHdr,
+                                       uint8_t const *pbPayload, uint32_t cbPayload, uint8_t cbHdrs,
+                                       PDMNETCSUMTYPE enmCsumType)
+{
+    PRTNETUDP pUdpHdr = (PRTNETUDP)&pbSegHdrs[offUdpHdr];
+    pUdpHdr->uh_ulen  = RT_H2N_U16(cbPayload + cbHdrs - offUdpHdr);
+    switch (enmCsumType)
+    {
+        case PDMNETCSUMTYPE_NONE:
+            pUdpHdr->uh_sum = 0;
+            break;
+        case PDMNETCSUMTYPE_COMPLETE:
+            pUdpHdr->uh_sum = RTNetUDPChecksum(u32PseudoSum, pUdpHdr);
+            break;
+        case PDMNETCSUMTYPE_PSEUDO:
+            pUdpHdr->uh_sum = ~RTNetIPv4FinalizeChecksum(u32PseudoSum);
+            break;
+        default:
+            NOREF(pbPayload);
+            AssertFailed();
+            break;
+    }
+}
+
+
+/**
+ * Update an UDP header after carving out an IP fragment
+ *
+ * @param   u32PseudoSum        The pseudo checksum.
+ * @param   pbSegHdrs           Pointer to the header bytes copy
+ * @param   pbFrame             Pointer to the frame start.
+ * @param   offUdpHdr           The offset into @a pbSegHdrs of the UDP header.
+ *
+ * @internal
+ */
+DECLINLINE(void) pdmNetGsoUpdateUdpHdrUfo(uint32_t u32PseudoSum, uint8_t *pbSegHdrs, const uint8_t *pbFrame, uint8_t offUdpHdr)
+{
+    PCRTNETUDP pcUdpHdrOrig = (PCRTNETUDP)&pbFrame[offUdpHdr];
+    PRTNETUDP  pUdpHdr = (PRTNETUDP)&pbSegHdrs[offUdpHdr];
+    pUdpHdr->uh_sum = RTNetUDPChecksum(u32PseudoSum, pcUdpHdrOrig);
+}
+
+
+/**
+ * Update a TCP header after carving out a segment.
+ *
+ * @param   u32PseudoSum        The pseudo checksum.
+ * @param   pbSegHdrs           Pointer to the header bytes / frame start.
+ * @param   offTcpHdr           The offset into @a pbSegHdrs of the TCP header.
+ * @param   pbPayload           Pointer to the payload bytes.
+ * @param   cbPayload           The amount of payload.
+ * @param   offPayload          The offset into the payload that we're splitting
+ *                              up.  We're ASSUMING that the payload follows
+ *                              immediately after the TCP header w/ options.
+ * @param   cbHdrs              The size of all the headers.
+ * @param   fLastSeg            Set if this is the last segment.
+ * @param   enmCsumType         Whether to checksum the payload, the pseudo
+ *                              header or nothing.
+ * @internal
+ */
+DECLINLINE(void) pdmNetGsoUpdateTcpHdr(uint32_t u32PseudoSum, uint8_t *pbSegHdrs, uint8_t offTcpHdr,
+                                       uint8_t const *pbPayload, uint32_t cbPayload, uint32_t offPayload, uint8_t cbHdrs,
+                                       bool fLastSeg, PDMNETCSUMTYPE enmCsumType)
+{
+    PRTNETTCP pTcpHdr = (PRTNETTCP)&pbSegHdrs[offTcpHdr];
+    pTcpHdr->th_seq = RT_H2N_U32(RT_N2H_U32(pTcpHdr->th_seq) + offPayload);
+    if (!fLastSeg)
+        pTcpHdr->th_flags &= ~(RTNETTCP_F_FIN | RTNETTCP_F_PSH);
+    switch (enmCsumType)
+    {
+        case PDMNETCSUMTYPE_NONE:
+            pTcpHdr->th_sum = 0;
+            break;
+        case PDMNETCSUMTYPE_COMPLETE:
+            pTcpHdr->th_sum = RTNetTCPChecksum(u32PseudoSum, pTcpHdr, pbPayload, cbPayload);
+            break;
+        case PDMNETCSUMTYPE_PSEUDO:
+            pTcpHdr->th_sum = ~RTNetIPv4FinalizeChecksum(u32PseudoSum);
+            break;
+        default:
+            NOREF(cbHdrs);
+            AssertFailed();
+            break;
+    }
+}
+
+
+/**
+ * Updates a IPv6 header after carving out a segment.
+ *
+ * @returns 32-bit intermediary checksum value for the pseudo header.
+ * @param   pbSegHdrs           Pointer to the header bytes.
+ * @param   offIpHdr            The offset into @a pbSegHdrs of the IP header.
+ * @param   cbSegPayload        The amount of segmented payload.  Not to be
+ *                              confused with the IP payload.
+ * @param   cbHdrs              The size of all the headers.
+ * @param   offPktHdr           Offset of the protocol packet header.  For the
+ *                              pseudo header checksum calulation.
+ * @param   bProtocol           The protocol type.  For the pseudo header.
+ * @internal
+ */
+DECLINLINE(uint32_t) pdmNetGsoUpdateIPv6Hdr(uint8_t *pbSegHdrs, uint8_t offIpHdr, uint32_t cbSegPayload, uint8_t cbHdrs,
+                                            uint8_t offPktHdr, uint8_t bProtocol)
+{
+    PRTNETIPV6 pIpHdr  = (PRTNETIPV6)&pbSegHdrs[offIpHdr];
+    uint16_t cbPayload = (uint16_t)(cbHdrs - (offIpHdr + sizeof(RTNETIPV6)) + cbSegPayload);
+    pIpHdr->ip6_plen   = RT_H2N_U16(cbPayload);
+    return RTNetIPv6PseudoChecksumEx(pIpHdr, bProtocol, (uint16_t)(cbHdrs - offPktHdr + cbSegPayload));
+}
+
+
+/**
+ * Updates a IPv4 header after carving out a segment.
+ *
+ * @returns 32-bit intermediary checksum value for the pseudo header.
+ * @param   pbSegHdrs           Pointer to the header bytes.
+ * @param   offIpHdr            The offset into @a pbSegHdrs of the IP header.
+ * @param   cbSegPayload        The amount of segmented payload.
+ * @param   iSeg                The segment index.
+ * @param   cbHdrs              The size of all the headers.
+ * @internal
+ */
+DECLINLINE(uint32_t) pdmNetGsoUpdateIPv4Hdr(uint8_t *pbSegHdrs, uint8_t offIpHdr, uint32_t cbSegPayload,
+                                            uint32_t iSeg, uint8_t cbHdrs)
+{
+    PRTNETIPV4 pIpHdr = (PRTNETIPV4)&pbSegHdrs[offIpHdr];
+    pIpHdr->ip_len    = RT_H2N_U16(cbHdrs - offIpHdr + cbSegPayload);
+    pIpHdr->ip_id     = RT_H2N_U16(RT_N2H_U16(pIpHdr->ip_id) + iSeg);
+    pIpHdr->ip_sum    = RTNetIPv4HdrChecksum(pIpHdr);
+    return RTNetIPv4PseudoChecksum(pIpHdr);
+}
+
+
+/**
+ * Updates a IPv4 header after carving out an IP fragment.
+ *
+ * @param   pbSegHdrs           Pointer to the header bytes.
+ * @param   offIpHdr            The offset into @a pbSegHdrs of the IP header.
+ * @param   cbSegPayload        The amount of segmented payload.
+ * @param   offFragment         The offset of this fragment for reassembly.
+ * @param   cbHdrs              The size of all the headers.
+ * @param   fLastFragment       True if this is the last fragment of datagram.
+ * @internal
+ */
+DECLINLINE(void) pdmNetGsoUpdateIPv4HdrUfo(uint8_t *pbSegHdrs, uint8_t offIpHdr, uint32_t cbSegPayload,
+                                           uint32_t offFragment, uint8_t cbHdrs, bool fLastFragment)
+{
+    PRTNETIPV4 pIpHdr = (PRTNETIPV4)&pbSegHdrs[offIpHdr];
+    pIpHdr->ip_len    = RT_H2N_U16(cbHdrs - offIpHdr + cbSegPayload);
+    pIpHdr->ip_off    = RT_H2N_U16((offFragment / 8) | (fLastFragment ? 0 : RTNETIPV4_FLAGS_MF));
+    pIpHdr->ip_sum    = RTNetIPv4HdrChecksum(pIpHdr);
+}
+
+
+/**
+ * Carves out the specified segment in a destructive manner.
+ *
+ * This is for sequentially carving out segments and pushing them along for
+ * processing or sending.  To avoid allocating a temporary buffer for
+ * constructing the segment in, we trash the previous frame by putting the
+ * header at the end of it.
+ *
+ * @returns Pointer to the segment frame that we've carved out.
+ * @param   pGso                The GSO context data.
+ * @param   pbFrame             Pointer to the GSO frame.
+ * @param   cbFrame             The size of the GSO frame.
+ * @param   pbHdrScatch         Pointer to a pGso->cbHdrs sized area where we
+ *                              can save the original header prototypes on the
+ *                              first call (@a iSeg is 0) and retrieve it on
+ *                              susequent calls. (Just use a 256 bytes
+ *                              buffer to make life easy.)
+ * @param   iSeg                The segment that we're carving out (0-based).
+ * @param   cSegs               The number of segments in the GSO frame.  Use
+ *                              PDMNetGsoCalcSegmentCount to find this.
+ * @param   pcbSegFrame         Where to return the size of the returned segment
+ *                              frame.
+ */
+DECLINLINE(void *) PDMNetGsoCarveSegmentQD(PCPDMNETWORKGSO pGso, uint8_t *pbFrame, size_t cbFrame, uint8_t *pbHdrScatch,
+                                           uint32_t iSeg, uint32_t cSegs, uint32_t *pcbSegFrame)
+{
+    /*
+     * Figure out where the payload is and where the header starts before we
+     * do the protocol specific carving.
+     *
+     * UDP GSO uses IPv4 fragmentation, meaning that UDP header is present in
+     * the first fragment only. When computing the total frame size of the
+     * first fragment we need to use PDMNETWORKGSO::cbHdrsTotal instead of
+     * PDMNETWORKGSO::cbHdrsSeg. In case of TCP GSO both cbHdrsTotal and
+     * cbHdrsSeg have the same value, so it will work as well.
+     */
+    uint8_t * const pbSegHdrs    = pbFrame + pGso->cbMaxSeg * iSeg;
+    uint8_t * const pbSegPayload = pbSegHdrs + pGso->cbHdrsSeg;
+    uint32_t const  cbSegPayload = pdmNetSegPayloadLen(pGso, iSeg, cSegs, (uint32_t)cbFrame);
+    uint32_t const  cbSegFrame   = cbSegPayload + (iSeg ? pGso->cbHdrsSeg : pGso->cbHdrsTotal);
+
+    /*
+     * Check assumptions (doing it after declaring the variables because of C).
+     */
+    Assert(iSeg < cSegs);
+    Assert(cSegs == PDMNetGsoCalcSegmentCount(pGso, cbFrame));
+    Assert(PDMNetGsoIsValid(pGso, sizeof(*pGso), cbFrame));
+
+    /*
+     * Copy the header and do the protocol specific massaging of it.
+     */
+    if (iSeg != 0)
+        memcpy(pbSegHdrs, pbHdrScatch, pGso->cbHdrsSeg);
+    else
+        memcpy(pbHdrScatch, pbSegHdrs, pGso->cbHdrsSeg); /* There is no need to save UDP header */
+
+    switch ((PDMNETWORKGSOTYPE)pGso->u8Type)
+    {
+        case PDMNETWORKGSOTYPE_IPV4_TCP:
+            pdmNetGsoUpdateTcpHdr(pdmNetGsoUpdateIPv4Hdr(pbSegHdrs, pGso->offHdr1, cbSegPayload, iSeg, pGso->cbHdrsSeg),
+                                  pbSegHdrs, pGso->offHdr2, pbSegPayload, cbSegPayload, iSeg * pGso->cbMaxSeg,
+                                  pGso->cbHdrsSeg, iSeg + 1 == cSegs, PDMNETCSUMTYPE_COMPLETE);
+            break;
+        case PDMNETWORKGSOTYPE_IPV4_UDP:
+            if (iSeg == 0)
+            {
+                /* uh_ulen shall not exceed cbFrame - pGso->offHdr2 (offset of UDP header) */
+                PRTNETUDP pUdpHdr = (PRTNETUDP)&pbFrame[pGso->offHdr2];
+                Assert(pGso->offHdr2 + RT_UOFFSET_AFTER(RTNETUDP, uh_ulen) <= cbFrame);
+                if ((unsigned)(pGso->offHdr2 + RT_BE2H_U16(pUdpHdr->uh_ulen)) > cbFrame)
+                {
+                    size_t cbUdp = cbFrame - pGso->offHdr2;
+                    if (cbUdp >= UINT16_MAX)
+                        pUdpHdr->uh_ulen = UINT16_MAX;
+                    else
+                        pUdpHdr->uh_ulen = RT_H2BE_U16((uint16_t)cbUdp);
+                }
+                /* uh_ulen shall be at least the size of UDP header */
+                if (RT_BE2H_U16(pUdpHdr->uh_ulen) < sizeof(RTNETUDP))
+                    pUdpHdr->uh_ulen = RT_H2BE_U16(sizeof(RTNETUDP));
+                pdmNetGsoUpdateUdpHdrUfo(RTNetIPv4PseudoChecksum((PRTNETIPV4)&pbFrame[pGso->offHdr1]),
+                                         pbSegHdrs, pbFrame, pGso->offHdr2);
+            }
+            pdmNetGsoUpdateIPv4HdrUfo(pbSegHdrs, pGso->offHdr1, cbSegPayload, iSeg * pGso->cbMaxSeg,
+                                      pdmNetSegHdrLen(pGso, iSeg), iSeg + 1 == cSegs);
+            break;
+        case PDMNETWORKGSOTYPE_IPV6_TCP:
+            pdmNetGsoUpdateTcpHdr(pdmNetGsoUpdateIPv6Hdr(pbSegHdrs, pGso->offHdr1, cbSegPayload, pGso->cbHdrsSeg,
+                                                         pGso->offHdr2, RTNETIPV4_PROT_TCP),
+                                  pbSegHdrs, pGso->offHdr2, pbSegPayload, cbSegPayload, iSeg * pGso->cbMaxSeg,
+                                  pGso->cbHdrsSeg, iSeg + 1 == cSegs, PDMNETCSUMTYPE_COMPLETE);
+            break;
+        case PDMNETWORKGSOTYPE_IPV6_UDP:
+            pdmNetGsoUpdateUdpHdr(pdmNetGsoUpdateIPv6Hdr(pbSegHdrs, pGso->offHdr1, cbSegPayload, pGso->cbHdrsSeg,
+                                                         pGso->offHdr2, RTNETIPV4_PROT_UDP),
+                                  pbSegHdrs, pGso->offHdr2, pbSegPayload, cbSegPayload, pGso->cbHdrsSeg, PDMNETCSUMTYPE_COMPLETE);
+            break;
+        case PDMNETWORKGSOTYPE_IPV4_IPV6_TCP:
+            pdmNetGsoUpdateIPv4Hdr(pbSegHdrs, pGso->offHdr1, cbSegPayload, iSeg, pGso->cbHdrsSeg);
+            pdmNetGsoUpdateTcpHdr(pdmNetGsoUpdateIPv6Hdr(pbSegHdrs, pgmNetGsoCalcIpv6Offset(pbSegHdrs, pGso->offHdr1),
+                                                         cbSegPayload, pGso->cbHdrsSeg, pGso->offHdr2, RTNETIPV4_PROT_TCP),
+                                  pbSegHdrs, pGso->offHdr2, pbSegPayload, cbSegPayload, iSeg * pGso->cbMaxSeg,
+                                  pGso->cbHdrsSeg, iSeg + 1 == cSegs, PDMNETCSUMTYPE_COMPLETE);
+            break;
+        case PDMNETWORKGSOTYPE_IPV4_IPV6_UDP:
+            pdmNetGsoUpdateIPv4Hdr(pbSegHdrs, pGso->offHdr1, cbSegPayload, iSeg, pGso->cbHdrsSeg);
+            pdmNetGsoUpdateUdpHdr(pdmNetGsoUpdateIPv6Hdr(pbSegHdrs, pgmNetGsoCalcIpv6Offset(pbSegHdrs, pGso->offHdr1),
+                                                         cbSegPayload, pGso->cbHdrsSeg, pGso->offHdr2, RTNETIPV4_PROT_UDP),
+                                  pbSegHdrs, pGso->offHdr2, pbSegPayload, cbSegPayload, pGso->cbHdrsSeg, PDMNETCSUMTYPE_COMPLETE);
+            break;
+        case PDMNETWORKGSOTYPE_INVALID:
+        case PDMNETWORKGSOTYPE_END:
+            /* no default! wnat gcc warnings. */
+            break;
+    }
+
+    *pcbSegFrame = cbSegFrame;
+    return pbSegHdrs;
+}
+
+
+/**
+ * Carves out the specified segment in a non-destructive manner.
+ *
+ * The segment headers and segment payload is kept separate here.  The GSO frame
+ * is still expected to be one linear chunk of data, but we don't modify any of
+ * it.
+ *
+ * @returns The offset into the GSO frame of the payload.
+ * @param   pGso                The GSO context data.
+ * @param   pbFrame             Pointer to the GSO frame.  Used for retrieving
+ *                              the header prototype and for checksumming the
+ *                              payload.  The buffer is not modified.
+ * @param   cbFrame             The size of the GSO frame.
+ * @param   iSeg                The segment that we're carving out (0-based).
+ * @param   cSegs               The number of segments in the GSO frame.  Use
+ *                              PDMNetGsoCalcSegmentCount to find this.
+ * @param   pbSegHdrs           Where to return the headers for the segment
+ *                              that's been carved out.  The buffer must be at
+ *                              least pGso->cbHdrs in size, using a 256 byte
+ *                              buffer is a recommended simplification.
+ * @param   pcbSegHdrs          Where to return the size of the returned
+ *                              segment headers.
+ * @param   pcbSegPayload       Where to return the size of the returned
+ *                              segment payload.
+ */
+DECLINLINE(uint32_t) PDMNetGsoCarveSegment(PCPDMNETWORKGSO pGso, const uint8_t *pbFrame, size_t cbFrame,
+                                           uint32_t iSeg, uint32_t cSegs, uint8_t *pbSegHdrs,
+                                           uint32_t *pcbSegHdrs, uint32_t *pcbSegPayload)
+{
+    /*
+     * Figure out where the payload is and where the header starts before we
+     * do the protocol specific carving.
+     */
+    uint32_t const        cbSegHdrs    = pdmNetSegHdrLen(pGso, iSeg);
+    uint8_t const * const pbSegPayload = pbFrame + cbSegHdrs + iSeg * pGso->cbMaxSeg;
+    uint32_t const        cbSegPayload = pdmNetSegPayloadLen(pGso, iSeg, cSegs, (uint32_t)cbFrame);
+
+    /*
+     * Check assumptions (doing it after declaring the variables because of C).
+     */
+    Assert(iSeg < cSegs);
+    Assert(cSegs == PDMNetGsoCalcSegmentCount(pGso, cbFrame));
+    Assert(PDMNetGsoIsValid(pGso, sizeof(*pGso), cbFrame));
+
+    /*
+     * Copy the header and do the protocol specific massaging of it.
+     */
+    memcpy(pbSegHdrs, pbFrame, pGso->cbHdrsTotal); /* include UDP header */
+
+    switch ((PDMNETWORKGSOTYPE)pGso->u8Type)
+    {
+        case PDMNETWORKGSOTYPE_IPV4_TCP:
+            pdmNetGsoUpdateTcpHdr(pdmNetGsoUpdateIPv4Hdr(pbSegHdrs, pGso->offHdr1, cbSegPayload, iSeg, cbSegHdrs),
+                                  pbSegHdrs, pGso->offHdr2, pbSegPayload, cbSegPayload, iSeg * pGso->cbMaxSeg,
+                                  cbSegHdrs, iSeg + 1 == cSegs, PDMNETCSUMTYPE_COMPLETE);
+            break;
+        case PDMNETWORKGSOTYPE_IPV4_UDP:
+            if (iSeg == 0)
+            {
+                /* uh_ulen shall not exceed cbFrame - pGso->offHdr2 (offset of UDP header) */
+                PRTNETUDP pUdpHdr = (PRTNETUDP)&pbFrame[pGso->offHdr2];
+                Assert(pGso->offHdr2 + RT_UOFFSET_AFTER(RTNETUDP, uh_ulen) <= cbFrame);
+                if ((unsigned)(pGso->offHdr2 + RT_BE2H_U16(pUdpHdr->uh_ulen)) > cbFrame)
+                {
+                    size_t cbUdp = cbFrame - pGso->offHdr2;
+                    if (cbUdp >= UINT16_MAX)
+                        pUdpHdr->uh_ulen = UINT16_MAX;
+                    else
+                        pUdpHdr->uh_ulen = RT_H2BE_U16((uint16_t)cbUdp);
+                }
+                /* uh_ulen shall be at least the size of UDP header */
+                if (RT_BE2H_U16(pUdpHdr->uh_ulen) < sizeof(RTNETUDP))
+                    pUdpHdr->uh_ulen = RT_H2BE_U16(sizeof(RTNETUDP));
+                pdmNetGsoUpdateUdpHdrUfo(RTNetIPv4PseudoChecksum((PRTNETIPV4)&pbFrame[pGso->offHdr1]),
+                                         pbSegHdrs, pbFrame, pGso->offHdr2);
+            }
+            pdmNetGsoUpdateIPv4HdrUfo(pbSegHdrs, pGso->offHdr1, cbSegPayload, iSeg * pGso->cbMaxSeg,
+                                      cbSegHdrs, iSeg + 1 == cSegs);
+            break;
+        case PDMNETWORKGSOTYPE_IPV6_TCP:
+            pdmNetGsoUpdateTcpHdr(pdmNetGsoUpdateIPv6Hdr(pbSegHdrs, pGso->offHdr1, cbSegPayload, cbSegHdrs,
+                                                         pGso->offHdr2, RTNETIPV4_PROT_TCP),
+                                  pbSegHdrs, pGso->offHdr2, pbSegPayload, cbSegPayload, iSeg * pGso->cbMaxSeg,
+                                  cbSegHdrs, iSeg + 1 == cSegs, PDMNETCSUMTYPE_COMPLETE);
+            break;
+        case PDMNETWORKGSOTYPE_IPV6_UDP:
+            pdmNetGsoUpdateUdpHdr(pdmNetGsoUpdateIPv6Hdr(pbSegHdrs, pGso->offHdr1, cbSegPayload, cbSegHdrs,
+                                                         pGso->offHdr2, RTNETIPV4_PROT_UDP),
+                                  pbSegHdrs, pGso->offHdr2, pbSegPayload, cbSegPayload, cbSegHdrs, PDMNETCSUMTYPE_COMPLETE);
+            break;
+        case PDMNETWORKGSOTYPE_IPV4_IPV6_TCP:
+            pdmNetGsoUpdateIPv4Hdr(pbSegHdrs, pGso->offHdr1, cbSegPayload, iSeg, cbSegHdrs);
+            pdmNetGsoUpdateTcpHdr(pdmNetGsoUpdateIPv6Hdr(pbSegHdrs, pgmNetGsoCalcIpv6Offset(pbSegHdrs, pGso->offHdr1),
+                                                         cbSegPayload, cbSegHdrs, pGso->offHdr2, RTNETIPV4_PROT_TCP),
+                                  pbSegHdrs, pGso->offHdr2, pbSegPayload, cbSegPayload, iSeg * pGso->cbMaxSeg,
+                                  cbSegHdrs, iSeg + 1 == cSegs, PDMNETCSUMTYPE_COMPLETE);
+            break;
+        case PDMNETWORKGSOTYPE_IPV4_IPV6_UDP:
+            pdmNetGsoUpdateIPv4Hdr(pbSegHdrs, pGso->offHdr1, cbSegPayload, iSeg, cbSegHdrs);
+            pdmNetGsoUpdateUdpHdr(pdmNetGsoUpdateIPv6Hdr(pbSegHdrs, pgmNetGsoCalcIpv6Offset(pbSegHdrs, pGso->offHdr1),
+                                                         cbSegPayload, cbSegHdrs, pGso->offHdr2, RTNETIPV4_PROT_UDP),
+                                  pbSegHdrs, pGso->offHdr2, pbSegPayload, cbSegPayload, cbSegHdrs, PDMNETCSUMTYPE_COMPLETE);
+            break;
+        case PDMNETWORKGSOTYPE_INVALID:
+        case PDMNETWORKGSOTYPE_END:
+            /* no default! wnat gcc warnings. */
+            break;
+    }
+
+    *pcbSegHdrs    = cbSegHdrs;
+    *pcbSegPayload = cbSegPayload;
+    return cbSegHdrs + iSeg * pGso->cbMaxSeg;
+}
+
+
+/**
+ * Prepares the GSO frame for direct use without any segmenting.
+ *
+ * @param   pGso                The GSO context.
+ * @param   pvFrame             The frame to prepare.
+ * @param   cbFrame             The frame size.
+ * @param   enmCsumType         Whether to checksum the payload, the pseudo
+ *                              header or nothing.
+ */
+DECLINLINE(void) PDMNetGsoPrepForDirectUse(PCPDMNETWORKGSO pGso, void *pvFrame, size_t cbFrame, PDMNETCSUMTYPE enmCsumType)
+{
+    /*
+     * Figure out where the payload is and where the header starts before we
+     * do the protocol bits.
+     */
+    uint8_t * const pbHdrs    = (uint8_t *)pvFrame;
+    uint8_t * const pbPayload = pbHdrs  + pGso->cbHdrsTotal;
+    uint32_t  const cbFrame32 = (uint32_t)cbFrame;
+    uint32_t  const cbPayload = cbFrame32 - pGso->cbHdrsTotal;
+
+    /*
+     * Check assumptions (doing it after declaring the variables because of C).
+     */
+    Assert(PDMNetGsoIsValid(pGso, sizeof(*pGso), cbFrame));
+
+    /*
+     * Get down to busienss.
+     */
+    switch ((PDMNETWORKGSOTYPE)pGso->u8Type)
+    {
+        case PDMNETWORKGSOTYPE_IPV4_TCP:
+            pdmNetGsoUpdateTcpHdr(pdmNetGsoUpdateIPv4Hdr(pbHdrs, pGso->offHdr1, cbFrame32 - pGso->cbHdrsTotal, 0, pGso->cbHdrsTotal),
+                                  pbHdrs, pGso->offHdr2, pbPayload, cbPayload, 0, pGso->cbHdrsTotal, true, enmCsumType);
+            break;
+        case PDMNETWORKGSOTYPE_IPV4_UDP:
+            pdmNetGsoUpdateUdpHdr(pdmNetGsoUpdateIPv4Hdr(pbHdrs, pGso->offHdr1, cbFrame32 - pGso->cbHdrsTotal, 0, pGso->cbHdrsTotal),
+                                  pbHdrs, pGso->offHdr2, pbPayload, cbPayload, pGso->cbHdrsTotal, enmCsumType);
+            break;
+        case PDMNETWORKGSOTYPE_IPV6_TCP:
+            pdmNetGsoUpdateTcpHdr(pdmNetGsoUpdateIPv6Hdr(pbHdrs, pGso->offHdr1, cbPayload, pGso->cbHdrsTotal,
+                                                         pGso->offHdr2, RTNETIPV4_PROT_TCP),
+                                  pbHdrs, pGso->offHdr2, pbPayload, cbPayload, 0, pGso->cbHdrsTotal, true, enmCsumType);
+            break;
+        case PDMNETWORKGSOTYPE_IPV6_UDP:
+            pdmNetGsoUpdateUdpHdr(pdmNetGsoUpdateIPv6Hdr(pbHdrs, pGso->offHdr1, cbPayload, pGso->cbHdrsTotal,
+                                                         pGso->offHdr2, RTNETIPV4_PROT_UDP),
+                                  pbHdrs, pGso->offHdr2, pbPayload, cbPayload, pGso->cbHdrsTotal, enmCsumType);
+            break;
+        case PDMNETWORKGSOTYPE_IPV4_IPV6_TCP:
+            pdmNetGsoUpdateIPv4Hdr(pbHdrs, pGso->offHdr1, cbPayload, 0, pGso->cbHdrsTotal);
+            pdmNetGsoUpdateTcpHdr(pdmNetGsoUpdateIPv6Hdr(pbHdrs, pgmNetGsoCalcIpv6Offset(pbHdrs, pGso->offHdr1),
+                                                         cbPayload, pGso->cbHdrsTotal, pGso->offHdr2, RTNETIPV4_PROT_TCP),
+                                  pbHdrs, pGso->offHdr2, pbPayload, cbPayload, 0, pGso->cbHdrsTotal, true, enmCsumType);
+            break;
+        case PDMNETWORKGSOTYPE_IPV4_IPV6_UDP:
+            pdmNetGsoUpdateIPv4Hdr(pbHdrs, pGso->offHdr1, cbPayload, 0, pGso->cbHdrsTotal);
+            pdmNetGsoUpdateUdpHdr(pdmNetGsoUpdateIPv6Hdr(pbHdrs, pgmNetGsoCalcIpv6Offset(pbHdrs, pGso->offHdr1),
+                                                         cbPayload, pGso->cbHdrsTotal, pGso->offHdr2, RTNETIPV4_PROT_UDP),
+                                  pbHdrs, pGso->offHdr2, pbPayload, cbPayload, pGso->cbHdrsTotal, enmCsumType);
+            break;
+        case PDMNETWORKGSOTYPE_INVALID:
+        case PDMNETWORKGSOTYPE_END:
+            /* no default! wnat gcc warnings. */
+            break;
+    }
+}
+
+
+/**
+ * Gets the GSO type name string.
+ *
+ * @returns Pointer to read only name string.
+ * @param   enmType             The type.
+ */
+DECLINLINE(const char *) PDMNetGsoTypeName(PDMNETWORKGSOTYPE enmType)
+{
+    switch (enmType)
+    {
+        case PDMNETWORKGSOTYPE_IPV4_TCP:        return "TCPv4";
+        case PDMNETWORKGSOTYPE_IPV6_TCP:        return "TCPv6";
+        case PDMNETWORKGSOTYPE_IPV4_UDP:        return "UDPv4";
+        case PDMNETWORKGSOTYPE_IPV6_UDP:        return "UDPv6";
+        case PDMNETWORKGSOTYPE_IPV4_IPV6_TCP:   return "4to6TCP";
+        case PDMNETWORKGSOTYPE_IPV4_IPV6_UDP:   return "4to6UDP";
+        case PDMNETWORKGSOTYPE_INVALID:         return "invalid";
+        case PDMNETWORKGSOTYPE_END:             return "end";
+    }
+    return "bad-gso-type";
+}
+
+/** @} */
+
+#endif /* !VBOX_INCLUDED_vmm_pdmnetinline_h */
+