ip6_output: update comments.
Clear up some comments and improve to panic messages. No functional changes. MFC after: 3 days
This commit is contained in:
Bjoern A. Zeeb
parent
e8c4b9d46b
commit
7c1daefe2c
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=358071
@ -181,7 +181,9 @@ static int copypktopts(struct ip6_pktopts *, struct ip6_pktopts *, int);
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do {\
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if (m) {\
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if (!hdrsplit) \
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panic("assumption failed: hdr not split"); \
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panic("%s:%d: assumption failed: "\
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"hdr not split: hdrsplit %d exthdrs %p",\
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__func__, __LINE__, hdrsplit, &exthdrs);\
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*mtod((m), u_char *) = *(p);\
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*(p) = (i);\
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p = mtod((m), u_char *);\
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@ -356,8 +358,9 @@ ip6_output_send(struct inpcb *inp, struct ifnet *ifp, struct ifnet *origifp,
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}
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/*
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* IP6 output. The packet in mbuf chain m contains a skeletal IP6
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* header (with pri, len, nxt, hlim, src, dst).
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* IP6 output.
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* The packet in mbuf chain m contains a skeletal IP6 header (with pri, len,
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* nxt, hlim, src, dst).
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* This function may modify ver and hlim only.
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* The mbuf chain containing the packet will be freed.
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* The mbuf opt, if present, will not be freed.
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@ -365,9 +368,8 @@ ip6_output_send(struct inpcb *inp, struct ifnet *ifp, struct ifnet *origifp,
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* skipped and ro->ro_rt would be used. If ro is present but ro->ro_rt is NULL,
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* then result of route lookup is stored in ro->ro_rt.
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*
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* type of "mtu": rt_mtu is u_long, ifnet.ifr_mtu is int, and
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* nd_ifinfo.linkmtu is u_int32_t. so we use u_long to hold largest one,
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* which is rt_mtu.
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* Type of "mtu": rt_mtu is u_long, ifnet.ifr_mtu is int, and nd_ifinfo.linkmtu
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* is uint32_t. So we use u_long to hold largest one, which is rt_mtu.
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*
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* ifpp - XXX: just for statistics
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*/
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@ -410,7 +412,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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INP_LOCK_ASSERT(inp);
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M_SETFIB(m, inp->inp_inc.inc_fibnum);
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if ((flags & IP_NODEFAULTFLOWID) == 0) {
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/* unconditionally set flowid */
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/* Unconditionally set flowid. */
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m->m_pkthdr.flowid = inp->inp_flowid;
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M_HASHTYPE_SET(m, inp->inp_flowtype);
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}
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@ -436,12 +438,12 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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bzero(&exthdrs, sizeof(exthdrs));
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if (opt) {
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/* Hop-by-Hop options header */
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/* Hop-by-Hop options header. */
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MAKE_EXTHDR(opt->ip6po_hbh, &exthdrs.ip6e_hbh);
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/* Destination options header(1st part) */
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/* Destination options header (1st part). */
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if (opt->ip6po_rthdr) {
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/*
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* Destination options header(1st part)
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* Destination options header (1st part).
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* This only makes sense with a routing header.
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* See Section 9.2 of RFC 3542.
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* Disabling this part just for MIP6 convenience is
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@ -452,9 +454,9 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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*/
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MAKE_EXTHDR(opt->ip6po_dest1, &exthdrs.ip6e_dest1);
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}
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/* Routing header */
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/* Routing header. */
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MAKE_EXTHDR(opt->ip6po_rthdr, &exthdrs.ip6e_rthdr);
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/* Destination options header(2nd part) */
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/* Destination options header (2nd part). */
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MAKE_EXTHDR(opt->ip6po_dest2, &exthdrs.ip6e_dest2);
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}
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@ -471,7 +473,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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optlen += exthdrs.ip6e_rthdr->m_len;
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unfragpartlen = optlen + sizeof(struct ip6_hdr);
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/* NOTE: we don't add AH/ESP length here (done in ip6_ipsec_output) */
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/* NOTE: we don't add AH/ESP length here (done in ip6_ipsec_output). */
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if (exthdrs.ip6e_dest2)
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optlen += exthdrs.ip6e_dest2->m_len;
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@ -490,7 +492,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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ip6 = mtod(m, struct ip6_hdr *);
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/* adjust mbuf packet header length */
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/* Adjust mbuf packet header length. */
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m->m_pkthdr.len += optlen;
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plen = m->m_pkthdr.len - sizeof(*ip6);
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@ -504,7 +506,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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m = exthdrs.ip6e_ip6;
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hdrsplit++;
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}
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/* adjust pointer */
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/* Adjust pointer. */
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ip6 = mtod(m, struct ip6_hdr *);
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if ((error = ip6_insert_jumboopt(&exthdrs, plen)) != 0)
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goto freehdrs;
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@ -516,26 +518,29 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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* Concatenate headers and fill in next header fields.
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* Here we have, on "m"
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* IPv6 payload
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* and we insert headers accordingly. Finally, we should be getting:
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* IPv6 hbh dest1 rthdr ah* [esp* dest2 payload]
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* and we insert headers accordingly.
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* Finally, we should be getting:
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* IPv6 hbh dest1 rthdr ah* [esp* dest2 payload].
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*
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* during the header composing process, "m" points to IPv6 header.
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* "mprev" points to an extension header prior to esp.
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* During the header composing process "m" points to IPv6
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* header. "mprev" points to an extension header prior to esp.
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*/
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u_char *nexthdrp = &ip6->ip6_nxt;
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mprev = m;
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/*
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* we treat dest2 specially. this makes IPsec processing
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* much easier. the goal here is to make mprev point the
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* We treat dest2 specially. This makes IPsec processing
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* much easier. The goal here is to make mprev point the
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* mbuf prior to dest2.
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*
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* result: IPv6 dest2 payload
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* Result: IPv6 dest2 payload.
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* m and mprev will point to IPv6 header.
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*/
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if (exthdrs.ip6e_dest2) {
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if (!hdrsplit)
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panic("assumption failed: hdr not split");
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panic("%s:%d: assumption failed: "
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"hdr not split: hdrsplit %d exthdrs %p",
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__func__, __LINE__, hdrsplit, &exthdrs);
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exthdrs.ip6e_dest2->m_next = m->m_next;
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m->m_next = exthdrs.ip6e_dest2;
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*mtod(exthdrs.ip6e_dest2, u_char *) = ip6->ip6_nxt;
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@ -543,7 +548,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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}
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/*
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* result: IPv6 hbh dest1 rthdr dest2 payload
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* Result: IPv6 hbh dest1 rthdr dest2 payload.
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* m will point to IPv6 header. mprev will point to the
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* extension header prior to dest2 (rthdr in the above case).
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*/
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@ -553,15 +558,13 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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MAKE_CHAIN(exthdrs.ip6e_rthdr, mprev, nexthdrp,
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IPPROTO_ROUTING);
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/*
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* If there is a routing header, discard the packet.
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*/
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/* If there is a routing header, discard the packet. */
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if (exthdrs.ip6e_rthdr) {
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error = EINVAL;
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goto bad;
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}
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/* Source address validation */
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/* Source address validation. */
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if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src) &&
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(flags & IPV6_UNSPECSRC) == 0) {
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error = EOPNOTSUPP;
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@ -576,9 +579,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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IP6STAT_INC(ip6s_localout);
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/*
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* Route packet.
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*/
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/* Route packet. */
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if (ro == NULL) {
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ro = &ip6route;
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bzero((caddr_t)ro, sizeof(*ro));
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@ -590,9 +591,9 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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fibnum = (inp != NULL) ? inp->inp_inc.inc_fibnum : M_GETFIB(m);
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again:
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/*
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* if specified, try to fill in the traffic class field.
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* do not override if a non-zero value is already set.
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* we check the diffserv field and the ecn field separately.
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* If specified, try to fill in the traffic class field.
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* Do not override if a non-zero value is already set.
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* We check the diffserv field and the ECN field separately.
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*/
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if (opt && opt->ip6po_tclass >= 0) {
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int mask = 0;
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@ -605,7 +606,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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ip6->ip6_flow |= htonl((opt->ip6po_tclass & mask) << 20);
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}
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/* fill in or override the hop limit field, if necessary. */
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/* Fill in or override the hop limit field, if necessary. */
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if (opt && opt->ip6po_hlim != -1)
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ip6->ip6_hlim = opt->ip6po_hlim & 0xff;
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else if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
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@ -617,7 +618,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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/*
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* Validate route against routing table additions;
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* a better/more specific route might have been added.
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* Make sure address family is set in route.
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* Make sure that the address family is set in route.
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*/
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if (inp) {
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ro->ro_dst.sin6_family = AF_INET6;
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@ -648,15 +649,13 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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}
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if (rt == NULL) {
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/*
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* If in6_selectroute() does not return a route entry,
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* If in6_selectroute() does not return a route entry
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* dst may not have been updated.
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*/
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*dst = dst_sa; /* XXX */
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}
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/*
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* then rt (for unicast) and ifp must be non-NULL valid values.
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*/
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/* Then rt (for unicast) and ifp must be non-NULL valid values. */
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if ((flags & IPV6_FORWARDING) == 0) {
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/* XXX: the FORWARDING flag can be set for mrouting. */
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in6_ifstat_inc(ifp, ifs6_out_request);
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@ -674,7 +673,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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src_sa.sin6_addr = ip6->ip6_src;
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dst0 = ip6->ip6_dst;
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/* re-initialize to be sure */
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/* Re-initialize to be sure. */
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bzero(&dst_sa, sizeof(dst_sa));
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dst_sa.sin6_family = AF_INET6;
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dst_sa.sin6_len = sizeof(dst_sa);
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@ -691,7 +690,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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*
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* Because the loopback interface cannot receive
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* packets with a different scope ID than its own,
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* there is a trick is to pretend the outgoing packet
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* there is a trick to pretend the outgoing packet
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* was received by the real network interface, by
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* setting "origifp" different from "ifp". This is
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* only allowed when "ifp" is a loopback network
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@ -729,7 +728,6 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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error = EHOSTUNREACH; /* XXX */
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goto bad;
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}
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/* All scope ID checks are successful. */
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if (rt && !IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
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@ -746,13 +744,12 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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}
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if (!IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
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m->m_flags &= ~(M_BCAST | M_MCAST); /* just in case */
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m->m_flags &= ~(M_BCAST | M_MCAST); /* Just in case. */
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} else {
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m->m_flags = (m->m_flags & ~M_BCAST) | M_MCAST;
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in6_ifstat_inc(ifp, ifs6_out_mcast);
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/*
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* Confirm that the outgoing interface supports multicast.
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*/
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/* Confirm that the outgoing interface supports multicast. */
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if (!(ifp->if_flags & IFF_MULTICAST)) {
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IP6STAT_INC(ip6s_noroute);
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in6_ifstat_inc(ifp, ifs6_out_discard);
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@ -847,8 +844,8 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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}
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/*
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* clear embedded scope identifiers if necessary.
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* in6_clearscope will touch the addresses only when necessary.
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* Clear embedded scope identifiers if necessary.
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* in6_clearscope() will touch the addresses only when necessary.
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*/
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in6_clearscope(&ip6->ip6_src);
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in6_clearscope(&ip6->ip6_dst);
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@ -878,7 +875,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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if (ip6_process_hopopts(m, (u_int8_t *)(hbh + 1),
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((hbh->ip6h_len + 1) << 3) - sizeof(struct ip6_hbh),
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&dummy, &plen) < 0) {
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/* m was already freed at this point */
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/* m was already freed at this point. */
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error = EINVAL;/* better error? */
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goto done;
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}
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@ -970,7 +967,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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* Send the packet to the outgoing interface.
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* If necessary, do IPv6 fragmentation before sending.
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*
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* the logic here is rather complex:
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* The logic here is rather complex:
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* 1: normal case (dontfrag == 0, alwaysfrag == 0)
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* 1-a: send as is if tlen <= path mtu
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* 1-b: fragment if tlen > path mtu
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@ -983,7 +980,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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* always fragment
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*
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* 4: if dontfrag == 1 && alwaysfrag == 1
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* error, as we cannot handle this conflicting request
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* error, as we cannot handle this conflicting request.
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*/
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sw_csum = m->m_pkthdr.csum_flags;
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if (!hdrsplit) {
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@ -1033,12 +1030,12 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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dontfrag = 1;
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else
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dontfrag = 0;
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if (dontfrag && alwaysfrag) { /* case 4 */
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/* conflicting request - can't transmit */
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if (dontfrag && alwaysfrag) { /* Case 4. */
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/* Conflicting request - can't transmit. */
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error = EMSGSIZE;
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goto bad;
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}
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if (dontfrag && tlen > IN6_LINKMTU(ifp) && !tso) { /* case 2-b */
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if (dontfrag && tlen > IN6_LINKMTU(ifp) && !tso) { /* Case 2-b. */
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/*
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* Even if the DONTFRAG option is specified, we cannot send the
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* packet when the data length is larger than the MTU of the
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@ -1053,10 +1050,8 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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goto bad;
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}
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/*
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* transmit packet without fragmentation
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*/
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if (dontfrag || (!alwaysfrag && tlen <= mtu)) { /* case 1-a and 2-a */
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/* Transmit packet without fragmentation. */
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if (dontfrag || (!alwaysfrag && tlen <= mtu)) { /* Cases 1-a and 2-a. */
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struct in6_ifaddr *ia6;
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ip6 = mtod(m, struct ip6_hdr *);
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@ -1072,16 +1067,14 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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goto done;
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}
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/*
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* try to fragment the packet. case 1-b and 3
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*/
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/* Try to fragment the packet. Cases 1-b and 3. */
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if (mtu < IPV6_MMTU) {
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/* path MTU cannot be less than IPV6_MMTU */
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/* Path MTU cannot be less than IPV6_MMTU. */
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error = EMSGSIZE;
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in6_ifstat_inc(ifp, ifs6_out_fragfail);
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goto bad;
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} else if (ip6->ip6_plen == 0) {
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/* jumbo payload cannot be fragmented */
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/* Jumbo payload cannot be fragmented. */
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error = EMSGSIZE;
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in6_ifstat_inc(ifp, ifs6_out_fragfail);
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goto bad;
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@ -1162,9 +1155,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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in6_ifstat_inc(ifp, ifs6_out_fragok);
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}
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/*
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* Remove leading garbages.
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*/
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/* Remove leading garbage. */
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sendorfree:
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m = m0->m_nextpkt;
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m0->m_nextpkt = 0;
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@ -1193,7 +1184,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
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return (error);
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freehdrs:
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m_freem(exthdrs.ip6e_hbh); /* m_freem will check if mbuf is 0 */
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m_freem(exthdrs.ip6e_hbh); /* m_freem() checks if mbuf is NULL. */
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m_freem(exthdrs.ip6e_dest1);
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m_freem(exthdrs.ip6e_rthdr);
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m_freem(exthdrs.ip6e_dest2);
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