Author: bz
Date: Tue Feb 18 11:28:00 2020
New Revision: 358071
URL: https://svnweb.freebsd.org/changeset/base/358071
Log:
ip6_output: update comments.
Clear up some comments and improve to panic messages.
No functional changes.
MFC after: 3 days
Modified:
head/sys/netinet6/ip6_output.c
Modified: head/sys/netinet6/ip6_output.c
==============================================================================
--- head/sys/netinet6/ip6_output.c Tue Feb 18 11:27:08 2020
(r358070)
+++ head/sys/netinet6/ip6_output.c Tue Feb 18 11:28:00 2020
(r358071)
@@ -181,7 +181,9 @@ static int copypktopts(struct ip6_pktopts *, struct ip
do {\
if (m) {\
if (!hdrsplit) \
- panic("assumption failed: hdr not split"); \
+ panic("%s:%d: assumption failed: "\
+ "hdr not split: hdrsplit %d exthdrs %p",\
+ __func__, __LINE__, hdrsplit, &exthdrs);\
*mtod((m), u_char *) = *(p);\
*(p) = (i);\
p = mtod((m), u_char *);\
@@ -356,8 +358,9 @@ done:
}
/*
- * IP6 output. The packet in mbuf chain m contains a skeletal IP6
- * header (with pri, len, nxt, hlim, src, dst).
+ * IP6 output.
+ * The packet in mbuf chain m contains a skeletal IP6 header (with pri, len,
+ * nxt, hlim, src, dst).
* This function may modify ver and hlim only.
* The mbuf chain containing the packet will be freed.
* The mbuf opt, if present, will not be freed.
@@ -365,9 +368,8 @@ done:
* skipped and ro->ro_rt would be used. If ro is present but ro->ro_rt is NULL,
* then result of route lookup is stored in ro->ro_rt.
*
- * type of "mtu": rt_mtu is u_long, ifnet.ifr_mtu is int, and
- * nd_ifinfo.linkmtu is u_int32_t. so we use u_long to hold largest one,
- * which is rt_mtu.
+ * Type of "mtu": rt_mtu is u_long, ifnet.ifr_mtu is int, and nd_ifinfo.linkmtu
+ * is uint32_t. So we use u_long to hold largest one, which is rt_mtu.
*
* ifpp - XXX: just for statistics
*/
@@ -410,7 +412,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
INP_LOCK_ASSERT(inp);
M_SETFIB(m, inp->inp_inc.inc_fibnum);
if ((flags & IP_NODEFAULTFLOWID) == 0) {
- /* unconditionally set flowid */
+ /* Unconditionally set flowid. */
m->m_pkthdr.flowid = inp->inp_flowid;
M_HASHTYPE_SET(m, inp->inp_flowtype);
}
@@ -436,12 +438,12 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
bzero(&exthdrs, sizeof(exthdrs));
if (opt) {
- /* Hop-by-Hop options header */
+ /* Hop-by-Hop options header. */
MAKE_EXTHDR(opt->ip6po_hbh, &exthdrs.ip6e_hbh);
- /* Destination options header(1st part) */
+ /* Destination options header (1st part). */
if (opt->ip6po_rthdr) {
/*
- * Destination options header(1st part)
+ * Destination options header (1st part).
* This only makes sense with a routing header.
* See Section 9.2 of RFC 3542.
* Disabling this part just for MIP6 convenience is
@@ -452,9 +454,9 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
*/
MAKE_EXTHDR(opt->ip6po_dest1, &exthdrs.ip6e_dest1);
}
- /* Routing header */
+ /* Routing header. */
MAKE_EXTHDR(opt->ip6po_rthdr, &exthdrs.ip6e_rthdr);
- /* Destination options header(2nd part) */
+ /* Destination options header (2nd part). */
MAKE_EXTHDR(opt->ip6po_dest2, &exthdrs.ip6e_dest2);
}
@@ -471,7 +473,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
optlen += exthdrs.ip6e_rthdr->m_len;
unfragpartlen = optlen + sizeof(struct ip6_hdr);
- /* NOTE: we don't add AH/ESP length here (done in ip6_ipsec_output) */
+ /* NOTE: we don't add AH/ESP length here (done in ip6_ipsec_output). */
if (exthdrs.ip6e_dest2)
optlen += exthdrs.ip6e_dest2->m_len;
@@ -490,7 +492,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
ip6 = mtod(m, struct ip6_hdr *);
- /* adjust mbuf packet header length */
+ /* Adjust mbuf packet header length. */
m->m_pkthdr.len += optlen;
plen = m->m_pkthdr.len - sizeof(*ip6);
@@ -504,7 +506,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
m = exthdrs.ip6e_ip6;
hdrsplit++;
}
- /* adjust pointer */
+ /* Adjust pointer. */
ip6 = mtod(m, struct ip6_hdr *);
if ((error = ip6_insert_jumboopt(&exthdrs, plen)) != 0)
goto freehdrs;
@@ -516,26 +518,29 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
* Concatenate headers and fill in next header fields.
* Here we have, on "m"
* IPv6 payload
- * and we insert headers accordingly. Finally, we should be getting:
- * IPv6 hbh dest1 rthdr ah* [esp* dest2 payload]
+ * and we insert headers accordingly.
+ * Finally, we should be getting:
+ * IPv6 hbh dest1 rthdr ah* [esp* dest2 payload].
*
- * during the header composing process, "m" points to IPv6 header.
- * "mprev" points to an extension header prior to esp.
+ * During the header composing process "m" points to IPv6
+ * header. "mprev" points to an extension header prior to esp.
*/
u_char *nexthdrp = &ip6->ip6_nxt;
mprev = m;
/*
- * we treat dest2 specially. this makes IPsec processing
- * much easier. the goal here is to make mprev point the
+ * We treat dest2 specially. This makes IPsec processing
+ * much easier. The goal here is to make mprev point the
* mbuf prior to dest2.
*
- * result: IPv6 dest2 payload
+ * Result: IPv6 dest2 payload.
* m and mprev will point to IPv6 header.
*/
if (exthdrs.ip6e_dest2) {
if (!hdrsplit)
- panic("assumption failed: hdr not split");
+ panic("%s:%d: assumption failed: "
+ "hdr not split: hdrsplit %d exthdrs %p",
+ __func__, __LINE__, hdrsplit, &exthdrs);
exthdrs.ip6e_dest2->m_next = m->m_next;
m->m_next = exthdrs.ip6e_dest2;
*mtod(exthdrs.ip6e_dest2, u_char *) = ip6->ip6_nxt;
@@ -543,7 +548,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
}
/*
- * result: IPv6 hbh dest1 rthdr dest2 payload
+ * Result: IPv6 hbh dest1 rthdr dest2 payload.
* m will point to IPv6 header. mprev will point to the
* extension header prior to dest2 (rthdr in the above case).
*/
@@ -553,15 +558,13 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
MAKE_CHAIN(exthdrs.ip6e_rthdr, mprev, nexthdrp,
IPPROTO_ROUTING);
- /*
- * If there is a routing header, discard the packet.
- */
+ /* If there is a routing header, discard the packet. */
if (exthdrs.ip6e_rthdr) {
error = EINVAL;
goto bad;
}
- /* Source address validation */
+ /* Source address validation. */
if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src) &&
(flags & IPV6_UNSPECSRC) == 0) {
error = EOPNOTSUPP;
@@ -576,9 +579,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
IP6STAT_INC(ip6s_localout);
- /*
- * Route packet.
- */
+ /* Route packet. */
if (ro == NULL) {
ro = &ip6route;
bzero((caddr_t)ro, sizeof(*ro));
@@ -590,9 +591,9 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
fibnum = (inp != NULL) ? inp->inp_inc.inc_fibnum : M_GETFIB(m);
again:
/*
- * if specified, try to fill in the traffic class field.
- * do not override if a non-zero value is already set.
- * we check the diffserv field and the ecn field separately.
+ * If specified, try to fill in the traffic class field.
+ * Do not override if a non-zero value is already set.
+ * We check the diffserv field and the ECN field separately.
*/
if (opt && opt->ip6po_tclass >= 0) {
int mask = 0;
@@ -605,7 +606,7 @@ again:
ip6->ip6_flow |= htonl((opt->ip6po_tclass & mask) <<
20);
}
- /* fill in or override the hop limit field, if necessary. */
+ /* Fill in or override the hop limit field, if necessary. */
if (opt && opt->ip6po_hlim != -1)
ip6->ip6_hlim = opt->ip6po_hlim & 0xff;
else if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
@@ -617,7 +618,7 @@ again:
/*
* Validate route against routing table additions;
* a better/more specific route might have been added.
- * Make sure address family is set in route.
+ * Make sure that the address family is set in route.
*/
if (inp) {
ro->ro_dst.sin6_family = AF_INET6;
@@ -648,15 +649,13 @@ again:
}
if (rt == NULL) {
/*
- * If in6_selectroute() does not return a route entry,
+ * If in6_selectroute() does not return a route entry
* dst may not have been updated.
*/
*dst = dst_sa; /* XXX */
}
- /*
- * then rt (for unicast) and ifp must be non-NULL valid values.
- */
+ /* Then rt (for unicast) and ifp must be non-NULL valid values. */
if ((flags & IPV6_FORWARDING) == 0) {
/* XXX: the FORWARDING flag can be set for mrouting. */
in6_ifstat_inc(ifp, ifs6_out_request);
@@ -674,7 +673,7 @@ again:
src_sa.sin6_addr = ip6->ip6_src;
dst0 = ip6->ip6_dst;
- /* re-initialize to be sure */
+ /* Re-initialize to be sure. */
bzero(&dst_sa, sizeof(dst_sa));
dst_sa.sin6_family = AF_INET6;
dst_sa.sin6_len = sizeof(dst_sa);
@@ -691,7 +690,7 @@ again:
*
* Because the loopback interface cannot receive
* packets with a different scope ID than its own,
- * there is a trick is to pretend the outgoing packet
+ * there is a trick to pretend the outgoing packet
* was received by the real network interface, by
* setting "origifp" different from "ifp". This is
* only allowed when "ifp" is a loopback network
@@ -729,7 +728,6 @@ again:
error = EHOSTUNREACH; /* XXX */
goto bad;
}
-
/* All scope ID checks are successful. */
if (rt && !IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
@@ -746,13 +744,12 @@ again:
}
if (!IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
- m->m_flags &= ~(M_BCAST | M_MCAST); /* just in case */
+ m->m_flags &= ~(M_BCAST | M_MCAST); /* Just in case. */
} else {
m->m_flags = (m->m_flags & ~M_BCAST) | M_MCAST;
in6_ifstat_inc(ifp, ifs6_out_mcast);
- /*
- * Confirm that the outgoing interface supports multicast.
- */
+
+ /* Confirm that the outgoing interface supports multicast. */
if (!(ifp->if_flags & IFF_MULTICAST)) {
IP6STAT_INC(ip6s_noroute);
in6_ifstat_inc(ifp, ifs6_out_discard);
@@ -847,8 +844,8 @@ again:
}
/*
- * clear embedded scope identifiers if necessary.
- * in6_clearscope will touch the addresses only when necessary.
+ * Clear embedded scope identifiers if necessary.
+ * in6_clearscope() will touch the addresses only when necessary.
*/
in6_clearscope(&ip6->ip6_src);
in6_clearscope(&ip6->ip6_dst);
@@ -878,7 +875,7 @@ again:
if (ip6_process_hopopts(m, (u_int8_t *)(hbh + 1),
((hbh->ip6h_len + 1) << 3) - sizeof(struct ip6_hbh),
&dummy, &plen) < 0) {
- /* m was already freed at this point */
+ /* m was already freed at this point. */
error = EINVAL;/* better error? */
goto done;
}
@@ -970,7 +967,7 @@ passout:
* Send the packet to the outgoing interface.
* If necessary, do IPv6 fragmentation before sending.
*
- * the logic here is rather complex:
+ * The logic here is rather complex:
* 1: normal case (dontfrag == 0, alwaysfrag == 0)
* 1-a: send as is if tlen <= path mtu
* 1-b: fragment if tlen > path mtu
@@ -983,7 +980,7 @@ passout:
* always fragment
*
* 4: if dontfrag == 1 && alwaysfrag == 1
- * error, as we cannot handle this conflicting request
+ * error, as we cannot handle this conflicting request.
*/
sw_csum = m->m_pkthdr.csum_flags;
if (!hdrsplit) {
@@ -1033,12 +1030,12 @@ passout:
dontfrag = 1;
else
dontfrag = 0;
- if (dontfrag && alwaysfrag) { /* case 4 */
- /* conflicting request - can't transmit */
+ if (dontfrag && alwaysfrag) { /* Case 4. */
+ /* Conflicting request - can't transmit. */
error = EMSGSIZE;
goto bad;
}
- if (dontfrag && tlen > IN6_LINKMTU(ifp) && !tso) { /* case 2-b */
+ if (dontfrag && tlen > IN6_LINKMTU(ifp) && !tso) { /* Case 2-b. */
/*
* Even if the DONTFRAG option is specified, we cannot send the
* packet when the data length is larger than the MTU of the
@@ -1053,10 +1050,8 @@ passout:
goto bad;
}
- /*
- * transmit packet without fragmentation
- */
- if (dontfrag || (!alwaysfrag && tlen <= mtu)) { /* case 1-a and 2-a */
+ /* Transmit packet without fragmentation. */
+ if (dontfrag || (!alwaysfrag && tlen <= mtu)) { /* Cases 1-a and 2-a. */
struct in6_ifaddr *ia6;
ip6 = mtod(m, struct ip6_hdr *);
@@ -1072,16 +1067,14 @@ passout:
goto done;
}
- /*
- * try to fragment the packet. case 1-b and 3
- */
+ /* Try to fragment the packet. Cases 1-b and 3. */
if (mtu < IPV6_MMTU) {
- /* path MTU cannot be less than IPV6_MMTU */
+ /* Path MTU cannot be less than IPV6_MMTU. */
error = EMSGSIZE;
in6_ifstat_inc(ifp, ifs6_out_fragfail);
goto bad;
} else if (ip6->ip6_plen == 0) {
- /* jumbo payload cannot be fragmented */
+ /* Jumbo payload cannot be fragmented. */
error = EMSGSIZE;
in6_ifstat_inc(ifp, ifs6_out_fragfail);
goto bad;
@@ -1162,9 +1155,7 @@ passout:
in6_ifstat_inc(ifp, ifs6_out_fragok);
}
- /*
- * Remove leading garbages.
- */
+ /* Remove leading garbage. */
sendorfree:
m = m0->m_nextpkt;
m0->m_nextpkt = 0;
@@ -1193,7 +1184,7 @@ done:
return (error);
freehdrs:
- m_freem(exthdrs.ip6e_hbh); /* m_freem will check if mbuf is 0 */
+ m_freem(exthdrs.ip6e_hbh); /* m_freem() checks if mbuf is NULL. */
m_freem(exthdrs.ip6e_dest1);
m_freem(exthdrs.ip6e_rthdr);
m_freem(exthdrs.ip6e_dest2);
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