man pages: deprecate Internet Class A/B/C

Mark functions inet_netof(), inet_lnaof(), and inet_makeaddr() as
deprecated, as they assume Class A/B/C.  inet_makeaddr() mostly works
when networks are a multiple of 8 bits, but warn for anything other
than historical classes.  Reduce other mentions of network classes.

MFC after:	1 month
Reviewed by:	bcr, #manpages
Differential Revision: https://reviews.freebsd.org/D32711

3 files changed, 19 insertions, 28 deletions

diff --git a/lib/libc/net/inet.3 b/lib/libc/net/inet.3
index a36cb313f7d3..cb44394d0a0c 100644
--- a/lib/libc/net/inet.3
+++ b/lib/libc/net/inet.3
@@ -28,7 +28,7 @@
 .\"     From: @(#)inet.3	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd June 14, 2007
+.Dd November 9, 2021
 .Dt INET 3
 .Os
 .Sh NAME
@@ -157,18 +157,20 @@ The routine
 .Fn inet_ntoa_r
 is the reentrant version of
 .Fn inet_ntoa .
-The routine
+The deprecated routine
 .Fn inet_makeaddr
 takes an Internet network number and a local
-network address and constructs an Internet address
+host address on that network, and constructs an Internet address
 from it.
-The routines
+It should only be assumed to work for historical class A/B/C networks.
+The deprecated routines
 .Fn inet_netof
 and
 .Fn inet_lnaof
 break apart Internet host addresses, returning
-the network number and local network address part,
-respectively.
+the network number and local host address part,
+respectively,
+assuming the historical class A/B/C network masks.
 .Pp
 All Internet addresses are returned in network
 order (bytes ordered from left to right).
@@ -203,17 +205,11 @@ ordered from right to left.
 .Pp
 When a three part address is specified, the last
 part is interpreted as a 16-bit quantity and placed
-in the right-most two bytes of the network address.
-This makes the three part address format convenient
-for specifying Class B network addresses as
-.Dq Li 128.net.host .
+in the least significant two bytes of the network address.
 .Pp
 When a two part address is supplied, the last part
 is interpreted as a 24-bit quantity and placed in
-the right most three bytes of the network address.
-This makes the two part address format convenient
-for specifying Class A network addresses as
-.Dq Li net.host .
+the least significant three bytes of the network address.
 .Pp
 When only one part is given, the value is stored
 directly in the network address without any byte
diff --git a/lib/libc/net/inet_net.3 b/lib/libc/net/inet_net.3
index f0721729ff05..4028984bd09b 100644
--- a/lib/libc/net/inet_net.3
+++ b/lib/libc/net/inet_net.3
@@ -32,7 +32,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 18, 2016
+.Dd November 9, 2021
 .Dt INET_NET 3
 .Os
 .Sh NAME
@@ -120,17 +120,11 @@ That is, little-endian bytes are ordered from right to left.
 .Pp
 When a three part number is specified, the last
 part is interpreted as a 16-bit quantity and placed
-in the rightmost two bytes of the Internet network number.
-This makes the three part number format convenient
-for specifying Class B network numbers as
-.Dq Li 128.net.host .
+in the least significant two bytes of the Internet network number.
 .Pp
 When a two part number is supplied, the last part
 is interpreted as a 24-bit quantity and placed in
-the rightmost three bytes of the Internet network number.
-This makes the two part number format convenient
-for specifying Class A network numbers as
-.Dq Li net.host .
+the least significant three bytes of the Internet network number.
 .Pp
 When only one part is given, the value is stored
 directly in the Internet network number without any byte
diff --git a/share/man/man5/resolver.5 b/share/man/man5/resolver.5
index d5c02599bafb..468c635839c6 100644
--- a/share/man/man5/resolver.5
+++ b/share/man/man5/resolver.5
@@ -28,7 +28,7 @@
 .\"     @(#)resolver.5	8.1 (Berkeley) 6/5/93
 .\" $FreeBSD$
 .\"
-.Dd May 25, 2021
+.Dd November 9, 2021
 .Dt RESOLVER 5
 .Os
 .Sh NAME
@@ -104,15 +104,16 @@ with a total of 256 characters.
 .It Sy sortlist
 Sortlist allows addresses returned by gethostbyname to be sorted.
 A sortlist is specified by IP address netmask pairs.
-The netmask is
-optional and defaults to the natural netmask of the net.
+If the netmask is not specified,
+it defaults to the historical Class A/B/C netmask of the net;
+this usage is deprecated.
 The IP address
-and optional network pairs are separated by slashes.
+and network pairs are separated by slashes.
 Up to 10 pairs may
 be specified.
 E.g.,
 .Pp
-.Dl "sortlist 130.155.160.0/255.255.240.0 130.155.0.0"
+.Dl "sortlist 10.9.1.0/255.255.240.0 10.9.0.0/255.255.0.0"
 .It Sy options
 Options allows certain internal resolver variables to be modified.
 The syntax is