Nowadays (since 2.3.4) glibc only sets the first ai_canonname

field if AI_CANONNAME was specified (the current
behavior is all that SUSv3 requires).

man3/getaddrinfo.3

@@ -86,13 +86,13 @@ structure used by this function contains the following members:
 .BR getaddrinfo (3)
 sets
 .I res
-to point to a dynamically-allocated link list of
+to point to a dynamically-allocated linked list of
 .B addrinfo
 structures, linked by the
 .I ai_next
 member.
 There are several reasons why
-the link list may have more than one
+the linked list may have more than one
 .B addrinfo
 structure, including: if the network host is
 multi-homed; or if the same service
@@ -180,20 +180,27 @@ flag suppresses any potentially lengthy network host address lookups.
 .PP
 The
 .BR getaddrinfo (3)
-function creates a link list of
+function creates a linked list of
 .B addrinfo
 structures, one for each network address subject to any restrictions
 imposed by the
 .I hints
 parameter.
+The
 .I ai_canonname
-is set to point to the official name of the host, if
+field of the first of these 
+.B addrinfo 
+structures is set to point to the official name of the host, if
 .I ai_flags
 in
 .I hints
 includes the
 .B AI_CANONNAME
 flag.
+.\" In glibc prior to 2.3.4, the ai_canonname of each addrinfo 
+.\" structure was set pointing to the canonical name; that was
+.\" more than SUSv3 specified, or other implementations provided.  
+.\" MTK, Aug 05
 .IR ai_family ,
 .IR ai_socktype ,
 and
@@ -239,7 +246,7 @@ is NULL the port number will be left uninitialized.
 The
 .BR freeaddrinfo (3)
 function frees the memory that was allocated
-for the dynamically allocated link list
+for the dynamically allocated linked list
 .IR res .
 .SH "RETURN VALUE"
 .BR getaddrinfo (3)