Add libpq function PQhostaddr().

There was a bug in the psql's meta command \conninfo. When the
IP address was specified in the hostaddr and psql used it to create
a connection (i.e., psql -d "hostaddr=xxx"), \conninfo could not
display that address. This is because \conninfo got the connection
information only from PQhost() which could not return hostaddr.

This patch adds PQhostaddr(), and changes \conninfo so that it
can display not only the host name that PQhost() returns but also
the IP address which PQhostaddr() returns.

The bug has existed since 9.1 where \conninfo was introduced.
But it's too late to add new libpq function into the released versions,
so no backpatch.

Author: MasaoFujii

doc/src/sgml/libpq.sgml

@@ -1464,6 +1464,24 @@ char *PQhost(const PGconn *conn);
      </listitem>
     </varlistentry>
 
+    <varlistentry id="libpq-pqhostaddr">
+     <term>
+      <function>PQhostaddr</function>
+      <indexterm>
+       <primary>PQhostaddr</primary>
+      </indexterm>
+     </term>
+
+     <listitem>
+      <para>
+       Returns the server numeric IP address of the connection.
+<synopsis>
+char *PQhostaddr(const PGconn *conn);
+</synopsis>
+      </para>
+     </listitem>
+    </varlistentry>
+
     <varlistentry id="libpq-pqport">
      <term>
       <function>PQport</function>

src/bin/psql/command.c

@@ -300,7 +300,7 @@ exec_command(const char *cmd,
 	else if (strcmp(cmd, "conninfo") == 0)
 	{
 		char	   *db = PQdb(pset.db);
-		char	   *host = PQhost(pset.db);
+		char	   *host = (PQhostaddr(pset.db) != NULL) ? PQhostaddr(pset.db) : PQhost(pset.db);
 
 		if (db == NULL)
 			printf(_("You are currently not connected to a database.\n"));

src/interfaces/libpq/exports.txt

@@ -165,3 +165,4 @@ lo_lseek64                162
 lo_tell64                 163
 lo_truncate64             164
 PQconninfo                165
+PQhostaddr                166

src/interfaces/libpq/fe-connect.c

@@ -5200,6 +5200,14 @@ PQhost(const PGconn *conn)
 	}
 }
 
+char *
+PQhostaddr(const PGconn *conn)
+{
+	if (!conn)
+		return NULL;
+	return conn->pghostaddr;
+}
+
 char *
 PQport(const PGconn *conn)
 {

src/interfaces/libpq/libpq-fe.h

@@ -301,6 +301,7 @@ extern char *PQdb(const PGconn *conn);
 extern char *PQuser(const PGconn *conn);
 extern char *PQpass(const PGconn *conn);
 extern char *PQhost(const PGconn *conn);
+extern char *PQhostaddr(const PGconn *conn);
 extern char *PQport(const PGconn *conn);
 extern char *PQtty(const PGconn *conn);
 extern char *PQoptions(const PGconn *conn);