Implement IQ responses to version, last activity, client time

* Implement IqVersionResponse(), XEP-0092
* Implement JabberIqLastResponse(), XEP-0012
* Implement UrnXmppTimeResponse(), XEP-0202
* Fix function descriptions

xmpp_information_query.go

@@ -3,6 +3,7 @@ package xmpp
 import (
 	"fmt"
 	"strconv"
+	"time"
 )
 
 const IQTypeGet = "get"
@@ -16,24 +17,24 @@ func (c *Client) Discovery() (string, error) {
 	return c.RawInformationQuery(c.jid, c.domain, reqID, IQTypeGet, XMPPNS_DISCO_ITEMS, "")
 }
 
-// Discover information about a node. Empty node queries info about server itself.
+// DiscoverNodeInfo discovers information about a node. Empty node queries info about server itself.
 func (c *Client) DiscoverNodeInfo(node string) (string, error) {
 	query := fmt.Sprintf("<query xmlns='%s' node='%s'/>", XMPPNS_DISCO_INFO, node)
 	return c.RawInformation(c.jid, c.domain, "info3", IQTypeGet, query)
 }
 
-// Discover information about given item from given jid.
+// DiscoverInfo discovers information about given item from given jid.
 func (c *Client) DiscoverInfo(from string, to string) (string, error) {
 	query := fmt.Sprintf("<query xmlns='%s'/>", XMPPNS_DISCO_INFO)
 	return c.RawInformation(from, to, "info3", IQTypeGet, query)
 }
 
-// Discover items that the server exposes
+// DiscoverServerItems discover items that the server exposes
 func (c *Client) DiscoverServerItems() (string, error) {
 	return c.DiscoverEntityItems(c.domain)
 }
 
-// Discover items that an entity exposes
+// DiscoverEntityItems discovers items that an entity exposes.
 func (c *Client) DiscoverEntityItems(jid string) (string, error) {
 	query := fmt.Sprintf("<query xmlns='%s'/>", XMPPNS_DISCO_ITEMS)
 	return c.RawInformation(c.jid, jid, "info1", IQTypeGet, query)
@@ -46,9 +47,73 @@ func (c *Client) RawInformationQuery(from, to, id, iqType, requestNamespace, bod
 	return id, err
 }
 
-// rawInformation send a IQ request with the payload body to the server
+// RawInformation sends a IQ request with the payload body to the server.
 func (c *Client) RawInformation(from, to, id, iqType, body string) (string, error) {
 	const xmlIQ = "<iq from='%s' to='%s' id='%s' type='%s'>%s</iq>"
 	_, err := fmt.Fprintf(StanzaWriter, xmlIQ, xmlEscape(from), xmlEscape(to), id, iqType, body)
 	return id, err
 }
+
+// IqVersionResponse responding with software version, according to xep-0092.
+func (c *Client) IqVersionResponse(v IQ, name, version, os string) (string, error) {
+	if name == "" {
+		name = "go-xmpp"
+	}
+
+	if version == "" {
+		version = "undefined"
+	}
+
+	query := "<query xmlns=\"jabber:iq:version\">" //nolint:wsl
+	query += fmt.Sprintf("<name>%s</name>", name)
+	query += fmt.Sprintf("<version>%s</version>", version)
+
+	if os != "" {
+		query += fmt.Sprintf("<os>%s</os>", os)
+	}
+
+	query += "</query>"
+
+	return c.RawInformation(
+		v.To,
+		v.From,
+		v.ID,
+		IQTypeResult,
+		query,
+	)
+}
+
+// JabberIqLastResponse responding with relative time since last activity.
+// Here lastActivity is unix time stamp when last activity took place since.
+func (c *Client) JabberIqLastResponse(v IQ, lastActivity int64) (string, error) {
+	query := fmt.Sprintf(
+		"<query xmlns=\"jabber:iq:last\" seconds=\"%d\" />",
+		time.Now().Unix()-lastActivity,
+	)
+
+	return c.RawInformation(
+		v.To,
+		v.From,
+		v.ID,
+		IQTypeResult,
+		query,
+	)
+}
+
+// UrnXmppTimeResponse implements response to query entity's current time (xep-0202).
+// TimezoneOffset have format +HH:MM or -HH:MM
+func (c *Client) UrnXmppTimeResponse(v IQ, timezoneOffset string) (string, error) {
+	query := fmt.Sprintf(
+		"<time xmlns=\"urn:xmpp:time\"><tzo>%s</tzo><utc>%s</utc></time>",
+		timezoneOffset,
+		time.Now().UTC().Format(time.RFC3339),
+	)
+
+	return c.RawInformation(
+		v.To,
+		v.From,
+		v.ID,
+		IQTypeResult,
+		query,
+	)
+}