add capability to tune in Unbound DNS host overrides

CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.3.0 (January 3rd, 2022)
+
+* refactor generic Session handling
+* add UnboundDNS support
+
 ## 0.2.1 (December 10th, 2021)
 
 * ignore case when comparing MAC identifiers

opnsense/dns.go

@@ -0,0 +1,370 @@
+package opnsense
+
+import (
+	"fmt"
+	"github.com/antchfx/htmlquery"
+	"github.com/asmcos/requests"
+	"golang.org/x/net/html"
+	"strings"
+)
+
+// DNSEntryStartingRow exposes the HTML row where static maps actually start from
+const DNSEntryStartingRow = 2
+
+const (
+	// DNSHost refers to the HTML table field for DNS host entry creation/edition
+	DNSHost = "Host"
+	// DNSDomain refers to the HTML table field for DNS host entry creation/edition
+	DNSDomain = "Domain"
+	// DNSType refers to the HTML table field for DNS host entry creation/edition
+	DNSType = "Type"
+	// DNSValue refers to the HTML table field for DNS host entry creation/edition
+	DNSValue = "Value"
+	// DNSDescription refers to the HTML table field for DNS host entry creation/edition
+	DNSDescription = "Description"
+)
+
+const (
+	// DNSServiceURI is the WebUI service URI
+	DNSServiceURI = "/services_unbound_overrides.php"
+	// DNSServiceEditURI is the WebUI service edit URI
+	DNSServiceEditURI = "/services_unbound_host_edit.php"
+)
+
+const (
+	// ErrDNSNoEntries is thrown when no entry can be found
+	ErrDNSNoEntries = "unable to retrieve list of DNS host overrides"
+	// ErrDNSHostExists is thrown when an entry already exists for this host override
+	ErrDNSHostExists = "DNS override for this host already exists"
+	// ErrDNSNoSuchEntry is thrown if no host override entry can be found
+	ErrDNSNoSuchEntry = "host override entry doesn't exists"
+)
+
+// DNSSession abstracts OPNSense UnboundDNS Overrides
+type DNSSession struct {
+	OPN    *OPNSession
+	Fields []string
+}
+
+// DNSHostEntry abstracts a DNS Host override
+type DNSHostEntry struct {
+	ID     int
+	Type   string
+	Host   string
+	Domain string
+	IP     string
+}
+
+///////////////////////
+// Private Functions //
+///////////////////////
+
+// GetStaticFieldNames extracts the HTML page host overrides headers for creation/edition
+func (s *DNSSession) GetStaticFieldNames(node *html.Node, start int) {
+	if len(s.Fields) > 0 {
+		// already filled-in, no need to go any further
+		return
+	}
+
+	q := fmt.Sprintf(`//table[@class="table table-striped"]//tr[%d]`, start)
+	headers := htmlquery.FindOne(node, q)
+	s.Fields = []string{}
+	for child := headers.FirstChild; child != nil; child = child.NextSibling {
+		if child.Type == html.ElementNode {
+			content := strings.TrimSpace(htmlquery.InnerText(child))
+			if len(content) > 0 {
+				s.Fields = append(s.Fields, content)
+			}
+		}
+	}
+}
+
+// GetStaticMappingField extracts a given DNS host override entry from OPNsense DNS overrides web page
+func (s *DNSSession) GetStaticMappingField(node *html.Node, f string) string {
+	res := ""
+
+	// find the requested field index in HTML table
+	id := index(s.Fields, f) + 1
+	if id == -1 {
+		return res
+	}
+
+	// XPath query to find the associated HTML node
+	q := fmt.Sprintf(`//td[%d]//text()`, id)
+	values, err := htmlquery.QueryAll(node, q)
+	if err != nil {
+		return res
+	}
+
+	// extract value
+	for _, v := range values {
+		if v.Type != html.TextNode {
+			continue
+		}
+		content := strings.TrimSpace(htmlquery.InnerText(v))
+		res = res + content
+	}
+
+	return res
+}
+
+// GetAllHostEntries retrieves the list of all configured DNS host overrides
+func (s *DNSSession) GetAllHostEntries() ([]DNSHostEntry, error) {
+
+	entries := []DNSHostEntry{}
+
+	// check for proper authentication
+	err := s.OPN.IsAuthenticated()
+	if err != nil {
+		return entries, err
+	}
+
+	// read out the service page
+	dnsURI := fmt.Sprintf("%s%s", s.OPN.RootURI, DNSServiceURI)
+	resp, err := s.OPN.Session.Get(dnsURI)
+	if err != nil {
+		return entries, err
+	}
+
+	// get HTML
+	page := strings.NewReader(resp.Text())
+	doc, err := htmlquery.Parse(page)
+	if err != nil {
+		return entries, err
+	}
+
+	// lookup for static fields types
+	s.GetStaticFieldNames(doc, DNSEntryStartingRow)
+
+	// XPath query to find all table rows
+	q := fmt.Sprintf(`//table[@class="table table-striped"]//tr`)
+	rows, err := htmlquery.QueryAll(doc, q)
+	if err != nil {
+		return entries, err
+	}
+
+	// retrieve all configured DNS host override entries
+	for i := DNSEntryStartingRow; i < len(rows); i++ {
+		r := rows[i]
+		e := DNSHostEntry{
+			ID:     i - DNSEntryStartingRow,
+			Type:   s.GetStaticMappingField(r, DNSType),
+			Host:   s.GetStaticMappingField(r, DNSHost),
+			Domain: s.GetStaticMappingField(r, DNSDomain),
+			IP:     s.GetStaticMappingField(r, DNSValue),
+		}
+		entries = append(entries, e)
+	}
+
+	return entries, nil
+}
+
+// HostsMatch compares if 2 host entries are alike
+func (s *DNSSession) HostsMatch(e1, e2 *DNSHostEntry) bool {
+	if (e1.Host == e2.Host) && (e1.Domain == e2.Domain) && (e1.Type == e2.Type) && (e1.IP == e2.IP) {
+		return true
+	}
+	return false
+}
+
+// FindHostEntry retrieves all entries select the one that matches
+func (s *DNSSession) FindHostEntry(h *DNSHostEntry) (*DNSHostEntry, error) {
+
+	// retrieves existing host entries
+	entries, err := s.GetAllHostEntries()
+	if err != nil {
+		return nil, err
+	}
+
+	// check if an entry exists
+	for _, e := range entries {
+		// we found it
+		if s.HostsMatch(h, &e) {
+			return &e, nil
+		}
+	}
+
+	return nil, s.OPN.Error(ErrDNSNoSuchEntry)
+}
+
+// FindHostEntryByID retrieves all entries select the one that matches the ID
+func (s *DNSSession) FindHostEntryByID(id int) (*DNSHostEntry, error) {
+
+	// retrieves existing host entries
+	entries, err := s.GetAllHostEntries()
+	if err != nil {
+		return nil, err
+	}
+
+	// check if an entry exists
+	for _, e := range entries {
+		// we found it
+		if e.ID == id {
+			return &e, nil
+		}
+	}
+
+	return nil, s.OPN.Error(ErrDNSNoSuchEntry)
+}
+
+// Apply validates the configuration and reload DNS server
+func (s *DNSSession) Apply(formName, formValue string) error {
+	// apply changes
+	data := requests.Datas{
+		"apply": "Apply changes",
+	}
+	if formName != "" || formValue != "" {
+		data[formName] = formValue
+	}
+
+	applyURI := fmt.Sprintf("%s%s", s.OPN.RootURI, DNSServiceURI)
+	_, err := s.OPN.Session.Post(applyURI, data)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// CreateOrEdit creates or edit an host override entry
+func (s *DNSSession) CreateOrEdit(e *DNSHostEntry) error {
+
+	// get the edit page to retrieve form secret values
+	editURI := fmt.Sprintf("%s%s", s.OPN.RootURI, DNSServiceEditURI)
+	if e.ID != -1 {
+		editURI = fmt.Sprintf("%s&id=%d", editURI, e.ID)
+	}
+	resp, err := s.OPN.Session.Get(editURI)
+	if err != nil {
+		return err
+	}
+
+	// get HTML
+	page := strings.NewReader(resp.Text())
+	doc, err := htmlquery.Parse(page)
+	if err != nil {
+		return err
+	}
+
+	// get form runtime values
+	q := fmt.Sprintf(`//div[@class="content-box"]//form//input`)
+	n := htmlquery.FindOne(doc, q)
+	formName := htmlquery.SelectAttr(n, "name")
+	formValue := htmlquery.SelectAttr(n, "value")
+
+	// create a new DHCP entry
+	data := requests.Datas{
+		formName: formValue,
+		"host":   e.Host,
+		"domain": e.Domain,
+		"rr":     e.Type,
+		"ip":     e.IP,
+		"descr":  "",
+		"Submit": "Save",
+	}
+	if e.ID != -1 {
+		data["id"] = fmt.Sprintf("%d", e.ID)
+	}
+
+	resp, err = s.OPN.Session.Post(editURI, data)
+	if err != nil {
+		return err
+	}
+
+	// apply changes
+	err = s.Apply(formName, formValue)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+//////////////////////
+// Public Functions //
+//////////////////////
+
+// CreateHostOverride creates a new DNS host override entry
+func (s *DNSSession) CreateHostOverride(h *DNSHostEntry) error {
+
+	e, err := s.FindHostEntry(h)
+
+	// check if the host override is not already registered
+	if e != nil {
+		return s.OPN.Error(ErrDNSHostExists)
+	}
+
+	// create the mapping entry
+	h.ID = -1
+	err = s.CreateOrEdit(h)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// ReadHostOverride retrieves DNS information for a specified host
+func (s *DNSSession) ReadHostOverride(h *DNSHostEntry) error {
+
+	// check if an entry exists
+	e, err := s.FindHostEntry(h)
+	if e == nil {
+		return err
+	}
+
+	// assign values accordingly
+	h.ID = e.ID
+
+	return nil
+}
+
+// UpdateHostOverride modifies an already existing host override
+func (s *DNSSession) UpdateHostOverride(h *DNSHostEntry) error {
+
+	// check if an entry exists for this specific ID
+	e, err := s.FindHostEntryByID(h.ID)
+	if e == nil {
+		return err
+	}
+
+	// update the mapping entry
+	h.ID = e.ID
+	err = s.CreateOrEdit(h)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// DeleteHostOverride destroy an existing DNS host entry
+func (s *DNSSession) DeleteHostOverride(h *DNSHostEntry) error {
+
+	// check if an entry exists
+	e, err := s.FindHostEntry(h)
+	if e == nil {
+		return err
+	}
+
+	// get the DNS page to retrieve form secret values
+	dnsURI := fmt.Sprintf("%s%s", s.OPN.RootURI, DNSServiceURI)
+
+	// destroy DNS host entry
+	data := requests.Datas{
+		"id":  fmt.Sprintf("%d", e.ID),
+		"act": "del",
+	}
+
+	_, err = s.OPN.Session.Post(dnsURI, data)
+	if err != nil {
+		return err
+	}
+
+	// apply changes
+	err = s.Apply("", "")
+	if err != nil {
+		return err
+	}
+
+	return nil
+}