initial commit: add Mail-in-a-Box Go client library and CLI with DNS record management

dns.go

@@ -0,0 +1,130 @@
+package miab
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+)
+
+// Client holds connection configuration for the Mail-in-a-Box admin DNS API.
+type Client struct {
+	host       string
+	username   string
+	password   string
+	httpClient *http.Client
+}
+
+// DNSRecord represents a single custom DNS record returned by the MIAB API.
+type DNSRecord struct {
+	Name  string `json:"name"`
+	Type  string `json:"type"`
+	Value string `json:"value"`
+}
+
+// NewClient constructs a Client. host should be the bare hostname (e.g. "box.example.com").
+func NewClient(host, username, password string) *Client {
+	return &Client{
+		host:     host,
+		username: username,
+		password: password,
+		httpClient: &http.Client{
+			Timeout: 30 * time.Second,
+		},
+	}
+}
+
+// SetRecord replaces all existing records of the given type for name with value (HTTP PUT).
+func (c *Client) SetRecord(name, recordType, value string) error {
+	_, err := c.do(http.MethodPut, c.buildURL(name, recordType), value)
+	return err
+}
+
+// DeleteRecord removes the record matching name, recordType and value (HTTP DELETE).
+// Pass an empty value to remove all records of that type for the name.
+func (c *Client) DeleteRecord(name, recordType, value string) error {
+	_, err := c.do(http.MethodDelete, c.buildURL(name, recordType), value)
+	return err
+}
+
+// AddRecord adds a record without replacing existing ones (HTTP POST).
+func (c *Client) AddRecord(name, recordType, value string) error {
+	_, err := c.do(http.MethodPost, c.buildURL(name, recordType), value)
+	return err
+}
+
+// ListRecords returns all custom DNS records. If recordType is non-empty, only
+// records of that type are returned.
+func (c *Client) ListRecords(recordType string) ([]DNSRecord, error) {
+	body, err := c.do(http.MethodGet, fmt.Sprintf("https://%s/admin/dns/custom", c.host), "")
+	if err != nil {
+		return nil, err
+	}
+
+	// MIAB returns an array of objects with fields: qname, rtype, value
+	var raw []struct {
+		QName string `json:"qname"`
+		RType string `json:"rtype"`
+		Value string `json:"value"`
+	}
+	if err := json.Unmarshal([]byte(body), &raw); err != nil {
+		return nil, fmt.Errorf("miab: failed to parse response: %w", err)
+	}
+
+	var records []DNSRecord
+	upper := strings.ToUpper(recordType)
+	for _, r := range raw {
+		if recordType == "" || r.RType == upper {
+			records = append(records, DNSRecord{
+				Name:  r.QName,
+				Type:  r.RType,
+				Value: r.Value,
+			})
+		}
+	}
+	return records, nil
+}
+
+// buildURL mirrors miab.py's get_miab_url: omits the record type segment for "A" records.
+func (c *Client) buildURL(name, recordType string) string {
+	if strings.ToUpper(recordType) == "A" {
+		return fmt.Sprintf("https://%s/admin/dns/custom/%s", c.host, name)
+	}
+	return fmt.Sprintf("https://%s/admin/dns/custom/%s/%s", c.host, name, strings.ToUpper(recordType))
+}
+
+// do executes an HTTP request with Basic Auth and returns the response body as a string.
+func (c *Client) do(method, url, body string) (string, error) {
+	var bodyReader io.Reader
+	if body != "" {
+		bodyReader = strings.NewReader(body)
+	}
+
+	req, err := http.NewRequest(method, url, bodyReader)
+	if err != nil {
+		return "", fmt.Errorf("miab: failed to create request: %w", err)
+	}
+	req.SetBasicAuth(c.username, c.password)
+	if body != "" {
+		req.Header.Set("Content-Type", "text/plain")
+	}
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("miab: request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return "", fmt.Errorf("miab: failed to read response body: %w", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("miab: unexpected status %d: %s", resp.StatusCode, strings.TrimSpace(string(respBody)))
+	}
+
+	return string(respBody), nil
+}