feat: Add [DOMAIN_EXPIRATION] placeholder for monitoring domain expiration using WHOIS (#325)

* feat: Add [DOMAIN_EXPIRATION] placeholder for monitoring domain expiration using WHOIS

* test: Fix issue caused by possibility of millisecond elapsed during previous tests

* test: Fix test with different behavior based on architecture

* docs: Revert accidental change to starttls example

* docs: Fix mistake in comment for Condition.hasIPPlaceholder()

vendor/github.com/TwiN/whois/.gitignore

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+.idea
+bin

vendor/github.com/TwiN/whois/LICENSE

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+MIT License
+
+Copyright (c) 2022 TwiN
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

vendor/github.com/TwiN/whois/Makefile

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+.PHONY: build-binaries
+
+build-binaries:
+	./scripts/build.sh

vendor/github.com/TwiN/whois/README.md

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+# whois
+![test](https://github.com/TwiN/whois/workflows/test/badge.svg?branch=master)
+
+Lightweight library for retrieving WHOIS information on a domain.
+
+It automatically retrieves the appropriate WHOIS server based on the domain's TLD by first querying IANA.
+
+
+## Usage
+### As an executable
+To install it:
+```console
+go install github.com/TwiN/whois/cmd/whois@latest
+```
+To run it:
+```console 
+whois example.com
+```
+
+### As a library
+```console
+go get github.com/TwiN/whois
+```
+
+#### Query
+If all you want is the text a WHOIS server would return you, you can use the `Query` method of the `whois.Client` type:
+```go
+package main
+
+import "github.com/TwiN/whois"
+
+func main() {
+    client := whois.NewClient()
+    output, err := client.Query("example.com")
+    if err != nil {
+    	panic(err)
+    }
+    println(output)
+}
+```
+
+#### QueryAndParse
+If you want specific pieces of information, you can use the `QueryAndParse` method of the `whois.Client` type:
+```go
+package main
+
+import "github.com/TwiN/whois"
+
+func main() {
+    client := whois.NewClient()
+    response, err := client.QueryAndParse("example.com")
+    if err != nil {
+    	panic(err)
+    }
+    println(response.ExpirationDate.String()) 
+}
+```
+Note that because there is no standardized format for WHOIS responses, this parsing may not be successful for every single TLD.
+
+Currently, the only fields parsed are:
+- `ExpirationDate`: The time.Time at which the domain will expire
+- `DomainStatuses`: The statuses that the domain currently has (e.g. `clientTransferProhibited`)
+- `NameServers`: The nameservers currently tied to the domain
+
+If you'd like one or more other fields to be parsed, please don't be shy and create an issue or a pull request.

vendor/github.com/TwiN/whois/whois.go

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+package whois
+
+import (
+	"io"
+	"net"
+	"strings"
+	"time"
+)
+
+const (
+	ianaWHOISServerAddress = "whois.iana.org:43"
+)
+
+type Client struct {
+	whoisServerAddress string
+}
+
+func NewClient() *Client {
+	return &Client{
+		whoisServerAddress: ianaWHOISServerAddress,
+	}
+}
+
+func (c Client) Query(domain string) (string, error) {
+	parts := strings.Split(domain, ".")
+	output, err := c.query(c.whoisServerAddress, parts[len(parts)-1])
+	if err != nil {
+		return "", err
+	}
+	if strings.Contains(output, "whois:") {
+		startIndex := strings.Index(output, "whois:") + 6
+		endIndex := strings.Index(output[startIndex:], "\n") + startIndex
+		whois := strings.TrimSpace(output[startIndex:endIndex])
+		if referOutput, err := c.query(whois+":43", domain); err == nil {
+			return referOutput, nil
+		}
+		return "", err
+	}
+	return output, nil
+}
+
+func (c Client) query(whoisServerAddress, domain string) (string, error) {
+	connection, err := net.DialTimeout("tcp", whoisServerAddress, 10*time.Second)
+	if err != nil {
+		return "", err
+	}
+	defer connection.Close()
+	connection.SetDeadline(time.Now().Add(5 * time.Second))
+	_, err = connection.Write([]byte(domain + "\r\n"))
+	if err != nil {
+		return "", err
+	}
+	output, err := io.ReadAll(connection)
+	if err != nil {
+		return "", err
+	}
+	return string(output), nil
+}
+
+type Response struct {
+	ExpirationDate time.Time
+	DomainStatuses []string
+	NameServers    []string
+}
+
+// QueryAndParse tries to parse the response from the WHOIS server
+// There is no standardized format for WHOIS responses, so this is an attempt at best.
+//
+// Being the selfish person that I am, I also only parse the fields that I need.
+// If you need more fields, please open an issue or pull request.
+func (c Client) QueryAndParse(domain string) (*Response, error) {
+	text, err := c.Query(domain)
+	if err != nil {
+		return nil, err
+	}
+	response := Response{}
+	for _, line := range strings.Split(text, "\n") {
+		line = strings.TrimSpace(line)
+		valueStartIndex := strings.Index(line, ":")
+		if valueStartIndex == -1 {
+			continue
+		}
+		key := strings.ToLower(strings.TrimSpace(line[:valueStartIndex]))
+		value := strings.TrimSpace(line[valueStartIndex+1:])
+		if response.ExpirationDate.Unix() != 0 && strings.Contains(key, "expir") && strings.Contains(key, "date") {
+			response.ExpirationDate, _ = time.Parse(time.RFC3339, strings.ToUpper(value))
+		} else if strings.Contains(key, "domain status") {
+			response.DomainStatuses = append(response.DomainStatuses, value)
+		} else if strings.Contains(key, "name server") {
+			response.NameServers = append(response.NameServers, value)
+		}
+	}
+	return &response, nil
+}