worker/app/models/check_settings.go

package models

import (
	"errors"
	"fmt"
	"net/http"
	"strings"
)

// CheckHeader provides functionality.
type CheckHeader struct {
	Key   string `json:"key"`
	Value string `json:"value"`
}

// CheckSettings provides functionality.
type CheckSettings struct {
	// HTTP Basic Auth Username
	HTTPUsername string `json:"http_username,omitempty"`
	// HTTP Basic Auth Password
	HTTPPassword string `json:"http_password,omitempty"`

	// ExpectedAnswer (default, redirect, custom)
	ExpectedAnswer string `json:"expected_answer,omitempty"`
	// Expected redirect location
	ExpectedLocation string `json:"expected_location,omitempty"`
	// Expected HTTP status codes for custom
	ExpectedHTTPCode int `json:"expected_http_code,omitempty"`

	// Keyword search type (off, present or absent)
	KeywordType string `json:"keyword_type,omitempty"`
	// Keyword to search for
	KeywordValue string `json:"keyword_value,omitempty"`

	SlowTime int `json:"slow_time"`
	Timeout  int `json:"timeout"`
	// Request Settings
	CheckIp        bool          `json:"checkip"` //nolint:revive // accepted lint exception
	CheckIPv6      bool          `json:"checkipv6"`
	RequestHeader  []CheckHeader `json:"request_headers"`
	RequestMethod  string        `json:"request_method"`
	RequestType    string        `json:"request_type"`
	RequestContent string        `json:"request_content"`
	// SSH Settings
	Port string `json:"port"`

	// Host optionally overrides the monitor host for checks that do
	// not naturally target the Monitor.Host (e.g. an ICMP/TCP/UDP
	// probe to a separate machine, or a different IP family). Used by
	// cping/ctcp/cudp.
	Host string `json:"host,omitempty"`

	// Count is the per-check packet count for ping. Defaults to 1 in
	// cping when zero or negative.
	Count int `json:"count,omitempty"`

	// PacketSize is the ICMP payload size for ping (bytes). Defaults
	// to 56 in cping when zero or negative.
	PacketSize int `json:"packet_size,omitempty"`

	// Distributed marks this check as eligible for execution on the
	// distributed worker pool (multi-region, multi-worker) instead of
	// only the in-process scheduler. Reserved for paid plans; the
	// controller layer enforces the plan check.
	Distributed bool `json:"distributed"`
}

// redirectCodes contains all HTTP redirect status codes.
var redirectCodes = []int{300, 301, 302, 303, 307, 308}

// CheckKeyword provides functionality.
func (s *CheckSettings) CheckKeyword(body []byte, warns []string) ([]string, error) {
	var err error

	switch s.KeywordType {
	case "", "off":
		return warns, nil
	case "present":
		if !strings.Contains(string(body), s.KeywordValue) {
			err = errors.New("expected keyword " + s.KeywordValue + " not found")
		}
	case "absent":
		if strings.Contains(string(body), s.KeywordValue) {
			err = errors.New("unexpected keyword " + s.KeywordValue + " found")
		}
	}

	return warns, err
}

// CheckAnswer provides functionality.
func (s *CheckSettings) CheckAnswer(resp *http.Response, body []byte) ([]string, error) {
	// log.Println("check answer, settings:")
	// spew.Dump(s)

	isRedirect := false

	for _, rc := range redirectCodes {
		if resp.StatusCode == rc {
			isRedirect = true
		}
	}

	location := resp.Header.Get("location")

	// log.Println("redirect?", isRedirect, location)

	switch s.ExpectedAnswer {
	case "", "default":
		if isRedirect {
			return s.CheckKeyword(body, []string{"redirect: " + location})
		} else if resp.StatusCode != 200 {
			return []string{}, fmt.Errorf("bad status code: %d", resp.StatusCode)
		}

	case "redirect":
		if !isRedirect {
			return []string{}, fmt.Errorf("bad status code: %d (expected redirect)", resp.StatusCode)
		}

		if s.ExpectedLocation != "" {
			if location != s.ExpectedLocation {
				return []string{}, fmt.Errorf(
					"bad location: %s (expected %s)",
					location,
					s.ExpectedLocation,
				)
			}
		}

	case "custom":
		if s.ExpectedHTTPCode == 0 {
			s.ExpectedHTTPCode = 200
		}
		if resp.StatusCode != s.ExpectedHTTPCode {
			return []string{}, fmt.Errorf("bad status code: %d (expected %d)", resp.StatusCode, s.ExpectedHTTPCode)
		}

		if s.ExpectedLocation != "" {
			if location != s.ExpectedLocation {
				return []string{}, fmt.Errorf(
					"bad location: %s (expected %s)",
					location,
					s.ExpectedLocation,
				)
			}
		}

	default:
		panic("bad expectedAnswer")
	}

	// return []string{}, nil
	return s.CheckKeyword(body, []string{})
}