Add in routine that checks internet connectivity for bot services (#287)

* Add in routine that checks internet connectivity for bot services

* Packaged connection checker

config/config.go

@@ -15,6 +15,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/thrasher-/gocryptotrader/connchecker"
 	"github.com/thrasher-/gocryptotrader/common"
 	"github.com/thrasher-/gocryptotrader/currency"
 	"github.com/thrasher-/gocryptotrader/currency/forexprovider"
@@ -104,18 +105,19 @@ type CurrencyPairFormatConfig struct {
 // prestart management of Portfolio, Communications, Webserver and Enabled
 // Exchanges
 type Config struct {
-	Name              string               `json:"name"`
-	EncryptConfig     int                  `json:"encryptConfig"`
-	GlobalHTTPTimeout time.Duration        `json:"globalHTTPTimeout"`
-	Logging           log.Logging          `json:"logging"`
-	Profiler          ProfilerConfig       `json:"profiler"`
-	NTPClient         NTPClientConfig      `json:"ntpclient"`
-	Currency          CurrencyConfig       `json:"currencyConfig"`
-	Communications    CommunicationsConfig `json:"communications"`
-	Portfolio         portfolio.Base       `json:"portfolioAddresses"`
-	Webserver         WebserverConfig      `json:"webserver"`
-	Exchanges         []ExchangeConfig     `json:"exchanges"`
-	BankAccounts      []BankAccount        `json:"bankAccounts"`
+	Name              string                  `json:"name"`
+	EncryptConfig     int                     `json:"encryptConfig"`
+	GlobalHTTPTimeout time.Duration           `json:"globalHTTPTimeout"`
+	Logging           log.Logging             `json:"logging"`
+	Profiler          ProfilerConfig          `json:"profiler"`
+	NTPClient         NTPClientConfig         `json:"ntpclient"`
+	Currency          CurrencyConfig          `json:"currencyConfig"`
+	Communications    CommunicationsConfig    `json:"communications"`
+	Portfolio         portfolio.Base          `json:"portfolioAddresses"`
+	Webserver         WebserverConfig         `json:"webserver"`
+	Exchanges         []ExchangeConfig        `json:"exchanges"`
+	BankAccounts      []BankAccount           `json:"bankAccounts"`
+	ConnectionMonitor ConnectionMonitorConfig `json:"connectionMonitor"`
 
 	// Deprecated config settings, will be removed at a future date
 	CurrencyPairFormat  *CurrencyPairFormatConfig `json:"currencyPairFormat,omitempty"`
@@ -124,6 +126,14 @@ type Config struct {
 	SMS                 *SMSGlobalConfig          `json:"smsGlobal,omitempty"`
 }
 
+// ConnectionMonitorConfig defines the connection monitor variables to ensure
+// that there is internet connectivity
+type ConnectionMonitorConfig struct {
+	DNSList          []string      `json:"preferredDNSList"`
+	PublicDomainList []string      `json:"preferredDomainList"`
+	CheckInterval    time.Duration `json:"checkInterval"`
+}
+
 // ProfilerConfig defines the profiler configuration to enable pprof
 type ProfilerConfig struct {
 	Enabled bool `json:"enabled"`
@@ -1158,6 +1168,24 @@ func (c *Config) DisableNTPCheck(input io.Reader) (string, error) {
 	return "", errors.New("something went wrong NTPCheck should never make it this far")
 }
 
+// CheckConnectionMonitorConfig checks and if zero value assigns default values
+func (c *Config) CheckConnectionMonitorConfig() {
+	m.Lock()
+	defer m.Unlock()
+
+	if c.ConnectionMonitor.CheckInterval == 0 {
+		c.ConnectionMonitor.CheckInterval = connchecker.DefaultCheckInterval
+	}
+
+	if len(c.ConnectionMonitor.DNSList) == 0 {
+		c.ConnectionMonitor.DNSList = connchecker.DefaultDNSList
+	}
+
+	if len(c.ConnectionMonitor.PublicDomainList) == 0 {
+		c.ConnectionMonitor.PublicDomainList = connchecker.DefaultDomainList
+	}
+}
+
 // GetFilePath returns the desired config file or the default config file name
 // based on if the application is being run under test or normal mode.
 func GetFilePath(file string) (string, error) {
@@ -1351,6 +1379,7 @@ func (c *Config) CheckConfig() error {
 		return fmt.Errorf(ErrCheckingConfigValues, err)
 	}
 
+	c.CheckConnectionMonitorConfig()
 	c.CheckCommunicationsConfig()
 
 	if c.Webserver.Enabled {

connchecker/connchecker.go

@@ -0,0 +1,121 @@
+package connchecker
+
+import (
+	"net"
+	"sync"
+	"time"
+
+	log "github.com/thrasher-/gocryptotrader/logger"
+)
+
+// DefaultCheckInterval is a const that defines the amount of time between
+// checking if the connection is lost
+const DefaultCheckInterval = time.Second
+
+// Default check lists
+var (
+	DefaultDNSList    = []string{"8.8.8.8", "8.8.4.4", "1.1.1.1", "1.0.0.1"}
+	DefaultDomainList = []string{"www.google.com", "www.cloudflare.com", "www.facebook.com"}
+)
+
+// New returns a new connection checker, if no values set it will default it out
+func New(dnsList, domainList []string, checkInterval time.Duration) *Checker {
+	c := &Checker{}
+	if len(dnsList) == 0 {
+		c.DNSList = DefaultDNSList
+	} else {
+		c.DNSList = dnsList
+	}
+
+	if len(domainList) == 0 {
+		c.DomainList = DefaultDomainList
+	} else {
+		c.DomainList = domainList
+	}
+
+	if checkInterval == 0 {
+		c.CheckInterval = DefaultCheckInterval
+	} else {
+		c.CheckInterval = checkInterval
+	}
+
+	go c.Monitor()
+	return c
+}
+
+// Checker defines a struct to determine connectivity to the interwebs
+type Checker struct {
+	DNSList       []string
+	DomainList    []string
+	CheckInterval time.Duration
+	shutdown      chan struct{}
+	wg            sync.WaitGroup
+	connected     bool
+	sync.Mutex
+}
+
+// Shutdown cleanly shutsdown monitor routine
+func (c *Checker) Shutdown() {
+	c.shutdown <- struct{}{}
+	c.wg.Wait()
+}
+
+// Monitor determines internet connectivity via a DNS lookup
+func (c *Checker) Monitor() {
+	c.wg.Add(1)
+	tick := time.NewTicker(time.Second)
+	defer func() { tick.Stop(); c.wg.Done() }()
+	c.connectionTest()
+	for {
+		select {
+		case <-tick.C:
+			c.connectionTest()
+		case <-c.shutdown:
+			return
+		}
+	}
+}
+
+// ConnectionTest determines if a connection to the internet is available by
+// iterating over a set list of dns ip and popular domains
+func (c *Checker) connectionTest() {
+	for i := range c.DNSList {
+		_, err := net.LookupAddr(c.DNSList[i])
+		if err == nil {
+			c.Lock()
+			if !c.connected {
+				log.Warnf("Internet connectivity re-established")
+				c.connected = true
+			}
+			c.Unlock()
+			return
+		}
+	}
+
+	for i := range c.DomainList {
+		_, err := net.LookupHost(c.DomainList[i])
+		if err == nil {
+			c.Lock()
+			if !c.connected {
+				log.Warnf("Internet connectivity re-established")
+				c.connected = true
+			}
+			c.Unlock()
+			return
+		}
+	}
+
+	c.Lock()
+	if c.connected {
+		log.Warnf("Internet connectivity lost")
+		c.connected = false
+	}
+	c.Unlock()
+}
+
+// IsConnected returns if there is internet connectivity
+func (c *Checker) IsConnected() bool {
+	c.Lock()
+	defer c.Unlock()
+	return c.connected
+}

main.go

@@ -8,12 +8,14 @@ import (
 	"os/signal"
 	"runtime"
 	"strconv"
+	"sync"
 	"syscall"
 	"time"
 
 	"github.com/thrasher-/gocryptotrader/common"
 	"github.com/thrasher-/gocryptotrader/communications"
 	"github.com/thrasher-/gocryptotrader/config"
+	"github.com/thrasher-/gocryptotrader/connchecker"
 	"github.com/thrasher-/gocryptotrader/currency"
 	"github.com/thrasher-/gocryptotrader/currency/coinmarketcap"
 	exchange "github.com/thrasher-/gocryptotrader/exchanges"
@@ -25,14 +27,16 @@ import (
 // Bot contains configuration, portfolio, exchange & ticker data and is the
 // overarching type across this code base.
 type Bot struct {
-	config     *config.Config
-	portfolio  *portfolio.Base
-	exchanges  []exchange.IBotExchange
-	comms      *communications.Communications
-	shutdown   chan bool
-	dryRun     bool
-	configFile string
-	dataDir    string
+	config       *config.Config
+	portfolio    *portfolio.Base
+	exchanges    []exchange.IBotExchange
+	comms        *communications.Communications
+	shutdown     chan bool
+	dryRun       bool
+	configFile   string
+	dataDir      string
+	connectivity *connchecker.Checker
+	sync.Mutex
 }
 
 const banner = `
@@ -129,6 +133,11 @@ func main() {
 		}
 	}
 
+	// Sets up internet connectivity monitor
+	bot.connectivity = connchecker.New(bot.config.ConnectionMonitor.DNSList,
+		bot.config.ConnectionMonitor.PublicDomainList,
+		bot.config.ConnectionMonitor.CheckInterval)
+
 	AdjustGoMaxProcs()
 	log.Debugf("Bot '%s' started.\n", bot.config.Name)
 	log.Debugf("Bot dry run mode: %v.\n", common.IsEnabled(bot.dryRun))
@@ -243,7 +252,7 @@ func HandleInterrupt() {
 	go func() {
 		sig := <-c
 		log.Debugf("Captured %v, shutdown requested.", sig)
-		bot.shutdown <- true
+		close(bot.shutdown)
 	}()
 }