logging and client info parsing changes, added trusted proxies

.gitignore

@@ -15,6 +15,8 @@
 
 # Custom Additions
 servtex
+config.json
+testfiles/tls
 *.aux
 *.log
 *.pdf

backend/backend.go

@@ -4,16 +4,24 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"os"
 	"io/fs"
+	"net"
+	"net/http"
+	"os"
 	"os/exec"
 	"path/filepath"
+	"slices"
 	"strings"
 	"time"
+	"embed"
+
 	"git.noctra.dev/noctra/servtex/globals"
 	"github.com/fsnotify/fsnotify"
 )
 
+//go:embed default_config.json
+var defaultConfig embed.FS
+
 // Returns the current time in the timezone specified in the config file
 func GetLocalTime() time.Time {
 	timezone, _ := time.LoadLocation(globals.AppConfig.Timezone)
@@ -49,6 +57,30 @@ func LogLine(message string, level int) {
 	globals.LogFile.WriteString(logline)
 }
 
+// Logs client info. Configured log level sets the verbosity.
+//
+// Bad Request if err != nil
+func VerifyLogRequest(request *http.Request) (err error) {
+	client, err := ProcessClientInfo(request)
+	if err != nil { return errors.New("Request Verification Failed") }
+
+	if client.Proxied && globals.AppConfig.LogLevelNumeric > 1 {
+		LogLine(fmt.Sprintf(
+				"Request: %s via %s - %s %s",
+				client.ClientIP, 
+				client.Proxy,
+				client.RequestType, 
+				client.RequestPath, 
+			), 
+			4,
+		)
+	} else {
+		LogLine(fmt.Sprintf("Request: %s - %s %s", client.ClientIP, client.RequestType, client.RequestPath), 4)
+	}
+
+	return nil
+}
+
 // Helper for configReader() that does the actual reading
 //
 // Also validates the populated fields
@@ -56,11 +88,11 @@ func configReaderParse(filePath string, configOptionStorage *globals.Config) err
 	jsonData, err := os.ReadFile(filePath)
 	if err == nil {
 		if err = json.Unmarshal(jsonData, &configOptionStorage); err != nil {
-			LogLine("Configuration file is invaldi JSON", 5)
+			LogLine("Configuration file is invalid JSON", 5)
 			return errors.New("Config file could not be read")
 		}
 	} else {
-		LogLine(fmt.Sprintf("Config at %s does not exist", filePath), 1)
+		LogLine("Configuration file does not exist", 1)
 		return errors.New("Config file does not exist")
 	}
 
@@ -77,7 +109,7 @@ func configReaderParse(filePath string, configOptionStorage *globals.Config) err
 			configOptionStorage.LogLevelNumeric = 3
 			LogLine("Defaulting to log level warning", 3)
 	}
-	return configValidator(*configOptionStorage)
+	return nil
 }
 
 // tbd what exactly happens here
@@ -85,6 +117,14 @@ func configValidator(config globals.Config) error {
 	return nil
 }
 
+func configPopulator(config globals.Config) error {
+	return nil
+}
+
+// Creates the configuration file populated with defaults
+func createConfigWithDefaults() {
+}
+
 // Reads config file and stores the options in configOptionStorage
 //
 // Tries the following paths
@@ -108,9 +148,15 @@ func ConfigReader(configFileName string, configOptionStorage *globals.Config) er
 
 	path := filepath.Join("~", ".config", "servtex", configFileName)
 	err = configReaderParse(path, configOptionStorage)
-	if err == nil { return nil }
+	if err != nil { return err }
 
-	return err 
+	err = configPopulator(*configOptionStorage)
+	if err != nil { return err }
+
+	err = configValidator(*configOptionStorage)
+	if err != nil { return err }
+
+	return nil
 }
 
 // Contents copied from https://github.com/fsnotify/fsnotify/blob/main/cmd/fsnotify/watch.go
@@ -240,3 +286,88 @@ func LatexCompile() error {
 	return nil
 }
 
+// Returns intersection of two slices
+func sliceIntersection[T comparable](left []T, right []T) (intersection []T) {
+	for _, leftItem := range left {
+		for _, rightItem := range right {
+			if leftItem == rightItem {
+				intersection = append(intersection, leftItem)
+			}
+		}
+	}
+	return intersection
+}
+
+// Checks whether the proxy is trusted. Returns trusted status and the proxy.
+//
+// If X-Forwarded-For chain is passed, only the last in chain will be considered
+func isTrustedProxy(proxy string, trustedProxies []string) (trusted bool, usedProxy string) {
+	// removes len()>0 checks
+	if proxy == "" { return false, "" }
+	// untrusted unless proven otherwise
+	trusted = false
+
+	// get (last) used proxy (in chain)
+	if slices.Contains(trustedProxies, proxy) { 
+		usedProxy = proxy
+	} else {
+		proxies := strings.Split(proxy, ",")[1:]
+		usedProxy = proxies[len(proxies)-1]
+	}
+
+	// check if proxy is trusted
+	if slices.Contains(trustedProxies, usedProxy) { return true, usedProxy }
+
+	// resolve trustedProxies in case a DNS name was configured
+	for _, trustedProxyDNS := range trustedProxies {
+		// get IPs of this dns name
+		trustedProxyIPs, err := net.LookupAddr(trustedProxyDNS)
+		if err != nil { continue }
+
+		// set usedProxy to DNS name if proxy is trusted
+		if slices.Contains(trustedProxyIPs, usedProxy) {
+			trusted = true
+			usedProxy = trustedProxyDNS
+			return trusted, usedProxy
+		}
+	}
+
+	return trusted, usedProxy
+}
+
+// Returns client info of the request. Error indicates untrusted Proxy or unavailable client IP.
+func ProcessClientInfo(request *http.Request) (client globals.ClientInfo, err error) {
+	client.ClientIP, _, err = net.SplitHostPort(request.RemoteAddr)
+	client.RequestType = request.Method
+	client.RequestPath = request.URL.Path
+	client.Proxy = ""
+	client.Proxied = false
+	client.ProxyTrusted = false
+
+	trustedProxies := globals.AppConfig.TrustedProxies
+
+	headerXRP := request.Header.Get("X-Real-IP")
+	if headerXRP != "" {
+		client.Proxied = true
+		client.ProxyTrusted, client.Proxy = isTrustedProxy(headerXRP, trustedProxies)
+		if !client.ProxyTrusted {
+			LogLine(fmt.Sprintf("Request sent via untrusted Proxy %s", client.Proxy), 4)
+			err = errors.New("Untrusted Proxy")
+		}
+		return client, err
+	}
+
+	headerXFF := request.Header.Get("X-Forwarded-For")
+	if headerXFF != "" {
+		client.Proxied = true
+		client.ProxyTrusted, client.Proxy = isTrustedProxy(headerXRP, trustedProxies)
+		if !client.ProxyTrusted {
+			LogLine(fmt.Sprintf("Request sent via untrusted Proxy %s", client.Proxy), 4)
+			err = errors.New("Untrusted Proxy")
+		}
+		return client, err
+	}
+
+	return client, err
+}
+

backend/default_config.json

@@ -0,0 +1,17 @@
+{
+	"timezone": "Europe/Berlin"
+	"logFilePath": "./servtex.log",
+	"logLevel": "warning",
+
+	"latexEngine": "lualatex",
+	"latexSourceFilePath": "./latex/Example.tex",
+	"latexOutputPath": "./latex/output",
+
+	"webserverDomain": "localhost",
+	"webserverPort": "8080",
+	"webserverSecure": true,
+	"webserverPortSecure": "8443",
+	"certificatePath": "./tls/testing.crt",
+	"certificateKeyPath": "./tls/testing.key",
+	"trustedProxies": []
+}

config.json

@@ -1,6 +1,7 @@
 {
-	"logLevel": "debug",
+	"timezone": "Europe/Berlin"
 	"logFilePath": "./servtex.log",
+	"logLevel": "debug",
 
 	"latexEngine": "lualatex",
 	"latexSourceFilePath": "./testfiles/Example.tex",
@@ -12,5 +13,5 @@
 	"webserverPortSecure": "8443",
 	"certificatePath": "./testfiles/tls/testing.crt",
 	"certificateKeyPath": "./testfiles/tls/testing.key",
-	"timezone": "Europe/Berlin"
+	"trustedProxies": []
 }

frontend/webserver.go

@@ -70,30 +70,46 @@ func sseOutputSend(writer *http.ResponseWriter) {
 	backend.LogLine("Output Event has been sent", 1)
 }
 
+
+
 // Server Side Event Handler
 //
 // Sends a Ping instead of actual data when no new data available to save bandwidth
 func SSEventHandler(writer http.ResponseWriter, request *http.Request) {
+	if err := backend.VerifyLogRequest(request); err != nil { http.Error(writer, "Bad Request", http.StatusBadRequest) }
+
 	writer.Header().Set("Content-Type", "text/event-stream")
 	writer.Header().Set("Cache-Control", "no-cache")
 	writer.Header().Set("Connection", "keep-alive")
 	ssePing(&writer)
 
-	lastExecution := "startup"
+
+	lastExecution := ""
 	for range time.Tick(time.Second) {
+		select {
+			case <-request.Context().Done():
+				backend.LogLine("SSE Context Done", 1)
+				return
+			default:
 				if lastExecution == globals.LatexExec.TimestampRFC {
 					ssePing(&writer)
 				} else {
 					sseStatusSend(&writer)
-			ssePDFSend(&writer)
 					sseOutputSend(&writer)
+					// let client keep current pdf, if compile failed
+					if globals.LatexExec.ExecutionState != "Failed" {
+						ssePDFSend(&writer)
+					}
 					lastExecution = globals.LatexExec.TimestampRFC
 				}
 			}
+	}
 }
 
 // Serves the compiled PDF file
 func PDFHandler(writer http.ResponseWriter, request *http.Request) {
+	if err := backend.VerifyLogRequest(request); err != nil { http.Error(writer, "Bad Request", http.StatusBadRequest) }
+
 	pdfPath := filepath.Join(globals.AppConfig.LatexOutputPath, "servtex.pdf")
 	pdf, err := os.Open(pdfPath)
 	if err != nil {
@@ -109,12 +125,16 @@ func PDFHandler(writer http.ResponseWriter, request *http.Request) {
 
 // Serves the main page of ServTeX
 func MainHandler(writer http.ResponseWriter, request *http.Request) {
+	if err := backend.VerifyLogRequest(request); err != nil { http.Error(writer, "Bad Request", http.StatusBadRequest) }
+
 	writer.Header().Set("Content-Type", "text/html")
 	main, _ := WebFiles.ReadFile("templates/main.html")
 	writer.Write(main)
 }
 
 func PDFCompile(writer http.ResponseWriter, request *http.Request) {
+	if err := backend.VerifyLogRequest(request); err != nil { http.Error(writer, "Bad Request", http.StatusBadRequest) }
+
 	backend.LatexCompile()
 }
 

globals/memory.go

@@ -5,11 +5,14 @@ import (
 	"sync"
 )
 
+var LogFile *os.File
+
 type Config struct {
 	// general
+	Timezone		string		`json:"timezone"`
+	LogFilePath		string		`json:"logFilePath"`
 	LogLevel		string		`json:"logLevel"`
 	LogLevelNumeric		int
-	LogFilePath		string	`json:"logFilePath"`
 
 	// latex
 	LatexEngine		string		`json:"latexEngine"`
@@ -23,7 +26,7 @@ type Config struct {
 	WebserverPortSecure	string		`json:"webserverPortSecure"`
 	CertificatePath		string		`json:"certificatePath"`
 	CertificateKeyPath	string		`json:"certificateKeyPath"`
-	Timezone		string	`json:"timezone"`
+	TrustedProxies		[]string	`json:"trustedProxies"`
 }
 var AppConfig Config
 
@@ -37,5 +40,12 @@ type LatexExecution struct {
 }
 var LatexExec LatexExecution
 
-var LogFile *os.File
+type ClientInfo struct {
+	ClientIP	string
+	RequestType	string 
+	RequestPath	string 
+	Proxy		string
+	Proxied		bool
+	ProxyTrusted	bool
+}
 

testfiles/Example.tex

@@ -3,6 +3,4 @@
 (This is an Example Document)
 Filewatcher Test Document
 Filewatcher Test Document
-Filewatcher Test Document
-Filewatcher Test Document
 \end{document}