From 565f54bff8bcec39da3a74eed91ee832fff7f932 Mon Sep 17 00:00:00 2001
From: Solderpunk <solderpunk@posteo.net>
Date: Sun, 9 Feb 2025 18:58:24 +0100
Subject: [PATCH] Factor out header parsing code for CGI and SCGI into one
 function, so the checks from last commit can be applied to both.

---
 dynamic.go | 87 ++++++++++++++++++++++++++++++------------------------
 1 file changed, 49 insertions(+), 38 deletions(-)

diff --git a/dynamic.go b/dynamic.go
index f1ec402..938b7f0 100644
--- a/dynamic.go
+++ b/dynamic.go
@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"context"
 	"crypto/tls"
+	"errors"
 	"io"
 	"log"
 	"net"
@@ -15,6 +16,35 @@ import (
 	"time"
 )
 
+func extractStatusFromDynamicResponse(reader *bufio.Reader, source string) (int, error) {
+	rawHeader, _, err := reader.ReadLine()
+	if err != nil {
+		log.Println("Unable to read header in dynamic output from " + source + ".")
+		return 0, err
+	}
+	header := string(rawHeader)
+	logErrorMsg := "Unable to parse first line of dynamic output from " +
+	               source +
+		       " as valid Gemini response header.  Line was: " +
+		       header
+	header_fields := strings.Fields(header)
+	if len(header_fields) == 0 {
+		log.Println(logErrorMsg)
+		return 0, errors.New("")
+	}
+	status, err := strconv.Atoi(header_fields[0])
+	if err != nil {
+		log.Println(logErrorMsg)
+		return 0, err
+	}
+	if status < 10 || status > 70 {
+		log.Println(logErrorMsg)
+		return 0, errors.New("")
+	}
+
+	return status, nil
+}
+
 func handleCGI(config SysConfig, path string, cgiPath string, URL *url.URL, logEntry *LogEntry, conn net.Conn) {
 	// Find the shortest leading part of path which maps to an executable file.
 	// Call this part scriptPath, and everything after it pathInfo.
@@ -72,6 +102,7 @@ func handleCGI(config SysConfig, path string, cgiPath string, URL *url.URL, logE
 		logEntry.Status = 42
 		return
 	}
+
 	// Extract response header
 	responseString := string(response)
 	if len(responseString) == 0 {
@@ -80,28 +111,16 @@ func handleCGI(config SysConfig, path string, cgiPath string, URL *url.URL, logE
 		logEntry.Status = 42
 		return
 	}
-	header, _, err := bufio.NewReader(strings.NewReader(string(response))).ReadLine()
-	if err != nil || len(header) == 0 {
-		log.Println("Unable to parse first line of output from CGI process " + path + " as valid Gemini response header.  Line was: " + string(header))
+
+	responseReader := bufio.NewReader(strings.NewReader(string(response)))
+	status, err := extractStatusFromDynamicResponse(responseReader, path)
+	if err != nil {
 		conn.Write([]byte("42 CGI error!\r\n"))
 		logEntry.Status = 42
 		return
+	} else {
+		logEntry.Status = status
 	}
-	header_fields := strings.Fields(string(header))
-	if len(header_fields) == 0 {
-		log.Println("Unable to parse first line of output from CGI process " + path + " as valid Gemini response header.  Line was: " + string(header))
-		conn.Write([]byte("42 CGI error!\r\n"))
-		logEntry.Status = 42
-		return
-	}
-	status, err := strconv.Atoi(header_fields[0])
-	if err != nil || status < 10 || status > 70 {
-		log.Println("Unable to parse first line of output from CGI process " + path + " as valid Gemini response header.  Line was: " + string(header))
-		conn.Write([]byte("42 CGI error!\r\n"))
-		logEntry.Status = 42
-		return
-	}
-	logEntry.Status = status
 
 	// Write response
 	conn.Write(response)
@@ -135,36 +154,28 @@ func handleSCGI(URL *url.URL, scgiPath string, scgiSocket string, config SysConf
 	socket.Write([]byte(","))
 
 	// Read and relay response
+	responseReader := bufio.NewReader(socket)
+	status, err := extractStatusFromDynamicResponse(responseReader, scgiSocket)
+	if err != nil {
+		conn.Write([]byte("42 SCGI error!\r\n"))
+		logEntry.Status = 42
+		return
+	} else {
+		logEntry.Status = status
+	}
+
 	buffer := make([]byte, 1027)
-	first := true
 	for {
-		n, err := socket.Read(buffer)
+		n, err := responseReader.Read(buffer)
 		if err != nil {
 			if err == io.EOF {
 				break
-			} else if !first {
+			} else {
 				// Err
 				log.Println("Error reading from SCGI socket " + scgiSocket + ": " + err.Error())
-				conn.Write([]byte("42 Error reading from SCGI service!\r\n"))
-				logEntry.Status = 42
-				return
-			} else {
 				break
 			}
 		}
-		// Extract status code from first line
-		if first {
-			first = false
-			lines := strings.SplitN(string(buffer), "\r\n", 2)
-			status, err := strconv.Atoi(strings.Fields(lines[0])[0])
-			if err != nil || status < 10 || status > 70 {
-				conn.Write([]byte("42 CGI error!\r\n"))
-				log.Println("Unable to parse first line of output from SCGI socket " + scgiSocket + " as valid Gemini response header.  Line was: " + lines[0])
-				logEntry.Status = 42
-				return
-			}
-			logEntry.Status = status
-		}
 		// Send to client
 		conn.Write(buffer[:n])
 	}