From 42d27c06472fabf80ef82aaf4587a9abb5e1eb1f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jose=20Luis=20Monta=C3=B1es=20Ojados?= <joseluis@zubi.group>
Date: Mon, 19 Jan 2026 16:32:57 +0100
Subject: [PATCH] fix: Implement proactive packet flushing based on
 Content-Length to resolve UI update lag

---
 internal/capture/capturer.go | 30 ++++++++++++++++++++++++++++--
 internal/capture/local.go    | 29 +++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 2 deletions(-)

diff --git a/internal/capture/capturer.go b/internal/capture/capturer.go
index 8efa0c5..a7e4f05 100644
--- a/internal/capture/capturer.go
+++ b/internal/capture/capturer.go
@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"fmt"
 	"io"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -111,6 +112,7 @@ func (c *Capturer) processStream(r io.Reader) {
 	var buffer strings.Builder
 	inSIPMessage := false
 	var msgNetInfo *NetInfo
+	contentLength := -1
 
 	for scanner.Scan() {
 		c.mu.Lock()
@@ -149,14 +151,38 @@ func (c *Capturer) processStream(r io.Reader) {
 			}
 
 			inSIPMessage = true
+			contentLength = -1 // Reset
 		}
 
 		if inSIPMessage {
 			buffer.WriteString(line)
 			buffer.WriteString("\r\n")
 
-			// Detect end of SIP message (double CRLF or content complete)
-			// This is simplified - real implementation would track Content-Length
+			// Check for Content-Length
+			lowerLine := strings.ToLower(line)
+			if strings.HasPrefix(lowerLine, "content-length:") || strings.HasPrefix(lowerLine, "l:") {
+				parts := strings.Split(line, ":")
+				if len(parts) >= 2 {
+					val := strings.TrimSpace(parts[1])
+					if val != "" {
+						if cl, err := strconv.Atoi(val); err == nil {
+							contentLength = cl
+						}
+					}
+				}
+			}
+
+			// Check for end of headers (empty line)
+			if line == "" {
+				// If Content-Length is 0 (or not found, treating as 0)
+				// Flush immediately
+				if contentLength <= 0 {
+					c.parseAndEmit(buffer.String(), msgNetInfo)
+					buffer.Reset()
+					inSIPMessage = false
+					contentLength = -1
+				}
+			}
 		}
 	}
 
diff --git a/internal/capture/local.go b/internal/capture/local.go
index fdcc90c..c9b6778 100644
--- a/internal/capture/local.go
+++ b/internal/capture/local.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"os/exec"
+	"strconv"
 	"strings"
 	"sync"
 
@@ -133,6 +134,7 @@ func (c *LocalCapturer) processStream(r io.Reader) {
 	var buffer strings.Builder
 	inSIPMessage := false
 	var msgNetInfo *NetInfo
+	contentLength := -1
 
 	for scanner.Scan() {
 		c.mu.Lock()
@@ -192,11 +194,38 @@ func (c *LocalCapturer) processStream(r io.Reader) {
 			}
 
 			inSIPMessage = true
+			contentLength = -1 // Reset for new message
 		}
 
 		if inSIPMessage {
 			buffer.WriteString(line)
 			buffer.WriteString("\r\n")
+
+			// Check for Content-Length
+			lowerLine := strings.ToLower(line)
+			if strings.HasPrefix(lowerLine, "content-length:") || strings.HasPrefix(lowerLine, "l:") {
+				parts := strings.Split(line, ":")
+				if len(parts) >= 2 {
+					val := strings.TrimSpace(parts[1])
+					if val != "" {
+						if cl, err := strconv.Atoi(val); err == nil {
+							contentLength = cl
+						}
+					}
+				}
+			}
+
+			// Check for end of headers (empty line)
+			if line == "" {
+				// If Content-Length is 0 (or not found, treating as 0 for safety in this context usually 0 for BYE/ACK)
+				// Flush immediately
+				if contentLength <= 0 {
+					c.parseAndEmit(buffer.String(), msgNetInfo)
+					buffer.Reset()
+					inSIPMessage = false
+					contentLength = -1
+				}
+			}
 		}
 	}