SSE connections fail silently through MITM proxies (missing auth challenge delegate) #50

Closed
#51
Closed
SSE connections fail silently through MITM proxies (missing auth challenge delegate)#50
#51

Description

@liefran-sim
liefran-sim
opened on May 11, 2026

Description

When using EventSource through an MITM proxy (e.g., mitmproxy, Charles Proxy), SSE connections fail silently even when the proxy's CA certificate is installed and trusted at the OS level.

Root Cause

SessionDelegate does not implement urlSession(_:didReceive challenge:completionHandler:). While the expected behavior is that URLSession falls back to default system trust evaluation, in practice this can cause the connection to be silently rejected when a custom delegate is set without handling authentication challenges.

Steps to Reproduce

  1. Install and trust a proxy CA certificate on an iOS device (e.g., mitmproxy CA)
  2. Configure the device to use the proxy
  3. Open an SSE connection using EventSource to an HTTPS endpoint
  4. The connection fails silently — no data events, no error events, the request never reaches the proxy

Expected Behavior

The SSE connection should succeed through the proxy since the CA certificate is installed and trusted at the OS level. URLSession should use the system's default trust evaluation which respects user-installed CA certificates.

Suggested Fix

Add explicit .performDefaultHandling to SessionDelegate:

func urlSession(
_ session:URLSession,
didReceive challenge:URLAuthenticationChallenge,
completionHandler:@escaping(URLSession.AuthChallengeDisposition,URLCredential?)->Void){completionHandler(.performDefaultHandling,nil)}

This explicitly delegates to the system's default trust evaluation, which correctly handles user-installed CA certificates. This has no effect on normal (non-proxy) connections.

Environment

  • iOS 18
  • EventSource (latest from main)
  • mitmproxy 11.x

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      , 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
       blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

      Skip to content
      SSE connections fail silently through MITM proxies (missing auth challenge delegate) #50
      Closed
      #51
      Closed
      SSE connections fail silently through MITM proxies (missing auth challenge delegate)#50
      #51
      Description
      @liefran-sim
      liefran-sim
      opened on May 11, 2026
      Description
      When using EventSource through an MITM proxy (e.g., mitmproxy, Charles Proxy), SSE connections fail silently even when the proxy's CA certificate is installed and trusted at the OS level.
      Root Cause
      SessionDelegate does not implement urlSession(_:didReceive challenge:completionHandler:). While the expected behavior is that URLSession falls back to default system trust evaluation, in practice this can cause the connection to be silently rejected when a custom delegate is set without handling authentication challenges.
      Steps to Reproduce
      1. Install and trust a proxy CA certificate on an iOS device (e.g., mitmproxy CA)
      2. Configure the device to use the proxy
      3. Open an SSE connection using EventSource to an HTTPS endpoint
      4. The connection fails silently — no data events, no error events, the request never reaches the proxy
      Expected Behavior
      The SSE connection should succeed through the proxy since the CA certificate is installed and trusted at the OS level. URLSession should use the system's default trust evaluation which respects user-installed CA certificates.
      Suggested Fix
      Add explicit .performDefaultHandling to SessionDelegate:
      func urlSession(
_ session:URLSession,
didReceive challenge:URLAuthenticationChallenge,
completionHandler:@escaping(URLSession.AuthChallengeDisposition,URLCredential?)->Void){completionHandler(.performDefaultHandling,nil)}
      This explicitly delegates to the system's default trust evaluation, which correctly handles user-installed CA certificates. This has no effect on normal (non-proxy) connections.
      Environment
      • iOS 18
      • EventSource (latest from main)
      • mitmproxy 11.x
      Metadata
      Metadata
      Assignees
      No one assigned
        Labels
        No labels
        No labels
        Projects
        No projects
          Milestone
          No milestone
          Relationships
          None yet
          Development
          No branches or pull requests
          Issue actions
          
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

          Skip to content
          SSE connections fail silently through MITM proxies (missing auth challenge delegate) #50
          Closed
          #51
          Closed
          SSE connections fail silently through MITM proxies (missing auth challenge delegate)#50
          #51
          Description
          @liefran-sim
          liefran-sim
          opened on May 11, 2026
          Description
          When using EventSource through an MITM proxy (e.g., mitmproxy, Charles Proxy), SSE connections fail silently even when the proxy's CA certificate is installed and trusted at the OS level.
          Root Cause
          SessionDelegate does not implement urlSession(_:didReceive challenge:completionHandler:). While the expected behavior is that URLSession falls back to default system trust evaluation, in practice this can cause the connection to be silently rejected when a custom delegate is set without handling authentication challenges.
          Steps to Reproduce
          1. Install and trust a proxy CA certificate on an iOS device (e.g., mitmproxy CA)
          2. Configure the device to use the proxy
          3. Open an SSE connection using EventSource to an HTTPS endpoint
          4. The connection fails silently — no data events, no error events, the request never reaches the proxy
          Expected Behavior
          The SSE connection should succeed through the proxy since the CA certificate is installed and trusted at the OS level. URLSession should use the system's default trust evaluation which respects user-installed CA certificates.
          Suggested Fix
          Add explicit .performDefaultHandling to SessionDelegate:
          func urlSession(
_ session:URLSession,
didReceive challenge:URLAuthenticationChallenge,
completionHandler:@escaping(URLSession.AuthChallengeDisposition,URLCredential?)->Void){completionHandler(.performDefaultHandling,nil)}
          This explicitly delegates to the system's default trust evaluation, which correctly handles user-installed CA certificates. This has no effect on normal (non-proxy) connections.
          Environment
          • iOS 18
          • EventSource (latest from main)
          • mitmproxy 11.x
          Metadata
          Metadata
          Assignees
          No one assigned
            Labels
            No labels
            No labels
            Projects
            No projects
              Milestone
              No milestone
              Relationships
              None yet
              Development
              No branches or pull requests
              Issue actions
              
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

              Skip to content
              SSE connections fail silently through MITM proxies (missing auth challenge delegate) #50
              Closed
              #51
              Closed
              SSE connections fail silently through MITM proxies (missing auth challenge delegate)#50
              #51
              Description
              @liefran-sim
              liefran-sim
              opened on May 11, 2026
              Description
              When using EventSource through an MITM proxy (e.g., mitmproxy, Charles Proxy), SSE connections fail silently even when the proxy's CA certificate is installed and trusted at the OS level.
              Root Cause
              SessionDelegate does not implement urlSession(_:didReceive challenge:completionHandler:). While the expected behavior is that URLSession falls back to default system trust evaluation, in practice this can cause the connection to be silently rejected when a custom delegate is set without handling authentication challenges.
              Steps to Reproduce
              1. Install and trust a proxy CA certificate on an iOS device (e.g., mitmproxy CA)
              2. Configure the device to use the proxy
              3. Open an SSE connection using EventSource to an HTTPS endpoint
              4. The connection fails silently — no data events, no error events, the request never reaches the proxy
              Expected Behavior
              The SSE connection should succeed through the proxy since the CA certificate is installed and trusted at the OS level. URLSession should use the system's default trust evaluation which respects user-installed CA certificates.
              Suggested Fix
              Add explicit .performDefaultHandling to SessionDelegate:
              func urlSession(
_ session:URLSession,
didReceive challenge:URLAuthenticationChallenge,
completionHandler:@escaping(URLSession.AuthChallengeDisposition,URLCredential?)->Void){completionHandler(.performDefaultHandling,nil)}
              This explicitly delegates to the system's default trust evaluation, which correctly handles user-installed CA certificates. This has no effect on normal (non-proxy) connections.
              Environment
              • iOS 18
              • EventSource (latest from main)
              • mitmproxy 11.x
              Metadata
              Metadata
              Assignees
              No one assigned
                Labels
                No labels
                No labels
                Projects
                No projects
                  Milestone
                  No milestone
                  Relationships
                  None yet
                  Development
                  No branches or pull requests
                  Issue actions
                  
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

                  Skip to content
                  SSE connections fail silently through MITM proxies (missing auth challenge delegate) #50
                  Closed
                  #51
                  Closed
                  SSE connections fail silently through MITM proxies (missing auth challenge delegate)#50
                  #51
                  Description
                  @liefran-sim
                  liefran-sim
                  opened on May 11, 2026
                  Description
                  When using EventSource through an MITM proxy (e.g., mitmproxy, Charles Proxy), SSE connections fail silently even when the proxy's CA certificate is installed and trusted at the OS level.
                  Root Cause
                  SessionDelegate does not implement urlSession(_:didReceive challenge:completionHandler:). While the expected behavior is that URLSession falls back to default system trust evaluation, in practice this can cause the connection to be silently rejected when a custom delegate is set without handling authentication challenges.
                  Steps to Reproduce
                  1. Install and trust a proxy CA certificate on an iOS device (e.g., mitmproxy CA)
                  2. Configure the device to use the proxy
                  3. Open an SSE connection using EventSource to an HTTPS endpoint
                  4. The connection fails silently — no data events, no error events, the request never reaches the proxy
                  Expected Behavior
                  The SSE connection should succeed through the proxy since the CA certificate is installed and trusted at the OS level. URLSession should use the system's default trust evaluation which respects user-installed CA certificates.
                  Suggested Fix
                  Add explicit .performDefaultHandling to SessionDelegate:
                  func urlSession(
_ session:URLSession,
didReceive challenge:URLAuthenticationChallenge,
completionHandler:@escaping(URLSession.AuthChallengeDisposition,URLCredential?)->Void){completionHandler(.performDefaultHandling,nil)}
                  This explicitly delegates to the system's default trust evaluation, which correctly handles user-installed CA certificates. This has no effect on normal (non-proxy) connections.
                  Environment
                  • iOS 18
                  • EventSource (latest from main)
                  • mitmproxy 11.x
                  Metadata
                  Metadata
                  Assignees
                  No one assigned
                    Labels
                    No labels
                    No labels
                    Projects
                    No projects
                      Milestone
                      No milestone
                      Relationships
                      None yet
                      Development
                      No branches or pull requests
                      Issue actions
                      
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

                      Skip to content
                      SSE connections fail silently through MITM proxies (missing auth challenge delegate) #50
                      Closed
                      #51
                      Closed
                      SSE connections fail silently through MITM proxies (missing auth challenge delegate)#50
                      #51
                      Description
                      @liefran-sim
                      liefran-sim
                      opened on May 11, 2026
                      Description
                      When using EventSource through an MITM proxy (e.g., mitmproxy, Charles Proxy), SSE connections fail silently even when the proxy's CA certificate is installed and trusted at the OS level.
                      Root Cause
                      SessionDelegate does not implement urlSession(_:didReceive challenge:completionHandler:). While the expected behavior is that URLSession falls back to default system trust evaluation, in practice this can cause the connection to be silently rejected when a custom delegate is set without handling authentication challenges.
                      Steps to Reproduce
                      1. Install and trust a proxy CA certificate on an iOS device (e.g., mitmproxy CA)
                      2. Configure the device to use the proxy
                      3. Open an SSE connection using EventSource to an HTTPS endpoint
                      4. The connection fails silently — no data events, no error events, the request never reaches the proxy
                      Expected Behavior
                      The SSE connection should succeed through the proxy since the CA certificate is installed and trusted at the OS level. URLSession should use the system's default trust evaluation which respects user-installed CA certificates.
                      Suggested Fix
                      Add explicit .performDefaultHandling to SessionDelegate:
                      func urlSession(
_ session:URLSession,
didReceive challenge:URLAuthenticationChallenge,
completionHandler:@escaping(URLSession.AuthChallengeDisposition,URLCredential?)->Void){completionHandler(.performDefaultHandling,nil)}
                      This explicitly delegates to the system's default trust evaluation, which correctly handles user-installed CA certificates. This has no effect on normal (non-proxy) connections.
                      Environment
                      • iOS 18
                      • EventSource (latest from main)
                      • mitmproxy 11.x
                      Metadata
                      Metadata
                      Assignees
                      No one assigned
                        Labels
                        No labels
                        No labels
                        Projects
                        No projects
                          Milestone
                          No milestone
                          Relationships
                          None yet
                          Development
                          No branches or pull requests
                          Issue actions
                          
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

                          Skip to content
                          SSE connections fail silently through MITM proxies (missing auth challenge delegate) #50
                          Closed
                          #51
                          Closed
                          SSE connections fail silently through MITM proxies (missing auth challenge delegate)#50
                          #51
                          Description
                          @liefran-sim
                          liefran-sim
                          opened on May 11, 2026
                          Description
                          When using EventSource through an MITM proxy (e.g., mitmproxy, Charles Proxy), SSE connections fail silently even when the proxy's CA certificate is installed and trusted at the OS level.
                          Root Cause
                          SessionDelegate does not implement urlSession(_:didReceive challenge:completionHandler:). While the expected behavior is that URLSession falls back to default system trust evaluation, in practice this can cause the connection to be silently rejected when a custom delegate is set without handling authentication challenges.
                          Steps to Reproduce
                          1. Install and trust a proxy CA certificate on an iOS device (e.g., mitmproxy CA)
                          2. Configure the device to use the proxy
                          3. Open an SSE connection using EventSource to an HTTPS endpoint
                          4. The connection fails silently — no data events, no error events, the request never reaches the proxy
                          Expected Behavior
                          The SSE connection should succeed through the proxy since the CA certificate is installed and trusted at the OS level. URLSession should use the system's default trust evaluation which respects user-installed CA certificates.
                          Suggested Fix
                          Add explicit .performDefaultHandling to SessionDelegate:
                          func urlSession(
_ session:URLSession,
didReceive challenge:URLAuthenticationChallenge,
completionHandler:@escaping(URLSession.AuthChallengeDisposition,URLCredential?)->Void){completionHandler(.performDefaultHandling,nil)}
                          This explicitly delegates to the system's default trust evaluation, which correctly handles user-installed CA certificates. This has no effect on normal (non-proxy) connections.
                          Environment
                          • iOS 18
                          • EventSource (latest from main)
                          • mitmproxy 11.x
                          Metadata
                          Metadata
                          Assignees
                          No one assigned
                            Labels
                            No labels
                            No labels
                            Projects
                            No projects
                              Milestone
                              No milestone
                              Relationships
                              None yet
                              Development
                              No branches or pull requests
                              Issue actions
                              
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

                              Skip to content
                              SSE connections fail silently through MITM proxies (missing auth challenge delegate) #50
                              Closed
                              #51
                              Closed
                              SSE connections fail silently through MITM proxies (missing auth challenge delegate)#50
                              #51
                              Description
                              @liefran-sim
                              liefran-sim
                              opened on May 11, 2026
                              Description
                              When using EventSource through an MITM proxy (e.g., mitmproxy, Charles Proxy), SSE connections fail silently even when the proxy's CA certificate is installed and trusted at the OS level.
                              Root Cause
                              SessionDelegate does not implement urlSession(_:didReceive challenge:completionHandler:). While the expected behavior is that URLSession falls back to default system trust evaluation, in practice this can cause the connection to be silently rejected when a custom delegate is set without handling authentication challenges.
                              Steps to Reproduce
                              1. Install and trust a proxy CA certificate on an iOS device (e.g., mitmproxy CA)
                              2. Configure the device to use the proxy
                              3. Open an SSE connection using EventSource to an HTTPS endpoint
                              4. The connection fails silently — no data events, no error events, the request never reaches the proxy
                              Expected Behavior
                              The SSE connection should succeed through the proxy since the CA certificate is installed and trusted at the OS level. URLSession should use the system's default trust evaluation which respects user-installed CA certificates.
                              Suggested Fix
                              Add explicit .performDefaultHandling to SessionDelegate:
                              func urlSession(
_ session:URLSession,
didReceive challenge:URLAuthenticationChallenge,
completionHandler:@escaping(URLSession.AuthChallengeDisposition,URLCredential?)->Void){completionHandler(.performDefaultHandling,nil)}
                              This explicitly delegates to the system's default trust evaluation, which correctly handles user-installed CA certificates. This has no effect on normal (non-proxy) connections.
                              Environment
                              • iOS 18
                              • EventSource (latest from main)
                              • mitmproxy 11.x
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