SocketsHttpHandler should throw instead of returning proxy response message when proxy tunnel creation fails #48679

Description

@geoffkizer

Description

For secure HTTP connections, we attempt to create a proxy tunnel using the CONNECT method against the proxy endpoint. This allows us to create an end-to-end secure SSL connection between client and destination server.

If the proxy CONNECT request fails, (i.e. returns a status other than 200), we return the proxy's response to the user. However, this means the user can't distinguish whether the response came from the proxy or the destination server. This is problematic because the user is using SSL and thus reasonably expects that any response has been securely delivered via the end-to-end secure connection.

I think we should change this behavior, and instead throw an HttpRequestException when a proxy tunnel CONNECT request fails. Something like "The proxy tunnel request to proxy {proxyUri} failed with status code {statusCode}."

Note that for non-secure requests, we always return the proxy response and the user can't tell whether the response came from the destination server unmodified, or was modified by the proxy, or was simply generated by the proxy without even contacting the destination server. This is intentional; for non-secure requests, proxies are explicitly allowed to do whatever they want to a request, including modifying it, blocking it entirely, etc.

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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" + '
      
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      SocketsHttpHandler should throw instead of returning proxy response message when proxy tunnel creation fails #48679

      Description

      @geoffkizer

      Description

      For secure HTTP connections, we attempt to create a proxy tunnel using the CONNECT method against the proxy endpoint. This allows us to create an end-to-end secure SSL connection between client and destination server.

      If the proxy CONNECT request fails, (i.e. returns a status other than 200), we return the proxy's response to the user. However, this means the user can't distinguish whether the response came from the proxy or the destination server. This is problematic because the user is using SSL and thus reasonably expects that any response has been securely delivered via the end-to-end secure connection.

      I think we should change this behavior, and instead throw an HttpRequestException when a proxy tunnel CONNECT request fails. Something like "The proxy tunnel request to proxy {proxyUri} failed with status code {statusCode}."

      Note that for non-secure requests, we always return the proxy response and the user can't tell whether the response came from the destination server unmodified, or was modified by the proxy, or was simply generated by the proxy without even contacting the destination server. This is intentional; for non-secure requests, proxies are explicitly allowed to do whatever they want to a request, including modifying it, blocking it entirely, etc.

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          , '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('^' + ".*" + '
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          SocketsHttpHandler should throw instead of returning proxy response message when proxy tunnel creation fails #48679

          Description

          @geoffkizer

          Description

          For secure HTTP connections, we attempt to create a proxy tunnel using the CONNECT method against the proxy endpoint. This allows us to create an end-to-end secure SSL connection between client and destination server.

          If the proxy CONNECT request fails, (i.e. returns a status other than 200), we return the proxy's response to the user. However, this means the user can't distinguish whether the response came from the proxy or the destination server. This is problematic because the user is using SSL and thus reasonably expects that any response has been securely delivered via the end-to-end secure connection.

          I think we should change this behavior, and instead throw an HttpRequestException when a proxy tunnel CONNECT request fails. Something like "The proxy tunnel request to proxy {proxyUri} failed with status code {statusCode}."

          Note that for non-secure requests, we always return the proxy response and the user can't tell whether the response came from the destination server unmodified, or was modified by the proxy, or was simply generated by the proxy without even contacting the destination server. This is intentional; for non-secure requests, proxies are explicitly allowed to do whatever they want to a request, including modifying it, blocking it entirely, etc.

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              , '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('^' + ".*" + '
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              SocketsHttpHandler should throw instead of returning proxy response message when proxy tunnel creation fails #48679

              Description

              @geoffkizer

              Description

              For secure HTTP connections, we attempt to create a proxy tunnel using the CONNECT method against the proxy endpoint. This allows us to create an end-to-end secure SSL connection between client and destination server.

              If the proxy CONNECT request fails, (i.e. returns a status other than 200), we return the proxy's response to the user. However, this means the user can't distinguish whether the response came from the proxy or the destination server. This is problematic because the user is using SSL and thus reasonably expects that any response has been securely delivered via the end-to-end secure connection.

              I think we should change this behavior, and instead throw an HttpRequestException when a proxy tunnel CONNECT request fails. Something like "The proxy tunnel request to proxy {proxyUri} failed with status code {statusCode}."

              Note that for non-secure requests, we always return the proxy response and the user can't tell whether the response came from the destination server unmodified, or was modified by the proxy, or was simply generated by the proxy without even contacting the destination server. This is intentional; for non-secure requests, proxies are explicitly allowed to do whatever they want to a request, including modifying it, blocking it entirely, etc.

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                  , '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

                  SocketsHttpHandler should throw instead of returning proxy response message when proxy tunnel creation fails #48679

                  Description

                  @geoffkizer

                  Description

                  For secure HTTP connections, we attempt to create a proxy tunnel using the CONNECT method against the proxy endpoint. This allows us to create an end-to-end secure SSL connection between client and destination server.

                  If the proxy CONNECT request fails, (i.e. returns a status other than 200), we return the proxy's response to the user. However, this means the user can't distinguish whether the response came from the proxy or the destination server. This is problematic because the user is using SSL and thus reasonably expects that any response has been securely delivered via the end-to-end secure connection.

                  I think we should change this behavior, and instead throw an HttpRequestException when a proxy tunnel CONNECT request fails. Something like "The proxy tunnel request to proxy {proxyUri} failed with status code {statusCode}."

                  Note that for non-secure requests, we always return the proxy response and the user can't tell whether the response came from the destination server unmodified, or was modified by the proxy, or was simply generated by the proxy without even contacting the destination server. This is intentional; for non-secure requests, proxies are explicitly allowed to do whatever they want to a request, including modifying it, blocking it entirely, etc.

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                      , '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

                      SocketsHttpHandler should throw instead of returning proxy response message when proxy tunnel creation fails #48679

                      Description

                      @geoffkizer

                      Description

                      For secure HTTP connections, we attempt to create a proxy tunnel using the CONNECT method against the proxy endpoint. This allows us to create an end-to-end secure SSL connection between client and destination server.

                      If the proxy CONNECT request fails, (i.e. returns a status other than 200), we return the proxy's response to the user. However, this means the user can't distinguish whether the response came from the proxy or the destination server. This is problematic because the user is using SSL and thus reasonably expects that any response has been securely delivered via the end-to-end secure connection.

                      I think we should change this behavior, and instead throw an HttpRequestException when a proxy tunnel CONNECT request fails. Something like "The proxy tunnel request to proxy {proxyUri} failed with status code {statusCode}."

                      Note that for non-secure requests, we always return the proxy response and the user can't tell whether the response came from the destination server unmodified, or was modified by the proxy, or was simply generated by the proxy without even contacting the destination server. This is intentional; for non-secure requests, proxies are explicitly allowed to do whatever they want to a request, including modifying it, blocking it entirely, etc.

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                          None yet

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                          , '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

                          SocketsHttpHandler should throw instead of returning proxy response message when proxy tunnel creation fails #48679

                          Description

                          @geoffkizer

                          Description

                          For secure HTTP connections, we attempt to create a proxy tunnel using the CONNECT method against the proxy endpoint. This allows us to create an end-to-end secure SSL connection between client and destination server.

                          If the proxy CONNECT request fails, (i.e. returns a status other than 200), we return the proxy's response to the user. However, this means the user can't distinguish whether the response came from the proxy or the destination server. This is problematic because the user is using SSL and thus reasonably expects that any response has been securely delivered via the end-to-end secure connection.

                          I think we should change this behavior, and instead throw an HttpRequestException when a proxy tunnel CONNECT request fails. Something like "The proxy tunnel request to proxy {proxyUri} failed with status code {statusCode}."

                          Note that for non-secure requests, we always return the proxy response and the user can't tell whether the response came from the destination server unmodified, or was modified by the proxy, or was simply generated by the proxy without even contacting the destination server. This is intentional; for non-secure requests, proxies are explicitly allowed to do whatever they want to a request, including modifying it, blocking it entirely, etc.

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                              , '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

                              SocketsHttpHandler should throw instead of returning proxy response message when proxy tunnel creation fails #48679

                              Description

                              @geoffkizer

                              Description

                              For secure HTTP connections, we attempt to create a proxy tunnel using the CONNECT method against the proxy endpoint. This allows us to create an end-to-end secure SSL connection between client and destination server.

                              If the proxy CONNECT request fails, (i.e. returns a status other than 200), we return the proxy's response to the user. However, this means the user can't distinguish whether the response came from the proxy or the destination server. This is problematic because the user is using SSL and thus reasonably expects that any response has been securely delivered via the end-to-end secure connection.

                              I think we should change this behavior, and instead throw an HttpRequestException when a proxy tunnel CONNECT request fails. Something like "The proxy tunnel request to proxy {proxyUri} failed with status code {statusCode}."

                              Note that for non-secure requests, we always return the proxy response and the user can't tell whether the response came from the destination server unmodified, or was modified by the proxy, or was simply generated by the proxy without even contacting the destination server. This is intentional; for non-secure requests, proxies are explicitly allowed to do whatever they want to a request, including modifying it, blocking it entirely, etc.

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