Provide better experience to Windows proxy users.

include/pch.h

@@ -9,6 +9,7 @@
 #include <process.h>
 #include <shellapi.h>
 #include <winhttp.h>
+#include <winreg.h>
 #endif
 
 #include <math.h>

include/vcpkg/base/system.proxy.h

@@ -0,0 +1,8 @@
+#pragma once
+#include <optional>
+#include <string>
+namespace vcpkg::System
+{
+    bool get_windows_proxy_enabled();
+    std::optional<std::string> get_windows_proxy_server();
+}

src/tls12-download.c

@@ -1,6 +1,45 @@
 #include <Windows.h>
 #include <process.h>
 #include <winhttp.h>
+
+/*
+ * Instead of WPAD, on Windows platform it is a user-friendly way to check
+ * HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings
+ * instead of only checking HTTPS_PROXY. Because most proxies on Windows
+ * doesn't set these environment variables.
+ */
+#include <winreg.h>
+/*
+ * This helper function reads proxy settings from registry, returns 1 if succeed
+ * and copy the proxy setting in outProxyBuffer, returns 0 if failed.
+ *
+ * According to the code below we can say the buffer's size passed in is 32767,
+ * which is for sure enough for reading proxy server from registry. So the size
+ * check is skipped.
+ */
+static int GetWindowsProxyFromRegistry(wchar_t* outProxyBuffer)
+{
+    HKEY proxy_reg;
+    DWORD len = 0;
+    DWORD enable = 0;
+
+    int ret =
+        RegOpenKeyW(HKEY_CURRENT_USER, L"Software\\Microsoft\\Windows\\CurrentVersion\\Internet Settings", &proxy_reg);
+    if (ret) return 0;
+
+    len = 4;
+    ret = RegGetValueW(proxy_reg, NULL, L"ProxyEnable", RRF_RT_REG_DWORD, NULL, &enable, &len);
+    if (ret) return 0;
+
+    if (!enable) return 0;
+
+    len = 32767;
+    ret = RegGetValueW(proxy_reg, NULL, L"ProxyServer", RRF_RT_REG_SZ, NULL, outProxyBuffer, &len);
+    if (ret) return 0;
+
+    return 1;
+}
+
 /*
  * This program must be as small as possible, because it is committed in binary form to the
  * vcpkg github repo to enable downloading the main vcpkg program on Windows 7, where TLS 1.2 is
@@ -188,7 +227,11 @@ int __stdcall entry()
     DWORD access_type;
     const wchar_t* proxy_setting;
     const wchar_t* proxy_bypass_setting;
-    if (GetEnvironmentVariableW(L"HTTPS_PROXY", https_proxy_env, sizeof(https_proxy_env) / sizeof(wchar_t)))
+    if (GetEnvironmentVariableW(L"HTTPS_PROXY", https_proxy_env, sizeof(https_proxy_env) / sizeof(wchar_t))
+        /*
+         * Check the windows proxy setting in registry too.
+         */
+        || GetWindowsProxyFromRegistry(https_proxy_env))
     {
         access_type = WINHTTP_ACCESS_TYPE_NAMED_PROXY;
         proxy_setting = https_proxy_env;

src/vcpkg/base/downloads.cpp

@@ -8,10 +8,6 @@
 #include <vcpkg/base/system.process.h>
 #include <vcpkg/base/util.h>
 
-#if defined(_WIN32)
-#include <VersionHelpers.h>
-#endif
-
 namespace vcpkg::Downloads
 {
 #if defined(_WIN32)
@@ -93,8 +89,7 @@ namespace vcpkg::Downloads
         static ExpectedS<WinHttpSession> make()
         {
             auto h = WinHttpOpen(L"vcpkg/1.0",
-                                 IsWindows8Point1OrGreater() ? WINHTTP_ACCESS_TYPE_AUTOMATIC_PROXY
-                                                             : WINHTTP_ACCESS_TYPE_DEFAULT_PROXY,
+                                 WINHTTP_ACCESS_TYPE_NO_PROXY,
                                  WINHTTP_NO_PROXY_NAME,
                                  WINHTTP_NO_PROXY_BYPASS,
                                  0);
@@ -116,31 +111,22 @@ namespace vcpkg::Downloads
 
                 WinHttpSetOption(ret.m_hSession.get(), WINHTTP_OPTION_PROXY, &proxy, sizeof(proxy));
             }
-            // Win7 IE Proxy fallback
-            else if (IsWindows7OrGreater() && !IsWindows8Point1OrGreater())
+            // IE Proxy fallback, this works on Windows 10
+            else
             {
-                // First check if any proxy has been found automatically
-                WINHTTP_PROXY_INFO proxyInfo;
-                DWORD proxyInfoSize = sizeof(WINHTTP_PROXY_INFO);
-                auto noProxyFound =
-                    !WinHttpQueryOption(ret.m_hSession.get(), WINHTTP_OPTION_PROXY, &proxyInfo, &proxyInfoSize) ||
-                    proxyInfo.dwAccessType == WINHTTP_ACCESS_TYPE_NO_PROXY;
-
-                // If no proxy was found automatically, use IE's proxy settings, if any
-                if (noProxyFound)
+                // We do not use WPAD anymore
+                // Directly read IE Proxy setting
+                WINHTTP_CURRENT_USER_IE_PROXY_CONFIG ieProxy;
+                if (WinHttpGetIEProxyConfigForCurrentUser(&ieProxy) && ieProxy.lpszProxy != nullptr)
                 {
-                    WINHTTP_CURRENT_USER_IE_PROXY_CONFIG ieProxy;
-                    if (WinHttpGetIEProxyConfigForCurrentUser(&ieProxy) && ieProxy.lpszProxy != nullptr)
-                    {
-                        WINHTTP_PROXY_INFO proxy;
-                        proxy.dwAccessType = WINHTTP_ACCESS_TYPE_NAMED_PROXY;
-                        proxy.lpszProxy = ieProxy.lpszProxy;
-                        proxy.lpszProxyBypass = ieProxy.lpszProxyBypass;
-                        WinHttpSetOption(ret.m_hSession.get(), WINHTTP_OPTION_PROXY, &proxy, sizeof(proxy));
-                        GlobalFree(ieProxy.lpszProxy);
-                        GlobalFree(ieProxy.lpszProxyBypass);
-                        GlobalFree(ieProxy.lpszAutoConfigUrl);
-                    }
+                    WINHTTP_PROXY_INFO proxy;
+                    proxy.dwAccessType = WINHTTP_ACCESS_TYPE_NAMED_PROXY;
+                    proxy.lpszProxy = ieProxy.lpszProxy;
+                    proxy.lpszProxyBypass = ieProxy.lpszProxyBypass;
+                    WinHttpSetOption(ret.m_hSession.get(), WINHTTP_OPTION_PROXY, &proxy, sizeof(proxy));
+                    GlobalFree(ieProxy.lpszProxy);
+                    GlobalFree(ieProxy.lpszProxyBypass);
+                    GlobalFree(ieProxy.lpszAutoConfigUrl);
                 }
             }
 

src/vcpkg/base/system.proxy.cpp

@@ -0,0 +1,40 @@
+#include <vcpkg/base/system.proxy.h>
+std::optional<std::string> vcpkg::System::get_windows_proxy_server()
+{
+#if defined(_WIN32)
+    HKEY proxy_reg;
+    DWORD buf_len = 0;
+
+    auto ret =
+        RegOpenKey(HKEY_CURRENT_USER, R"(Software\Microsoft\Windows\CurrentVersion\Internet Settings)", &proxy_reg);
+    if (ret) return nullptr;
+
+    ret = RegGetValue(proxy_reg, nullptr, "ProxyServer", RRF_RT_REG_SZ, nullptr, nullptr, &buf_len);
+    if (ret) return nullptr;
+
+    std::string srv(buf_len, '\0');
+    ret = RegGetValue(proxy_reg, nullptr, "ProxyServer", RRF_RT_REG_SZ, nullptr, srv.data(), &buf_len);
+    if (ret) return nullptr;
+
+    return srv;
+#else
+    return nullptr;
+#endif
+}
+bool vcpkg::System::get_windows_proxy_enabled()
+{
+#if defined(_WIN32)
+    HKEY proxy_reg;
+    DWORD enable = 0;
+    DWORD len = 4;
+
+    auto ret =
+        RegOpenKey(HKEY_CURRENT_USER, R"(Software\Microsoft\Windows\CurrentVersion\Internet Settings)", &proxy_reg);
+
+    ret = RegGetValue(proxy_reg, nullptr, "ProxyEnable", RRF_RT_REG_DWORD, nullptr, &enable, &len);
+
+    return enable;
+#else
+    return false;
+#endif
+}

src/vcpkg/build.cpp

@@ -8,6 +8,7 @@
 #include <vcpkg/base/system.debug.h>
 #include <vcpkg/base/system.print.h>
 #include <vcpkg/base/system.process.h>
+#include <vcpkg/base/system.proxy.h>
 #include <vcpkg/base/util.h>
 
 #include <vcpkg/binarycaching.h>
@@ -396,6 +397,24 @@ namespace vcpkg::Build
                 if (auto p_val = val.get()) env.emplace(var, *p_val);
             }
 
+            /*
+             * On Windows 10 (>= 8.1) it is a user-friendly way to automatically set HTTP_PROXY and HTTPS_PROXY
+             * environment variables by reading proxy settings via WinHttpGetDefaultProxyConfiguration, preventing users
+             * set and unset these variables manually (which is not a decent way).
+             */
+            if (System::get_windows_proxy_enabled())
+            {
+                auto proxy = System::get_windows_proxy_server();
+                if (proxy.has_value())
+                {
+                    // Most HTTP proxy DOES proxy HTTPS requests.
+                    env.emplace("HTTP_PROXY", proxy.value().c_str());
+                    env.emplace("HTTPS_PROXY", proxy.value().c_str());
+
+                    System::print2(
+                        "-- Automatically setting HTTP(S)_PROXY environment variables to ", proxy.value(), "\n");
+                }
+            }
             return {env};
         });