Message-ID: <gh-pgjdbc-pgjdbc-4045@github.com>
From: "davecramer (@davecramer)" <noreply+davecramer@github.com>
To: "pgjdbc/pgjdbc" <noreply+pgjdbc-pgjdbc@github.com>
Date: Thu, 30 Apr 2026 11:18:20 +0000
Subject: [pgjdbc/pgjdbc] PR #4045:  fix: append default non-proxy hosts when socksNonProxyHosts is set
List-Id: <gh-pgjdbc-pgjdbc.github.com>
X-GitHub-Additions: 29
X-GitHub-Author-Id: 406518
X-GitHub-Author-Login: davecramer
X-GitHub-Base: master
X-GitHub-Changed-Files: 2
X-GitHub-Commits: 1
X-GitHub-Deletions: 2
X-GitHub-Head-Branch: fix_hostspec_4044
X-GitHub-Head-SHA: 7f9e1a639dd4dfb188287dcec6b33e9d26a24e94
X-GitHub-Issue: 4045
X-GitHub-Merge-SHA: bd59eb2113fc486fd2345cf051bc022031b37507
X-GitHub-Merged-By: vlsi
X-GitHub-Repo: pgjdbc/pgjdbc
X-GitHub-State: merged
X-GitHub-Type: pull_request
X-GitHub-Url: https://github.com/pgjdbc/pgjdbc/pull/4045
Content-Type: text/plain; charset=utf-8

  When socksNonProxyHosts is set by the system (e.g., macOS sets it to
  "local|*.local|169.254/16|*.169.254/16"), HostSpec used it as-is,
  completely replacing DEFAULT_NON_PROXY_HOSTS. Since 127.0.0.1 wasn't
  in the system-supplied list, HostSpec would pass an unresolved
  InetSocketAddress through the SOCKS proxy. But SocksSocketImpl (via
  DefaultProxySelector) always appends its built-in defaults to the
  property value, so it would bypass the proxy for 127.0.0.1 and try
  to connect directly with the still-unresolved address, causing an
  UnknownHostException.

  Align HostSpec with java.net.DefaultProxySelector by always merging
  DEFAULT_NON_PROXY_HOSTS with the user-supplied socksNonProxyHosts
  value instead of treating them as mutually exclusive.

  Fixes #4044

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diff --git a/pgjdbc/src/main/java/org/postgresql/util/HostSpec.java b/pgjdbc/src/main/java/org/postgresql/util/HostSpec.java
index b7649ab42f..c37d1e975e 100644
--- a/pgjdbc/src/main/java/org/postgresql/util/HostSpec.java
+++ b/pgjdbc/src/main/java/org/postgresql/util/HostSpec.java
@@ -71,8 +71,15 @@ public Boolean shouldResolve() {
   }
 
   private Boolean matchesNonProxyHosts() {
-    String nonProxyHosts = System.getProperty("socksNonProxyHosts", DEFAULT_NON_PROXY_HOSTS);
-    if (nonProxyHosts == null || this.host.isEmpty()) {
+    String nonProxyHosts = System.getProperty("socksNonProxyHosts");
+    if (nonProxyHosts == null || nonProxyHosts.isEmpty()) {
+      nonProxyHosts = DEFAULT_NON_PROXY_HOSTS;
+    } else {
+      // Align with java.net.DefaultProxySelector which always appends its
+      // built-in defaults (localhost, 127.*, etc.) to the user-supplied value.
+      nonProxyHosts = nonProxyHosts + "|" + DEFAULT_NON_PROXY_HOSTS;
+    }
+    if (this.host.isEmpty()) {
       return false;
     }
 
diff --git a/pgjdbc/src/test/java/org/postgresql/test/util/HostSpecTest.java b/pgjdbc/src/test/java/org/postgresql/test/util/HostSpecTest.java
index 7aad5bc88b..0614900d90 100644
--- a/pgjdbc/src/test/java/org/postgresql/test/util/HostSpecTest.java
+++ b/pgjdbc/src/test/java/org/postgresql/test/util/HostSpecTest.java
@@ -86,6 +86,26 @@ void shouldResolveWithSocksNonProxyHostsNotMatching() throws Exception {
     assertFalse(hostSpec.shouldResolve());
   }
 
+  @Test
+  void shouldResolveLocalhostIpWhenNonProxyHostsSetWithoutIt() throws Exception {
+    // Reproduces the macOS scenario: socksNonProxyHosts is set by the JVM
+    // (e.g. "local|*.local|169.254/16|*.169.254/16") but does NOT include 127.0.0.1.
+    // DefaultProxySelector always appends its built-in defaults (localhost, 127.*, etc.),
+    // so HostSpec must do the same to avoid an UnknownHostException from unresolved addresses.
+    System.setProperty("socksProxyHost", "127.0.0.1");
+    System.setProperty("socksNonProxyHosts", "local|*.local|169.254/16|*.169.254/16");
+    HostSpec hostSpec = new HostSpec("127.0.0.1", 5432);
+    assertTrue(hostSpec.shouldResolve());
+  }
+
+  @Test
+  void shouldResolveLocalhostWhenNonProxyHostsSetWithoutIt() throws Exception {
+    System.setProperty("socksProxyHost", "127.0.0.1");
+    System.setProperty("socksNonProxyHosts", "local|*.local");
+    HostSpec hostSpec = new HostSpec("localhost", 5432);
+    assertTrue(hostSpec.shouldResolve());
+  }
+
   @Test
   void shouldReturnEmptyLocalAddressBind() throws Exception {
     HostSpec hostSpec = new HostSpec("example.org", 5432);