From 2d6134d276e69eeedede821c609610369c235fef Mon Sep 17 00:00:00 2001
From: Samuele Cerea <samuele@cerea.dev>
Date: Wed, 19 Nov 2025 23:10:54 +0100
Subject: [PATCH] Handle connection string for unix sockets correctly

When connecting to a unix socket the path should be interpreted as the
path to the directory that contains the socket rather that the path to
the socket itself.
---
 CHANGELOG                |  1 +
 spec/pq/conninfo_spec.cr |  2 +-
 src/pq/connection.cr     |  6 ++++--
 src/pq/conninfo.cr       | 28 +++++++++++++++-------------
 4 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 742bd017..2566c12b 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -5,6 +5,7 @@ v? upcoming
 * Add support for COPY (thanks @17dec)
 * Add pg log source to log entries (thanks @hugopl)
 * Update crystal-db to 0.14 (thanks @bcardiff)
+* Handle connections strings with unix domain sockets correctly (thanks @samu698)
 
 v0.29.0    2024-11-05
 =====================
diff --git a/spec/pq/conninfo_spec.cr b/spec/pq/conninfo_spec.cr
index 5c063da8..07207a9c 100644
--- a/spec/pq/conninfo_spec.cr
+++ b/spec/pq/conninfo_spec.cr
@@ -140,7 +140,7 @@ describe PQ::ConnInfo, ".from_conninfo_string" do
     env_var_bubble do
       ENV["PGHOST"] = "/path"
       ci = PQ::ConnInfo.from_conninfo_string("postgres://")
-      ci.host.should eq("/path/.s.PGSQL.5432")
+      ci.host.should eq("/path")
     end
   end
 end
diff --git a/src/pq/connection.cr b/src/pq/connection.cr
index c226ddd4..581ca44d 100644
--- a/src/pq/connection.cr
+++ b/src/pq/connection.cr
@@ -22,8 +22,10 @@ module PQ
 
     def initialize(@conninfo : ConnInfo)
       begin
-        if @conninfo.host[0] == '/'
-          soc = UNIXSocket.new(@conninfo.host)
+        if Path.new(@conninfo.host).absolute?
+          socket_name = ".s.PGSQL.#{@conninfo.port}"
+          socket_path = File.join(@conninfo.host, socket_name)
+          soc = UNIXSocket.new(socket_path)
         else
           soc = TCPSocket.new(@conninfo.host, @conninfo.port)
         end
diff --git a/src/pq/conninfo.cr b/src/pq/conninfo.cr
index 6e1b9223..9dfcd2a0 100644
--- a/src/pq/conninfo.cr
+++ b/src/pq/conninfo.cr
@@ -4,7 +4,7 @@ require "system/user"
 
 module PQ
   struct ConnInfo
-    SOCKET_SEARCH = %w(/run/postgresql/.s.PGSQL.5432 /tmp/.s.PGSQL.5432 /var/run/postgresql/.s.PGSQL.5432)
+    SOCKET_SEARCH = %w(/run/postgresql /tmp /var/run/postgresql)
 
     SUPPORTED_AUTH_METHODS = %w[cleartext md5 scram-sha-256 scram-sha-256-plus]
 
@@ -42,11 +42,11 @@ module PQ
 
     # Create a new ConnInfo from all parts
     def initialize(host : String? = nil, database : String? = nil, user : String? = nil, password : String? = nil, port : Int | String? = nil, sslmode : String | Symbol? = nil, application_name : String? = nil)
-      @host = default_host host
+      @port = (port || ENV.fetch("PGPORT", "5432")).to_i
+      @host = default_host(host, @port)
       db = default_database database
       @database = db.lchop('/')
       @user = default_user user
-      @port = (port || ENV.fetch("PGPORT", "5432")).to_i
       @sslmode = default_sslmode sslmode
       @password = password || ENV.fetch("PGPASSWORD", PgPass.locate(@host, @port, @database, @user))
       @application_name = default_application_name application_name
@@ -77,7 +77,8 @@ module PQ
     def initialize(uri : URI)
       params = URI::Params.parse(uri.query.to_s)
       hostname = uri.hostname.presence || params.fetch("host", "")
-      initialize(hostname, uri.path, uri.user, uri.password, uri.port, :prefer, params.fetch("application_name", nil))
+      port = uri.port || params["port"]?
+      initialize(hostname, uri.path, uri.user, uri.password, port, :prefer, params.fetch("application_name", nil))
       if q = uri.query
         HTTP::Params.parse(q) do |key, value|
           handle_sslparam(key, value)
@@ -121,18 +122,19 @@ module PQ
       end
     end
 
-    private def default_host(h)
-      return h if h && !h.blank?
-
-      if pghost = ENV["PGHOST"]?
-        return pghost[0] == '/' ? "#{pghost}/.s.PGSQL.5432" : pghost
-      end
+    private def default_host(h, port)
+      socket_name = ".s.PGSQL.#{port}"
 
-      SOCKET_SEARCH.each do |s|
-        return s if File.exists?(s)
+      if host = h.presence || ENV["PGHOST"]?
+        host = Path.new(host)
+        # For backwards compatibility:
+        # Check if the path is pointing to the socket file and replace it with
+        # the directory that contains the socket instead
+        host = host.basename == socket_name ? host.parent : host
+        return host.to_s
       end
 
-      "localhost"
+      SOCKET_SEARCH.find { |s| File.exists?(File.join(s, socket_name)) } || "localhost"
     end
 
     private def default_database(db)