From dbd93ddbb6068c18cf1b2f85daa94695c761b4a8 Mon Sep 17 00:00:00 2001
From: Gary Pendergast <gary@pento.net>
Date: Thu, 28 Sep 2017 05:37:44 +0000
Subject: [PATCH] Database: Add support for connecting to IPv6 hosts

IPv4 addresses are scarce, overworked, and underpaid. They're ready to retire, but we just won't let them go. If you care about their wellbeing, switch to IPv6 today.

Props schlessera, birgire.
Fixes #41722.


Built from https://develop.svn.wordpress.org/trunk@41629


git-svn-id: http://core.svn.wordpress.org/trunk@41464 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/version.php |  2 +-
 wp-includes/wp-db.php   | 84 +++++++++++++++++++++++++++++++----------
 2 files changed, 66 insertions(+), 20 deletions(-)

diff --git a/wp-includes/version.php b/wp-includes/version.php
index ac10b195bc..850aa36572 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-41628';
+$wp_version = '4.9-alpha-41629';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
diff --git a/wp-includes/wp-db.php b/wp-includes/wp-db.php
index c601bcaba1..e96714fa23 100644
--- a/wp-includes/wp-db.php
+++ b/wp-includes/wp-db.php
@@ -1460,24 +1460,23 @@ class wpdb {
 		if ( $this->use_mysqli ) {
 			$this->dbh = mysqli_init();
 
-			// mysqli_real_connect doesn't support the host param including a port or socket
-			// like mysql_connect does. This duplicates how mysql_connect detects a port and/or socket file.
-			$port = null;
-			$socket = null;
-			$host = $this->dbhost;
-			$port_or_socket = strstr( $host, ':' );
-			if ( ! empty( $port_or_socket ) ) {
-				$host = substr( $host, 0, strpos( $host, ':' ) );
-				$port_or_socket = substr( $port_or_socket, 1 );
-				if ( 0 !== strpos( $port_or_socket, '/' ) ) {
-					$port = intval( $port_or_socket );
-					$maybe_socket = strstr( $port_or_socket, ':' );
-					if ( ! empty( $maybe_socket ) ) {
-						$socket = substr( $maybe_socket, 1 );
-					}
-				} else {
-					$socket = $port_or_socket;
-				}
+			$host    = $this->dbhost;
+			$port    = null;
+			$socket  = null;
+			$is_ipv6 = false;
+			
+			if ( $host_data = $this->parse_db_host( $this->dbhost ) ) {
+				list( $host, $port, $socket, $is_ipv6 ) = $host_data;
+			}
+
+			/*
+			 * If using the `mysqlnd` library, the IPv6 address needs to be
+			 * enclosed in square brackets, whereas it doesn't while using the
+			 * `libmysqlclient` library.
+			 * @see https://bugs.php.net/bug.php?id=67563
+			 */
+			if ( $is_ipv6 && extension_loaded( 'mysqlnd' ) ) {
+				$host = "[$host]";
 			}
 
 			if ( WP_DEBUG ) {
@@ -1489,7 +1488,8 @@ class wpdb {
 			if ( $this->dbh->connect_errno ) {
 				$this->dbh = null;
 
-				/* It's possible ext/mysqli is misconfigured. Fall back to ext/mysql if:
+				/*
+				 * It's possible ext/mysqli is misconfigured. Fall back to ext/mysql if:
 		 		 *  - We haven't previously connected, and
 		 		 *  - WP_USE_EXT_MYSQL isn't set to false, and
 		 		 *  - ext/mysql is loaded.
@@ -1569,6 +1569,52 @@ class wpdb {
 		return false;
 	}
 
+	/**
+	 * Parse the DB_HOST setting to interpret it for mysqli_real_connect.
+	 *
+	 * mysqli_real_connect doesn't support the host param including a port or
+	 * socket like mysql_connect does. This duplicates how mysql_connect detects
+	 * a port and/or socket file.
+	 *
+	 * @since 4.9.0
+	 *
+	 * @param string $host The DB_HOST setting to parse.
+	 * @return array|bool Array containing the host, the port, the socket and whether
+	 *                    it is an IPv6 address, in that order. If $host couldn't be parsed,
+	 *                    returns false.
+	 */
+	public function parse_db_host( $host ) {
+		$port    = null;
+		$socket  = null;
+		$is_ipv6 = false;
+
+		// We need to check for an IPv6 address first.
+		// An IPv6 address will always contain at least two colons.
+		if ( substr_count( $host, ':' ) > 1 ) {
+			$pattern = '#^(?:\[)?(?<host>[0-9a-fA-F:]+)(?:\]:(?<port>[\d]+))?(?:/(?<socket>.+))?#';
+			$is_ipv6 = true;
+		} else {
+			// We seem to be dealing with an IPv4 address.
+			$pattern = '#^(?<host>[^:/]*)(?::(?<port>[\d]+))?(?::(?<socket>.+))?#';
+		}
+
+		$matches = array();
+		$result = preg_match( $pattern, $host, $matches );
+
+		if ( 1 !== $result ) {
+			// Couldn't parse the address, bail.
+			return false;
+		}
+
+		foreach ( array( 'host', 'port', 'socket' ) as $component ) {
+			if ( array_key_exists( $component, $matches ) ) {
+				$$component = $matches[$component];
+			}
+		}
+
+		return array( $host, $port, $socket, $is_ipv6 );
+	}
+
 	/**
 	 * Checks that the connection to the database is still up. If not, try to reconnect.
 	 *