From a0825e6ce0ea4b6202df925c14d6eeee52b1b782 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max.kellermann@gmail.com>
Date: Wed, 29 Jan 2025 19:05:10 +0100
Subject: [PATCH] net/PeerCredentials: add getpeereid() support

---
 src/event/ServerSocket.cxx   |  8 --------
 src/net/PeerCredentials.hxx  | 13 +++++++++++++
 src/net/SocketDescriptor.cxx |  9 +++++++++
 3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/src/event/ServerSocket.cxx b/src/event/ServerSocket.cxx
index 0f6f06cc5..5e221d3de 100644
--- a/src/event/ServerSocket.cxx
+++ b/src/event/ServerSocket.cxx
@@ -105,19 +105,11 @@ static constexpr Domain server_socket_domain("server_socket");
 static int
 get_remote_uid(SocketDescriptor s) noexcept
 {
-#ifdef HAVE_GETPEEREID
-	uid_t euid;
-	gid_t egid;
-
-	if (getpeereid(s.Get(), &euid, &egid) == 0)
-		return euid;
-#else
 	const auto cred = s.GetPeerCredentials();
 	if (!cred.IsDefined())
 		return -1;
 
 	return cred.GetUid();
-#endif
 }
 
 inline void
diff --git a/src/net/PeerCredentials.hxx b/src/net/PeerCredentials.hxx
index 510f60f3b..ea2cfcc53 100644
--- a/src/net/PeerCredentials.hxx
+++ b/src/net/PeerCredentials.hxx
@@ -20,6 +20,9 @@ class SocketPeerCredentials {
 
 #ifdef HAVE_STRUCT_UCRED
 	struct ucred cred;
+#elif defined(HAVE_GETPEEREID)
+	uid_t uid;
+	gid_t gid;
 #endif
 
 public:
@@ -31,6 +34,9 @@ public:
 		c.cred.pid = 0;
 		c.cred.uid = -1;
 		c.cred.gid = -1;
+#elif defined(HAVE_GETPEEREID)
+		c.uid = static_cast<uid_t>(-1);
+		c.gid = static_cast<gid_t>(-1);
 #endif
 		return c;
 	}
@@ -38,6 +44,9 @@ public:
 	constexpr bool IsDefined() const noexcept {
 #ifdef HAVE_STRUCT_UCRED
 		return cred.pid > 0;
+#elif defined(HAVE_GETPEEREID)
+		return uid != static_cast<uid_t>(-1) ||
+			gid != static_cast<gid_t>(-1);
 #else
 		return false;
 #endif
@@ -54,6 +63,8 @@ public:
 	constexpr auto GetUid() const noexcept {
 #ifdef HAVE_STRUCT_UCRED
 		return cred.uid;
+#elif defined(HAVE_GETPEEREID)
+		return uid;
 #else
 		return -1;
 #endif
@@ -62,6 +73,8 @@ public:
 	constexpr auto GetGid() const noexcept {
 #ifdef HAVE_STRUCT_UCRED
 		return cred.gid;
+#elif defined(HAVE_GETPEEREID)
+		return gid;
 #else
 		return -1;
 #endif
diff --git a/src/net/SocketDescriptor.cxx b/src/net/SocketDescriptor.cxx
index 162ccea0e..3d3ab9ada 100644
--- a/src/net/SocketDescriptor.cxx
+++ b/src/net/SocketDescriptor.cxx
@@ -13,6 +13,10 @@
 #include "io/UniqueFileDescriptor.hxx"
 #endif
 
+#ifdef HAVE_GETPEEREID
+#include <unistd.h> // for getpeereid()
+#endif
+
 #ifdef _WIN32
 #include <ws2tcpip.h>
 #else
@@ -235,6 +239,11 @@ SocketDescriptor::GetPeerCredentials() const noexcept
 		      &cred.cred, sizeof(cred.cred)) < sizeof(cred.cred))
 		return SocketPeerCredentials::Undefined();
 	return cred;
+#elif defined(HAVE_GETPEEREID)
+	SocketPeerCredentials cred;
+	return getpeereid(Get(), &cred.uid, &cred.gid) == 0
+		? cred
+		: SocketPeerCredentials::Undefined();
 #else
 	return SocketPeerCredentials::Undefined();
 #endif