From 90b86a17d8965b54e58bc3b861288cf37d53c5f1 Mon Sep 17 00:00:00 2001
From: Yat Ho <lagoho7@gmail.com>
Date: Sat, 21 Oct 2023 00:32:42 +0800
Subject: [PATCH] fix: encode `ip` in network byte order for udp announce
 (#6126) (#6132)

* fix: encode `ip` in network byte order for udp announce (#6126)

(cherry picked from commit c70c49e87bf29828045920b7cd2ac2741107daf6)

* fixup! fix: encode `ip` in network byte order for udp announce (#6126)
---
 libtransmission/announcer-udp.cc | 18 +++++++++++++-----
 libtransmission/tr-buffer.h      | 17 +++++++++++++++++
 2 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/libtransmission/announcer-udp.cc b/libtransmission/announcer-udp.cc
index 20e09ad62..f26c80f33 100644
--- a/libtransmission/announcer-udp.cc
+++ b/libtransmission/announcer-udp.cc
@@ -166,7 +166,10 @@ private:
 
 struct tau_announce_request
 {
-    tau_announce_request(uint32_t announce_ip, tr_announce_request const& in, tr_announce_response_func on_response)
+    tau_announce_request(
+        std::optional<tr_address> announce_ip,
+        tr_announce_request const& in,
+        tr_announce_response_func on_response)
         : on_response_{ std::move(on_response) }
     {
         // https://www.bittorrent.org/beps/bep_0015.html sets key size at 32 bits
@@ -187,7 +190,14 @@ struct tau_announce_request
         buf.add_uint64(in.leftUntilComplete);
         buf.add_uint64(in.up);
         buf.add_uint32(get_tau_announce_event(in.event));
-        buf.add_uint32(announce_ip);
+        if (announce_ip && announce_ip->is_ipv4())
+        {
+            buf.add_address(*announce_ip);
+        }
+        else
+        {
+            buf.add_uint32(0U);
+        }
         buf.add_uint32(in.key);
         buf.add_uint32(in.numwant);
         buf.add_port(in.port);
@@ -588,9 +598,7 @@ public:
         }
 
         // Since size of IP field is only 4 bytes long, we can only announce IPv4 addresses
-        auto const addr = mediator_.announceIP();
-        uint32_t const announce_ip = addr && addr->is_ipv4() ? addr->addr.addr4.s_addr : 0;
-        tracker->announces.emplace_back(announce_ip, request, std::move(on_response));
+        tracker->announces.emplace_back(mediator_.announceIP(), request, std::move(on_response));
         tracker->upkeep(false);
     }
 
diff --git a/libtransmission/tr-buffer.h b/libtransmission/tr-buffer.h
index cbb912ab9..ed0072cce 100644
--- a/libtransmission/tr-buffer.h
+++ b/libtransmission/tr-buffer.h
@@ -16,6 +16,7 @@
 
 #include "error.h"
 #include "net.h" // tr_socket_t
+#include "tr-assert.h"
 #include "utils-ev.h"
 #include "utils.h" // for tr_htonll(), tr_ntohll()
 
@@ -355,6 +356,22 @@ public:
         add(&nport, sizeof(nport));
     }
 
+    void add_address(tr_address const& addr)
+    {
+        switch (addr.type)
+        {
+        case TR_AF_INET:
+            add(&addr.addr.addr4.s_addr, sizeof(addr.addr.addr4.s_addr));
+            break;
+        case TR_AF_INET6:
+            add(&addr.addr.addr6.s6_addr, sizeof(addr.addr.addr6.s6_addr));
+            break;
+        default:
+            TR_ASSERT_MSG(false, "invalid type");
+            break;
+        }
+    }
+
     void add_uint8(uint8_t uch)
     {
         add(&uch, 1);