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

libtransmission/announcer-udp.cc

@@ -169,7 +169,10 @@ 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);
@@ -585,9 +595,7 @@ public:
         }
 
         // Since size of IP field is only 4 bytes long, we can only announce IPv4 addresses
-        auto const addr = mediator_.announce_ip();
-        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_.announce_ip(), request, std::move(on_response));
         tracker->upkeep(false);
     }
 

libtransmission/net.h

@@ -181,13 +181,13 @@ struct tr_address
     template<typename OutputIt>
     static OutputIt to_compact_ipv4(OutputIt out, in_addr const& addr4)
     {
-        return std::copy_n(reinterpret_cast<std::byte const*>(&addr4), sizeof(addr4), out);
+        return std::copy_n(reinterpret_cast<std::byte const*>(&addr4.s_addr), sizeof(addr4.s_addr), out);
     }
 
     template<typename OutputIt>
     static OutputIt to_compact_ipv6(OutputIt out, in6_addr const& addr6)
     {
-        return std::copy_n(reinterpret_cast<std::byte const*>(&addr6), sizeof(addr6), out);
+        return std::copy_n(reinterpret_cast<std::byte const*>(&addr6.s6_addr), sizeof(addr6.s6_addr), out);
     }
 
     template<typename OutputIt>

libtransmission/tr-buffer.h

@@ -160,35 +160,32 @@ public:
 
     void add_uint16(uint16_t hs)
     {
-        uint16_t const ns = htons(hs);
-        add(&ns, sizeof(ns));
+        add_uint16_n(htons(hs));
     }
 
-    void add_hton16(uint16_t hs)
+    void add_uint16_n(uint16_t ns)
     {
-        add_uint16(hs);
+        add(&ns, sizeof(ns));
     }
 
     void add_uint32(uint32_t hl)
     {
-        uint32_t const nl = htonl(hl);
-        add(&nl, sizeof(nl));
+        add_uint32_n(htonl(hl));
     }
 
-    void eadd_hton32(uint32_t hl)
+    void add_uint32_n(uint32_t nl)
     {
-        add_uint32(hl);
+        add(&nl, sizeof(nl));
     }
 
     void add_uint64(uint64_t hll)
     {
-        uint64_t const nll = tr_htonll(hll);
-        add(&nll, sizeof(nll));
+        add_uint64_n(tr_htonll(hll));
     }
 
-    void add_hton64(uint64_t hll)
+    void add_uint64_n(uint64_t nll)
     {
-        add_uint64(hll);
+        add(&nll, sizeof(nll));
     }
 
     void add_port(tr_port port)
@@ -197,6 +194,22 @@ 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;
+        }
+    }
+
     size_t add_socket(tr_socket_t sockfd, size_t n_bytes, tr_error** error = nullptr)
     {
         auto const [buf, buflen] = reserve_space(n_bytes);