ssh/Connection: add noexcept to SendPacket()

This method cannot throw; it only enqueues the buffer.  Adding
`noexcept` allows doing the same with many other functions.

src/SessionChannel.cxx

@@ -56,7 +56,7 @@ SessionChannel::~SessionChannel() noexcept
 }
 
 void
-SessionChannel::CloseIfInactive()
+SessionChannel::CloseIfInactive() noexcept
 {
 	if (!IsActive())
 		Close();

src/SessionChannel.hxx

@@ -66,24 +66,22 @@ private:
 	/**
 	 * Call SSH::Channel::SendEof() if all data sources have ended.
 	 *
-	 * Throws on error.
-	 *
 	 * @return true if SendEof() was called
 	 */
-	bool MaybeSendEof() {
+	bool MaybeSendEof() noexcept {
 		if (stdout_pipe.IsDefined() || stderr_pipe.IsDefined() || tty.IsDefined())
 			return false;
 
 		SendEof();
 		return true;
 	}
 
-	void CloseIfInactive();
+	void CloseIfInactive() noexcept;
 
 	/**
 	 * Combination of MaybeSendEof() and CloseIfInactive().
 	 */
-	void MaybeSendEofAndClose() {
+	void MaybeSendEofAndClose() noexcept {
 		if (MaybeSendEof())
 			CloseIfInactive();
 	}

src/ssh/CConnection.cxx

@@ -154,7 +154,7 @@ IsOpeningChannel(const Channel &channel) noexcept
 }
 
 void
-CConnection::CloseChannel(Channel &channel)
+CConnection::CloseChannel(Channel &channel) noexcept
 {
 	assert(!IsTombstoneChannel(channel));
 	assert(!IsOpeningChannel(channel));
@@ -276,15 +276,10 @@ CConnection::AsyncChannelOpenSuccess(Channel &channel) noexcept
 	opening.cancel_ptr = {};
 	delete &opening;
 
-	try {
-		SendPacket(MakeChannelOpenConfirmation(channel.GetPeerChannel(),
-						       local_channel,
-						       MAXIMUM_PACKET_SIZE,
-						       channel));
-	} catch (...) {
-		OnBufferedError(std::current_exception());
-		return;
-	}
+	SendPacket(MakeChannelOpenConfirmation(channel.GetPeerChannel(),
+					       local_channel,
+					       MAXIMUM_PACKET_SIZE,
+					       channel));
 
 	channels[local_channel] = &channel;
 }
@@ -303,11 +298,7 @@ CConnection::AsyncChannelOpenFailure(ChannelInit init,
 	opening.cancel_ptr = {};
 	delete &opening;
 
-	try {
-		SendPacket(MakeChannelOpenFailure(init.peer_channel, reason_code, description));
-	} catch (...) {
-		OnBufferedError(std::current_exception());
-	}
+	SendPacket(MakeChannelOpenFailure(init.peer_channel, reason_code, description));
 }
 
 inline void

src/ssh/CConnection.hxx

@@ -64,10 +64,7 @@ public:
 			 ChannelFactory &factory,
 			 CancellablePointer &cancel_ptr);
 
-	/**
-	 * Throws on error.
-	 */
-	void CloseChannel(Channel &channel);
+	void CloseChannel(Channel &channel) noexcept;
 
 	/**
 	 * Exception class to be thrown from inside CreateChannel(),

src/ssh/Channel.cxx

@@ -22,7 +22,7 @@ Channel::Channel(CConnection &_connection, ChannelInit init,
 Channel::~Channel() noexcept = default;
 
 void
-Channel::Close()
+Channel::Close() noexcept
 {
 	connection.CloseChannel(*this);
 }
@@ -36,7 +36,7 @@ Channel::ConsumeReceiveWindow(std::size_t nbytes) noexcept
 }
 
 void
-Channel::SendWindowAdjust(uint_least32_t nbytes)
+Channel::SendWindowAdjust(uint_least32_t nbytes) noexcept
 {
 	assert(nbytes > 0);
 	assert(nbytes <= SIZE_MAX - receive_window);
@@ -81,15 +81,15 @@ Channel::SendStderr(std::span<const std::byte> src)
 }
 
 void
-Channel::SendEof()
+Channel::SendEof() noexcept
 {
 	PacketSerializer s{MessageNumber::CHANNEL_EOF};
 	s.WriteU32(GetPeerChannel());
 	connection.SendPacket(std::move(s));
 }
 
 void
-Channel::SendExitStatus(uint_least32_t exit_status)
+Channel::SendExitStatus(uint_least32_t exit_status) noexcept
 {
 	auto s = MakeChannelReqest(GetPeerChannel(), "exit-status"sv, false);
 	s.WriteU32(exit_status);

src/ssh/Channel.hxx

@@ -68,18 +68,15 @@ public:
 		return send_window;
 	}
 
-	/**
-	 * Throws on error.
-	 */
-	void Close();
+	void Close() noexcept;
 
-	void SendWindowAdjust(uint_least32_t nbytes);
+	void SendWindowAdjust(uint_least32_t nbytes) noexcept;
 	void SendData(std::span<const std::byte> src);
 	void SendExtendedData(ChannelExtendedDataType data_type,
 			      std::span<const std::byte> src);
 	void SendStderr(std::span<const std::byte> src);
-	void SendEof();
-	void SendExitStatus(uint_least32_t exit_status);
+	void SendEof() noexcept;
+	void SendExitStatus(uint_least32_t exit_status) noexcept;
 	void SendExitSignal(std::string_view signal_name, bool core_dumped,
 			    std::string_view error_message);
 

src/ssh/Connection.cxx

@@ -72,7 +72,7 @@ Connection::IsEncrypted() const noexcept
 }
 
 inline void
-Connection::SendPacket(std::span<const std::byte> src)
+Connection::SendPacket(std::span<const std::byte> src) noexcept
 {
 	if (metrics != nullptr) {
 		++metrics->packets_sent;
@@ -86,7 +86,7 @@ Connection::SendPacket(std::span<const std::byte> src)
 }
 
 void
-Connection::SendPacket(PacketSerializer &&s)
+Connection::SendPacket(PacketSerializer &&s) noexcept
 {
 	const auto *send_cipher = output.GetCipher();
 	SendPacket(s.Finish(send_cipher
@@ -108,9 +108,9 @@ Connection::DoDisconnect(DisconnectReasonCode reason_code, std::string_view msg)
 {
 	OnDisconnecting(reason_code, msg);
 
-	try {
-		SendPacket(MakeDisconnect(reason_code, msg));
+	SendPacket(MakeDisconnect(reason_code, msg));
 
+	try {
 		/* attempt to flush the DISCONNECT packet immediately
                    before we close the socket */
 		switch (output.Flush()) {

src/ssh/Connection.hxx

@@ -135,13 +135,10 @@ protected:
 		authenticated = true;
 	}
 
-	void SendPacket(std::span<const std::byte> src);
+	void SendPacket(std::span<const std::byte> src) noexcept;
 
 public:
-	/**
-	 * Throws on error.
-	 */
-	void SendPacket(PacketSerializer &&s);
+	void SendPacket(PacketSerializer &&s) noexcept;
 
 	void SendPacket(MessageNumber msg, std::span<const std::byte> src);