Specify queue id as a configuration parameter

Pcap++/header/XdpDevice.h

@@ -11,6 +11,8 @@
 /// @
 namespace pcpp
 {
+#define XDP_MAX_RXTX_QUEUES 16
+
 	/// @class XdpDevice
 	/// A class wrapping the main functionality of using AF_XDP (XSK) sockets
 	/// which are optimized for high performance packet processing.
@@ -76,6 +78,10 @@ namespace pcpp
 			/// The max number of packets to be received or sent in one batch
 			uint16_t rxTxBatchSize;
 
+			/// The queue identifier for the underlying socket. This value should be less than the number
+			/// of hardware queues supported by the device
+			uint16_t queueId;
+
 			/// A c'tor for this struct. Each parameter has a default value described below.
 			/// @param[in] attachMode AF_XDP operation mode. The default value is auto mode
 			/// @param[in] umemNumFrames Number of UMEM frames to allocate. The default value is 4096
@@ -87,10 +93,11 @@ namespace pcpp
 			/// @param[in] txSize The size of the TX ring used by the AF_XDP socket. The default value is 2048
 			/// @param[in] rxTxBatchSize The max number of packets to be received or sent in one batch. The default
 			/// value is 64
+			/// @param[in] queueId The hardware queue id of the underlying socket. The default value is 0
 			explicit XdpDeviceConfiguration(AttachMode attachMode = AutoMode, uint16_t umemNumFrames = 0,
 			                                uint16_t umemFrameSize = 0, uint32_t fillRingSize = 0,
 			                                uint32_t completionRingSize = 0, uint32_t rxSize = 0, uint32_t txSize = 0,
-			                                uint16_t rxTxBatchSize = 0)
+			                                uint16_t rxTxBatchSize = 0, uint32_t queueId = 0)
 			{
 				this->attachMode = attachMode;
 				this->umemNumFrames = umemNumFrames;
@@ -100,6 +107,7 @@ namespace pcpp
 				this->rxSize = rxSize;
 				this->txSize = txSize;
 				this->rxTxBatchSize = rxTxBatchSize;
+				this->queueId = queueId;
 			}
 		};
 
@@ -238,6 +246,24 @@ namespace pcpp
 		/// @return Current device statistics
 		XdpDeviceStats getStatistics();
 
+		/// @return Return queue identifier for underlying socket
+		uint32_t getQueueId()
+		{
+			if(m_Config) 
+			{
+				return m_Config->queueId;
+
+			}
+
+			return 0;
+		}
+
+		/// Get number of RX or TX hardware queues for device
+		/// @param[in] interfaceName The interface name to use to detect hardware queues
+		/// @param[in] tx  If true, return TX queues, otherwise RX. Default is false
+		/// @return The number of hardware queues associated with the device. 
+		static uint32_t getNumQueues(const std::string& interfaceName, bool tx = false);
+
 	private:
 		class XdpUmem
 		{

Pcap++/src/XdpDevice.cpp

@@ -10,9 +10,11 @@
 #include <net/if.h>
 #include <sys/mman.h>
 #include <unistd.h>
+#include <dirent.h>
 #include <vector>
 #include <functional>
 #include <algorithm>
+#include <regex>
 #include <poll.h>
 
 namespace pcpp
@@ -419,7 +421,7 @@ namespace pcpp
 			xskConfig.xdp_flags = XDP_FLAGS_DRV_MODE;
 		}
 
-		int ret = xsk_socket__create(&socketInfo->xsk, m_InterfaceName.c_str(), 0, umemInfo->umem, &socketInfo->rx,
+		int ret = xsk_socket__create(&socketInfo->xsk, m_InterfaceName.c_str(), m_Config->queueId, umemInfo->umem, &socketInfo->rx,
 		                             &socketInfo->tx, &xskConfig);
 		if (ret)
 		{
@@ -429,6 +431,7 @@ namespace pcpp
 		}
 
 		m_SocketInfo = socketInfo;
+
 		return true;
 	}
 
@@ -449,6 +452,7 @@ namespace pcpp
 		uint32_t rxSize = config.rxSize ? config.rxSize : XSK_RING_CONS__DEFAULT_NUM_DESCS;
 		uint32_t txSize = config.txSize ? config.txSize : XSK_RING_PROD__DEFAULT_NUM_DESCS;
 		uint32_t batchSize = config.rxTxBatchSize ? config.rxTxBatchSize : DEFAULT_BATCH_SIZE;
+		uint32_t qId = config.queueId; // default is zero
 
 		if (frameSize != getpagesize())
 		{
@@ -499,13 +503,21 @@ namespace pcpp
 			return false;
 		}
 
+		unsigned int nhwqueues = getNumQueues(m_InterfaceName);
+		if (qId >= nhwqueues)
+		{
+			PCPP_LOG_ERROR("Queue Id (" << qId << ") must be less than the number hardware queues (" << nhwqueues << ") of device");
+			return false;
+		}
+
 		config.umemNumFrames = numFrames;
 		config.umemFrameSize = frameSize;
 		config.fillRingSize = fillRingSize;
 		config.completionRingSize = completionRingSize;
 		config.rxSize = rxSize;
 		config.txSize = txSize;
 		config.rxTxBatchSize = batchSize;
+		config.queueId = qId;
 
 		return true;
 	}
@@ -636,4 +648,36 @@ namespace pcpp
 		return m_Stats;
 	}
 
+	uint32_t XdpDevice::getNumQueues(const std::string& iface, bool tx)
+	{
+		// returns number of hardware queues associated with the device
+		uint32_t rxtxqueues = 0;
+		std::string prefix = tx ? "tx-" : "rx-";
+		std::string path = "/sys/class/net/" + iface + "/queues/";
+		DIR *dir = opendir(path.c_str());
+
+		if(dir)
+		{
+			std::regex rxtx_regex("^" + prefix + "[0-9]+$");
+
+			struct dirent* entry;
+			while((entry = readdir(dir)) != nullptr)
+			{
+				if(std::regex_match(entry->d_name, rxtx_regex))
+				{
+					rxtxqueues++;
+				}
+			}
+
+			closedir(dir);
+		}
+
+		else
+		{
+			PCPP_LOG_ERROR("Error getting number of hardware queues from " << iface);
+		}
+
+		return rxtxqueues;
+	}
+
 }  // namespace pcpp