echo_server.patch

diff --git a/src/example/01_recv/recv.c b/src/example/01_recv/recv.c
index 9e4fd33..cdac4bf 100644
--- a/src/example/01_recv/recv.c
+++ b/src/example/01_recv/recv.c
@@ -1,21 +1,62 @@
-
-
 #include <rte_eal.h>
 #include <rte_ethdev.h>
 #include <rte_mbuf.h>
 
 #include <stdio.h>
-#include <arpa/inet.h>
+#include <netinet/in.h>
 
 #define NUM_MBUFS (4096-1)
 
 #define BURST_SIZE	32
 
+/* utils */
+#define rte_htons rte_cpu_to_be_16
+#define rte_htonl rte_cpu_to_be_32
+
+#define rte_ntohs rte_be_to_cpu_16
+#define rte_ntohl rte_be_to_cpu_32
+
+/* IP network to ascii representation */
+const char *
+inet_ntop2(uint32_t ip)
+{
+  static char buf[16];
+  const unsigned char *bytep;
+
+  bytep = (const unsigned char *)&ip;
+  sprintf(buf, "%d.%d.%d.%d", bytep[0], bytep[1], bytep[2], bytep[3]);
+  return buf;
+}
+
+/*
+ * IP network to ascii representation. To use
+ * for multiple IP address convertion into the same call.
+ */
+char *
+inet_ntoa2(uint32_t ip, char *buf)
+{
+  const unsigned char *bytep;
+
+  bytep = (const unsigned char *)&ip;
+  sprintf(buf, "%d.%d.%d.%d", bytep[0], bytep[1], bytep[2], bytep[3]);
+  return buf;
+}
+/* end of utils */
+
 int g_dpdk_port_id = 0; // 端口id
 // 端口默认信息
 static const struct rte_eth_conf port_conf_default = {
   .rxmode = {.max_rx_pkt_len = RTE_ETHER_MAX_LEN }
 };
+// 点分十进制ipv4地址变为数字ipv4地址
+#define MAKE_IPV4_ADDR(a, b, c, d) (a + (b<<8) + (c<<16) + (d<<24))
+// 本地ip,即dpdk端口的ip(由于dpdk绕过了内核协议栈所以需要自己设置)
+static uint32_t g_local_ip = MAKE_IPV4_ADDR(10, 66 ,24, 68);

+// 六元组sip,dip,smac,dmac,sport,dport用来发送数据包,由于本项目只用于实验所以以全局变量形式
+static uint32_t g_src_ip;
+static uint32_t g_dst_ip;
+
+static uint8_t g_src_mac[RTE_ETHER_ADDR_LEN];
+static uint8_t g_dst_mac[RTE_ETHER_ADDR_LEN];
+
+static uint16_t g_src_port;
+static uint16_t g_dst_port;
 // 绑定网卡,初始化dpdk端口
 static void ht_init_port(struct rte_mempool *mbuf_pool) {
 
@@ -28,21 +69,99 @@ static void ht_init_port(struct rte_mempool *mbuf_pool) {
   rte_eth_dev_info_get(g_dpdk_port_id, &dev_info);
   // 3. 配置rx队列和tx队列的数量
   const int num_rx_queues = 1; // 最多8个
-  const int num_tx_queues = 0;
+  const int num_tx_queues = 1; // 写队列设置为1
   struct rte_eth_conf port_conf = port_conf_default;
   rte_eth_dev_configure(g_dpdk_port_id, num_rx_queues, num_tx_queues, &port_conf);
 
-  // 4. 设置哪一个队列去接收数据, 128是队列承载的数据包最大数量
-  if (rte_eth_rx_queue_setup(g_dpdk_port_id, 0 , 128, 
+  // 4. 设置哪一个队列去接收数据, 1024是队列承载的数据包最大数量(程序员配置的)
+  if (rte_eth_rx_queue_setup(g_dpdk_port_id, 0 , 1024, 
     rte_eth_dev_socket_id(g_dpdk_port_id),NULL, mbuf_pool) < 0) {
     rte_exit(EXIT_FAILURE, "Could not setup RX queue\n");
   }
-  // 5. 启动接收队列(在这里只有接收队列,其实是启动g_dpdk_port_id这个端口)
+  // 5. 设置tx队列,tx队列初始化
+  struct rte_eth_txconf txq_conf = dev_info.default_txconf;
+  txq_conf.offloads = port_conf.rxmode.offloads; // 上面的设置:即接收的包多大就发多大的数据包
+  if (rte_eth_tx_queue_setup(g_dpdk_port_id, 0 , 1024, // 参数为: 对应网口,对应的队列,队列最大包数量,socket id,send的配置
+    rte_eth_dev_socket_id(g_dpdk_port_id), &txq_conf) < 0) {
+    rte_exit(EXIT_FAILURE, "Could not setup TX queue\n");
+  }
+
+  // 6. 其实是启动g_dpdk_port_id这个端口,有发送也有接收
   if (rte_eth_dev_start(g_dpdk_port_id) < 0 ) {
     rte_exit(EXIT_FAILURE, "Could not start\n");
   }
 }
 
+// 构建一个最简单的udp包,data参数是要发送的udp的payload
+static int ht_encode_udp_packet(uint8_t *msg, unsigned char *data, uint16_t total_len)
+{
+  // encode 构建udp包
+
+  // 1. ethernet头,以太网头
+  struct rte_ether_hdr *eth = (struct rte_ether_hdr *)msg;
+  rte_memcpy(eth->s_addr.addr_bytes, g_src_mac, RTE_ETHER_ADDR_LEN);
+  rte_memcpy(eth->d_addr.addr_bytes, g_dst_mac, RTE_ETHER_ADDR_LEN);
+  eth->ether_type = rte_htons(RTE_ETHER_TYPE_IPV4);
+
+  // 2 iphdr 设置ip头
+  // msg + sizeof(struct rte_ether_hdr) 相当于eth+1
+  struct rte_ipv4_hdr *ip = (struct rte_ipv4_hdr *)(msg + sizeof(struct rte_ether_hdr));
+  ip->version_ihl = 0x45;
+  ip->type_of_service = 0; // ip的类型
+  ip->total_length = rte_htons(total_len - sizeof(struct rte_ether_hdr)); // 转成网络字节序(大端序)
+  ip->packet_id = 0;
+  ip->fragment_offset = 0;
+  ip->time_to_live = 64; // ttl = 64
+  ip->next_proto_id = IPPROTO_UDP; // ip头要标识下一部分是什么协议
+  ip->src_addr = g_src_ip;
+  ip->dst_addr = g_dst_ip;
+  
+  ip->hdr_checksum = 0; // 一开始置0防止checksum计算出错 
+  ip->hdr_checksum = rte_ipv4_cksum(ip);
+
+  // 3 udphdr 
+  struct rte_udp_hdr *udp = (struct rte_udp_hdr *)(msg + sizeof(struct rte_ether_hdr) + sizeof(struct rte_ipv4_hdr));
+  udp->src_port = g_src_port;
+  udp->dst_port = g_dst_port;
+  uint16_t udplen = total_len - sizeof(struct rte_ether_hdr) - sizeof(struct rte_ipv4_hdr);
+  udp->dgram_len = rte_htons(udplen);
+  // 数据放到udp头之下(udp payload),udp+1为即是以udp hdr为一单位偏移.实为偏移到udp hdr末尾
+  rte_memcpy((uint8_t*)(udp+1), data, udplen);
+
+  udp->dgram_cksum = 0;
+  udp->dgram_cksum = rte_ipv4_udptcp_cksum(ip, udp);
+
+  char ip_buf[16] = {0};
+  printf(" --> src: %s:%d, ", inet_ntoa2(g_src_ip, ip_buf), rte_ntohs(g_src_port)); // 网络字节序大端序转为主机字节序小端序
+
+  printf("dst: %s:%d\n", inet_ntoa2(g_dst_ip, ip_buf), rte_ntohs(g_dst_port));
+
+  return 0;
+
+}
+
+// 发送数据包,参数分别为:内存buffer,payload,length(payload)长度
+static struct rte_mbuf * ht_send_udp(struct rte_mempool *mbuf_pool, uint8_t *data, uint16_t length) {
+
+  // mempool --> mbuf(从mempool里获取数据buffer流)
+
+  const unsigned total_len = length + 42; // 42是eth header + ip hdr + udp hdr
+
+  struct rte_mbuf *mbuf = rte_pktmbuf_alloc(mbuf_pool);
+  if (!mbuf) {
+    rte_exit(EXIT_FAILURE, "rte_pktmbuf_alloc\n");
+  }
+
+  mbuf->pkt_len = total_len; // 包的长度
+  mbuf->data_len = total_len; // 数据的长度
+  // 偏移uint8_t也就是一个字节一个字节处理
+  uint8_t *pktdata = rte_pktmbuf_mtod(mbuf, uint8_t*);
+
+  ht_encode_udp_packet(pktdata, data, total_len);
+
+  return mbuf;
+}
+
 
 int main(int argc, char *argv[]) {
   // dpdk环境初始化,巨页,内存,cpu亲和等的设置
@@ -82,17 +201,31 @@ int main(int argc, char *argv[]) {
         // udp的头
         struct rte_udp_hdr *udphdr = (struct rte_udp_hdr *)(iphdr + 1);
 
-        uint16_t length = ntohs(udphdr->dgram_len); // 两个字节以上都要转换ntohs
+        // 发送包所需要的六元组dmac,sip,dip,sport,dport获取并填充
+        // 由于是发echo reply所以需要交换。比如dmac是取获取到的包的smac
+        rte_memcpy(g_dst_mac, ehdr->s_addr.addr_bytes, RTE_ETHER_ADDR_LEN);
+        
+        rte_memcpy(&g_src_ip, &iphdr->dst_addr, sizeof(uint32_t));
+        rte_memcpy(&g_dst_ip, &iphdr->src_addr, sizeof(uint32_t));
+
+        rte_memcpy(&g_src_port, &udphdr->dst_port, sizeof(uint16_t));
+        rte_memcpy(&g_dst_port, &udphdr->src_port, sizeof(uint16_t));
+
+        uint16_t length = rte_ntohs(udphdr->dgram_len); // 两个字节以上都要转换ntohs
         *((char*)udphdr + length) = '\0';	// 最后一段置为0
         // 打印接收到的udp数据
-        struct in_addr addr;
-        addr.s_addr = iphdr->src_addr;
-        printf("src: %s:%d, ", inet_ntoa(addr), udphdr->src_port);
+        char ip_buf[16] = {0};
+        printf("src: %s:%d, ", inet_ntoa2(iphdr->src_addr, ip_buf), udphdr->src_port);
+
+        printf("dst: %s:%d, %s\n", inet_ntoa2(iphdr->src_addr, ip_buf), udphdr->src_port, (char *)(udphdr+1));
+
+        // 发送udp echo
+        struct rte_mbuf *txbuf = ht_send_udp(mbuf_pool, (uint8_t *)(udphdr+1), length);
+        rte_eth_tx_burst(g_dpdk_port_id, 0, &txbuf, 1);// rte_eth_rx_burst发送数据
+        rte_pktmbuf_free(txbuf); // 发送用的mbuf同样放回到内存池中
 
-        addr.s_addr = iphdr->dst_addr;
-        printf("dst: %s:%d, %s\n", inet_ntoa(addr), udphdr->src_port, (char *)(udphdr+1));
         rte_pktmbuf_free(mbufs[i]); // 放回内存池
       }
     }
   }
-}
\ No newline at end of file
+}