feat: add new test source code

tests/network/index.md

@@ -0,0 +1,4 @@
+
+- [通过多 IP 达成单机百万连接](tests/network/test02)
+- [通过端口重用达成单机百万连接](tests/network/test03)
+- [一个模拟 tcpdump 的简单抓包程序](tests/network/test04)

tests/network/test04/main.c

@@ -0,0 +1,133 @@
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <linux/if_ether.h>
+#include <linux/in.h>
+
+#define BUFFER_MAX 2048
+
+typedef int int32;
+typedef unsigned int u_int32;
+typedef unsigned char u_char;
+typedef unsigned short u_short;
+
+//参考内核 struct ethhdr 定义 (include/uapi/linux/if_ether.h）
+typedef struct eth_hdr {
+	 char h_dest[6];	
+	 char h_source[6];
+	 short h_proto;
+}__attribute__((packed));
+
+//参考内核 struct iphdr 定义（include/uapi/linux/ip.h）
+typedef struct iphdr{
+	#ifdef __LITTLE_ENDIAN_BIFIELD
+		u_char ip_len:4, ip_ver:4;
+	#else
+		u_char ip_ver:4, ip_len:4;
+	#endif
+	u_char  tos;
+	u_short total_len;
+	u_short id;
+	u_short flags_off;
+	u_char  ttl;
+	u_char  protocol;
+	u_short check;
+	u_int32 saddr;
+	u_int32 daddr;
+}__attribute__((packed));
+
+int main(int argc, char *argv[])
+{
+	int  sock;
+	char buffer[BUFFER_MAX];
+	int len;
+
+	struct eth_hdr *mac_hdr; 
+	struct iphdr *ip_hdr;
+	char* p;
+
+	if( (sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))) < 0 ){
+		printf("Create socket error.\n");
+		exit(0);
+	}
+
+	while(1){
+		len = recvfrom(sock, buffer, BUFFER_MAX, 0, NULL, NULL);
+		if (len < 46) {
+			printf("Catch packet length error.\n" );
+			close(sock);
+			exit(0);
+		}
+		
+		printf("截获内容长度 %d\n", len);
+
+		mac_hdr = buffer;	
+		ip_hdr = buffer + sizeof(struct ethhdr);
+
+		printf("源 MAC:%X:%X:%X:%X:%X:%X",
+				(u_char)mac_hdr->h_source[0],
+				(u_char)mac_hdr->h_source[1],
+				(u_char)mac_hdr->h_source[2],
+				(u_char)mac_hdr->h_source[3],
+				(u_char)mac_hdr->h_source[4],
+				(u_char)mac_hdr->h_source[5]
+			);
+
+		printf(" ==> 目的 MAC:%X:%X:%X:%X:%X\n",
+				(u_char)mac_hdr->h_dest[0],
+				(u_char)mac_hdr->h_dest[1],
+				(u_char)mac_hdr->h_dest[2],
+				(u_char)mac_hdr->h_dest[3],
+				(u_char)mac_hdr->h_dest[4],
+				(u_char)mac_hdr->h_dest[5]
+			);
+
+		p = (char*)&ip_hdr->saddr;
+		printf("源 IP: %d.%d.%d.%d",
+				(u_char)p[0], 
+				(u_char)p[1], 
+				(u_char)p[2],
+				(u_char)p[3]
+			);
+
+		p = (char*)&ip_hdr->daddr;
+		printf(" ==> 目的 IP: %d.%d.%d.%d\n",
+				(u_char)p[0], 
+				(u_char)p[1], 
+				(u_char)p[2],
+				(u_char)p[3]
+			);
+
+	printf("协议类型：");
+		switch(ip_hdr->protocol) {
+			 case IPPROTO_ICMP: 
+				  printf("ICMP"); 
+				  break;
+			case IPPROTO_IGMP: 
+				printf("IGMP"); 
+				break;
+			case IPPROTO_IPIP: 
+				printf("IPIP"); 
+				break;
+			case IPPROTO_TCP:  
+				printf("TCP"); 
+				break;
+			case IPPROTO_UDP:  
+				printf("UDP"); 
+				break;
+			case IPPROTO_RAW: 
+				printf("RAW"); 
+				break;
+			default: 
+				printf("Unknown type"); 
+				break;
+		}
+
+		printf("\n\n");
+	}
+
+	close(sock);
+	return 0;
+}