我想用C语言实现 ethernet/IP 协议栈的程序

实现Ethernet/IP协议栈的程序需要熟悉以太网协议和IP协议等相关知识，并且需要掌握C语言编程技巧。下面是一个简单的C语言实现Ethernet/IP协议栈的程序的示例：

/* Ethernet/IP协议栈示例程序 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#define ETH_FRAME_SIZE 1514
#define IP_HEADER_SIZE 20
#define IP_PROTOCOL_TCP 6

struct ether_header {
    uint8_t dest[6];
    uint8_t src[6];
    uint16_t type;
};

struct ip_header {
    uint8_t version;
    uint8_t header_length;
    uint16_t total_length;
    uint16_t id;
    uint16_t flags;
    uint8_t ttl;
    uint8_t protocol;
    uint16_t checksum;
    struct in_addr src;
    struct in_addr dest;
};

struct tcp_header {
    uint16_t src_port;
    uint16_t dest_port;
    uint32_t seq_num;
    uint32_t ack_num;
    uint8_t offset;
    uint8_t flags;
    uint16_t window;
    uint16_t checksum;
    uint16_t urgent;
};

int main() {
    int sockfd;
    struct sockaddr_in addr;
    char buffer[ETH_FRAME_SIZE];
    struct ether_header *eth_header = (struct ether_header *) buffer;
    struct ip_header *ip_header = (struct ip_header *) (buffer + sizeof(struct ether_header));
    struct tcp_header *tcp_header = (struct tcp_header *) (buffer + sizeof(struct ether_header) + sizeof(struct ip_header));

    // 创建套接字
    sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
    if (sockfd < 0) {
        perror("socket");
        exit(1);
    }

    // 设置IP头部信息
    memset(ip_header, 0, sizeof(struct ip_header));
    ip_header->version = 4;
    ip_header->header_length = 5;
    ip_header->total_length = htons(ETH_FRAME_SIZE - sizeof(struct ether_header));
    ip_header->ttl = 64;
    ip_header->protocol = IP_PROTOCOL_TCP;
    inet_aton("192.168.1.100", &ip_header->src);
    inet_aton("192.168.1.200", &ip_header->dest);

    // 设置TCP头部信息
    memset(tcp_header, 0, sizeof(struct tcp_header));
    tcp_header->src_port = htons(1234);
    tcp_header->dest_port = htons(5678);
    tcp_header->seq_num = htonl(1);
    tcp_header->ack_num = htonl(0);
    tcp_header->offset = 5;
    tcp_header->flags = 0x02;
    tcp_header->window = htons(5840);

    // 设置以太网头部信息
    memset(eth_header, 0, sizeof(struct ether_header));
    eth_header->dest[0] = 0x00;
    eth_header->dest[1] = 0x11;
    eth_header->dest[2] = 0x22;
    eth_header->dest[3] = 0x33;
    eth_header->dest[4] = 0x44;
    eth_header->dest[5] = 0x55;
    eth_header->src[0] = 0x66;
    eth_header->src[1] = 0x77;
    eth_header->src[2] = 0x88;
    eth_header->src[3] = 0x99;
    eth_header->src[4] = 0xaa;
    eth_header->src[5] = 0xbb;
    eth_header->type = htons(0x0800);

    // 发送数据
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = inet_addr("192.168.1.200");
    memset(addr.sin_zero, 0, sizeof(addr.sin_zero));
    if (sendto(sockfd, buffer, ETH_FRAME_SIZE, 0, (struct sockaddr *) &addr, sizeof(struct sockaddr)) < 0) {
        perror("sendto");
        exit(1);
    }

    // 关闭套接字
    close(sockfd);

    return 0;
}

这个示例程序实现了一个简单的以太网数据包的发送，其中包含了以太网头部、IP头部和TCP头部等信息。在实际应用中，需要根据具体需求实现更完整的Ethernet/IP协议栈，包括数据包的接收、解析和处理等功能。