server.c

Linux下网络编程

#include <sys/socket.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <malloc.h>
#include <pthread.h>

#define SERVER_PORT 8080 /*端口*/
#define MAX_SIZE 25 /*滑动窗口的大小*/
#define PACKET_SIZE 1400 /*每次读取的大小*/

typedef struct packet
{
	int number; /*包的编号*/
	int length; /*包的数据的大小*/
	char buffer[PACKET_SIZE]; /*每次读取10*1024个字节*/
}packet_t;

typedef struct packet_control_block
{
	packet_t *pt;/*包的指针，每次用malloc进行产生，成功发送后释放*/
	int state;/*包的状态---省略，在成功能发送就将其从Packet_State中删除即可*/
	clock_t start;/*发送的起始时间，用以判断是否超时*/
	int count;/*已被发送的次数，用以判断网络是否故障*/
}PCB_t;

typedef struct thread_parameter
{
	FILE *fp;
	int sockfd;
	struct sockaddr* addr_client;
}paras_t;

PCB_t Packet_State[MAX_SIZE] = {0}; /*构建一PCB控制块，包含5个元素，即滑动窗口的大小*/
int Send_State = 1; /*当前文件的发送状态，是否发送完毕，以接受下一个请求*/

void get_filename(char buf_filename[], char buf_request[]);
void create_thread(FILE *fp, int sockfd, struct sockaddr *addr_client);
void deal_request(char buf_request[], int sockfd, struct sockaddr *addr_client);
void thread_send(void *ps);


int main()
{
	int sockfd;
	if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
	{
		printf("socket error!!!\n");
		return 1;
	}

	struct sockaddr_in addr_server;
	addr_server.sin_family = AF_INET;
	addr_server.sin_port = htons(SERVER_PORT);
	addr_server.sin_addr.s_addr = htonl(INADDR_ANY);
	if (bind(sockfd, (struct sockaddr*)&addr_server, sizeof(struct sockaddr)) == -1)
	{
		printf("bind error!!!\n");
		return 1;
	}

	struct sockaddr_in addr_client;
	int addrlen = sizeof(struct sockaddr_in);
	while (1)
	{
		char buf_request[32] = {0};
		if (recvfrom(sockfd, buf_request, 32, 0, (struct sockaddr*)&addr_client, &addrlen) <= 0)
		{
			printf("recvfrom error!!!\n");
			return 1;
		}

		deal_request(buf_request, sockfd, (struct sockaddr*)&addr_client);

	}

	return 0;
}

/*
**************************************************
*用于从得到的字符串取出要获得文件名
**************************************************
*/
void get_filename(char buf_filename[], char buf_request[])
{
	char root_directory[] = "./file_read";
	char *p1 = strstr(buf_request, " ");
	char *p2 = strchr(++p1, '\0');
	int len = p2 - p1;
	memcpy(buf_filename, root_directory, strlen(root_directory));
	memcpy(buf_filename + strlen(root_directory), p1, len);
}

/*
**************************************************
*在满足条件下创建一个新的线程进行发送数据操作
**************************************************
*/
void create_thread(FILE *fp, int sockfd, struct sockaddr *addr_client)
{

	pthread_t pt;
	paras_t *ps = (paras_t *)malloc(sizeof(paras_t));
	ps->fp = fp;
	ps->sockfd = sockfd;
	ps->addr_client = addr_client;
	pthread_create(&pt, NULL, (void *)thread_send, (void *)ps);
	pthread_detach(pt); /*分离线程*/
}

/*
**************************************************
*处理来自客户端的请求
**************************************************
*/
void deal_request(char buf_request[], int sockfd, struct sockaddr *addr_client)
{
	if (!memcmp(buf_request, "GET", 3))
	{
		if (Send_State)/*当前能够进行文件的发送*/
		{
			char buf_filename[32] = {0};
			get_filename(buf_filename, buf_request);
			FILE *fp;
			if ((fp = fopen(buf_filename, "rb")) == NULL)
			{
				printf("fopen error!!!\n");
				return;
			}

			create_thread(fp, sockfd, addr_client);
			create_thread(fp, sockfd, addr_client);
			create_thread(fp, sockfd, addr_client);
			Send_State = 0;
		}
	}
	else
	{
		int i = 0;
		//for (;i < MAX_SIZE;i++)
		{
			//if (!(Packet_State[i].pt))
				//break;
			int number1 = (Packet_State[i].pt)->number;
			char buf[8] = {0};
			memcpy(buf, buf_request + 4, 5);
			int number2;
			sscanf(buf, "%d", &number2);
			if (number1 == number2)
			{
				if (!memcmp(buf_request, "ACK", 3))
				{
					printf("the %d block has been sended successfully!!!\n", number1);
					//free(Packet_State[i].pt);
					//memset(&Packet_State[i], '\0', sizeof(PCB_t));
					Packet_State[i].state = 1;
				}
				else if (!memcmp(buf_request, "ERROR", 5))
				{
					Packet_State[i].count = 0;
					Packet_State[i].start = 0;
				}
				//break;
			}
		}
	}
}

/*
**************************************************
*线程函数，主要用于数据的发送
**************************************************
*/
void thread_send(void *ps)
{
	FILE *fp = ((paras_t*)ps)->fp;
	int sockfd = ((paras_t*)ps)->sockfd;
	struct sockaddr addr_client = *(((paras_t*)ps)->addr_client);
	free(ps); /*释放内存*/
	while (1)
	{
		int i = 0;
		int count = 0;
		int state = 1; /*判断是否读到文件末尾*/
		static int next_packet = 0; /*记录当前块中最大的编号*/
		for (;i < MAX_SIZE;i++)
		{
			if (Packet_State[i].state)
			{
				free(Packet_State[i].pt);
				Packet_State[i].pt = NULL;
			}
			if (!Packet_State[i].pt)
			{
				if (feof(fp))
				{
					count++;
					if (count == MAX_SIZE)
					{
						Send_State = 1;
						return;
					}
					continue;
				}

				packet_t *pt = (packet_t *)malloc(sizeof(packet_t));
				pt->number = next_packet;
				int len = fread(pt->buffer, 1, PACKET_SIZE, fp);
				pt->length = len;
				Packet_State[i].pt = pt;
				Packet_State[i].count = 0;
				Packet_State[i].start = 0;
				Packet_State[i].state = 0;
				next_packet++;
			}

			if (Packet_State[i].count > 10)
			{
				printf("net error!!!\n");
				return;
			}
			int start = Packet_State[i].start;
			if (start == 0 || time(NULL) - start > 1)
			{
				printf("the %d block has been sended!!!", (Packet_State[i].pt)->number);
				int length = sendto(sockfd, Packet_State[i].pt, (Packet_State[i].pt)->length + 8, 0,
				                    &addr_client, sizeof(struct sockaddr));
				Packet_State[i].start = time(NULL);
				Packet_State[i].count++;
				printf("the length is %d!!!\n\n", length - 8);
			}
		}
	}
}