第46天-UDP协议的网络程序（2013.09.22）

　　1.并发服务器与客户端 （UDP）

//client.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <netinet/in.h>
#include <fcntl.h>

#define MAX 10
#define MAXLINE 18
#define SERV_PORT 8000

int main(int argc, char *argv[])
{
    struct sockaddr_in servaddr;
    int sockfd = 0, n = 0, number = 0;
    char buf[MAXLINE] = {0};
    char str[INET_ADDRSTRLEN] = {0};
    char find[MAXLINE] = {0};
    socklen_t servaddr_len;
    int len = 0, fr = 0, fw = 0, data_len = 0, read_len = 0;

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    inet_pton(AF_INET, argv[1], &servaddr.sin_addr);
    servaddr.sin_port = htons(SERV_PORT);

    while((fgets(buf, MAXLINE, stdin) != NULL))
    {
        if('
' == buf[strlen(buf) - 1]) {
            buf[strlen(buf) - 1] = '';
        }

        int fr = open(buf, O_RDONLY);
        bzero(find, sizeof(find));
        len = strlen(buf);
        number = -1;
        //*((int *)(find + 0)) = number;
        memcpy(find, &number, 4);
        memcpy(&find[4], &len, 4);
        memcpy(&find[8], buf, len);
        n = sendto(sockfd, find, MAXLINE, 0, (struct sockaddr *)&servaddr, sizeof(servaddr));
        if(-1 == n) {
            perror("sendto");
            exit(1);
        }
        int i = 0;
        for(i = 0; i != MAXLINE; i ++)
        {
            printf("%x", find[i]);
        }
        printf("
");

        n = recvfrom(sockfd, &fw, 4, 0, NULL, 0);
        printf("fw = %d
", fw);
        //---------------------------------------------------------
        data_len = lseek(fr, 0, SEEK_END);
        lseek(fr, 0, SEEK_SET);
        printf("data_len = %d
", data_len);
        //==========================================================
        while(data_len > 0)
        {
            bzero(find, sizeof(find));
            //bzero(buf, sizeof(buf));
            //memcpy(find, &fr, 4);
            *((int *)(find)) = fw;
            if(data_len < MAX) {
                read_len = read(fr, buf, data_len);
                //memcpy(&find[4], &read_len, 4);
                *((int *)(find + 4)) = read_len;
                memcpy(&find[8], buf, read_len);
            }
            else {
                read_len = read(fr, buf, MAX);
                //memcpy(&find[4], (char *)MAX, 4);
                *((int *)(find + 4)) = MAX;
                memcpy(&find[8], buf, MAX);
            }
            printf("read_len = %d
", read_len);
            printf("%s
", &find[8]);
            n = sendto(sockfd, find, MAXLINE, 0, (struct sockaddr *)&servaddr, sizeof(servaddr));
            data_len -= read_len;
            printf("%d = data_len
", data_len);
        }
        //===============================================================
        bzero(find, sizeof(find));
        *((int *)(find)) = fw;
        n = sendto(sockfd, find, MAXLINE, 0, (struct sockaddr *)&servaddr, sizeof(servaddr));
        //======================================================================================
        bzero(buf, sizeof(buf));
        close(fr);
#if 0
        n = recvfrom(sockfd, find, MAXLINE, 0, NULL, 0);
        if(-1 == n) {
            perror("recvform error");
            exit(1);
        }
        write(STDOUT_FILENO, find, n);
#endif
    }

    close(sockfd);

    return 0;
}

//server.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <netinet/in.h>

#define MAX 10
#define MAXLINE 18
#define SERV_PORT 8000

int main(int argc, char *argv[])
{
    struct sockaddr_in servaddr, cliaddr;
    socklen_t cliaddr_len;
    int sockfd = 0;
    char buf[MAXLINE] = {0};
    char itemp[MAXLINE] = {0};
    char filename[MAX] = {0};
    char str[INET_ADDRSTRLEN] = {0};
    int i = 0, n = 0, file_len = 0, data_len = 0, fw = 0, write_len = 0, f_get = 0;

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(SERV_PORT);

    bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));

    printf("Accepting connections ...
");
    cliaddr_len = sizeof(cliaddr);

    while(1)
    {
        //--------------------------------------------------
        bzero(buf, sizeof(buf));
        n = recvfrom(sockfd, buf, MAXLINE, 0, (struct sockaddr *)&cliaddr, &cliaddr_len);
        printf("received from %s at PORT %d
", (char *)inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)), ntohs(cliaddr.sin_port));
        if(-1 == n) {
            perror("recvfrom error");
            exit(1);
        }
        f_get = *((int *)(buf)); 
        printf("fw == %d
", f_get);
        if(-1 == f_get) {
            memcpy(&file_len, &buf[4], 4);
            printf("filename_len = %d
", file_len);
            memcpy(filename, &buf[8], file_len);
            printf("filename = %s
", filename);
            fw = open(filename, O_WRONLY | O_TRUNC | O_CREAT, 0644);
            if(fw < 0) {
                perror("open fw");
                exit(1);
            } 
            n = sendto(sockfd, &fw, 4, 0, (struct sockaddr *)&cliaddr, sizeof(cliaddr));
        }
        else if(f_get == fw){
            write_len = *((int *)(buf + 4));
            printf("%d
", write_len);
            if(0 == write_len) {
                close(f_get);
            }
            else {
                write(f_get, &buf[8], write_len);
            }
        }
        bzero(filename, sizeof(filename));
        bzero(buf, sizeof(buf));
    }

    return 0;
}

 　　2.函数原型 ： #include <sys/socket.h>　　#include <sys/types.h>

　　　　　　　　ssize_t sendto(int sockfd, const void *buf, size_t len, int flags, const struct sockaddr *dest_addr, socklen_t addrlen);　　//发送数据报

　　　　　　　　ssize_t recvfrom(int sockfd, void *buf, size_t len, int flags, struct sockaddr *src_addr, socklen_t *addrlen);　　　　//接受数据报