Linux网络编程之使用UDP传输文件

                Linux网络编程之使用UDP传输文件
    本文转载自http://blog.csdn.net/gqb_driver/article/details/8970207 作者:gqb666

    最近在写Linux网络方面的demo,用UDP实现了一个简单的传输文件程序，适用于网卡设备及TCP/IP协议栈及网络环境测试时使用。当然这里要说的是，一般通过网络传输文件不会选择UDP协议，因为UPD提供不可靠的传输，文件传输过程中会出现丢包现象而导致文件传输错误。这里要实现UDP传输文件的目的是为了测试网卡的丢包率，然后与正常网络的丢包率进行比较，从而可以检验网卡及网络环境的质量。本文仅将其雏形写出。其功能是使用UDP协议从client端向server端传输文件，用法如下:

     编译：

           client:gcc -o client client.c

           server:gcc -o server server.c

     运行：

           client端：./client <端口号> <上传文件名>

           server端：./server <端口号> <保存为文件名>

其中，server端先运行，client端与server端的端口号必须一致并且不能与已知端口冲突（例如8888即可）

下面将代码贴上：

server端代码:server.c

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

#define    FINISH_FLAG "FILE_TRANSPORT_FINISH"
#define    MAXLINE        1024

void usage(char *command)
{
    printf("usage :%s portnum filename\n", command);
    exit(0);
}
int main(int argc,char **argv)
{
    struct sockaddr_in     serv_addr;
    struct sockaddr_in     clie_addr;
    char                   buf[MAXLINE];
    int sock_id;
    int recv_len;
    int clie_addr_len;
    FILE *fp;

    if (argc != 3) {
        usage(argv[0]);
    }
    /* Create the the file commented by guoqingbo*/
    if ((fp = fopen(argv[2], "w")) == NULL) {
        perror("Creat file failed");
        exit(0);
    }
    if ((sock_id = socket(AF_INET,SOCK_DGRAM,0)) < 0) {
        perror("Create socket failed\n");
        exit(0);
    }
    /*fill the server sockaddr_in struct commented by guoqingbo*/
    memset(&serv_addr,0,sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(atoi(argv[1]));
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);

    if (bind(sock_id,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0 ) {
        perror("Bind socket faild\n");
        exit(0);
    }
    /* server part commented by guoqingbo*/
    clie_addr_len = sizeof(clie_addr);
    bzero(buf, MAXLINE);
    while (recv_len = recvfrom(sock_id, buf, MAXLINE, 0,(struct sockaddr *)&clie_addr, &clie_addr_len)) {
        if(recv_len < 0) {
            printf("Recieve data from client failed!\n");
            break;
        }
        printf("#");
        if ( strstr(buf, FINISH_FLAG) != NULL ) {
            printf("\nFinish receiver finish_flag\n");
            break;
        }
        int write_length = fwrite(buf, sizeof(char), recv_len, fp);
        if (write_length < recv_len) {
            printf("File write failed\n");
            break;
        }
        bzero(buf, MAXLINE);
    }

    printf("Finish recieve\n");
    fclose(fp);
    close(sock_id);
    return 0;
}

client端代码:client.c

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

#define    FINISH_FLAG "FILE_TRANSPORT_FINISH"
#define    MAXLINE        1024

void usage(char *command)
{
    printf("usage :%s ipaddr portnum filename\n", command);
    exit(0);
}
int main(int argc,char **argv)
{
    FILE *fp;
    struct sockaddr_in     serv_addr;
    char                   buf[MAXLINE];
    int sock_id;
    int read_len;
    int send_len;
    int serv_addr_len;
    int i_ret;
    int i;

    if (argc != 4) {
        usage(argv[0]);
    }
    /* open the file to be transported commanted by guoqingbo*/
    if ((fp = fopen(argv[3],"r")) == NULL) {
        perror("Open file failed\n");
        exit(0);
    }
    /* create the socket commanted by guoqingbo*/
    if ((sock_id = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
        perror("Create socket failed");
        exit(0);
    }
    memset(&serv_addr,0,sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(atoi(argv[2]));
    inet_pton(AF_INET, argv[1], &serv_addr.sin_addr);
    serv_addr_len = sizeof(serv_addr);
    /* connect the server commanted by guoqingbo*/
    i_ret = connect(sock_id, (struct sockaddr *)&serv_addr, sizeof(struct sockaddr));
    if (-1 == i_ret) {
        perror("Connect socket failed!\n");
        exit(0);
    }
    /* transport the file commented by guoqingbo*/
    bzero(buf, MAXLINE);
    while ( (read_len = fread(buf, sizeof(char), MAXLINE, fp)) > 0 ) {
        send_len = send(sock_id, buf, read_len, 0);
        if ( send_len < 0 ) {
            perror("Send data failed\n");
            exit(0);
        }
        bzero(buf, MAXLINE);
    }
    fclose(fp);
    /* send the end_flag commented by guoqingbo*/
    bzero(buf, MAXLINE);
    strcpy(buf, FINISH_FLAG);
    buf[strlen(buf)] = '\0';
    for (i = 1000; i>0; i--) {
        send_len = send(sock_id, buf, strlen(buf)+1, 0);
        if ( send_len < 0 ) {
            printf("Finish send the end string\n");
            break;
        }
    }
    close(sock_id);
    printf("Send finish\n");
    return 0;
}