刚学习socket编程，写了一个下载文件的小程序，写的不好大家不要吐槽。

客户端：

#include<stdio.h>
#include<stdlib.h>
#include<arpa/inet.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<string.h>
#include<unistd.h>
#define BUFF_SIZE 100
int main(int argv,char *args[]){
    int servsock;
    struct sockaddr_in servaddr;
    if(argv!=3){
        printf("Usage:%s <ip><port>",args[0]);
        exit(1);
    }
    servsock = socket(PF_INET,SOCK_STREAM,0);
    if(servsock == -1)
    {
        printf("socket() error\n");
        exit(1);
    }
    memset(&servaddr,0,sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = inet_addr(args[1]);
    servaddr.sin_port = htons(atoi(args[2]));
    if(connect(servsock,(struct sockaddr*)&servaddr,sizeof(servaddr)) ==-1)
    {
        printf("connect() error\n");
        exit(1);
    }else{
        printf("connected.....\n");
    }
    printf("please input filename:");
    char filename[BUFF_SIZE];
    memset(filename,0,sizeof(char)*BUFF_SIZE);
    scanf("%s",filename);
    write(servsock,filename,strlen(filename));
    int successFlag;
    read(servsock,&successFlag,sizeof(successFlag));
    if(successFlag!=1){
        printf("input file is not existed!\n successFlag is %d\n",successFlag);
        exit(1);
    }else{
        FILE *fp = fopen(filename,"w");
        while(1){
            memset(filename,0,BUFF_SIZE);
            int revlen = read(servsock,filename,BUFF_SIZE);
            if(revlen ==0)
                break;
            fputs(filename,fp);
        }
        fclose(fp);
        printf("complete!\n");
    }
    close(servsock);
    return 0;
}

服务器：

#include<stdio.h>
#include<stdlib.h>
#include<arpa/inet.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<string.h>
#include<unistd.h>
#define BUFF_SIZE 100
int main(int argv,char *args[]){
    int servsock,clntsock;
    struct sockaddr_in servaddr,clntaddr;
    if(argv!=2){
        printf("Usage:%s <port>",args[0]);
        exit(1);
    }
    servsock = socket(PF_INET,SOCK_STREAM,0);
    memset(&servaddr,0,sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(atoi(args[1]));
    if(bind(servsock,(struct sockaddr*)&servaddr,sizeof(servaddr)) ==-1)
    {
        printf("bind() error\n");
        exit(1);
    }
    if(listen(servsock,5) ==-1)
    {
        printf("listen() error\n");
        exit(1);
    }
    socklen_t len = sizeof(clntaddr);
    clntsock = accept(servsock,(struct sockaddr*)&clntaddr,&len);
    char filename[BUFF_SIZE];
    int msglen=read(clntsock,filename,BUFF_SIZE);
    filename[msglen]=0;
    printf("receiver filename is: %s\n",filename);
    FILE *fp = fopen(filename,"r");
    int successFlag = 0;
    if(fp)
        successFlag = 1;
    write(clntsock,&successFlag,sizeof(successFlag));
    if(fp == NULL){
        printf("NULL\n");
        close(clntsock);
        close(servsock);
        return 0;
    }
    while(fgets(filename,BUFF_SIZE,fp)!=NULL){
        int ll = strlen(filename);
        printf("length:%d content:%s",ll,filename);
        write(clntsock,filename,strlen(filename));
    }
    fclose(fp);
    close(clntsock);
    close(servsock);
    return 0;
}