客户端程序：client.c

include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <signal.h>
#include <ctype.h>
#include <arpa/inet.h>
#include <netdb.h>

#define PORT 20002
#define LENGTH 1024 

void error(const char *msg)
{
        perror(msg);
        exit(1);
}

int main(int argc, char *argv[])
{
        int sockfd; 
        int nsockfd;
        char revbuf[LENGTH]; 
        struct sockaddr_in remote_addr;

        if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
        {
            error("ERROR: Failed to obtain Socket Descriptor!\n");
        }

        remote_addr.sin_family = AF_INET; 
        remote_addr.sin_port = htons(PORT);  
        inet_pton(AF_INET, "127.0.0.1", &remote_addr.sin_addr);
        bzero(&(remote_addr.sin_zero), 8);

        if (connect(sockfd, (struct sockaddr *)&remote_addr, sizeof(struct sockaddr)) == -1)
        {
            error("ERROR: Failed to connect to the host!\n");
        }
        else 
            printf("[Client] Connected to server at port %d...ok!\n", PORT);

        //需要上传的文件路径及名称
        char* fs_name = "/home/lyn/aaa.jpg";
        char sdbuf[LENGTH]; 
        printf("[Client] Sending %s to the Server...", fs_name);
        FILE *fs = fopen(fs_name, "rb");
        if(fs == NULL)
        {
            printf("ERROR: File %s not found.\n", fs_name);
            exit(1);
        }

        bzero(sdbuf, LENGTH);
        int fs_block_sz;
        while((fs_block_sz = fread(sdbuf, sizeof(char), LENGTH, fs))>0)
        {
            if(send(sockfd, sdbuf, fs_block_sz, 0) < 0)
            {
                printf("ERROR: Failed to send file %s.\n", fs_name);
                break;
            }
            bzero(sdbuf, LENGTH);
        }
        printf("Ok File %s from Client was Sent!\n", fs_name);
        close (sockfd);
        printf("[Client] Connection lost.\n");
        return (0);
}

服务端程序：server.c

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <signal.h>
#include <ctype.h>          
#include <arpa/inet.h>
#include <netdb.h>

#define PORT 20002 
#define BACKLOG 5
#define LENGTH 512

void error(const char *msg)
{
	perror(msg);
	exit(1);
}

int main ()
{
	int sockfd; 
	int nsockfd; 
	int num;
	int sin_size; 
	struct sockaddr_in addr_local; 
	struct sockaddr_in addr_remote; 
	char revbuf[LENGTH]; 

	if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1 )
	{
	    error("ERROR: Failed to obtain Socket Descriptor.\n");
	}
	else 
		printf("[Server] Obtaining socket descriptor successfully.\n");

	addr_local.sin_family = AF_INET;
	addr_local.sin_port = htons(PORT); 
	addr_local.sin_addr.s_addr = INADDR_ANY; 
	bzero(&(addr_local.sin_zero), 8); 

	if( bind(sockfd, (struct sockaddr*)&addr_local, sizeof(struct sockaddr)) == -1 )
	{
	    error("ERROR: Failed to bind Port.\n");
	}
	else 
		printf("[Server] Binded tcp port %d in addr 192.168.11.139 sucessfully.\n",PORT);

	if(listen(sockfd,BACKLOG) == -1)
	{
	    error("ERROR: Failed to listen Port.\n");
	}
	else
		printf ("[Server] Listening the port %d successfully.\n", PORT);

	int success = 0;
	while(success == 0)
	{
	    sin_size = sizeof(struct sockaddr_in);

	    if ((nsockfd = accept(sockfd, (struct sockaddr *)&addr_remote, &sin_size)) == -1) 
		{
	        error("ERROR: Obtaining new Socket Despcritor.\n");
		}
	    else 
			printf("[Server] Server has got connected from %s.\n", inet_ntoa(addr_remote.sin_addr));

        //要上传到服务器的位置
		char* fr_name = "../image/aa.jpg";
		FILE *fr = fopen(fr_name, "wb");
		if(fr == NULL)
			printf("File %s Cannot be opened file on server.\n", fr_name);
		else
		{
			bzero(revbuf, LENGTH); 
			int fr_block_sz = 0;
			while(fr_block_sz = recv(nsockfd, revbuf, LENGTH, 0)) 
			{
			    if(fr_block_sz < 0)
			    {
			        error("Error receiving file from client to server.\n");
			    }
			    int write_sz = fwrite(revbuf, sizeof(char), fr_block_sz, fr);
			    if(write_sz < fr_block_sz)
			    {
			        error("File write failed on server.\n");
			    }
			    else if(fr_block_sz == -1)//如果不判断==-1的话只能写512个字节哦～
			    {
				break;
			    }
			    bzero(revbuf, LENGTH);
			}
			printf("Ok received from client!\n");
			fclose(fr);
		}

                close(nsockfd);
	        printf("[Server] Connection with Client closed. Server will wait now...\n");
	        while(waitpid(-1, NULL, WNOHANG) > 0);
	}
}