基于C语言实现HTTP POST 表单形式上传文件

- 日理万妓 2023-06-15 11:29 8阅读 0赞

2018-12-03 23:14:18 [fangye945a][] 阅读数 3028更多

分类专栏： [C语言学习][C] [Http学习][Http]

本文链接：[https://blog.csdn.net/fangye945a/article/details/84780904][https_blog.csdn.net_fangye945a_article_details_84780904]

最近在C语言项目开发中，需要用到了http上传文件，又不想用curl库，于是打算基于socket用C语言实现，也正好研究一波表单上传形式。

1、首先写一个上传文件html文件: **file.html**

<!DOCTYPE>
    <html>
      <head>
        <meta charset="utf-8">
        <title>File upload</title>
      </head>
      <body>
        <div>
          <form role="form" action="http://test.inteink.com/Server/interface_picture_upload.action?appid=wmj_BZ2WeU7K1iP&appsecret=MXkMcT43JsIgAwBwVJ30EbA2ovIcpfCQ&sn=T1868881608",
                method="POST" enctype="multipart/form-data">
    			
                
                <input type="file" name="file" multiple>
                <button type="submit">Upload</button>
          </form>
        </div>
      </body>
    </html>

2、用火狐浏览器打开这个文件，选择一张图片点击传，并抓包,  如下所示。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Zhbmd5ZTk0NWE_size_16_color_FFFFFF_t_70][]

OK，把头信息照抄一遍，头里面有些信息可以不要，也能上传成功，自己慢慢去尝试。

然后，再看一下参数项的请求负载。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Zhbmd5ZTk0NWE_size_16_color_FFFFFF_t_70 1][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Zhbmd5ZTk0NWE_size_16_color_FFFFFF_t_70 2][]

简单分析下，发现请求负载中出现了几次 -----------------------------5907704431277628128378170588--，查询相关资料得知这是表单分隔符，可以自己定义。然后发现中间出现了一大串乱码，毫无疑问，这一定就是我们上传的文件内容了。按照这个思路，再计算一下Content-Length 的大小，定义一个足够大得buffer，将文件数据按这种形式放入buffer，写入套接字中即可。

因为http一般都会有回复信息，所以将数据写入完成后，立即读取套接字，将回复的信息保存至buffer中进行分析。

如下为自己写的代码以供大家参考：

**http\_post.c**

#include <stdlib.h>  
    #include <sys/types.h>  
    #include <stdio.h>  
    #include <sys/socket.h>  
    #include <netinet/in.h>  
    #include <string.h>  
    #include <sys/stat.h>  
    #include "post.h"
     
     
    unsigned char header[1024]={0}; 
    unsigned char send_request[1024]={0};
    unsigned char send_end[1024]={0};
    unsigned char http_boundary[64]={0};
      
    unsigned long get_file_size(const char *path)  //获取文件大小
    {    
        unsigned long filesize = -1;        
        struct stat statbuff;    
        if(stat(path, &statbuff) < 0){    
            return filesize;    
        }else{    
            filesize = statbuff.st_size;    
        }    
        return filesize;    
    }   
     
    int http_post_upload_pic(const unsigned char *IP, const unsigned int port,char *URL, const char *filepath,
    									char *ack_json, int ack_len) //Post方式上传图片
    {
    	int cfd = -1;
        int recbytes = -1;
        int sin_size = -1;
    	char buffer[1024*10]={0};     
        struct sockaddr_in s_add,c_add;
    	
    	cfd = socket(AF_INET, SOCK_STREAM, 0);  //创建socket套接字
        if(-1 == cfd)  
        {  
            printf("socket fail ! \r\n");  
            return -1;  
        }
    	
    	bzero(&s_add,sizeof(struct sockaddr_in));  
        s_add.sin_family=AF_INET; //IPV4
        s_add.sin_addr.s_addr= inet_addr(IP);  
        s_add.sin_port=htons(port);
        printf("s_addr = %#x ,port : %#x\r\n",s_add.sin_addr.s_addr,s_add.sin_port);
     
    	if(-1 == connect(cfd,(struct sockaddr *)(&s_add), sizeof(struct sockaddr)))  //建立TCP连接
        {  
            printf("connect fail !\r\n");  
            return -1;  
        }
     
    	//获取毫秒级的时间戳用于boundary的值
    	long long int timestamp;
    	struct timeval tv;
    	gettimeofday(&tv,NULL);
    	timestamp = (long long int)tv.tv_sec * 1000 + tv.tv_usec;
    	snprintf(http_boundary,64,"---------------------------%lld",timestamp);
    	
    	unsigned long totalsize = 0;
    	unsigned long filesize = get_file_size(filepath); //文件大小
    	unsigned long request_len = snprintf(send_request,1024,UPLOAD_REQUEST,http_boundary,filepath); //请求信息
    	unsigned long end_len = snprintf(send_end,1024,"\r\n--%s--\r\n",http_boundary); //结束信息
    	totalsize = filesize + request_len + end_len;
     
    	unsigned long head_len = snprintf(header,1024,HTTP_HEAD,SERVER_PATH,URL,http_boundary,totalsize); //头信息
    	totalsize += head_len;
     
        char* request = (char*)malloc(totalsize);	//申请内存用于存放要发送的数据
        if (request == NULL){  
            printf("malloc request fail !\r\n");  
            return -1;  
        }  
        request[0] = '\0';
     
    	/******* 拼接http字节流信息 *********/	
        strcat(request,header);  									//http头信息
        strcat(request,send_request);    							//文件图片请求信息
    	FILE* fp = fopen(filepath, "rb+");							//打开要上传的图片
        if (fp == NULL){  
            printf("open file fail!\r\n");  
            return -1;  
        }
    	int readbyte = fread(request+head_len+request_len, 1, filesize, fp);//读取上传的图片信息
        if(readbyte < 1024) //小于1024个字节 则认为图片有问题
    	{
    		printf("Read picture data fail!\r\n");  
            return -1;
    	}
        memcpy(request+head_len+request_len+filesize,send_end,end_len);  //http结束信息
     
    	/*********  发送http 请求 ***********/
    	if(-1 == write(cfd,request,totalsize)) 					
        {  
            printf("send http package fail!\r\n");  
            return -1;  
        }
     
    	/*********  接受http post 回复的json信息 ***********/
    	if(-1 == (recbytes = read(cfd,buffer,10240)))  
        {  
            printf("read http ACK fail !\r\n");  
            return -1;  
        }  
       	buffer[recbytes]='\0';
    	int index = 0,start_flag = 0;
    	int ack_json_len = 0;
    	for(index = 0; index<recbytes; index++)
    	{
    		if(buffer[index] == '{')
    		{
    			start_flag = 1;
    		}
    		if(start_flag)
    			ack_json[ack_json_len++] = buffer[index];  //遇到左大括号则开始拷贝
     
    		if(buffer[index] == '}')		//遇到右大括号则停止拷贝
    		{
    			ack_json[ack_json_len] = '\0';
    			break;
    		}
    	}
    	if(ack_json_len > 0 && ack_json[ack_json_len-1] == '}')  //遇到花括号且有json字符串
    	{
    		printf("Receive:%s\n",ack_json);
    	}
    	else
    	{
    		ack_json[0] = '\0';
    		printf("Receive http ACK fail!!\n");
    		printf("--- ack_json_len = %d\n",ack_json_len);
    	}
    	
        free(request);  
        fclose(fp);  
        close(cfd);
    	return 0;
    }
     
    int main(int argc, char *argv[])  
    {  
    	int ack_len = 256;
    	char ack_json[256]={0};
    	int ret = http_post_upload_pic(SERVER_ADDR, SERVER_PORT,SERVER_URL,argv[1],ack_json,ack_len); //Post方式上传图片
    	if(ret == -1)
    	{
    		printf("\n\n----------- Post picture Fail!!\n");
    	}
    	return 0;  
    }

**http\_post.h**

#ifndef __HTTP_POST__
    #define __HTTP_POST__
     
    #define SERVER_ADDR	"47.97.190.1"
    #define SERVER_PORT	80
    #define SERVER_URL	"test.inteink.com"
    #define SERVER_PATH	"/Server/interface_picture_upload.action?appid=wmj_BZ2WeU7K1iP&appsecret=MXkMcT43JsIgAwBwVJ30EbA2ovIcpfCQ&sn=T1868881608"
     
    #define HTTP_HEAD 	"POST %s HTTP/1.1\r\n"\
    					"Host: %s\r\n"\
    					"User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:59.0) Gecko/20100101 Firefox/59.0\r\n"\
    					"Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n"\
    					"Accept-Language: en-US,en;q=0.5\r\n"\
    					"Accept-Encoding: gzip, deflate\r\n"\
    					"Content-Type: multipart/form-data; boundary=%s\r\n"\
    					"Content-Length: %ld\r\n"\
    					"Connection: close\r\n"\
    					"Upgrade-Insecure-Requests: 1\r\n"\
    					"DNT: 1\r\n\r\n"\
    					
    					
    #define UPLOAD_REQUEST	"--%s\r\n"\
    						"Content-Disposition: form-data; name=\"file\"; filename=\"%s\"\r\n"\
    						"Content-Type: image/jpeg\r\n\r\n"
    						
    unsigned long get_file_size(const char *path);
     
    int http_post_upload_pic(const unsigned char *IP, const unsigned int port,char *URL, const char *filepath,
    									char *ack_json, int ack_len); //Post方式上传图片
     
    #endif

[fangye945a]: https://me.csdn.net/fangye945a
[C]: https://blog.csdn.net/fangye945a/article/category/7683726
[Http]: https://blog.csdn.net/fangye945a/article/category/7683743
[CC 4.0 BY-SA]: http://creativecommons.org/licenses/by-sa/4.0/
[https_blog.csdn.net_fangye945a_article_details_84780904]: https://blog.csdn.net/fangye945a/article/details/84780904
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