感觉webclient里的webclient_file存在内存泄漏

发布于 2019-10-31 17:35:49 浏览：1947 订阅该版

之前用webclient-master时候遇到过内存泄漏，现在整理工程改成固定版本webclient-v2.1.0，感觉还是有泄漏现象，官方代码库更新一下把Bug去掉吧！

2019.07月份的笔记
——————————————————————————————————
貌似存在内存泄漏
```
msh />free
total memory: 56464
used memory : 27472
maximum allocated memory: 30840
msh />web_post_file_test
[D/web] host address: 192.168.137.1 , port: 880
[D/web] request header:
[D/web] GET /web_upload/ HTTP/1.1
[D/web] Host: 192.168.137.1
[D/web] User-Agent: RT-Thread HTTP Agent

msh />free
total memory: 56464
used memory : 31580
maximum allocated memory: 49408
msh />web_post_file_test
[D/web] host address: 192.168.137.1 , port: 880
[D/web] request header:
[D/web] GET /web_upload/ HTTP/1.1
[D/web] Host: 192.168.137.1
[D/web] User-Agent: RT-Thread HTTP Agent

msh />free
total memory: 56464
used memory : 35688
maximum allocated memory: 53516
msh />web_post_file_test
[D/web] host address: 192.168.137.1 , port: 880
[D/web] request header:
[D/web] GET /web_upload/ HTTP/1.1
[D/web] Host: 192.168.137.1
[D/web] User-Agent: RT-Thread HTTP Agent

[E/at.skt] no memory for esp8266 device(esp0) URC receive buffer(2920).
msh />
```

首先是发现 webclient_post_file 中在初始化 `session->header` 时没有处理 `session->header->length`
```c
//int webclient_post_file(const char* URI, const char* filename, const char* form_data)
session->header->buffer = web_strdup(header);//附近没有session->header->length有关的代码
```
之后发现 `session->header->buffer = web_strdup(header); `语句貌似很危险
尝试按`web_post_test`调用的`webclient_post_comm`的方式初始化header
解决了之前怀疑的内存泄漏的问题
接下来比较Fiddler向MVC发的File抓包，发现`“Content-Length:”`是在`“boundary”`里面的，遂改之

```c
/**
 * post file to http server.
 *
 * @param URI input server address
 * @param filename post data filename
 * @param form_data form data
 *
 * @return <0: POST request failed
 * =0: success
 */
#define webclient_post_file_backup (0)
int webclient_post_file(const char* URI, const char* filename,
 const char* form_data)
{
 size_t length;
 char boundary[60];
 int fd = -1, rc = WEBCLIENT_OK;
 unsigned char *buffer = RT_NULL, *buffer_ptr;
 struct webclient_session* session = RT_NULL;

fd = open(filename, O_RDONLY, 0);
 if (fd < 0)
 {
 LOG_D("post file failed, open file(%s) error.", filename);
 rc = -WEBCLIENT_FILE_ERROR;
 goto __exit;
 }

/* get the size of file */
    length = lseek(fd, 0, SEEK_END);
    lseek(fd, 0, SEEK_SET);

buffer = (unsigned char *) web_malloc(WEBCLIENT_RESPONSE_BUFSZ);
    if (buffer == RT_NULL)
    {
        LOG_D("post file failed, no memory for response buffer.");
        rc = -WEBCLIENT_NOMEM;
        goto __exit;
    }

#if webclient_post_file_backup
    char *header = RT_NULL;
    header = (char *) web_malloc(WEBCLIENT_HEADER_BUFSZ);
    if (header == RT_NULL)
    {
        LOG_D("post file failed, no memory for header buffer.");
        rc = -WEBCLIENT_NOMEM;
        goto __exit;
    }
    rt_memset(header,0,WEBCLIENT_HEADER_BUFSZ);
    #endif

/* build boundary */
    rt_snprintf(boundary, sizeof(boundary), "----------------------------%012d", rt_tick_get());

/* build encapsulated mime_multipart information*/
 buffer_ptr = buffer;
 /* first boundary */
 buffer_ptr += rt_snprintf((char*) buffer_ptr,
 WEBCLIENT_RESPONSE_BUFSZ - (buffer_ptr - buffer), "--%s ", boundary);
 buffer_ptr += rt_snprintf((char*) buffer_ptr,
 WEBCLIENT_RESPONSE_BUFSZ - (buffer_ptr - buffer),
 "Content-Disposition: form-data; %s ", form_data);
 buffer_ptr += rt_snprintf((char*) buffer_ptr,
 WEBCLIENT_RESPONSE_BUFSZ - (buffer_ptr - buffer),
 //"Content-Type: application/octet-stream ");
 "Content-Type: image/jpeg ");
 /* calculate content-length */
 length += buffer_ptr - buffer;
 length += rt_strlen(boundary) + 6; /* add the last boundary */

#if webclient_post_file_backup
 /* build header for upload */
 char *header_ptr;
 header_ptr = header;
 header_ptr += rt_snprintf(header_ptr,
 WEBCLIENT_HEADER_BUFSZ - (header_ptr - header),
 "Content-Length: %d ", length);
 header_ptr += rt_snprintf(header_ptr,
 WEBCLIENT_HEADER_BUFSZ - (header_ptr - header),
 "Content-Type: multipart/form-data; boundary=%s ", boundary);

session = webclient_session_create(WEBCLIENT_HEADER_BUFSZ);
    if(session == RT_NULL)
    {
        rc = -WEBCLIENT_NOMEM;
        goto __exit;
    }

session->header->buffer = web_strdup(header);
 //session->header->length = (size_t)(-1);
 #else
 /* build header for upload */
 session = webclient_session_create(WEBCLIENT_HEADER_BUFSZ);
 if(session == RT_NULL)
 {
 rc = -WEBCLIENT_NOMEM;
 goto __exit;
 }
 //session->header->buffer = web_strdup(header);
 //调整"Content-Length:"到boundary内部
 webclient_header_fields_add(session, "Content-Type: multipart/form-data; boundary=%s ", boundary);
 webclient_header_fields_add(session, "Content-Length: %d ", length);
 #endif
 
 rc = webclient_post(session, URI, NULL);
 rt_thread_mdelay(100);
 if( rc< 0)
 {
 goto __exit;
 }

/* send mime_multipart */
    webclient_write(session, buffer, buffer_ptr - buffer);
    rt_thread_mdelay(100);

/* send file data */
 while (1)
 {
 length = read(fd, buffer, WEBCLIENT_RESPONSE_BUFSZ);
 if (length <= 0)
 {
 break;
 }

webclient_write(session, buffer, length);
        rt_thread_mdelay(100);
    }

/* send last boundary */
 rt_snprintf((char*) buffer, WEBCLIENT_RESPONSE_BUFSZ, " --%s-- ", boundary);
 webclient_write(session, buffer, rt_strlen(boundary) + 6);

__exit:
    if (fd >= 0)
    {
        close(fd);
    }

if (session != RT_NULL)
    {
        webclient_close(session);
    }

if (buffer != RT_NULL)
    {
        web_free(buffer);
    }

#if webclient_post_file_backup
    if (header != RT_NULL)
    {
        web_free(header);
    }
    #endif

return 0;
}
```