curl使用小结

最近在学习curl，顺便记录一下：

常用函数简要说明

curl_easy_init()

初始化一个licurl简单会话，这个API应该最先调用，它会返回一个handle，供其他API使用。

curl_easy_cleanup()

清除CURL指针，如果前面调用了curl_easy_init()，后面就一定要调用curl_easy_cleanup()，相当于释放资源。

curl_easy_setopt()

给curl的easy handle设置一个传输选项，这是一个很重要的函数，也是用的最多的一个，如果你要对curl进行什么操作，大多需要透过这个API去设定。

curl_easy_perform()

执行传输任务

curl_easy_getinfo()

从curl handle提取相应的信息

curl_easy_setopt常用设置说明

CURLOPT_URL

设定要访问的URL

CURLOPT_VERBOSE

打开一些传输过程的信息，常用于调试时，查看信息

CURLOPT_FOLLOWLOCATION

打开重定向跟踪

CURLOPT_WRITEFUNCTION、CURLOPT_WRITEDATA

CURLOPT_WRITEFUNCTION：设置一个回调函数，用于保存接收到的数据

回调函数：size_t write_callback(char *ptr, size_t size, size_t nmemb, void *userdata);

ptr：指向接收到的数据

userdata：CURLOPT_WRITEDATA设置的参数

写入数据的大小为size*nmemb

CURLOPT_WRITEDATA：用于设定上面回调函数的最后一个参数

CURLOPT_HEADERFUNCTION、CURLOPT_HEADERDATA

上面两个选项主要用于保存header data，使用方法可以参考CURLOPT_WRITEFUNCTION和CURLOPT_WRITEDATA

CURLOPT_NOPROGRESS、CURLOPT_PROGRESSFUNCTION、CURLOPT_PROGRESSDATA

这三个选项主要用来得到当前任务的传输进度，具体用法可以参考下面的例子

curl_easy_getinfo常用设置说明

CURLINFO_REDIRECT_URL

获取重定向的URL

CURLINFO_CONTENT_TYPE

获取传输的数据类型

CURLINFO_SIZE_DOWNLOAD

下载文件的大小

CURLINFO_TOTAL_TIME

下载文件所花的总时间

CURLINFO_SPEED_DOWNLOAD

下载文件的平均速度

例程

http post

INT32 libcurl_http_post(const CHAR * url, const CHAR * postFields)
{
CURL *curl;
CURLcode res;

curl = curl_easy_init();
if(curl)
{
curl_easy_setopt(curl, CURLOPT_URL, url);
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, postFields);

res = curl_easy_perform(curl);
if(CURLE_OK != res)
{
curl_easy_cleanup(curl);
return LIBCURL_RET_FAIL;
}

curl_easy_cleanup(curl);
}

return LIBCURL_RET_OK;
}

获取重定向URL

INT32 libcurl_get_redirect_url(const CHAR * url)
{
char *redirectUrl;

CURLcode res;
res = curl_global_init(CURL_GLOBAL_ALL);

CURL *curl = curl_easy_init();
if(curl)
{
char *version = curl_version();
printf("CURL version is %s\n", version);

curl_easy_setopt(curl, CURLOPT_URL, url);
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);

res = curl_easy_perform(curl);
if(CURLE_OK == res)
{
curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
curl_easy_getinfo(curl, CURLINFO_REDIRECT_URL, &redirectUrl);
printf("Redirect URL is : %s\n", redirectUrl);
}

curl_easy_cleanup(curl);
curl_global_cleanup();
}

return LIBCURL_RET_OK;
}

获取http头

static size_t libcurl_http_get_header_callback(void *ptr, size_t size, size_t nmemb, void *stream)
{
FILE *fp = (FILE *)stream;

return fwrite(ptr, size, nmemb, fp);
}

INT32 libcurl_http_get_header(const CHAR * url, const CHAR * pageSavePath)
{
CURL *curl;
CURLcode res;
FILE *fp;

res = curl_global_init(CURL_GLOBAL_ALL);
if(CURLE_OK != res)
{
return LIBCURL_RET_FAIL;
}

curl = curl_easy_init();
if(curl)
{

if(NULL == (fp = fopen(pageSavePath, "w+")))
{
printf("Open file error\n");
return LIBCURL_RET_FAIL;
}

curl_easy_setopt(curl, CURLOPT_URL, url);
//curl_easy_setopt(curl, CURLOPT_HEADER, 1);
curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, libcurl_http_get_header_callback);
curl_easy_setopt(curl, CURLOPT_HEADERDATA, fp);

res = curl_easy_perform(curl);
if(CURLE_OK != res)
{
curl_easy_cleanup(curl);
return LIBCURL_RET_FAIL;
}

curl_easy_cleanup(curl);
}
return LIBCURL_RET_OK;
}

保存一个网页

static size_t libcurl_http_get_page_callback(void *ptr, size_t size, size_t nmemb, void *stream)
{
FILE *fp = (FILE *)stream;
size_t return_size = fwrite(ptr, size, nmemb, fp);

return return_size;
}

INT32 libcurl_http_get_page(const char * url, const char *pageSavePath)
{
CURL *curl;
CURLcode res;
FILE *fp = NULL;

if(NULL == (fp =fopen(pageSavePath, "wb")))
{
printf("open fail\r\n");
fclose(fp);
return LIBCURL_RET_FAIL;
}

res = curl_global_init(CURL_GLOBAL_ALL);
if(CURLE_OK != res)
{
return LIBCURL_RET_FAIL;
}

curl = curl_easy_init();
if(curl)
{
curl_easy_setopt(curl, CURLOPT_URL, url);
curl_easy_setopt( curl, CURLOPT_WRITEFUNCTION, libcurl_http_get_page_callback);
curl_easy_setopt( curl, CURLOPT_WRITEDATA, (void *)fp);

res = curl_easy_perform(curl);
if(CURLE_OK == res)
{
char *contentType;
res = curl_easy_getinfo(curl, CURLINFO_CONTENT_TYPE, &contentType);
if((CURLE_OK == res) && contentType)
printf("We received Content-Type: %s\n", contentType);
}

curl_easy_cleanup(curl);
}

fclose(fp);

return LIBCURL_RET_OK;
}

下载一个文件并显示下载进度

static size_t libcurl_file_download_callback(void *ptr, size_t size, size_t nmemb, void *stream)
{
FILE *fp = (FILE *)stream;

return fwrite(ptr, size, nmemb, fp);
}

static INT32 libcurl_file_download_progress_callback(void *p,
double t, /* dltotal */
double d, /* dlnow */
double ultotal,
double ulnow)
{
int currentPercent = 0;
if(t != 0)
{
currentPercent = (int)((double)100*(d/t));
}

printf("download percent : %d\n", currentPercent);

return LIBCURL_RET_OK;
}

INT32 libcurl_file_download(const CHAR *url, const CHAR * fileSavePath)
{
CURL *curl;
CURLcode res;
FILE *fp;

res = curl_global_init(CURL_GLOBAL_ALL);

curl = curl_easy_init();
if(curl)
{
if(NULL == (fp = fopen(fileSavePath, "w+")))
{
printf("Open file error\n");
return LIBCURL_RET_FAIL;
}

curl_easy_setopt(curl, CURLOPT_URL, url);

curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, libcurl_file_download_callback);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);

curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0L);
curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, libcurl_file_download_progress_callback);
curl_easy_setopt(curl, CURLOPT_PROGRESSDATA,curl);
//curl_easy_setopt(curl, CURLOPT_RANGE,"0-300000");
//curl_easy_setopt(curl, CURLOPT_RANGE,"300001-600000");
//curl_easy_setopt(curl, CURLOPT_RANGE,"600001-900000");
//curl_easy_setopt(curl, CURLOPT_RANGE,"0-500000");

curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);                        // display debug msg

res = curl_easy_perform(curl);
if(CURLE_OK == res)
{
double val;
char *contentType;

res = curl_easy_getinfo(curl, CURLINFO_SIZE_DOWNLOAD, &val);
if((CURLE_OK == res) && (val>0))
printf("Data downloaded: %0.0f bytes.\n", val);

res = curl_easy_getinfo(curl, CURLINFO_TOTAL_TIME, &val);
if((CURLE_OK == res) && (val>0))
printf("Total download time: %0.3f sec.\n", val);

res = curl_easy_getinfo(curl, CURLINFO_SPEED_DOWNLOAD, &val);
if((CURLE_OK == res) && (val>0))
printf("Average download speed: %0.3f kbyte/sec.\n", val / 1024);

res = curl_easy_getinfo(curl, CURLINFO_CONTENT_TYPE, &contentType);
if((CURLE_OK == res) && contentType)
printf("Content-Type: %s\n", contentType);

}

if(fp)
fclose(fp);

curl_easy_cleanup(curl);
}

return LIBCURL_RET_OK;
}

ftp 上传

INT32 libcurl_ftp_upload_file(const CHAR * ftpAddress, const CHAR * localFilePath, const CHAR * userPwd)
{
CURL *curl;
CURLcode res;

struct stat file_info;
curl_off_t fsize;

if(stat(localFilePath, &file_info))
{
printf("Can not open %s\n", localFilePath);
return LIBCURL_RET_FAIL;
}

fsize = (curl_off_t)file_info.st_size;

FILE *fp = fopen(localFilePath, "rb");

res = curl_global_init(CURL_GLOBAL_ALL);
if(CURLE_OK != res)
{
return LIBCURL_RET_FAIL;
}

curl = curl_easy_init();
if(curl)
{
curl_easy_setopt(curl, CURLOPT_USERPWD, userPwd);
curl_easy_setopt(curl, CURLOPT_URL, ftpAddress);

curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
//curl_easy_setopt(curl, CURLOPT_PUT, 1L);
curl_easy_setopt(curl, CURLOPT_READDATA, fp);
curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE, (curl_off_t)fsize);

res = curl_easy_perform(curl);
if(CURLE_OK != res)
{
curl_easy_cleanup(curl);
return LIBCURL_RET_FAIL;
}

if(fp)
fclose(fp);

curl_easy_cleanup(curl);
curl_global_cleanup();
}

return LIBCURL_RET_OK;
}

ftp 下载

static size_t libcurl_ftp_download_callback(void *ptr, size_t size, size_t nmemb, void *stream)
{
FILE *fp = (FILE *)stream;

return fwrite(ptr, size, nmemb, fp);
}

INT32 libcurl_ftp_download_file(const CHAR * ftpAddress, const CHAR * userPwd, const CHAR * fileSavePath)
{
CURL *curl;
CURLcode res;

FILE *fp = fopen(fileSavePath, "w+");
if(NULL == fp)
{
printf("Open file error\n");
return LIBCURL_RET_FAIL;
}

res = curl_global_init(CURL_GLOBAL_ALL);
if(CURLE_OK != res)
{
return LIBCURL_RET_FAIL;
}

curl = curl_easy_init();
if(curl)
{
curl_easy_setopt(curl, CURLOPT_USERPWD, userPwd);
curl_easy_setopt(curl, CURLOPT_URL, ftpAddress);

curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, libcurl_ftp_download_callback);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);

res = curl_easy_perform(curl);
if(CURLE_OK != res)
{
curl_easy_cleanup(curl);
return LIBCURL_RET_FAIL;
}

if(fp)
fclose(fp);

curl_easy_cleanup(curl);
curl_global_cleanup();
}

return LIBCURL_RET_OK;
}

保存下载内容到buffer中

struct MemoryStruct {
CHAR *memory;
size_t size;
};

struct MemoryStruct chunk;

static size_t curl_http_write_memory_cb(void *contents, size_t size, size_t nmemb, void *userp)
{
size_t realsize = size * nmemb;
struct MemoryStruct *mem = (struct MemoryStruct *)userp;

mem->memory = realloc(mem->memory, mem->size + realsize + 1);
if (mem->memory == NULL) {
/* out of memory! */
printf("not enough memory (realloc returned NULL)\n");
exit(EXIT_FAILURE);
}

memcpy(&(mem->memory[mem->size]), contents, realsize);
mem->size += realsize;
mem->memory[mem->size] = 0;

return realsize;
}

INT32 curl_http_get_page(const CHAR * url)
{
CURL *curl;
CURLcode res;

chunk.memory = malloc(1);  /* will be grown as needed by the realloc above */
chunk.size = 0;    /* no data at this point */

res = curl_global_init(CURL_GLOBAL_ALL);
if(CURLE_OK != res)
{
return CURL_RET_FAIL;
}

curl = curl_easy_init();
if(curl)
{
curl_easy_setopt(curl, CURLOPT_URL, url);
curl_easy_setopt( curl, CURLOPT_WRITEFUNCTION, curl_http_write_memory_cb);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&chunk);

curl_easy_perform(curl);
curl_easy_cleanup(curl);
}

return CURL_RET_OK;
}

参考资料

百度百科libcurl

libcurl官网

curl_easy_setopt说明文档

curl_easy_getinfo说明文档

最全的libcurl库资源整理