Cocos2d-x中libcurl库的使用(3)HTTP的介绍

1、HTTP验证

HTTP目前支持的验证方法有：basic、Digest、NTLM、Negotiate、GSS-Negotiate、SPENGO，可以通过CURLOPT_HTTPAUTH属性来设置具体的验证方式，如：curl_easy_setopt(easy_handle,CURLOPT_HTTPAUTH,CURLAUTH_DIGEST);向代理服务器发送验证信息时，可以通过CURLOPT_PROXYAUTH设置验证方式，也可以同时设置多种验证方式，通过CURLOPT_HTTPAUTH或CURLOPT_PROXYAUTH属性设置多种验证方式。curl_easy_setopt(easy_handle,CURLOPT_PROXYAUTH,CURLAUTH_NTLM)

libcurl在运行时会选择一种它认为是最好的方式与服务器通信。

2、libcurl之HTTP Post

使用post方式向服务器提交数据，通过html中使用<form>标签提交数据一样，只需向libcurl提供一个包含数据的字符串即可。下面是libcurl库中提供的demo

#include <stdio.h>
#include <curl/curl.h>

int main(void)
{
CURL *curl;
CURLcode res;

/* In windows, this will init the winsock stuff */
curl_global_init(CURL_GLOBAL_ALL);

/* get a curl handle */
curl = curl_easy_init();
if(curl) {
/* First set the URL that is about to receive our POST. This URL can
just as well be a https:// URL if that is what should receive the
data. */
curl_easy_setopt(curl, CURLOPT_URL, "http://postit.example.com/moo.cgi");
/* Now specify the POST data */
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "name=daniel&project=curl");

/* Perform the request, res will get the return code */
res = curl_easy_perform(curl);
/* Check for errors */
if(res != CURLE_OK)
fprintf(stderr, "curl_easy_perform() failed: %s\n",
curl_easy_strerror(res));

/* always cleanup */
curl_easy_cleanup(curl);
}
curl_global_cleanup();
return 0;
}

3、libcurl之Multi Post

#include <stdio.h>
#include <string.h>
#include <sys/time.h>

#include <curl/curl.h>

int main(void)
{
CURL *curl;

CURLM *multi_handle;
int still_running;

struct curl_httppost *formpost=NULL;
struct curl_httppost *lastptr=NULL;
struct curl_slist *headerlist=NULL;
static const char buf[] = "Expect:";

/* Fill in the file upload field. This makes libcurl load data from
the given file name when curl_easy_perform() is called. */
curl_formadd(&formpost,
&lastptr,
CURLFORM_COPYNAME, "sendfile",
CURLFORM_FILE, "postit2.c",
CURLFORM_END);

/* Fill in the filename field */
curl_formadd(&formpost,
&lastptr,
CURLFORM_COPYNAME, "filename",
CURLFORM_COPYCONTENTS, "postit2.c",
CURLFORM_END);

/* Fill in the submit field too, even if this is rarely needed */
curl_formadd(&formpost,
&lastptr,
CURLFORM_COPYNAME, "submit",
CURLFORM_COPYCONTENTS, "send",
CURLFORM_END);

curl = curl_easy_init();
multi_handle = curl_multi_init();

/* initalize custom header list (stating that Expect: 100-continue is not
wanted */
headerlist = curl_slist_append(headerlist, buf);
if(curl && multi_handle) {

/* what URL that receives this POST */
curl_easy_setopt(curl, CURLOPT_URL, "http://www.example.com/upload.cgi");
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);

curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headerlist);
curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost);

curl_multi_add_handle(multi_handle, curl);

curl_multi_perform(multi_handle, &still_running);

do {
struct timeval timeout;
int rc; /* select() return code */

fd_set fdread;
fd_set fdwrite;
fd_set fdexcep;
int maxfd = -1;

long curl_timeo = -1;

FD_ZERO(&fdread);
FD_ZERO(&fdwrite);
FD_ZERO(&fdexcep);

/* set a suitable timeout to play around with */
timeout.tv_sec = 1;
timeout.tv_usec = 0;

curl_multi_timeout(multi_handle, &curl_timeo);
if(curl_timeo >= 0) {
timeout.tv_sec = curl_timeo / 1000;
if(timeout.tv_sec > 1)
timeout.tv_sec = 1;
else
timeout.tv_usec = (curl_timeo % 1000) * 1000;
}

/* get file descriptors from the transfers */
curl_multi_fdset(multi_handle, &fdread, &fdwrite, &fdexcep, &maxfd);

/* In a real-world program you OF COURSE check the return code of the
function calls.  On success, the value of maxfd is guaranteed to be
greater or equal than -1.  We call select(maxfd + 1, ...), specially in
case of (maxfd == -1), we call select(0, ...), which is basically equal
to sleep. */

rc = select(maxfd+1, &fdread, &fdwrite, &fdexcep, &timeout);

switch(rc) {
case -1:
/* select error */
break;
case 0:
default:
/* timeout or readable/writable sockets */
printf("perform!\n");
curl_multi_perform(multi_handle, &still_running);
printf("running: %d!\n", still_running);
break;
}
} while(still_running);

curl_multi_cleanup(multi_handle);

/* always cleanup */
curl_easy_cleanup(curl);

/* then cleanup the formpost chain */
curl_formfree(formpost);

/* free slist */
curl_slist_free_all (headerlist);
}
return 0;
}

Multi Post可以提交二进制数据(或大量数据)的更好的方法，在RFC1867、RFC2388找到定义，在Post时，有不同的数据单元，每个单元有自己的名称与内容，内容可以是文本的，也可以是二进制的，同时，每个数据单元都可以有自己的消息头。这些数据单元组成一个链表，提交到HTTP服务器，也可以添加不同的数据单元，然后提交到服务器。