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digitalmars.D.learn - CURL: Save response to string

reply Nrgyzer <nrgyzer gmail.com> writes:
Hi guys,

I know... there's a lib for curl but I'm using an old CURL-binding for D...
I've the following problem: I'm sending my login data to
a web page and I want store the response of curl_easy_perform() in a string. So
I'm using the following few lines to do that:

string temp;

size_t callback(char* ptr, size_t size, size_t, nmemb, string* stream) {
   temp ~= *ptr;
   // or: How can I append ptr to my stream?
   // When I use '*stream ~= cast(char) ptr;' I get an memory violation...
}

void main() {
	CURL* curl = curl_easy_init();

	curl_httppost* post;

	curl_formadd(&post, &last, CURLFORM_COPYNAME, toStringz("username"),
CURLFORM_COPYCONTENTS, toStringz("username"),
CURLFORM_END);
	curl_formadd(&post, &last, CURLFORM_COPYNAME, toStringz("password"),
CURLFORM_COPYCONTENTS, toStringz("password"),
CURLFORM_END);
	curl_easy_setopt(curl, CURLOPT_HTTPPOST, post);
	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &callback);
	curl_easy_setopt(curl, CURLOPT_WRITEDATA, &temp);
	curl_easy_setopt(curl, CURLOPT_URL, toStringz("https://myURL.tld/login.php"));
	curl_easy_perform(curl);
	writeln(temp);
}

But when I run the code, temp is completely empty... does anyone know how to
fix that or what I'm doing wrong?

Thanks for all suggestions!
Jun 30 2012
next sibling parent simendsjo <simendsjo gmail.com> writes:
On Sat, 30 Jun 2012 23:49:51 +0200, Nrgyzer <nrgyzer gmail.com> wrote:


 Hi guys,

 I know... there's a lib for curl but I'm using an old CURL-binding for  
 D... I've the following problem: I'm sending my login data to
 a web page and I want store the response of curl_easy_perform() in a  
 string. So I'm using the following few lines to do that:

 string temp;

 size_t callback(char* ptr, size_t size, size_t, nmemb, string* stream) {
    temp ~= *ptr;
    // or: How can I append ptr to my stream?
    // When I use '*stream ~= cast(char) ptr;' I get an memory  
 violation...
 }


Wild guess without knowing curl:

temp ~= *ptr; will add the first character of ptr to temp.
Is ptr zero terminated?
You can convert a pointer to an array by using the slice syntax:
temp ~= ptr[0..size]; // assuming size is the number of elements in ptr
Jun 30 2012
prev sibling parent Jonathan M Davis <jmdavisProg gmx.com> writes:
On Saturday, June 30, 2012 21:49:51 Nrgyzer wrote:

 Hi guys,
 
 I know... there's a lib for curl but I'm using an old CURL-binding for D...
 I've the following problem: I'm sending my login data to a web page and I
 want store the response of curl_easy_perform() in a string. So I'm using
 the following few lines to do that:
 
 string temp;
 
 size_t callback(char* ptr, size_t size, size_t, nmemb, string* stream) {
    temp ~= *ptr;
    // or: How can I append ptr to my stream?
    // When I use '*stream ~= cast(char) ptr;' I get an memory violation...
 }
 
 void main() {
 	CURL* curl = curl_easy_init();
 
 	curl_httppost* post;
 
 	curl_formadd(&post, &last, CURLFORM_COPYNAME, toStringz("username"),
 CURLFORM_COPYCONTENTS, toStringz("username"), CURLFORM_END);
 	curl_formadd(&post, &last, CURLFORM_COPYNAME, toStringz("password"),
 CURLFORM_COPYCONTENTS, toStringz("password"), CURLFORM_END);
 	curl_easy_setopt(curl, CURLOPT_HTTPPOST, post);
 	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &callback);
 	curl_easy_setopt(curl, CURLOPT_WRITEDATA, &temp);
 	curl_easy_setopt(curl, CURLOPT_URL,
 toStringz("https://myURL.tld/login.php")); curl_easy_perform(curl);
 	writeln(temp);
 }
 
 But when I run the code, temp is completely empty... does anyone know how to
 fix that or what I'm doing wrong?
 
 Thanks for all suggestions!


cast(char)ptr is casting a pointer to a char. That's not what you want at all. 
Assuming that size is the length of the string that ptr points to (not 
including a terminating '\0'), then do

temp ~= ptr[0 .. size];

If size _does_ include a terminating '\0', then do

temp ~= ptr[0 .. size - 1];

- Jonathan M Davis
Jun 30 2012