crequests.c File Reference

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>
#include "crequests.h"

Include dependency graph for crequests.c:

Functions
CREQ_CTX *	creq_init (void)
	Initialize the creq library for a new request.
void	creq_add_header (CREQ_CTX *ctx, char *header)
	Adds a header to the header list for sending.
void	creq_set_proxy (CREQ_CTX *ctx, char *proxy)
	Sets a proxy for sending requests.
void	creq_close (CREQ_CTX *ctx)
	Cleans up the library and memory after using it.
void	creq_set_allow_redirects (CREQ_CTX *ctx, int val)
	Tells the library if it should follow redirection.
void	creq_set_verify (CREQ_CTX *ctx, int val)
	Enables/disables SSL/TLS verification.
void	creq_set_timeout (CREQ_CTX *ctx, long timesec)
	Sets timeout for both connection and data transfer.
void	creq_set_useragent (CREQ_CTX *ctx, char *ua)
	Add user-agent to the request header.
void	creq_get (CREQ_CTX *ctx, char *url)
	Sends a GET request to the specified URL.
void	creq_post (CREQ_CTX *ctx, char *url)
	Sends a post request.
void	creq_head (CREQ_CTX *ctx, char *url)
	Sends a head request.
char *	creq_error (CREQ_CTX *ctx)
	Returns the possible error message.
void	creq_add_param (CREQ_CTX *ctx, char *key, char *value)
	Sets a GET/POST param.
char *	creq_get_content (CREQ_CTX *ctx)
	Returns the content of the request.
char *	creq_get_response_header (CREQ_CTX *ctx, char *key)
	Returns the value for a given header name.

Function Documentation

creq_add_header()

void creq_add_header	(	CREQ_CTX *	ctx,
		char *	header
	)

Adds a header to the header list for sending.

Parameters

ctx	The context returned by creq_init()
header	The header you want to set in a form of "header-name: header-value"

This function sets a new header for the request. The header param will be copied by the library. So it's up to the user to free the allocated memory for the passed parameter.

This function has no return value.

int main(){
    CREQ_CTX * ctx = creq_init();
    if (!ctx){
        fprintf(stdout, "Fail to init the library....\n");
        return 1;
    }
    // Using stack for the new header. Will be copied to the internal structure.
    creq_add_header(ctx, "Authorization: Bearer thisismytoken");
    creq_get(ctx, "https://example.org");
    creq_close(ctx);
    return 0;
}

creq_add_param()

void creq_add_param	(	CREQ_CTX *	ctx,
		char *	key,
		char *	value
	)

Sets a GET/POST param.

Parameters

ctx	Context returned by creq_init()
key	Pointer to null-terminated string as the name of the parameter
value	Pointer to the null-terminated string as the value of the parameter

Sets a parameter for GET/POST request. The parameter must be text. You CAN NOT use this method to set binary values. The function calculates the length of the key and value parameters using strlen() function. Binary data may have null characters which will result in wrong calculation of the length.

The key and value of each param are copied internally. So the caller must free() them (if it's necessary) after the call.

In case your parameter does not have a key (you want to send just a value), set the key to NULL.

'value' can never be NULL.

This function has no return value.

int main(){
    CREQ_CTX * ctx = creq_init();
    if (!ctx){
        fprintf(stderr, "Can not init the library...\n");
        return 1;
    }
    char url[] = "https://httpbin.org/get"
    // this will be the same as: https://httpbin.org/get?name=John+Doe
    creq_add_param(ctx, "name", "John Doe");
    creq_set_timeout(ctx, 10);
    creq_get(ctx, url);
    if (ctx->err_code != CREQ_ERROR_SUCCESS){
        fprintf(stderr, "Error(%d:%d): %s\n", ctx->err_code, ctx->curl_code, creq_error(ctx));
        creq_close(ctx);
        return 1;
    }
    // now that everything is good, we can print stuff
    // print http status code
    fprintf(stdout, "Status Code: %d\n", ctx->response->status_code);
    //  print my ip address
    fprintf(stdout, "My IP address is: %s\n", creq_get_content(ctx));
    creq_close(ctx);
    return 0;
}

creq_close()

void creq_close

(

CREQ_CTX *

ctx

)

Cleans up the library and memory after using it.

Parameters

ctx	Context returned by creq_init()

Whenever you call creq_init(), you must call this method to clean up all the allocated memory and the internal structure for you.

creq_error()

char * creq_error

(

CREQ_CTX *

ctx

)

Returns the possible error message.

Parameters

ctx	Context returned by creq_init()

Users should not free the returned pointer by this function. The returned pointer is stack-based and should be consumed or copied after calling this function.

Returns

a pointer to the error message.

creq_get()

void creq_get	(	CREQ_CTX *	ctx,
		char *	url
	)

Sends a GET request to the specified URL.

Parameters

ctx	Context returned by creq_init()
url	A pointer to the URL

This function sends a GET request to the specified URL. The url param will be copied internally to the library so users can free the memory for url after use.

Returns

The function does not return any result. All the results will be stored in the context and cat be retrieved using ctx parameter.

// Send get request to get the IP address and print the status code
int main(){
    CREQ_CTX * ctx = creq_init();
    if (!ctx){
        fprintf(stderr, "Can not init the library...\n");
        return 1;
    }
    char url[] = "https://ipinfo.io/ip"
    creq_set_timeout(ctx, 10);
    creq_get(ctx, url);
    if (ctx->err_code != CREQ_ERROR_SUCCESS){
        fprintf(stderr, "Error(%d:%d): %s\n", ctx->err_code, ctx->curl_code, creq_error(ctx));
        creq_close(ctx);
        return 1;
    }
    // now that everything is good, we can print stuff
    // print http status code
    fprintf(stdout, "Status Code: %d\n", ctx->response->status_code);
    //  print my ip address
    fprintf(stdout, "My IP address is: %s\n", creq_get_content(ctx));
    creq_close(ctx);
    return 0;
}

creq_get_content()

char * creq_get_content

(

CREQ_CTX *

ctx

)

Returns the content of the request.

Parameters

ctx	Context returned by creq_init()

This function returns a pointer to the place where the response body is stored.

You can use this method if you are sure the content does not have any null character in it (e.g., the content is some HTML data or like that).

If you know that the content is some binary data (e.g., a dowloaded binary file), Then you should use ctx->response->mem and ctx->response->len and then iterate over the content. Therefore, I wouldn't use this method unless I am 100% sure the result is text. Look at the example for more information.

int main(){
    CREQ_CTX * ctx = creq_init();
    if (!ctx){
        fprintf(stderr, "Can not init the context\n");
        return 1;
    }
    // let's download a binary file (Internet Download Manager :-D )
    char url[] = "https://mirror2.internetdownloadmanager.com/idman641build11.exe?v=lt&filename=idman641build11.exe";
    creq_get(ctx, url);
    if (ctx->err_code != CREQ_ERROR_SUCCESS){
        fprintf(stderr, "ERROR(%d:%d): %s\n", ctx->err_code, ctx->curl_code, creq_error(ctx));
        return 2;
    }
    // store the result in a file called idm.exe
    FILE * fp = fopen("idm.exe", "wb");
    if (!fp){
        fprintf(stderr, "Can not open a file to write.....\n");
        return 3;
    }
    // we should not use creq_get_content() method as we have binary content
    // instead, we use ctx->response->len and ctx->response->mem
    for (unsigned int i=0; i<ctx->response->len; ++i){
        fputc(ctx->response->mem[i], fp);
    }
    fclose(fp);
    return 0;
}

Returns

A pointer to the memory related to the content of the request

creq_get_response_header()

char * creq_get_response_header	(	CREQ_CTX *	ctx,
		char *	key
	)

Returns the value for a given header name.

Parameters

ctx	Context returned by creq_init()
key	A pointer to the null-terminated string specifying the header name.

HTTP headers are case-insensitive. So no matter what you send as a key to this function, it will use strcasecmp() function to compare it to the list of headers and returns the value if there is a match. Otherwise, it returns NULL.

Returns

A pointer to a null-terminated string as the value of a given header or NULL

creq_head()

void creq_head	(	CREQ_CTX *	ctx,
		char *	url
	)

Sends a head request.

Parameters

ctx	Context returned by creq_init()
url	A pointer to the URL to send HEAD request to.

This function sends a HEAD request to the given URL. It works exactly as creq_get() but there is no body in response just headers.

Look at the creq_get() doc for the example.

This function has no return value.

creq_init()

CREQ_CTX * creq_init

(

void

)

Initialize the creq library for a new request.

This must be the first function to call when you want to use this library. This function will initialize all the necessary structures and values.

You should always use a new context for each request. If you want to send 10 requests, call creq_init() 10 times to get 10 context and then close all of them by calling creq_close() for each context.

Returns

A pointer to CREQ_CTX structure on success or NULL on failure.

int main(){
    // initialize the library
    CREQ_CTX * ctx = creq_init();
    if (!ctx){
        fprintf(stdout, "Failed to init the library...\n");
        return 1;
    }
    // continue doing stuff here
    creq_close(ctx);
    return 0;
}

creq_post()

void creq_post	(	CREQ_CTX *	ctx,
		char *	url
	)

Sends a post request.

Parameters

ctx	Context returned by creq_init()
url	A pointer to the URL

This function sends a post request to the given URL. The library copies the given url to its internal structure so users can free the url after using this function.

Post parameters are added using creq_add_param() method. Note that currently, this method does not support file upload. This means all the params must be text and not binary data.

The default encoding type of the data is application/x-www-form-urlencoded.

as long as the binary data is base64-encoded or any other human readable characters, it should be fine to send it with this method.

This function has no return value.

int main(){
    CREQ_CTX * ctx = creq_init();
    if (!ctx){
        fprintf(stderr, "Can not init the library...\n");
        return 1;
    }
    char url[] = "https://reqbin.com/echo/post/json"
    creq_set_timeout(ctx, 10);
    creq_post(ctx, url);
    if (ctx->err_code != CREQ_ERROR_SUCCESS){
        fprintf(stderr, "Error(%d:%d): %s\n", ctx->err_code, ctx->curl_code, creq_error(ctx));
        creq_close(ctx);
        return 1;
    }
    // now that everything is good, we can print stuff
    // print http status code
    fprintf(stdout, "Status Code: %d\n", ctx->response->status_code);
    // print the output
    fprintf(stdout, "%s\n", creq_get_content(ctx));
    creq_close(ctx);
    return 0;
}

creq_set_allow_redirects()

void creq_set_allow_redirects	(	CREQ_CTX *	ctx,
		int	val
	)

Tells the library if it should follow redirection.

Parameters

ctx	Context returned by creq_init()
val	0 to disable redirection and 1 to enable it (default).

By default, the library will follow redirection up to 10 times. You can pass 0 to this function to disable this behavior.

This function has no return value.

int main(){
    CREQ_CTX *ctx = creq_init();
    if (!ctx){
        fprintf(stdout, "Fail to init the library....\n");
        return 1;
    }
    // Let's not follow the redirection
    creq_set_allow_redirects(ctx, 0);
    creq_get(ctx, "http://example.com");
    creq_close();
    return 0;
}

creq_set_proxy()

void creq_set_proxy	(	CREQ_CTX *	ctx,
		char *	proxy
	)

Sets a proxy for sending requests.

Parameters

ctx	Context returned by creq_init()
proxy	proxy string (as used in curl command line)

This function sets a proxy for the library.

Proxy is usually in a form of protocol://IP:PORT.

protocol can be http, https, socks5, socks5h and socks4.

For example: socks5h://127.0.0.1:1031

The proxy parameter will be coppied to the internal structure. So it's up the user to free the passed proxy param.

This function has no return value.

int main(){
    CREQ_CTX *ctx = creq_init();
    if (!ctx){
        fprintf(stdout, "Fail to init the library....\n");
        return 1;
    }
    // Let's force it to use socks5
    creq_set_proxy(ctx, "socks5://1.2.3.4:1080");
    creq_get(ctx, "http://example.com");
    creq_close();
    return 0;
}

creq_set_timeout()

void creq_set_timeout	(	CREQ_CTX *	ctx,
		long	timesec
	)

Sets timeout for both connection and data transfer.

Parameters

ctx	Context returned by creq_init()
timesec	Maximum number of second to wait for connection and receiving data

It's always a good practice to set a timeout for each request. This function sets the timeout to timesec seconds. For example, setting the timeout to 10 means that the request has at most 10 seconds to connect to the server and transfer the data. If it takes more than that, the library will return timeout error.

This function has no return value.

creq_set_useragent()

void creq_set_useragent	(	CREQ_CTX *	ctx,
		char *	ua
	)

Add user-agent to the request header.

Using this function, you can set your user-agent as a header in the request. You can also use creq_add_header() function to do the same thing. I created a separate function for it since it is used a lot of time.

The library copy the user-agent string internally. So the user should free the ua parameter after use.

Parameters

ctx	Context returned by creq_init()
ua	A pointer to the new user-agent.

creq_set_verify()

void creq_set_verify	(	CREQ_CTX *	ctx,
		int	val
	)

Enables/disables SSL/TLS verification.

Parameters

ctx	Context returned by creq_init()
val	either zero (disable verification) or one (enable verification).

By default, the SSL verification is enabled internally by curl library. It's not safe to disable it but if you know what you are doing, you can disable SSL verification by passing zero to this function.

This function has no return value.