r/http_curl.h

// Written by retoor@molodetz.nl

// This code defines a simple HTTP client using libcurl in C. It provides functions for executing POST and GET HTTP requests with JSON data, including authorization via a bearer token. The functions `curl_post` and `curl_get` handle these operations and return the server's response as a string.

// Uses libcurl for HTTP requests and includes a custom "auth.h" for API key resolution.

// MIT License
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions: the above copyright
// notice and this permission notice shall be included in all copies or substantial
// portions of the Software. The Software is provided "as is", without warranty of
// any kind, express or implied, including but not limited to the warranties of
// merchantability, fitness for a particular purpose and noninfringement. In no
// event shall the authors or copyright holders be liable for any claim, damages
// or other liability, whether in an action of contract, tort or otherwise, arising
// from, out of or in connection with the software or the use or other dealings in
// the Software.


#ifndef HTTP_CURL
#define HTTP_CURL

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

struct ResponseBuffer {
    char *data;
    size_t size;
};

static size_t WriteCallback(void *contents, size_t size, size_t nmemb, void *userp) {
    size_t total_size = size * nmemb;
    struct ResponseBuffer *response = (struct ResponseBuffer *)userp;
    char *ptr = realloc(response->data, response->size + total_size + 1);
    if (ptr == NULL) {
        fprintf(stderr, "Failed to allocate memory for response\n");
        return 0;
    }
    response->data = ptr;
    memcpy(&(response->data[response->size]), contents, total_size);
    response->size += total_size;
    response->data[response->size] = '\0';
    return total_size;
}

char *curl_post(const char *url, const char *data) {
    CURL *curl;
    CURLcode res;
    struct ResponseBuffer response = {malloc(1), 0};

    if (!response.data) return NULL;

    curl = curl_easy_init();
    if (curl) {
        struct curl_slist *headers = NULL;
        curl_easy_setopt(curl, CURLOPT_URL, url);
        headers = curl_slist_append(headers, "Content-Type: application/json");
        char bearer_header[1337];
        sprintf(bearer_header, "Authorization: Bearer %s", resolve_api_key());
        headers = curl_slist_append(headers, bearer_header);
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
        curl_easy_setopt(curl, CURLOPT_POSTFIELDS, data);
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&response);
        res = curl_easy_perform(curl);
        if (res != CURLE_OK) {
            fprintf(stderr, "An error occurred: %s\n", curl_easy_strerror(res));
        }
        curl_slist_free_all(headers);
        curl_easy_cleanup(curl);
        return response.data;
    }
    return NULL;
}

char *curl_get(const char *url) {
    CURL *curl;
    CURLcode res;
    struct ResponseBuffer response = {malloc(1), 0};

    if (!response.data) return NULL;

    curl = curl_easy_init();
    if (curl) {
        struct curl_slist *headers = NULL;
        curl_easy_setopt(curl, CURLOPT_URL, url);
        headers = curl_slist_append(headers, "Content-Type: application/json");
        char bearer_header[1337];
        sprintf(bearer_header, "Authorization: Bearer %s", resolve_api_key());
        headers = curl_slist_append(headers, bearer_header);
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&response);
        res = curl_easy_perform(curl);
        if (res != CURLE_OK) {
            fprintf(stderr, "An error occurred: %s\n", curl_easy_strerror(res));
        }
        curl_slist_free_all(headers);
        curl_easy_cleanup(curl);
    }
    return response.data;
}

#endif