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This is my libcurl request (curl_example.cpp)

#include <iostream>
#include <string>
#include <curl/curl.h>
#include <vector>
#include <fstream>      // std::ifstream
using namespace std;
using namespace cv;
static size_t WriteCallback(void *contents, size_t size, size_t nmemb, void *userp)
{
    ((std::string*)userp)->append((char*)contents, size * nmemb);
    return size * nmemb;
}

int main(void)
{
    CURL *curl;
    CURLcode res;
    std::string readBuffer;
    int length=80000;
    char c = 'z';
    string encoded_png=std::string(length, c);
    std::string url_data="http://0.0.0.0:18080/params?query="+encoded_png;
    struct curl_slist *headerlist=NULL;
    curl = curl_easy_init();
    if(curl) 
    {
        curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "GET");
        curl_easy_setopt(curl, CURLOPT_URL,url_data.c_str()) ;
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &readBuffer);
        res = curl_easy_perform(curl);
        curl_easy_cleanup(curl);
        std::cout <<"readBuffer:"<< readBuffer << std::endl;
    }
    return 0;
}

This is my Crow c++ server code (crow_example.cpp)

#include<iostream>
#include "crow.h"
#include<string>
using namespace std;
int main()
{

    crow::SimpleApp app;
        CROW_ROUTE(app, "/params")
    ([](const crow::request& req){
        std::ostringstream os;

        // To get a simple string from the url params
        // To see it in action /params?foo='blabla'
        os << "Params: " << req.url_params << "\n\n"; 
        os << "The string received is " << (req.url_params.get("query") == nullptr ? "not " : "") << "found.\n";
                return crow::response{os.str()};
    });    
    app.port(18080).multithreaded().run();
}

with length=80000; When I run the crow c++ server and query the server with libcurl I could able to receive the string in crow as well as get the response in curl.

with length = 85000;.//more than 80,000 I am not able to receive any string at the crow server as well there is no response from the libcurl request.

With the python flask server, I could receive the string with any length. But the crow server is not working and I am not able to figure out what is the rootcause.

Any help or inputs appreciated.

shaik.t
  • 11
  • 3
  • Does the request actually get sent? You should be able to use tcpdump program to monitor the connection. Actually, I am astonished that you can send a URL that is more than 80,000 bytes in length. Normally, you send that information in the body, rather than in the URI. – Bob Dalgleish Mar 23 '21 at 15:38
  • @BobDalgleish I could able to send 80,000 bytes in length through the URL. I tried sending the information in the body but didn`t work. – shaik.t Apr 05 '21 at 05:35

0 Answers0