没有源可用于Curl_expire（）

Question

我有一个调用java web服务的C程序，我正在使用curl库，我的问题是当代码执行行时

curl_easy_cleanup(curl);

程序返回错误：没有源可用于Curl_expire（），我的主要方法是llamadaServicio

这是我的C代码：

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

struct string {
  char *ptr;
  size_t len;
};

int key=0xF;
void encrypt(char string[]);
void decrypt(char string[]);

void init_string(struct string *s){
    s->len = 0;
    s->ptr = malloc(s->len+1);
    if (s->ptr == NULL) {
        fprintf(stderr, "malloc() failed\n");
        exit(EXIT_FAILURE);
    }
    s->ptr[0] = '\0';
}

size_t writefunc(void *ptr, size_t size, size_t nmemb, struct string *s)
{
  size_t new_len = s->len + size*nmemb;
  s->ptr = realloc(s->ptr, new_len+1);
  if (s->ptr == NULL) {
    fprintf(stderr, "realloc() failed\n");
    exit(EXIT_FAILURE);
  }
  memcpy(s->ptr+s->len, ptr, size*nmemb);
  s->ptr[new_len] = '\0';
  s->len = new_len;

  return size*nmemb;
}

const char * llamadaServicio(char * entrada) {

    char dest[]="\x00";
    CURL *curl;
    CURLcode res;
    //struct json_token *arr, *arr2, *tok, *tok2;
    struct curl_slist *list = NULL;
    char str[100];
    char in[]="entrada: ";
    strcpy(str,entrada);
    encrypt(str);
    strcat(in,str);
    list=curl_slist_append(list,in);
    struct string s;

    curl = curl_easy_init();
    if(curl) {
        init_string(&s);
        curl_easy_setopt(curl, CURLOPT_URL, "http://localhost:8080/WSEnlaceGrupoControl/service/enlace/enlaceTransaccion");
    curl_easy_setopt(curl, CURLOPT_TIMEOUT_MS, 50000);
    //curl_easy_setopt(curl, CURLOPT_HTTPGET, 1);
    //curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, (long) strlen(data));
    //curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "GET");
    //curl_easy_setopt(curl, CURLOPT_POSTFIELDS, data);
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, list);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writefunc);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &s);
    res = curl_easy_perform(curl);

    if(CURLE_OK == res){

        decrypt(s.ptr);
        strcpy(dest,s.ptr);
        free(s.ptr);
    } else if(CURLE_OPERATION_TIMEDOUT == res) {
        strncpy(dest, "28|Error de conexion.\x00", strlen("28|Error de conexion.\x00"));
    } else if(CURLE_HTTP_POST_ERROR == res) {
        strncpy(dest, "28|Error de conexion.\x00", strlen("28|Error de conexion.\x00"));
    }
    curl_easy_cleanup(curl);
}
return dest;
}

void encrypt(char string[]){
    unsigned int i;
    for(i=0;i<strlen(string);++i){
        string[i] = string[i] - key;
    }
}

void decrypt(char string[]){
    unsigned int i;
    for(i=0;i<strlen(string);++i){
        string[i] = string[i] + key;
    }
}

提前感谢，