C ++ libcurl响应仅显示响应的第一行

如何解决C ++ libcurl响应仅显示响应的第一行

编辑：运行更多命令后，似乎仅显示了以*开头的行。有什么办法阻止吗？

我正试图在我的C ++程序中使用libcurl库，以使用IMAP协议接收电子邮件。问题在于，来自CURL调用的响应仅返回一行，并切断了应返回的其余内容。我知道请求本身是有效的，因为当我使用curl_easy_setopt(curl,CURLOPT_VERBOSE,1L);启用详细模式时，它在输出中具有完整的结果。

例如，当我使用curl_easy_setopt(curl,"FETCH 10000 (FLAGS BODY[HEADER.FIELDS (DATE FROM SUBJECT)])");时，响应为：

* 10000 FETCH (FLAGS (\Seen) BODY[HEADER.FIELDS (DATE FROM SUBJECT)] {140}

当我打开详细模式时，控制台会显示完整结果：

< A003 OK [READ-WRITE] INBOX selected. (Success)
> A004 FETCH 10000 (FLAGS BODY[HEADER.FIELDS (DATE FROM SUBJECT)])
< * 10000 FETCH (FLAGS (\Seen) BODY[HEADER.FIELDS (DATE FROM SUBJECT)] {140}
< Date: Wed,1 Apr 2020 01:59:45 -0500
< From: [REMOVED NAME] <[REMOVED EMAIL]>
< Subject: Testing subject here
< 
< )
< A004 OK Success

我尝试了多种输出数据的方法：将其输出到stdout，一个外部文件以及在内存中（然后打印）。我觉得CURL结果只是由于某种原因没有返回比第一行更多的结果。如果有帮助，下面是代码（我正在使用wxWidgets）：

App.cpp -忽略大部分内容，仅调用函数

#include "App.h"
#include "Frame.h"
#include "Config.h"
#include "IMAP.h"


wxIMPLEMENT_APP(App);

bool App::OnInit() {
    curl_global_init(CURL_GLOBAL_SSL);
    try {
        Config config("settings.conf");
        for(const auto& account : config["accounts"]) {
            const char* url = account["incoming_server"].asCString();
            const char* username = account["username"].asCString();
            const char* password = account["password"].asCString();
            IMAP connection(url,IMAP_DEFAULT_PORT);
            if(connection.auth(username,password) == IMAP_SUCCESS) {
                connection.select("INBOX");
                auto folders = connection.getFolders();
            }
        }
    } catch(std::exception& e) {
        std::cerr << e.what() << std::endl;
        exit(0);
    }

    curl_global_cleanup();
    exit(1);

    Frame *frame = new Frame("MailDuck",wxDefaultPosition,wxSize(100,100));
    frame->Show(true);
    frame->Centre();
    return true;
}

App.cpp

#include "IMAP.h"

IMAP::IMAP(const char *url,int port) {
    this->url = url;
    this->port = port;
}

IMAP_CODE IMAP::auth(const char *username,const char *password) {
    this->username = username;
    this->password = password;
    if(execute().size == -1) return IMAP_FAILED;
    else return IMAP_SUCCESS;
}

std::vector<Folder> IMAP::getFolders() {
    std::vector<Folder> folders;
    memory mem = execute("FETCH 10000 (FLAGS BODY[HEADER.FIELDS (DATE FROM SUBJECT)])");
    std::cout << mem.response << std::endl;
    free(mem.response);
    return folders;
}

IMAP::memory IMAP::execute(const char *command) {
    CURL *curl;
    CURLcode res = CURLE_OK;
    struct memory chunk { (char *) malloc(1),0 };
    curl = curl_easy_init();
    std::string finalURL;
    finalURL.append(this->url);
    finalURL.append("/");
    finalURL.append(this->mailbox);
    if(curl) {
        curl_easy_setopt(curl,CURLOPT_USE_SSL,CURLUSESSL_ALL);
        curl_easy_setopt(curl,CURLOPT_USERNAME,this->username);
        curl_easy_setopt(curl,CURLOPT_PASSWORD,this->password);
        curl_easy_setopt(curl,CURLOPT_URL,finalURL.c_str());
        curl_easy_setopt(curl,1L);
        curl_easy_setopt(curl,CURLOPT_WRITEDATA,(void *)&chunk);
        curl_easy_setopt(curl,CURLOPT_WRITEFUNCTION,write_function);
        curl_easy_setopt(curl,CURLOPT_CUSTOMREQUEST,command);
        res = curl_easy_perform(curl);
        if(res != CURLE_OK) chunk.size = -1;
        curl_easy_cleanup(curl);
    } else chunk.size = -1;
    if(chunk.size == -1) std::cerr << "ERROR >> Unable to call command: " << command << std::endl;
    return chunk;
}

size_t IMAP::write_function(void *data,size_t size,size_t nmemb,void *userp) {
    size_t real_size = size * nmemb;
    auto *mem = (struct memory *) userp;
    char *ptr = (char *) realloc(mem->response,mem->size + real_size + 1);
    if(ptr == NULL) return 0;
    mem->response = ptr;
    memcpy(&(mem->response[mem->size]),data,real_size);
    mem->size += real_size;
    mem->response[mem->size] = 0;
    return real_size;
}

void IMAP::select(const char *box) {
    this->mailbox = box;
}

IMAP.h

#ifndef MAILDUCK_IMAP_H
#define MAILDUCK_IMAP_H


#include <map>
#include <vector>
#include <string>
#include <json/json.h>
#include <curl/curl.h>
#include <iostream>
#include <istream>

enum {
    IMAP_DEFAULT_PORT = 993,};

enum IMAP_CODE {
    IMAP_SUCCESS = 1,IMAP_FAILED = 0
};

class Folder : public std::vector<Folder> {
public:
    std::string name;
};

class IMAP {
private:
    const char *url,*username,*password,*mailbox = "";
    int port;
    struct memory { char *response; size_t size; };
    memory execute(const char *command = nullptr);
    static size_t write_function(void *data,void *userp);
public:
    IMAP(const char *url,int port);
    IMAP_CODE auth(const char* username,const char* password);
    std::vector<Folder> getFolders();
    void select(const char *mailbox);
};


#endif

我对此一直停留了一段时间，因此，我感谢任何人都可以提供的见解。

解决方法

想通了！对于所有像我一样被困住的人：

显然，其余数据卡在标题数据中，因此添加以下内容：

struct memory chunk { (char *) malloc(1),0 };
curl_easy_setopt(curl,CURLOPT_HEADERFUNCTION,header_callback);
curl_easy_setopt(curl,CURLOPT_HEADERDATA,(void *)&chunk);

然后我的写功能与另一个完全一样...

size_t IMAP::header_callback(char *data,size_t size,size_t nmemb,void *userp) {
    size_t real_size = size * nmemb;
    auto *mem = (struct memory *) userp;
    char *ptr = (char *) realloc(mem->response,mem->size + real_size + 1);
    if(ptr == NULL) return 0;
    mem->response = ptr;
    memcpy(&(mem->response[mem->size]),data,real_size);
    mem->size += real_size;
    mem->response[mem->size] = 0;
    return real_size;
}

现在我得到了完整的答复。