coyote/client.cpp

#include <cassert>
#include <stdexcept>
#include <nlohmann/json.hpp>

#include "client.h"
#include "models.h"

MastodonClient mastodon_client;

static void share_lock(CURL* curl, curl_lock_data data, curl_lock_access access, void* clientp);
static void share_unlock(CURL* curl, curl_lock_data data, void* clientp);
static size_t curl_write_cb(char* ptr, size_t size, size_t nmemb, void* userdata);

template<typename A>
void setopt(CURLSH* share, CURLSHoption option, A parameter) {
    CURLSHcode code = curl_share_setopt(share, option, parameter);
    if (code) {
        throw CurlShareException(code);
    }
}

template<typename A>
void setopt(CURL* curl, CURLoption option, A parameter) {
    CURLcode code = curl_easy_setopt(curl, option, parameter);
    if (code) {
        throw CurlException(code);
    }
}


MastodonClient::MastodonClient() {
    this->_share = curl_share_init();
    if (!this->_share) {
        throw std::bad_alloc();
    }

    try {
        setopt(this->_share, CURLSHOPT_SHARE, CURL_LOCK_DATA_DNS);
        setopt(this->_share, CURLSHOPT_SHARE, CURL_LOCK_DATA_SSL_SESSION);
        setopt(this->_share, CURLSHOPT_SHARE, CURL_LOCK_DATA_CONNECT);
        setopt(this->_share, CURLSHOPT_SHARE, CURL_LOCK_DATA_PSL);
        setopt(this->_share, CURLSHOPT_SHARE, CURL_LOCK_DATA_HSTS);

        setopt(this->_share, CURLSHOPT_LOCKFUNC, share_lock);
        setopt(this->_share, CURLSHOPT_UNLOCKFUNC, share_unlock);
        setopt(this->_share, CURLSHOPT_USERDATA, this->_share_locks);
    } catch (const std::exception& e) {
        curl_share_cleanup(this->_share);
        throw;
    }

    int err = pthread_key_create(&this->_easy_key, curl_easy_cleanup);
    if (err) {
        curl_share_cleanup(this->_share);
        throw std::system_error(err, std::generic_category(), "pthread_key_create()");
    }
}

MastodonClient::~MastodonClient() {
    curl_share_cleanup(this->_share);

    int err = pthread_key_delete(this->_easy_key);
    if (err) {
        perror("pthread_key_delete()");
    }
}

std::optional<Account> MastodonClient::get_account_by_username(const std::string& host, const std::string& username) {
    using namespace std::string_literals;

    try {
        std::string resp = this->_send_request("https://"s + host + "/api/v1/accounts/lookup?acct=" + username);
        return nlohmann::json::parse(std::move(resp));
    } catch (const CurlException& e) {
        if (e.code != CURLE_HTTP_RETURNED_ERROR || this->_response_status_code() != 404) {
            throw;
        }

        return std::nullopt;
    }
}

CURL* MastodonClient::_get_easy() {
    CURL* curl = pthread_getspecific(this->_easy_key);
    if (!curl) {
        curl = curl_easy_init();
        if (!curl) {
            throw std::bad_alloc();
        }

        try {
            setopt(curl, CURLOPT_SHARE, this->_share);
            setopt(curl, CURLOPT_FAILONERROR, 1L);
        } catch (const std::exception& e) {
            curl_easy_cleanup(curl);
            throw;
        }

        int err = pthread_setspecific(this->_easy_key, curl);
        if (err) {
            curl_easy_cleanup(curl);
            throw std::system_error(err, std::generic_category(), "pthread_setspecific()");
        }
    }

    return curl;
}

std::string MastodonClient::_send_request(const std::string& url) {
    std::string res;
    CURL* curl = this->_get_easy();

    setopt(curl, CURLOPT_URL, url.c_str());
    setopt(curl, CURLOPT_WRITEFUNCTION, curl_write_cb);
    setopt(curl, CURLOPT_WRITEDATA, &res);
    CURLcode code = curl_easy_perform(curl);
    if (code) {
        throw CurlException(code);
    }

    return res;
}

long MastodonClient::_response_status_code() {
    long response_code;
    CURLcode code = curl_easy_getinfo(this->_get_easy(), CURLINFO_RESPONSE_CODE, &response_code);
    if (code) {
        throw CurlException(code);
    }
    return response_code;
}


static void share_lock(CURL* curl, curl_lock_data data, curl_lock_access access, void* clientp) {
    (void)curl;
    (void)access;

    std::mutex* mutexes = reinterpret_cast<std::mutex*>(clientp);
    assert(CURL_LOCK_DATA_LAST > data);
    mutexes[data].lock();
}

static void share_unlock(CURL* curl, curl_lock_data data, void* clientp) {
    (void)curl;

    std::mutex* mutexes = reinterpret_cast<std::mutex*>(clientp);
    assert(CURL_LOCK_DATA_LAST > data);
    mutexes[data].unlock();
}

static size_t curl_write_cb(char* ptr, size_t size, size_t nmemb, void* userdata) {
    size_t realsize = size * nmemb;
    std::string* str = reinterpret_cast<std::string*>(userdata);

    // XXX should we bother with exceptions
    str->append(ptr, realsize);

    return realsize;
}