static void server_send_cb(EV_P_ ev_io *w, int revents)
{
    struct server_ctx *server_send_ctx = (struct server_ctx *)w;
    struct server *server = server_send_ctx->server;
    struct remote *remote = server->remote;
    if (server->buf_len == 0) {
        // close and free
        close_and_free_remote(EV_A_ remote);
        close_and_free_server(EV_A_ server);
        return;
    } else {
        // has data to send
        ssize_t s = send(server->fd, server->buf + server->buf_idx,
                         server->buf_len, 0);
        if (s < 0) {
            if (errno != EAGAIN && errno != EWOULDBLOCK) {
                ERROR("send");
                close_and_free_remote(EV_A_ remote);
                close_and_free_server(EV_A_ server);
            }
            return;
        } else if (s < server->buf_len) {
            // partly sent, move memory, wait for the next time to send
            server->buf_len -= s;
            server->buf_idx += s;
            return;
        } else {
            // all sent out, wait for reading
            server->buf_len = 0;
            server->buf_idx = 0;
            ev_io_stop(EV_A_ & server_send_ctx->io);
            if (remote != NULL) {
                ev_io_start(EV_A_ & remote->recv_ctx->io);
            } else {
                close_and_free_remote(EV_A_ remote);
                close_and_free_server(EV_A_ server);
                return;
            }
        }
    }

}

void
free_cb(void *key, void *element)
{
    remote_ctx_t *remote_ctx = (remote_ctx_t *)element;

    if (verbose) {
        LOGI("[udp] one connection freed");
    }

    close_and_free_remote(EV_DEFAULT, remote_ctx);
}

void free_cb(void *element)
{
    struct remote_ctx *remote_ctx = (struct remote_ctx *)element;

    if (verbose)
    {
        LOGD("free a remote ctx");
    }

    close_and_free_remote(EV_DEFAULT, remote_ctx);
}

static void free_connections(struct ev_loop *loop)
{
    struct cork_dllist_item *curr;
    for (curr = cork_dllist_start(&connections);
         !cork_dllist_is_end(&connections, curr);
         curr = curr->next) {
        struct server *server = cork_container_of(curr, struct server, entries);
        struct remote *remote = server->remote;
        close_and_free_server(loop, server);
        close_and_free_remote(loop, remote);
    }
}

static void server_timeout_cb(EV_P_ ev_timer *watcher, int revents)
{
    struct server_ctx *server_ctx = (struct server_ctx *) (((void*)watcher)
                                    - sizeof(ev_io));
    struct server *server = server_ctx->server;
    struct remote *remote = server->remote;

    LOGE("TCP connection timeout");

    close_and_free_remote(EV_A_ remote);
    close_and_free_server(EV_A_ server);
}

static void remote_timeout_cb(EV_P_ ev_timer *watcher, int revents)
{
    remote_ctx_t *remote_ctx = (remote_ctx_t *)(((void *)watcher)
                                                - sizeof(ev_io));
    remote_t *remote = remote_ctx->remote;
    server_t *server = remote->server;

    ev_timer_stop(EV_A_ watcher);

    close_and_free_remote(EV_A_ remote);
    close_and_free_server(EV_A_ server);
}

static void remote_timeout_cb(EV_P_ ev_timer *watcher, int revents)
{
    struct remote_ctx *remote_ctx = (struct remote_ctx *)(((void *)watcher)
                                                          - sizeof(ev_io));
    struct remote *remote = remote_ctx->remote;
    struct server *server = remote->server;

    LOGD("remote timeout");

    close_and_free_remote(EV_A_ remote);
    close_and_free_server(EV_A_ server);
}

static void
remote_timeout_cb(EV_P_ ev_timer *watcher, int revents)
{
    remote_ctx_t *remote_ctx
        = cork_container_of(watcher, remote_ctx_t, watcher);

    remote_t *remote = remote_ctx->remote;
    server_t *server = remote->server;

    ev_timer_stop(EV_A_ watcher);

    close_and_free_remote(EV_A_ remote);
    close_and_free_server(EV_A_ server);
}

static void remote_timeout_cb(EV_P_ ev_timer *watcher, int revents)
{
    struct remote_ctx *remote_ctx = (struct remote_ctx *)(((void *)watcher)
                                                          - sizeof(ev_io));
    struct remote *remote = remote_ctx->remote;
    struct server *server = remote->server;

    if (verbose) {
        LOGI("TCP connection timeout");
    }

    close_and_free_remote(EV_A_ remote);
    close_and_free_server(EV_A_ server);
}

static void
delayed_connect_cb(EV_P_ ev_timer *watcher, int revents)
{
    server_t *server = cork_container_of(watcher, server_t,
                                         delayed_connect_watcher);
    remote_t *remote = server->remote;

    int r = connect(remote->fd, remote->addr,
                    get_sockaddr_len(remote->addr));

    if (r == -1 && errno != CONNECT_IN_PROGRESS) {
        ERROR("connect");
        close_and_free_remote(EV_A_ remote);
        close_and_free_server(EV_A_ server);
        return;
    } else {
        // listen to remote connected event
        ev_io_start(EV_A_ & remote->send_ctx->io);
        ev_timer_start(EV_A_ & remote->send_ctx->watcher);
    }
}

//.........这里部分代码省略.........
        cache_hit = 1;
        // detect destination mismatch
        if (remote_ctx->addr_header_len != addr_header_len
            || memcmp(addr_header, remote_ctx->addr_header, addr_header_len) != 0) {
            if (dst_addr.ss_family != AF_INET && dst_addr.ss_family != AF_INET6) {
                need_query = 1;
            }
        } else {
            memcpy(&dst_addr, &remote_ctx->dst_addr, sizeof(struct sockaddr_storage));
        }
    } else {
        if (dst_addr.ss_family == AF_INET || dst_addr.ss_family == AF_INET6) {
            int remotefd = create_remote_socket(dst_addr.ss_family == AF_INET6);
            if (remotefd != -1) {
                setnonblocking(remotefd);
#ifdef SO_BROADCAST
                set_broadcast(remotefd);
#endif
#ifdef SO_NOSIGPIPE
                set_nosigpipe(remotefd);
#endif
#ifdef IP_TOS
                // Set QoS flag
                int tos = 46;
                setsockopt(remotefd, IPPROTO_IP, IP_TOS, &tos, sizeof(tos));
#endif
#ifdef SET_INTERFACE
                if (server_ctx->iface) {
                    if (setinterface(remotefd, server_ctx->iface) == -1)
                        ERROR("setinterface");
                }
#endif
                remote_ctx                  = new_remote(remotefd, server_ctx);
                remote_ctx->src_addr        = src_addr;
                remote_ctx->server_ctx      = server_ctx;
                remote_ctx->addr_header_len = addr_header_len;
                memcpy(remote_ctx->addr_header, addr_header, addr_header_len);
                memcpy(&remote_ctx->dst_addr, &dst_addr, sizeof(struct sockaddr_storage));
            } else {
                ERROR("[udp] bind() error");
                goto CLEAN_UP;
            }
        }
    }

    if (remote_ctx != NULL && !need_query) {
        size_t addr_len = get_sockaddr_len((struct sockaddr *)&dst_addr);
        int s           = sendto(remote_ctx->fd, buf->data + addr_header_len,
                                 buf->len - addr_header_len, 0,
                                 (struct sockaddr *)&dst_addr, addr_len);

        if (s == -1) {
            ERROR("[udp] sendto_remote");
            if (!cache_hit) {
                close_and_free_remote(EV_A_ remote_ctx);
            }
        } else {
            if (!cache_hit) {
                // Add to conn cache
                remote_ctx->af = dst_addr.ss_family;
                char *key = hash_key(remote_ctx->af, &remote_ctx->src_addr);
                cache_insert(server_ctx->conn_cache, key, HASH_KEY_LEN, (void *)remote_ctx);

                ev_io_start(EV_A_ & remote_ctx->io);
                ev_timer_start(EV_A_ & remote_ctx->watcher);
            }
        }
    } else {
        struct addrinfo hints;
        memset(&hints, 0, sizeof(struct addrinfo));
        hints.ai_family   = AF_UNSPEC;
        hints.ai_socktype = SOCK_DGRAM;
        hints.ai_protocol = IPPROTO_UDP;

        struct query_ctx *query_ctx = new_query_ctx(buf->data + addr_header_len,
                                                    buf->len - addr_header_len);
        query_ctx->server_ctx      = server_ctx;
        query_ctx->addr_header_len = addr_header_len;
        query_ctx->src_addr        = src_addr;
        memcpy(query_ctx->addr_header, addr_header, addr_header_len);

        if (need_query) {
            query_ctx->remote_ctx = remote_ctx;
        }

        struct ResolvQuery *query = resolv_query(host, query_resolve_cb,
                                                 NULL, query_ctx, htons(atoi(port)));
        if (query == NULL) {
            ERROR("[udp] unable to create DNS query");
            close_and_free_query(EV_A_ query_ctx);
            goto CLEAN_UP;
        }
        query_ctx->query = query;
    }
#endif

CLEAN_UP:
    bfree(buf);
    ss_free(buf);
}

static void
query_resolve_cb(struct sockaddr *addr, void *data)
{
    struct query_ctx *query_ctx = (struct query_ctx *)data;
    struct ev_loop *loop        = query_ctx->server_ctx->loop;

    if (verbose) {
        LOGI("[udp] udns resolved");
    }

    query_ctx->query = NULL;

    if (addr == NULL) {
        LOGE("[udp] udns returned an error");
    } else {
        remote_ctx_t *remote_ctx = query_ctx->remote_ctx;
        int cache_hit            = 0;

        // Lookup in the conn cache
        if (remote_ctx == NULL) {
            char *key = hash_key(AF_UNSPEC, &query_ctx->src_addr);
            cache_lookup(query_ctx->server_ctx->conn_cache, key, HASH_KEY_LEN, (void *)&remote_ctx);
        }

        if (remote_ctx == NULL) {
            int remotefd = create_remote_socket(addr->sa_family == AF_INET6);
            if (remotefd != -1) {
                setnonblocking(remotefd);
#ifdef SO_BROADCAST
                set_broadcast(remotefd);
#endif
#ifdef SO_NOSIGPIPE
                set_nosigpipe(remotefd);
#endif
#ifdef IP_TOS
                // Set QoS flag
                int tos = 46;
                setsockopt(remotefd, IPPROTO_IP, IP_TOS, &tos, sizeof(tos));
#endif
#ifdef SET_INTERFACE
                if (query_ctx->server_ctx->iface) {
                    if (setinterface(remotefd, query_ctx->server_ctx->iface) == -1)
                        ERROR("setinterface");
                }
#endif
                remote_ctx                  = new_remote(remotefd, query_ctx->server_ctx);
                remote_ctx->src_addr        = query_ctx->src_addr;
                remote_ctx->server_ctx      = query_ctx->server_ctx;
                remote_ctx->addr_header_len = query_ctx->addr_header_len;
                memcpy(remote_ctx->addr_header, query_ctx->addr_header,
                       query_ctx->addr_header_len);
            } else {
                ERROR("[udp] bind() error");
            }
        } else {
            cache_hit = 1;
        }

        if (remote_ctx != NULL) {
            memcpy(&remote_ctx->dst_addr, addr, sizeof(struct sockaddr_storage));

            size_t addr_len = get_sockaddr_len(addr);
            int s           = sendto(remote_ctx->fd, query_ctx->buf->data, query_ctx->buf->len,
                                     0, addr, addr_len);

            if (s == -1) {
                ERROR("[udp] sendto_remote");
                if (!cache_hit) {
                    close_and_free_remote(EV_A_ remote_ctx);
                }
            } else {
                if (!cache_hit) {
                    // Add to conn cache
                    char *key = hash_key(AF_UNSPEC, &remote_ctx->src_addr);
                    cache_insert(query_ctx->server_ctx->conn_cache, key, HASH_KEY_LEN, (void *)remote_ctx);
                    ev_io_start(EV_A_ & remote_ctx->io);
                    ev_timer_start(EV_A_ & remote_ctx->watcher);
                }
            }
        }
    }

    // clean up
    close_and_free_query(EV_A_ query_ctx);
}

static void
remote_recv_cb(EV_P_ ev_io *w, int revents)
{
    ssize_t r;
    remote_ctx_t *remote_ctx = (remote_ctx_t *)w;
    server_ctx_t *server_ctx = remote_ctx->server_ctx;

    // server has been closed
    if (server_ctx == NULL) {
        LOGE("[udp] invalid server");
        close_and_free_remote(EV_A_ remote_ctx);
        return;
    }

    if (verbose) {
        LOGI("[udp] remote receive a packet");
    }

    struct sockaddr_storage src_addr;
    socklen_t src_addr_len = sizeof(struct sockaddr_storage);
    memset(&src_addr, 0, src_addr_len);

    buffer_t *buf = ss_malloc(sizeof(buffer_t));
    balloc(buf, buf_size);

    // recv
    r = recvfrom(remote_ctx->fd, buf->data, buf_size, 0, (struct sockaddr *)&src_addr, &src_addr_len);

    if (r == -1) {
        // error on recv
        // simply drop that packet
        ERROR("[udp] remote_recv_recvfrom");
        goto CLEAN_UP;
    } else if (r > packet_size) {
        if (verbose) {
            LOGI("[udp] remote_recv_recvfrom fragmentation");
        }
    }

    buf->len = r;

#ifdef MODULE_LOCAL
    int err = server_ctx->crypto->decrypt_all(buf, server_ctx->crypto->cipher, buf_size);
    if (err) {
        // drop the packet silently
        goto CLEAN_UP;
    }

#ifdef MODULE_REDIR
    struct sockaddr_storage dst_addr;
    memset(&dst_addr, 0, sizeof(struct sockaddr_storage));
    int len = parse_udprelay_header(buf->data, buf->len, NULL, NULL, &dst_addr);

    if (dst_addr.ss_family != AF_INET && dst_addr.ss_family != AF_INET6) {
        LOGI("[udp] ss-redir does not support domain name");
        goto CLEAN_UP;
    }
#else
    int len = parse_udprelay_header(buf->data, buf->len, NULL, NULL, NULL);
#endif

    if (len == 0) {
        LOGI("[udp] error in parse header");
        // error in parse header
        goto CLEAN_UP;
    }

    // server may return using a different address type other than the type we
    // have used during sending
#if defined(MODULE_TUNNEL) || defined(MODULE_REDIR)
    // Construct packet
    buf->len -= len;
    memmove(buf->data, buf->data + len, buf->len);
#else
#ifdef __ANDROID__
    rx += buf->len;
    stat_update_cb();
#endif
    // Construct packet
    brealloc(buf, buf->len + 3, buf_size);
    memmove(buf->data + 3, buf->data, buf->len);
    memset(buf->data, 0, 3);
    buf->len += 3;
#endif

#endif

#ifdef MODULE_REMOTE

    rx += buf->len;

    char addr_header_buf[512];
    char *addr_header   = remote_ctx->addr_header;
    int addr_header_len = remote_ctx->addr_header_len;

    if (remote_ctx->af == AF_INET || remote_ctx->af == AF_INET6) {
        addr_header_len = construct_udprelay_header(&src_addr, addr_header_buf);
        addr_header     = addr_header_buf;
    }

//.........这里部分代码省略.........

static void
remote_send_cb(EV_P_ ev_io *w, int revents)
{
    remote_ctx_t *remote_send_ctx = (remote_ctx_t *)w;
    remote_t *remote              = remote_send_ctx->remote;
    server_t *server              = remote->server;

    ev_timer_stop(EV_A_ & remote_send_ctx->watcher);

    if (!remote_send_ctx->connected) {
        int r = 0;
        if (remote->addr == NULL) {
            struct sockaddr_storage addr;
            memset(&addr, 0, sizeof(struct sockaddr_storage));
            socklen_t len = sizeof addr;
            r = getpeername(remote->fd, (struct sockaddr *)&addr, &len);
        }
        if (r == 0) {
            remote_send_ctx->connected = 1;

            ev_io_stop(EV_A_ & remote_send_ctx->io);
            ev_io_stop(EV_A_ & server->recv_ctx->io);
            ev_io_start(EV_A_ & remote->recv_ctx->io);
            ev_timer_start(EV_A_ & remote->recv_ctx->watcher);

            // send destaddr
            buffer_t ss_addr_to_send;
            buffer_t *abuf = &ss_addr_to_send;
            balloc(abuf, BUF_SIZE);

            if (server->hostname_len > 0
                    && validate_hostname(server->hostname, server->hostname_len)) { // HTTP/SNI
                uint16_t port;
                if (AF_INET6 == server->destaddr.ss_family) { // IPv6
                    port = (((struct sockaddr_in6 *)&(server->destaddr))->sin6_port);
                } else {                             // IPv4
                    port = (((struct sockaddr_in *)&(server->destaddr))->sin_port);
                }

                abuf->data[abuf->len++] = 3;          // Type 3 is hostname
                abuf->data[abuf->len++] = server->hostname_len;
                memcpy(abuf->data + abuf->len, server->hostname, server->hostname_len);
                abuf->len += server->hostname_len;
                memcpy(abuf->data + abuf->len, &port, 2);
            } else if (AF_INET6 == server->destaddr.ss_family) { // IPv6
                abuf->data[abuf->len++] = 4;          // Type 4 is IPv6 address

                size_t in6_addr_len = sizeof(struct in6_addr);
                memcpy(abuf->data + abuf->len,
                       &(((struct sockaddr_in6 *)&(server->destaddr))->sin6_addr),
                       in6_addr_len);
                abuf->len += in6_addr_len;
                memcpy(abuf->data + abuf->len,
                       &(((struct sockaddr_in6 *)&(server->destaddr))->sin6_port),
                       2);
            } else {                             // IPv4
                abuf->data[abuf->len++] = 1; // Type 1 is IPv4 address

                size_t in_addr_len = sizeof(struct in_addr);
                memcpy(abuf->data + abuf->len,
                       &((struct sockaddr_in *)&(server->destaddr))->sin_addr, in_addr_len);
                abuf->len += in_addr_len;
                memcpy(abuf->data + abuf->len,
                       &((struct sockaddr_in *)&(server->destaddr))->sin_port, 2);
            }

            abuf->len += 2;

            int err = crypto->encrypt(abuf, server->e_ctx, BUF_SIZE);
            if (err) {
                LOGE("invalid password or cipher");
                bfree(abuf);
                close_and_free_remote(EV_A_ remote);
                close_and_free_server(EV_A_ server);
                return;
            }

            err = crypto->encrypt(remote->buf, server->e_ctx, BUF_SIZE);
            if (err) {
                LOGE("invalid password or cipher");
                bfree(abuf);
                close_and_free_remote(EV_A_ remote);
                close_and_free_server(EV_A_ server);
                return;
            }

            bprepend(remote->buf, abuf, BUF_SIZE);
            bfree(abuf);
        } else {
            ERROR("getpeername");
            // not connected
            close_and_free_remote(EV_A_ remote);
            close_and_free_server(EV_A_ server);
            return;
        }
    }

    if (remote->buf->len == 0) {
        // close and free
        close_and_free_remote(EV_A_ remote);
//.........这里部分代码省略.........

static void remote_recv_cb(EV_P_ ev_io *w, int revents)
{
    remote_ctx_t *remote_recv_ctx = (remote_ctx_t *)w;
    remote_t *remote              = remote_recv_ctx->remote;
    server_t *server              = remote->server;

    ev_timer_again(EV_A_ & remote->recv_ctx->watcher);

#ifdef ANDROID
    stat_update_cb(loop);
#endif

    ssize_t r = recv(remote->fd, server->buf->array, BUF_SIZE, 0);

    if (r == 0) {
        // connection closed
        close_and_free_remote(EV_A_ remote);
        close_and_free_server(EV_A_ server);
        return;
    } else if (r < 0) {
        if (errno == EAGAIN || errno == EWOULDBLOCK) {
            // no data
            // continue to wait for recv
            return;
        } else {
            ERROR("remote_recv_cb_recv");
            close_and_free_remote(EV_A_ remote);
            close_and_free_server(EV_A_ server);
            return;
        }
    }

    server->buf->len = r;

    if (!remote->direct) {
#ifdef ANDROID
        rx += server->buf->len;
#endif
        if ( r == 0 )
            return;
        // SSR beg
        if (server->obfs_plugin) {
            obfs_class *obfs_plugin = server->obfs_plugin;
            if (obfs_plugin->client_decode) {
                int needsendback;
                server->buf->len = obfs_plugin->client_decode(server->obfs, &server->buf->array, server->buf->len, &server->buf->capacity, &needsendback);
                if (server->buf->len < 0) {
                    LOGE("client_decode");
                    close_and_free_remote(EV_A_ remote);
                    close_and_free_server(EV_A_ server);
                    return;
                }
            }
        }
        int err = ss_decrypt(server->buf, server->d_ctx);
        if (err) {
            LOGE("remote invalid password or cipher");
            close_and_free_remote(EV_A_ remote);
            close_and_free_server(EV_A_ server);
            return;
        }
        if (server->protocol_plugin) {
            obfs_class *protocol_plugin = server->protocol_plugin;
            if (protocol_plugin->client_post_decrypt) {
                server->buf->len = protocol_plugin->client_post_decrypt(server->protocol, &server->buf->array, server->buf->len, &server->buf->capacity);
                if (server->buf->len < 0) {
                    LOGE("client_post_decrypt");
                    close_and_free_remote(EV_A_ remote);
                    close_and_free_server(EV_A_ server);
                    return;
                }
                if ( server->buf->len == 0 )
                    return;
            }
        }
        // SSR end
    }

    int s = send(server->fd, server->buf->array, server->buf->len, 0);

    if (s == -1) {
        if (errno == EAGAIN || errno == EWOULDBLOCK) {
            // no data, wait for send
            server->buf->idx = 0;
            ev_io_stop(EV_A_ & remote_recv_ctx->io);
            ev_io_start(EV_A_ & server->send_ctx->io);
            return;
        } else {
            ERROR("remote_recv_cb_send");
            close_and_free_remote(EV_A_ remote);
            close_and_free_server(EV_A_ server);
            return;
        }
    } else if (s < server->buf->len) {
        server->buf->len -= s;
        server->buf->idx  = s;
        ev_io_stop(EV_A_ & remote_recv_ctx->io);
        ev_io_start(EV_A_ & server->send_ctx->io);
        return;
    }
//.........这里部分代码省略.........

static void
remote_send_cb(EV_P_ ev_io *w, int revents)
{
    remote_ctx_t *remote_send_ctx = (remote_ctx_t *)w;
    remote_t *remote              = remote_send_ctx->remote;
    server_t *server              = remote->server;

    if (!remote_send_ctx->connected) {
        struct sockaddr_storage addr;
        socklen_t len = sizeof addr;
        int r         = getpeername(remote->fd, (struct sockaddr *)&addr, &len);
        if (r == 0) {
            remote_send_ctx->connected = 1;
            ev_io_stop(EV_A_ & remote_send_ctx->io);
            ev_io_stop(EV_A_ & server->recv_ctx->io);
            ev_timer_stop(EV_A_ & remote_send_ctx->watcher);
            ev_timer_start(EV_A_ & remote->recv_ctx->watcher);

            // send destaddr
            buffer_t ss_addr_to_send;
            buffer_t *abuf = &ss_addr_to_send;
            balloc(abuf, BUF_SIZE);

            if (server->hostname_len > 0) { // HTTP/SNI
                uint16_t port;
                if (AF_INET6 == server->destaddr.ss_family) { // IPv6
                    port = (((struct sockaddr_in6 *)&(server->destaddr))->sin6_port);
                } else {                             // IPv4
                    port = (((struct sockaddr_in *)&(server->destaddr))->sin_port);
                }

                abuf->array[abuf->len++] = 3;          // Type 3 is hostname
                abuf->array[abuf->len++] = server->hostname_len;
                memcpy(abuf->array + abuf->len, server->hostname, server->hostname_len);
                abuf->len += server->hostname_len;
                memcpy(abuf->array + abuf->len, &port, 2);
            } else if (AF_INET6 == server->destaddr.ss_family) { // IPv6
                abuf->array[abuf->len++] = 4;          // Type 4 is IPv6 address

                size_t in6_addr_len = sizeof(struct in6_addr);
                memcpy(abuf->array + abuf->len,
                       &(((struct sockaddr_in6 *)&(server->destaddr))->sin6_addr),
                       in6_addr_len);
                abuf->len += in6_addr_len;
                memcpy(abuf->array + abuf->len,
                       &(((struct sockaddr_in6 *)&(server->destaddr))->sin6_port),
                       2);
            } else {                             // IPv4
                abuf->array[abuf->len++] = 1; // Type 1 is IPv4 address

                size_t in_addr_len = sizeof(struct in_addr);
                memcpy(abuf->array + abuf->len,
                       &((struct sockaddr_in *)&(server->destaddr))->sin_addr, in_addr_len);
                abuf->len += in_addr_len;
                memcpy(abuf->array + abuf->len,
                       &((struct sockaddr_in *)&(server->destaddr))->sin_port, 2);
            }

            abuf->len += 2;

            if (auth) {
                abuf->array[0] |= ONETIMEAUTH_FLAG;
                ss_onetimeauth(abuf, server->e_ctx->evp.iv, BUF_SIZE);
            }

            brealloc(remote->buf, remote->buf->len + abuf->len, BUF_SIZE);
            memmove(remote->buf->array + abuf->len, remote->buf->array, remote->buf->len);
            memcpy(remote->buf->array, abuf->array, abuf->len);
            remote->buf->len += abuf->len;
            bfree(abuf);

            int err = ss_encrypt(remote->buf, server->e_ctx, BUF_SIZE);
            if (err) {
                LOGE("invalid password or cipher");
                close_and_free_remote(EV_A_ remote);
                close_and_free_server(EV_A_ server);
                return;
            }

            ev_io_start(EV_A_ & remote->recv_ctx->io);
        } else {
            ERROR("getpeername");
            // not connected
            close_and_free_remote(EV_A_ remote);
            close_and_free_server(EV_A_ server);
            return;
        }
    }

    if (remote->buf->len == 0) {
        // close and free
        close_and_free_remote(EV_A_ remote);
        close_and_free_server(EV_A_ server);
        return;
    } else {
        // has data to send
        ssize_t s = send(remote->fd, remote->buf->array + remote->buf->idx,
                         remote->buf->len, 0);
        if (s == -1) {
            if (errno != EAGAIN && errno != EWOULDBLOCK) {
//.........这里部分代码省略.........

static void server_recv_cb(EV_P_ ev_io *w, int revents)
{
    struct server_ctx *server_recv_ctx = (struct server_ctx *)w;
    struct server *server = server_recv_ctx->server;
    struct remote *remote = server->remote;

    if (remote == NULL) {
        close_and_free_server(EV_A_ server);
        return;
    }

    ssize_t r = recv(server->fd, remote->buf, BUF_SIZE, 0);

    if (r == 0) {
        // connection closed
        close_and_free_remote(EV_A_ remote);
        close_and_free_server(EV_A_ server);
        return;
    } else if (r < 0) {
        if (errno == EAGAIN || errno == EWOULDBLOCK) {
            // no data
            // continue to wait for recv
            return;
        } else {
            ERROR("server recv");
            close_and_free_remote(EV_A_ remote);
            close_and_free_server(EV_A_ server);
            return;
        }
    }

    if (auth) {
        remote->buf = ss_gen_hash(remote->buf, &r, &remote->counter, server->e_ctx, BUF_SIZE);
    }

    remote->buf = ss_encrypt(BUF_SIZE, remote->buf, &r, server->e_ctx);

    if (remote->buf == NULL) {
        LOGE("invalid password or cipher");
        close_and_free_remote(EV_A_ remote);
        close_and_free_server(EV_A_ server);
        return;
    }

    int s = send(remote->fd, remote->buf, r, 0);

    if (s == -1) {
        if (errno == EAGAIN || errno == EWOULDBLOCK) {
            // no data, wait for send
            remote->buf_len = r;
            remote->buf_idx = 0;
            ev_io_stop(EV_A_ & server_recv_ctx->io);
            ev_io_start(EV_A_ & remote->send_ctx->io);
            return;
        } else {
            ERROR("send");
            close_and_free_remote(EV_A_ remote);
            close_and_free_server(EV_A_ server);
            return;
        }
    } else if (s < r) {
        remote->buf_len = r - s;
        remote->buf_idx = s;
        ev_io_stop(EV_A_ & server_recv_ctx->io);
        ev_io_start(EV_A_ & remote->send_ctx->io);
        return;
    }
}

static void remote_send_cb(EV_P_ ev_io *w, int revents)
{
    struct remote_ctx *remote_send_ctx = (struct remote_ctx *)w;
    struct remote *remote = remote_send_ctx->remote;
    struct server *server = remote->server;

    if (!remote_send_ctx->connected) {
        struct sockaddr_storage addr;
        socklen_t len = sizeof addr;

        int r = getpeername(remote->fd, (struct sockaddr *)&addr, &len);
        if (r == 0) {
            remote_send_ctx->connected = 1;
            ev_io_stop(EV_A_ & remote_send_ctx->io);
            ev_timer_stop(EV_A_ & remote_send_ctx->watcher);
            char *ss_addr_to_send = malloc(BUF_SIZE);
            ssize_t addr_len = 0;

            ss_addr_t *sa = &server->destaddr;
            struct cork_ip ip;
            if (cork_ip_init(&ip, sa->host) != -1) {
                if (ip.version == 4) {
                    // send as IPv4
                    struct in_addr host;
                    int host_len = sizeof(struct in_addr);

                    if (dns_pton(AF_INET, sa->host, &host) == -1) {
                        FATAL("IP parser error");
                    }
                    ss_addr_to_send[addr_len++] = 1;
                    memcpy(ss_addr_to_send + addr_len, &host, host_len);
                    addr_len += host_len;
                } else if (ip.version == 6) {
                    // send as IPv6
                    struct in6_addr host;
                    int host_len = sizeof(struct in6_addr);

                    if (dns_pton(AF_INET6, sa->host, &host) == -1) {
                        FATAL("IP parser error");
                    }
                    ss_addr_to_send[addr_len++] = 4;
                    memcpy(ss_addr_to_send + addr_len, &host, host_len);
                    addr_len += host_len;
                } else {
                    FATAL("IP parser error");
                }
            } else {
                // send as domain
                int host_len = strlen(sa->host);

                ss_addr_to_send[addr_len++] = 3;
                ss_addr_to_send[addr_len++] = host_len;
                memcpy(ss_addr_to_send + addr_len, sa->host, host_len);
                addr_len += host_len;
            }

            uint16_t port = htons(atoi(sa->port));
            memcpy(ss_addr_to_send + addr_len, &port, 2);
            addr_len += 2;

            ss_addr_to_send = ss_encrypt(BUF_SIZE, ss_addr_to_send, &addr_len,
                                         server->e_ctx);
            if (ss_addr_to_send == NULL) {
                LOGE("invalid password or cipher");
                close_and_free_remote(EV_A_ remote);
                close_and_free_server(EV_A_ server);
                return;
            }

            int s = send(remote->fd, ss_addr_to_send, addr_len, 0);
            free(ss_addr_to_send);

            if (s < addr_len) {
                LOGE("failed to send addr");
                close_and_free_remote(EV_A_ remote);
                close_and_free_server(EV_A_ server);
                return;
            }

            ev_io_start(EV_A_ & remote->recv_ctx->io);
            ev_io_start(EV_A_ & server->recv_ctx->io);

            return;
        } else {
            ERROR("getpeername");
            // not connected
            close_and_free_remote(EV_A_ remote);
            close_and_free_server(EV_A_ server);
            return;
        }
    } else {
        if (remote->buf_len == 0) {
            // close and free
            close_and_free_remote(EV_A_ remote);
            close_and_free_server(EV_A_ server);
            return;
        } else {
            // has data to send
            ssize_t s = send(remote->fd, remote->buf + remote->buf_idx,
                             remote->buf_len, 0);
//.........这里部分代码省略.........

static void remote_recv_cb(EV_P_ ev_io *w, int revents)
{
    struct remote_ctx *remote_recv_ctx = (struct remote_ctx *)w;
    struct remote *remote = remote_recv_ctx->remote;
    struct server *server = remote->server;

    ev_timer_again(EV_A_ & remote->recv_ctx->watcher);

    ssize_t r = recv(remote->fd, server->buf, BUF_SIZE, 0);

    if (r == 0) {
        // connection closed
        close_and_free_remote(EV_A_ remote);
        close_and_free_server(EV_A_ server);
        return;
    } else if (r < 0) {
        if (errno == EAGAIN || errno == EWOULDBLOCK) {
            // no data
            // continue to wait for recv
            return;
        } else {
            ERROR("remote_recv_cb_recv");
            close_and_free_remote(EV_A_ remote);
            close_and_free_server(EV_A_ server);
            return;
        }
    }

    if (!remote->direct) {
        server->buf = ss_decrypt(BUF_SIZE, server->buf, &r, server->d_ctx);
        if (server->buf == NULL) {
            LOGE("invalid password or cipher");
            close_and_free_remote(EV_A_ remote);
            close_and_free_server(EV_A_ server);
            return;
        }
    }

    int s = send(server->fd, server->buf, r, 0);

    if (s == -1) {
        if (errno == EAGAIN || errno == EWOULDBLOCK) {
            // no data, wait for send
            server->buf_len = r;
            server->buf_idx = 0;
            ev_io_stop(EV_A_ & remote_recv_ctx->io);
            ev_io_start(EV_A_ & server->send_ctx->io);
            return;
        } else {
            ERROR("remote_recv_cb_send");
            close_and_free_remote(EV_A_ remote);
            close_and_free_server(EV_A_ server);
            return;
        }
    } else if (s < r) {
        server->buf_len = r - s;
        server->buf_idx = s;
        ev_io_stop(EV_A_ & remote_recv_ctx->io);
        ev_io_start(EV_A_ & server->send_ctx->io);
        return;
    }
}

static void server_recv_cb (EV_P_ ev_io *w, int revents)
{
    struct server_ctx *server_recv_ctx = (struct server_ctx *)w;
    struct server *server = server_recv_ctx->server;
    struct remote *remote = server->remote;

    if (remote == NULL)
    {
        close_and_free_server(EV_A_ server);
        return;
    }

    ssize_t r = recv(server-&