src/submission/cmd-helo.c

/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */

#include "submission-common.h"
#include "str.h"
#include "ostream.h"
#include "smtp-client.h"
#include "smtp-client-connection.h"

#include "submission-commands.h"

/*
 * EHLO, HELO commands
 */

struct cmd_helo_context {
    struct client *client;
    struct smtp_server_cmd_ctx *cmd;
    struct smtp_server_cmd_helo *data;

    struct smtp_client_command *cmd_proxied;
};

static void cmd_helo_update_xclient(struct client *client,
                    struct smtp_server_cmd_helo *data)
{
    struct smtp_proxy_data proxy_data;

    if (!client->set->submission_relay_trusted)
        return;

    i_zero(&proxy_data);
    proxy_data.helo = data->helo.domain;
    proxy_data.proto = (data->helo.old_smtp ?
        SMTP_PROXY_PROTOCOL_SMTP : SMTP_PROXY_PROTOCOL_ESMTP);

    (void)smtp_client_connection_send_xclient
        (client->proxy_conn, &proxy_data);
    client->xclient_sent = TRUE;
}

static void cmd_helo_do_reply(struct client *client,
                  struct smtp_server_cmd_ctx *cmd)
{
    struct cmd_helo_context *helo = cmd->context;
    enum smtp_capability proxy_caps =
        smtp_client_connection_get_capabilities(client->proxy_conn);
    struct smtp_server_reply *reply;
    uoff_t cap_size;

    reply = smtp_server_reply_create_ehlo(cmd->cmd);
    if (!helo->data->helo.old_smtp) {
        string_t *burl_params = t_str_new(256);

        str_append(burl_params, "imap");
        if (*client->set->imap_urlauth_host == '\0' ||
            strcmp(client->set->imap_urlauth_host,
                   URL_HOST_ALLOW_ANY) == 0) {
            str_printfa(burl_params, " imap://%s",
                    client->set->hostname);
        } else {
            str_printfa(burl_params, " imap://%s",
                    client->set->imap_urlauth_host);
        }
        if (client->set->imap_urlauth_port != 143) {
            str_printfa(burl_params, ":%u",
                    client->set->imap_urlauth_port);
        }

        if ((proxy_caps & SMTP_CAPABILITY_8BITMIME) != 0)
            smtp_server_reply_ehlo_add(reply, "8BITMIME");
        smtp_server_reply_ehlo_add(reply, "AUTH");
        if ((proxy_caps & SMTP_CAPABILITY_BINARYMIME) != 0 &&
            (proxy_caps & SMTP_CAPABILITY_CHUNKING) != 0)
            smtp_server_reply_ehlo_add(reply, "BINARYMIME");
        smtp_server_reply_ehlo_add_param(reply,
            "BURL", "%s", str_c(burl_params));
        smtp_server_reply_ehlo_add(reply, "CHUNKING");
        if ((proxy_caps & SMTP_CAPABILITY_DSN) != 0)
            smtp_server_reply_ehlo_add(reply, "DSN");
        smtp_server_reply_ehlo_add(reply,
            "ENHANCEDSTATUSCODES");
        smtp_server_reply_ehlo_add(reply,
            "PIPELINING");

        cap_size = client_get_max_mail_size(client);
        if (cap_size > 0) {
            smtp_server_reply_ehlo_add_param(reply,
                "SIZE", "%"PRIuUOFF_T, cap_size);
        } else {
            smtp_server_reply_ehlo_add(reply, "SIZE");
        }
        smtp_server_reply_ehlo_add(reply, "VRFY");
    }
    smtp_server_reply_submit(reply);
}

static void cmd_helo_reply(struct smtp_server_cmd_ctx *cmd)
{
    struct cmd_helo_context *helo = cmd->context;
    struct client *client = helo->client;

    /* proxy an XCLIENT command */
    if (helo->data->changed)
        cmd_helo_update_xclient(client, helo->data);

    T_BEGIN {
        cmd_helo_do_reply(client, cmd);
    } T_END;
}

static void cmd_helo_proxy_cb(const struct smtp_reply *proxy_reply,
                  struct cmd_helo_context *cmd_helo)
{
    struct smtp_server_cmd_ctx *cmd = cmd_helo->cmd;
    struct client *client = cmd_helo->client;
    struct smtp_reply reply;

    if (!client_command_handle_proxy_reply(client, proxy_reply, &reply))
        return;

    if ((proxy_reply->status / 100) == 2) {
        cmd_helo_reply(cmd);
    } else {
        /* RFC 2034, Section 4:

           These codes must appear in all 2xx, 4xx, and 5xx response
           lines other than initial greeting and any response to HELO
           or EHLO.
         */
        reply.enhanced_code = SMTP_REPLY_ENH_CODE_NONE;
        smtp_server_reply_forward(cmd, &reply);
    }
}

static void cmd_helo_start(struct smtp_server_cmd_ctx *cmd)
{
    struct cmd_helo_context *helo = cmd->context;
    struct client *client = helo->client;

    /* proxy an XCLIENT command */
    if (helo->data->changed)
        cmd_helo_update_xclient(client, helo->data);
}

int cmd_helo(void *conn_ctx, struct smtp_server_cmd_ctx *cmd,
         struct smtp_server_cmd_helo *data)
{
    struct client *client = conn_ctx;
    struct cmd_helo_context *helo;

    helo = p_new(cmd->pool, struct cmd_helo_context, 1);
    helo->client = client;
    helo->cmd = cmd;
    helo->data = data;
    cmd->context = helo;

    if (!data->first || smtp_server_connection_get_state(client->conn)
        >= SMTP_SERVER_STATE_READY) {
        /* this is not the first HELO/EHLO; just proxy a RSET command */
        cmd->hook_next = cmd_helo_start;
        helo->cmd_proxied = smtp_client_command_rset_submit
            (client->proxy_conn, 0, cmd_helo_proxy_cb, helo);
        return 0;
    }

    /* respond right away */
    cmd_helo_reply(cmd);
    return 1;
}