ngx_mail_smtp_handler.c

Nginx是一个高性能的HTTP和反向代理服务器

    ngx_mail_session_t  *s;

    c = rev->data;
    s = c->data;

    ngx_log_debug0(NGX_LOG_DEBUG_MAIL, c->log, 0, "smtp auth state");

    if (rev->timedout) {
        ngx_log_error(NGX_LOG_INFO, c->log, NGX_ETIMEDOUT, "client timed out");
        c->timedout = 1;
        ngx_mail_close_connection(c);
        return;
    }

    if (s->out.len) {
        ngx_log_debug0(NGX_LOG_DEBUG_MAIL, c->log, 0, "smtp send handler busy");
        s->blocked = 1;
        return;
    }

    s->blocked = 0;

    rc = ngx_mail_read_command(s, c);

    if (rc == NGX_AGAIN || rc == NGX_ERROR) {
        return;
    }

    s->out.len = sizeof(smtp_ok) - 1;
    s->out.data = smtp_ok;

    if (rc == NGX_OK) {
        switch (s->mail_state) {

        case ngx_smtp_start:

            switch (s->command) {

            case NGX_SMTP_HELO:
            case NGX_SMTP_EHLO:
                rc = ngx_mail_smtp_helo(s, c);
                break;

            case NGX_SMTP_AUTH:
                rc = ngx_mail_smtp_auth(s, c);
                break;

            case NGX_SMTP_QUIT:
                s->quit = 1;
                s->out.len = sizeof(smtp_bye) - 1;
                s->out.data = smtp_bye;
                break;

            case NGX_SMTP_MAIL:
                rc = ngx_mail_smtp_mail(s, c);
                break;

            case NGX_SMTP_NOOP:
            case NGX_SMTP_RSET:
                break;

            case NGX_SMTP_STARTTLS:
                rc = ngx_mail_smtp_starttls(s, c);
                s->out.len = sizeof(smtp_starttls) - 1;
                s->out.data = smtp_starttls;
                break;

            default:
                rc = NGX_MAIL_PARSE_INVALID_COMMAND;
                break;
            }

            break;

        case ngx_smtp_auth_login_username:
            rc = ngx_mail_auth_login_username(s, c);

            s->out.len = sizeof(smtp_password) - 1;
            s->out.data = smtp_password;
            s->mail_state = ngx_smtp_auth_login_password;
            break;

        case ngx_smtp_auth_login_password:
            rc = ngx_mail_auth_login_password(s, c);
            break;

        case ngx_smtp_auth_plain:
            rc = ngx_mail_auth_plain(s, c, 0);
            break;

        case ngx_smtp_auth_cram_md5:
            rc = ngx_mail_auth_cram_md5(s, c);
            break;
        }
    }

    switch (rc) {

    case NGX_DONE:
        ngx_mail_auth(s, c);
        return;

    case NGX_ERROR:
        ngx_mail_session_internal_server_error(s);
        return;

    case NGX_MAIL_PARSE_INVALID_COMMAND:
        s->mail_state = ngx_smtp_start;
        s->state = 0;

        s->out.len = sizeof(smtp_invalid_command) - 1;
        s->out.data = smtp_invalid_command;

        /* fall through */

    case NGX_OK:
        s->args.nelts = 0;
        s->buffer->pos = s->buffer->start;
        s->buffer->last = s->buffer->start;

        if (s->state) {
            s->arg_start = s->buffer->start;
        }

        ngx_mail_send(c->write);
    }
}


static ngx_int_t
ngx_mail_smtp_helo(ngx_mail_session_t *s, ngx_connection_t *c)
{
    ngx_str_t                 *arg;
    ngx_mail_smtp_srv_conf_t  *sscf;

    if (s->args.nelts != 1) {
        s->out.len = sizeof(smtp_invalid_argument) - 1;
        s->out.data = smtp_invalid_argument;
        s->state = 0;
        return NGX_OK;
    }

    arg = s->args.elts;

    s->smtp_helo.len = arg[0].len;

    s->smtp_helo.data = ngx_palloc(c->pool, arg[0].len);
    if (s->smtp_helo.data == NULL) {
        return NGX_ERROR;
    }

    ngx_memcpy(s->smtp_helo.data, arg[0].data, arg[0].len);

    sscf = ngx_mail_get_module_srv_conf(s, ngx_mail_smtp_module);

    if (s->command == NGX_SMTP_HELO) {
        s->out = sscf->server_name;

    } else {
        s->esmtp = 1;

#if (NGX_MAIL_SSL)

        if (c->ssl == NULL) {
            ngx_mail_ssl_conf_t  *sslcf;

            sslcf = ngx_mail_get_module_srv_conf(s, ngx_mail_ssl_module);

            if (sslcf->starttls == NGX_MAIL_STARTTLS_ON) {
                s->out = sscf->starttls_capability;
                return NGX_OK;
            }

            if (sslcf->starttls == NGX_MAIL_STARTTLS_ONLY) {
                s->out = sscf->starttls_only_capability;
                return NGX_OK;
            }
        }
#endif

        s->out = sscf->capability;
    }

    return NGX_OK;
}


static ngx_int_t
ngx_mail_smtp_auth(ngx_mail_session_t *s, ngx_connection_t *c)
{
    ngx_int_t                  rc;
    ngx_mail_core_srv_conf_t  *cscf;
    ngx_mail_smtp_srv_conf_t  *sscf;

#if (NGX_MAIL_SSL)
    if (ngx_mail_starttls_only(s, c)) {
        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }
#endif

    if (s->args.nelts == 0) {
        s->out.len = sizeof(smtp_invalid_argument) - 1;
        s->out.data = smtp_invalid_argument;
        s->state = 0;
        return NGX_OK;
    }

    rc = ngx_mail_auth_parse(s, c);

    switch (rc) {

    case NGX_MAIL_AUTH_LOGIN:

        s->out.len = sizeof(smtp_username) - 1;
        s->out.data = smtp_username;
        s->mail_state = ngx_smtp_auth_login_username;

        return NGX_OK;

    case NGX_MAIL_AUTH_PLAIN:

        s->out.len = sizeof(smtp_next) - 1;
        s->out.data = smtp_next;
        s->mail_state = ngx_smtp_auth_plain;

        return NGX_OK;

    case NGX_MAIL_AUTH_CRAM_MD5:

        sscf = ngx_mail_get_module_srv_conf(s, ngx_mail_smtp_module);

        if (!(sscf->auth_methods & NGX_MAIL_AUTH_CRAM_MD5_ENABLED)) {
            return NGX_MAIL_PARSE_INVALID_COMMAND;
        }

        if (s->salt.data == NULL) {
            cscf = ngx_mail_get_module_srv_conf(s, ngx_mail_core_module);

            if (ngx_mail_salt(s, c, cscf) != NGX_OK) {
                return NGX_ERROR;
            }
        }

        if (ngx_mail_auth_cram_md5_salt(s, c, "334 ", 4) == NGX_OK) {
            s->mail_state = ngx_smtp_auth_cram_md5;
            return NGX_OK;
        }

        return NGX_ERROR;
    }

    return rc;
}


static ngx_int_t
ngx_mail_smtp_mail(ngx_mail_session_t *s, ngx_connection_t *c)
{
    ngx_mail_smtp_log_rejected_command(s, c, "client was rejected: \"%V\"");

    s->out.len = sizeof(smtp_auth_required) - 1;
    s->out.data = smtp_auth_required;

    return NGX_OK;
}


static ngx_int_t
ngx_mail_smtp_starttls(ngx_mail_session_t *s, ngx_connection_t *c)
{
#if (NGX_MAIL_SSL)
    ngx_mail_ssl_conf_t  *sslcf;

    if (c->ssl == NULL) {
        sslcf = ngx_mail_get_module_srv_conf(s, ngx_mail_ssl_module);
        if (sslcf->starttls) {

            /*
             * RFC3207 requires us to discard any knowledge
             * obtained from client before STARTTLS.
             */

            s->smtp_helo.len = 0;
            s->smtp_helo.data = NULL;

            c->read->handler = ngx_mail_starttls_handler;
            return NGX_OK;
        }
    }

#endif

    return NGX_MAIL_PARSE_INVALID_COMMAND;
}


static ngx_int_t
ngx_mail_smtp_discard_command(ngx_mail_session_t *s, ngx_connection_t *c,
    char *err)
{
    ssize_t    n;

    n = c->recv(c, s->buffer->last, s->buffer->end - s->buffer->last);

    if (n == NGX_ERROR || n == 0) {
        ngx_mail_close_connection(c);
        return NGX_ERROR;
    }

    if (n > 0) {
        s->buffer->last += n;
    }

    if (n == NGX_AGAIN) {
        if (ngx_handle_read_event(c->read, 0) == NGX_ERROR) {
            ngx_mail_session_internal_server_error(s);
            return NGX_ERROR;
        }

        return NGX_AGAIN;
    }

    ngx_mail_smtp_log_rejected_command(s, c, err);

    s->buffer->pos = s->buffer->start;
    s->buffer->last = s->buffer->start;

    return NGX_OK;
}


static void
ngx_mail_smtp_log_rejected_command(ngx_mail_session_t *s, ngx_connection_t *c,
    char *err)
{
    u_char      ch;
    ngx_str_t   cmd;
    ngx_uint_t  i;

    if (c->log->log_level < NGX_LOG_INFO) {
        return;
    }

    cmd.len = s->buffer->last - s->buffer->start;
    cmd.data = s->buffer->start;

    for (i = 0; i < cmd.len; i++) {
        ch = cmd.data[i];

        if (ch != CR && ch != LF) {
            continue;
        }

        cmd.data[i] = '_';
    }

    cmd.len = i;

    ngx_log_error(NGX_LOG_INFO, c->log, 0, err, &cmd);
}