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view src/mail/ngx_mail_smtp_module.c @ 7851:aa5f8825f24d

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Resolver: fixed label types handling in ngx_resolver_copy(). Previously, anything with any of the two high bits set were interpreted as compression pointers. This is incorrect, as RFC 1035 clearly states that "The 10 and 01 combinations are reserved for future use". Further, the 01 combination is actually allocated for EDNS extended label type (see RFC 2671 and RFC 6891), not really used though. Fix is to reject unrecognized label types rather than misinterpreting them as compression pointers.
author Maxim Dounin <mdounin@mdounin.ru>
date Tue, 25 May 2021 15:17:41 +0300
parents f18c285c2e59
children dc955d274130
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>
#include <ngx_mail.h>
#include <ngx_mail_smtp_module.h>


static void *ngx_mail_smtp_create_srv_conf(ngx_conf_t *cf);
static char *ngx_mail_smtp_merge_srv_conf(ngx_conf_t *cf, void *parent,
    void *child);


static ngx_conf_bitmask_t  ngx_mail_smtp_auth_methods[] = {
    { ngx_string("plain"), NGX_MAIL_AUTH_PLAIN_ENABLED },
    { ngx_string("login"), NGX_MAIL_AUTH_LOGIN_ENABLED },
    { ngx_string("cram-md5"), NGX_MAIL_AUTH_CRAM_MD5_ENABLED },
    { ngx_string("external"), NGX_MAIL_AUTH_EXTERNAL_ENABLED },
    { ngx_string("none"), NGX_MAIL_AUTH_NONE_ENABLED },
    { ngx_null_string, 0 }
};


static ngx_str_t  ngx_mail_smtp_auth_methods_names[] = {
    ngx_string("PLAIN"),
    ngx_string("LOGIN"),
    ngx_null_string,  /* APOP */
    ngx_string("CRAM-MD5"),
    ngx_string("EXTERNAL"),
    ngx_null_string   /* NONE */
};


static ngx_mail_protocol_t  ngx_mail_smtp_protocol = {
    ngx_string("smtp"),
    { 25, 465, 587, 0 },
    NGX_MAIL_SMTP_PROTOCOL,

    ngx_mail_smtp_init_session,
    ngx_mail_smtp_init_protocol,
    ngx_mail_smtp_parse_command,
    ngx_mail_smtp_auth_state,

    ngx_string("451 4.3.2 Internal server error" CRLF),
    ngx_string("421 4.7.1 SSL certificate error" CRLF),
    ngx_string("421 4.7.1 No required SSL certificate" CRLF)
};


static ngx_command_t  ngx_mail_smtp_commands[] = {

    { ngx_string("smtp_client_buffer"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_size_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_smtp_srv_conf_t, client_buffer_size),
      NULL },

    { ngx_string("smtp_greeting_delay"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_msec_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_smtp_srv_conf_t, greeting_delay),
      NULL },

    { ngx_string("smtp_capabilities"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_1MORE,
      ngx_mail_capabilities,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_smtp_srv_conf_t, capabilities),
      NULL },

    { ngx_string("smtp_auth"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_1MORE,
      ngx_conf_set_bitmask_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_smtp_srv_conf_t, auth_methods),
      &ngx_mail_smtp_auth_methods },

      ngx_null_command
};


static ngx_mail_module_t  ngx_mail_smtp_module_ctx = {
    &ngx_mail_smtp_protocol,               /* protocol */

    NULL,                                  /* create main configuration */
    NULL,                                  /* init main configuration */

    ngx_mail_smtp_create_srv_conf,         /* create server configuration */
    ngx_mail_smtp_merge_srv_conf           /* merge server configuration */
};


ngx_module_t  ngx_mail_smtp_module = {
    NGX_MODULE_V1,
    &ngx_mail_smtp_module_ctx,             /* module context */
    ngx_mail_smtp_commands,                /* module directives */
    NGX_MAIL_MODULE,                       /* module type */
    NULL,                                  /* init master */
    NULL,                                  /* init module */
    NULL,                                  /* init process */
    NULL,                                  /* init thread */
    NULL,                                  /* exit thread */
    NULL,                                  /* exit process */
    NULL,                                  /* exit master */
    NGX_MODULE_V1_PADDING
};


static void *
ngx_mail_smtp_create_srv_conf(ngx_conf_t *cf)
{
    ngx_mail_smtp_srv_conf_t  *sscf;

    sscf = ngx_pcalloc(cf->pool, sizeof(ngx_mail_smtp_srv_conf_t));
    if (sscf == NULL) {
        return NULL;
    }

    sscf->client_buffer_size = NGX_CONF_UNSET_SIZE;
    sscf->greeting_delay = NGX_CONF_UNSET_MSEC;

    if (ngx_array_init(&sscf->capabilities, cf->pool, 4, sizeof(ngx_str_t))
        != NGX_OK)
    {
        return NULL;
    }

    return sscf;
}


static char *
ngx_mail_smtp_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
{
    ngx_mail_smtp_srv_conf_t *prev = parent;
    ngx_mail_smtp_srv_conf_t *conf = child;

    u_char                    *p, *auth, *last;
    size_t                     size;
    ngx_str_t                 *c;
    ngx_uint_t                 i, m, auth_enabled;
    ngx_mail_core_srv_conf_t  *cscf;

    ngx_conf_merge_size_value(conf->client_buffer_size,
                              prev->client_buffer_size,
                              (size_t) ngx_pagesize);

    ngx_conf_merge_msec_value(conf->greeting_delay,
                              prev->greeting_delay, 0);

    ngx_conf_merge_bitmask_value(conf->auth_methods,
                              prev->auth_methods,
                              (NGX_CONF_BITMASK_SET
                               |NGX_MAIL_AUTH_PLAIN_ENABLED
                               |NGX_MAIL_AUTH_LOGIN_ENABLED));


    cscf = ngx_mail_conf_get_module_srv_conf(cf, ngx_mail_core_module);

    size = sizeof("220  ESMTP ready" CRLF) - 1 + cscf->server_name.len;

    p = ngx_pnalloc(cf->pool, size);
    if (p == NULL) {
        return NGX_CONF_ERROR;
    }

    conf->greeting.len = size;
    conf->greeting.data = p;

    *p++ = '2'; *p++ = '2'; *p++ = '0'; *p++ = ' ';
    p = ngx_cpymem(p, cscf->server_name.data, cscf->server_name.len);
    ngx_memcpy(p, " ESMTP ready" CRLF, sizeof(" ESMTP ready" CRLF) - 1);


    size = sizeof("250 " CRLF) - 1 + cscf->server_name.len;

    p = ngx_pnalloc(cf->pool, size);
    if (p == NULL) {
        return NGX_CONF_ERROR;
    }

    conf->server_name.len = size;
    conf->server_name.data = p;

    *p++ = '2'; *p++ = '5'; *p++ = '0'; *p++ = ' ';
    p = ngx_cpymem(p, cscf->server_name.data, cscf->server_name.len);
    *p++ = CR; *p = LF;


    if (conf->capabilities.nelts == 0) {
        conf->capabilities = prev->capabilities;
    }

    size = sizeof("250-") - 1 + cscf->server_name.len + sizeof(CRLF) - 1;

    c = conf->capabilities.elts;
    for (i = 0; i < conf->capabilities.nelts; i++) {
        size += sizeof("250 ") - 1 + c[i].len + sizeof(CRLF) - 1;
    }

    auth_enabled = 0;

    for (m = NGX_MAIL_AUTH_PLAIN_ENABLED, i = 0;
         m <= NGX_MAIL_AUTH_EXTERNAL_ENABLED;
         m <<= 1, i++)
    {
        if (m & conf->auth_methods) {
            size += 1 + ngx_mail_smtp_auth_methods_names[i].len;
            auth_enabled = 1;
        }
    }

    if (auth_enabled) {
        size += sizeof("250 AUTH") - 1 + sizeof(CRLF) - 1;
    }

    p = ngx_pnalloc(cf->pool, size);
    if (p == NULL) {
        return NGX_CONF_ERROR;
    }

    conf->capability.len = size;
    conf->capability.data = p;

    last = p;

    *p++ = '2'; *p++ = '5'; *p++ = '0'; *p++ = '-';
    p = ngx_cpymem(p, cscf->server_name.data, cscf->server_name.len);
    *p++ = CR; *p++ = LF;

    for (i = 0; i < conf->capabilities.nelts; i++) {
        last = p;
        *p++ = '2'; *p++ = '5'; *p++ = '0'; *p++ = '-';
        p = ngx_cpymem(p, c[i].data, c[i].len);
        *p++ = CR; *p++ = LF;
    }

    auth = p;

    if (auth_enabled) {
        last = p;

        *p++ = '2'; *p++ = '5'; *p++ = '0'; *p++ = ' ';
        *p++ = 'A'; *p++ = 'U'; *p++ = 'T'; *p++ = 'H';

        for (m = NGX_MAIL_AUTH_PLAIN_ENABLED, i = 0;
             m <= NGX_MAIL_AUTH_EXTERNAL_ENABLED;
             m <<= 1, i++)
        {
            if (m & conf->auth_methods) {
                *p++ = ' ';
                p = ngx_cpymem(p, ngx_mail_smtp_auth_methods_names[i].data,
                               ngx_mail_smtp_auth_methods_names[i].len);
            }
        }

        *p++ = CR; *p = LF;

    } else {
        last[3] = ' ';
    }

    size += sizeof("250 STARTTLS" CRLF) - 1;

    p = ngx_pnalloc(cf->pool, size);
    if (p == NULL) {
        return NGX_CONF_ERROR;
    }

    conf->starttls_capability.len = size;
    conf->starttls_capability.data = p;

    p = ngx_cpymem(p, conf->capability.data, conf->capability.len);

    ngx_memcpy(p, "250 STARTTLS" CRLF, sizeof("250 STARTTLS" CRLF) - 1);

    p = conf->starttls_capability.data
        + (last - conf->capability.data) + 3;
    *p = '-';

    size = (auth - conf->capability.data)
            + sizeof("250 STARTTLS" CRLF) - 1;

    p = ngx_pnalloc(cf->pool, size);
    if (p == NULL) {
        return NGX_CONF_ERROR;
    }

    conf->starttls_only_capability.len = size;
    conf->starttls_only_capability.data = p;

    p = ngx_cpymem(p, conf->capability.data, auth - conf->capability.data);

    ngx_memcpy(p, "250 STARTTLS" CRLF, sizeof("250 STARTTLS" CRLF) - 1);

    if (last < auth) {
        p = conf->starttls_only_capability.data
            + (last - conf->capability.data) + 3;
        *p = '-';
    }

    return NGX_CONF_OK;
}