ngx_mail_smtp_handler.c

Nginx是一个高性能的HTTP和反向代理服务器

/*
 * Copyright (C) Igor Sysoev
 */


#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_resolve_addr_handler(ngx_resolver_ctx_t *ctx);
static void ngx_mail_smtp_resolve_name_handler(ngx_resolver_ctx_t *ctx);
static void ngx_mail_smtp_greeting(ngx_mail_session_t *s, ngx_connection_t *c);
static void ngx_mail_smtp_invalid_pipelining(ngx_event_t *rev);
static ngx_int_t ngx_mail_smtp_create_buffer(ngx_mail_session_t *s,
    ngx_connection_t *c);

static ngx_int_t ngx_mail_smtp_helo(ngx_mail_session_t *s, ngx_connection_t *c);
static ngx_int_t ngx_mail_smtp_auth(ngx_mail_session_t *s, ngx_connection_t *c);
static ngx_int_t ngx_mail_smtp_mail(ngx_mail_session_t *s, ngx_connection_t *c);
static ngx_int_t ngx_mail_smtp_starttls(ngx_mail_session_t *s,
    ngx_connection_t *c);

static ngx_int_t ngx_mail_smtp_discard_command(ngx_mail_session_t *s,
    ngx_connection_t *c, char *err);
static void ngx_mail_smtp_log_rejected_command(ngx_mail_session_t *s,
    ngx_connection_t *c, char *err);


static u_char  smtp_ok[] = "250 2.0.0 OK" CRLF;
static u_char  smtp_bye[] = "221 2.0.0 Bye" CRLF;
static u_char  smtp_starttls[] = "220 2.0.0 Start TLS" CRLF;
static u_char  smtp_next[] = "334 " CRLF;
static u_char  smtp_username[] = "334 VXNlcm5hbWU6" CRLF;
static u_char  smtp_password[] = "334 UGFzc3dvcmQ6" CRLF;
static u_char  smtp_invalid_command[] = "500 5.5.1 Invalid command" CRLF;
static u_char  smtp_invalid_pipelining[] =
   "503 5.5.0 Improper use of SMTP command pipelining" CRLF;
static u_char  smtp_invalid_argument[] = "501 5.5.4 Invalid argument" CRLF;
static u_char  smtp_auth_required[] = "530 5.7.1 Authentication required" CRLF;


static ngx_str_t  smtp_unavailable = ngx_string("[UNAVAILABLE]");
static ngx_str_t  smtp_tempunavail = ngx_string("[TEMPUNAVAIL]");


void
ngx_mail_smtp_init_session(ngx_mail_session_t *s, ngx_connection_t *c)
{
    struct sockaddr_in        *sin;
    ngx_resolver_ctx_t        *ctx;
    ngx_mail_core_srv_conf_t  *cscf;

    cscf = ngx_mail_get_module_srv_conf(s, ngx_mail_core_module);

    if (cscf->resolver == NULL) {
        s->host = smtp_unavailable;
        ngx_mail_smtp_greeting(s, c);
        return;
    }

    c->log->action = "in resolving client address";

    ctx = ngx_resolve_start(cscf->resolver, NULL);
    if (ctx == NULL) {
        ngx_mail_close_connection(c);
        return;
    }

    /* AF_INET only */

    sin = (struct sockaddr_in *) c->sockaddr;

    ctx->addr = sin->sin_addr.s_addr;
    ctx->handler = ngx_mail_smtp_resolve_addr_handler;
    ctx->data = s;
    ctx->timeout = cscf->resolver_timeout;

    if (ngx_resolve_addr(ctx) != NGX_OK) {
        ngx_mail_close_connection(c);
    }
}


static void
ngx_mail_smtp_resolve_addr_handler(ngx_resolver_ctx_t *ctx)
{
    ngx_connection_t          *c;
    ngx_mail_session_t        *s;
    ngx_mail_core_srv_conf_t  *cscf;

    s = ctx->data;
    c = s->connection;

    if (ctx->state) {
        ngx_log_error(NGX_LOG_ERR, c->log, 0,
                      "%V could not be resolved (%i: %s)",
                      &c->addr_text, ctx->state,
                      ngx_resolver_strerror(ctx->state));

        if (ctx->state == NGX_RESOLVE_NXDOMAIN) {
            s->host = smtp_unavailable;

        } else {
            s->host = smtp_tempunavail;
        }

        ngx_resolve_addr_done(ctx);

        ngx_mail_smtp_greeting(s, s->connection);

        return;
    }

    c->log->action = "in resolving client hostname";

    s->host.data = ngx_pstrdup(c->pool, &ctx->name);
    if (s->host.data == NULL) {
        ngx_resolve_addr_done(ctx);
        ngx_mail_close_connection(c);
        return;
    }

    s->host.len = ctx->name.len;

    ngx_resolve_addr_done(ctx);

    ngx_log_debug1(NGX_LOG_DEBUG_MAIL, c->log, 0,
                   "address resolved: %V", &s->host);

    cscf = ngx_mail_get_module_srv_conf(s, ngx_mail_core_module);

    ctx = ngx_resolve_start(cscf->resolver, NULL);
    if (ctx == NULL) {
        ngx_mail_close_connection(c);
        return;
    }

    ctx->name = s->host;
    ctx->type = NGX_RESOLVE_A;
    ctx->handler = ngx_mail_smtp_resolve_name_handler;
    ctx->data = s;
    ctx->timeout = cscf->resolver_timeout;

    if (ngx_resolve_name(ctx) != NGX_OK) {
        ngx_mail_close_connection(c);
    }
}


static void
ngx_mail_smtp_resolve_name_handler(ngx_resolver_ctx_t *ctx)
{
    in_addr_t            addr;
    ngx_uint_t           i;
    ngx_connection_t    *c;
    struct sockaddr_in  *sin;
    ngx_mail_session_t  *s;

    s = ctx->data;
    c = s->connection;

    if (ctx->state) {
        ngx_log_error(NGX_LOG_ERR, c->log, 0,
                      "%V could not be resolved (%i: %s)",
                      &ctx->name, ctx->state,
                      ngx_resolver_strerror(ctx->state));

        if (ctx->state == NGX_RESOLVE_NXDOMAIN) {
            s->host = smtp_unavailable;

        } else {
            s->host = smtp_tempunavail;
        }

    } else {

        /* AF_INET only */

        sin = (struct sockaddr_in *) c->sockaddr;

        for (i = 0; i < ctx->naddrs; i++) {

            addr = ctx->addrs[i];

            ngx_log_debug4(NGX_LOG_DEBUG_MAIL, c->log, 0,
                           "name was resolved to %ud.%ud.%ud.%ud",
                           (ntohl(addr) >> 24) & 0xff,
                           (ntohl(addr) >> 16) & 0xff,
                           (ntohl(addr) >> 8) & 0xff,
                           ntohl(addr) & 0xff);

            if (addr == sin->sin_addr.s_addr) {
                goto found;
            }
        }

        s->host = smtp_unavailable;
    }

found:

    ngx_resolve_name_done(ctx);

    ngx_mail_smtp_greeting(s, c);
}


static void
ngx_mail_smtp_greeting(ngx_mail_session_t *s, ngx_connection_t *c)
{
    ngx_msec_t                 timeout;
    ngx_mail_core_srv_conf_t  *cscf;
    ngx_mail_smtp_srv_conf_t  *sscf;

    ngx_log_debug1(NGX_LOG_DEBUG_MAIL, c->log, 0,
                   "smtp greeting for \"%V\"", &s->host);

    cscf = ngx_mail_get_module_srv_conf(s, ngx_mail_core_module);
    sscf = ngx_mail_get_module_srv_conf(s, ngx_mail_smtp_module);

    timeout = sscf->greeting_delay ? sscf->greeting_delay : cscf->timeout;
    ngx_add_timer(c->read, timeout);

    if (ngx_handle_read_event(c->read, 0) == NGX_ERROR) {
        ngx_mail_close_connection(c);
    }

    if (sscf->greeting_delay) {
         c->read->handler = ngx_mail_smtp_invalid_pipelining;
         return;
    }

    c->read->handler = ngx_mail_smtp_init_protocol;

    s->out = sscf->greeting;

    ngx_mail_send(c->write);
}


static void
ngx_mail_smtp_invalid_pipelining(ngx_event_t *rev)
{
    ngx_connection_t          *c;
    ngx_mail_session_t        *s;
    ngx_mail_core_srv_conf_t  *cscf;
    ngx_mail_smtp_srv_conf_t  *sscf;

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

    c->log->action = "in delay pipelining state";

    if (rev->timedout) {

        ngx_log_debug0(NGX_LOG_DEBUG_MAIL, c->log, 0, "delay greeting");

        rev->timedout = 0;

        cscf = ngx_mail_get_module_srv_conf(s, ngx_mail_core_module);

        c->read->handler = ngx_mail_smtp_init_protocol;

        ngx_add_timer(c->read, cscf->timeout);

        if (ngx_handle_read_event(c->read, 0) == NGX_ERROR) {
            ngx_mail_close_connection(c);
            return;
        }

        sscf = ngx_mail_get_module_srv_conf(s, ngx_mail_smtp_module);

        s->out = sscf->greeting;

    } else {

        ngx_log_debug0(NGX_LOG_DEBUG_MAIL, c->log, 0, "invalid pipelining");

        if (s->buffer == NULL) {
            if (ngx_mail_smtp_create_buffer(s, c) != NGX_OK) {
                return;
            }
        }

        if (ngx_mail_smtp_discard_command(s, c,
                                "client was rejected before greeting: \"%V\"")
            != NGX_OK)
        {
            return;
        }

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

    ngx_mail_send(c->write);
}


void
ngx_mail_smtp_init_protocol(ngx_event_t *rev)
{
    ngx_connection_t    *c;
    ngx_mail_session_t  *s;

    c = rev->data;

    c->log->action = "in 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;
    }

    s = c->data;

    if (s->buffer == NULL) {
        if (ngx_mail_smtp_create_buffer(s, c) != NGX_OK) {
            return;
        }
    }

    s->mail_state = ngx_smtp_start;
    c->read->handler = ngx_mail_smtp_auth_state;

    ngx_mail_smtp_auth_state(rev);
}


static ngx_int_t
ngx_mail_smtp_create_buffer(ngx_mail_session_t *s, ngx_connection_t *c)
{
    ngx_mail_smtp_srv_conf_t  *sscf;

    if (ngx_array_init(&s->args, c->pool, 2, sizeof(ngx_str_t)) == NGX_ERROR) {
        ngx_mail_session_internal_server_error(s);
        return NGX_ERROR;
    }

    sscf = ngx_mail_get_module_srv_conf(s, ngx_mail_smtp_module);

    s->buffer = ngx_create_temp_buf(c->pool, sscf->client_buffer_size);
    if (s->buffer == NULL) {
        ngx_mail_session_internal_server_error(s);
        return NGX_ERROR;
    }

    return NGX_OK;
}


void
ngx_mail_smtp_auth_state(ngx_event_t *rev)
{
    ngx_int_t            rc;
    ngx_connection_t    *c;