ngx_mail_proxy_module.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_event_connect.h>
#include <ngx_mail.h>


typedef struct {
    ngx_flag_t  enable;
    ngx_flag_t  pass_error_message;
    ngx_flag_t  xclient;
    size_t      buffer_size;
    ngx_msec_t  timeout;
} ngx_mail_proxy_conf_t;


static void ngx_mail_proxy_block_read(ngx_event_t *rev);
static void ngx_mail_proxy_pop3_handler(ngx_event_t *rev);
static void ngx_mail_proxy_imap_handler(ngx_event_t *rev);
static void ngx_mail_proxy_smtp_handler(ngx_event_t *rev);
static void ngx_mail_proxy_dummy_handler(ngx_event_t *ev);
static ngx_int_t ngx_mail_proxy_read_response(ngx_mail_session_t *s,
    ngx_uint_t state);
static void ngx_mail_proxy_handler(ngx_event_t *ev);
static void ngx_mail_proxy_upstream_error(ngx_mail_session_t *s);
static void ngx_mail_proxy_internal_server_error(ngx_mail_session_t *s);
static void ngx_mail_proxy_close_session(ngx_mail_session_t *s);
static void *ngx_mail_proxy_create_conf(ngx_conf_t *cf);
static char *ngx_mail_proxy_merge_conf(ngx_conf_t *cf, void *parent,
    void *child);


static ngx_command_t  ngx_mail_proxy_commands[] = {

    { ngx_string("proxy"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_proxy_conf_t, enable),
      NULL },

    { ngx_string("proxy_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_proxy_conf_t, buffer_size),
      NULL },

    { ngx_string("proxy_timeout"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_msec_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_proxy_conf_t, timeout),
      NULL },

    { ngx_string("proxy_pass_error_message"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_flag_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_proxy_conf_t, pass_error_message),
      NULL },

    { ngx_string("xclient"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_proxy_conf_t, xclient),
      NULL },

      ngx_null_command
};


static ngx_mail_module_t  ngx_mail_proxy_module_ctx = {
    NULL,                                  /* protocol */

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

    ngx_mail_proxy_create_conf,            /* create server configuration */
    ngx_mail_proxy_merge_conf              /* merge server configuration */
};


ngx_module_t  ngx_mail_proxy_module = {
    NGX_MODULE_V1,
    &ngx_mail_proxy_module_ctx,            /* module context */
    ngx_mail_proxy_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 u_char  smtp_ok[] = "235 2.0.0 OK" CRLF;


void
ngx_mail_proxy_init(ngx_mail_session_t *s, ngx_peer_addr_t *peer)
{
    int                        keepalive;
    ngx_int_t                  rc;
    ngx_mail_proxy_ctx_t      *p;
    ngx_mail_proxy_conf_t     *pcf;
    ngx_mail_core_srv_conf_t  *cscf;

    s->connection->log->action = "connecting to upstream";

    cscf = ngx_mail_get_module_srv_conf(s, ngx_mail_core_module);

    if (cscf->so_keepalive) {
        keepalive = 1;

        if (setsockopt(s->connection->fd, SOL_SOCKET, SO_KEEPALIVE,
                       (const void *) &keepalive, sizeof(int))
                == -1)
        {
            ngx_log_error(NGX_LOG_ALERT, s->connection->log, ngx_socket_errno,
                          "setsockopt(SO_KEEPALIVE) failed");
        }
    }

    p = ngx_pcalloc(s->connection->pool, sizeof(ngx_mail_proxy_ctx_t));
    if (p == NULL) {
        ngx_mail_session_internal_server_error(s);
        return;
    }

    s->proxy = p;

    p->upstream.sockaddr = peer->sockaddr;
    p->upstream.socklen = peer->socklen;
    p->upstream.name = &peer->name;
    p->upstream.get = ngx_event_get_peer;
    p->upstream.log = s->connection->log;
    p->upstream.log_error = NGX_ERROR_ERR;

    rc = ngx_event_connect_peer(&p->upstream);

    if (rc == NGX_ERROR || rc == NGX_BUSY || rc == NGX_DECLINED) {
        ngx_mail_proxy_internal_server_error(s);
        return;
    }

    ngx_add_timer(p->upstream.connection->read, cscf->timeout);

    p->upstream.connection->data = s;
    p->upstream.connection->pool = s->connection->pool;

    s->connection->read->handler = ngx_mail_proxy_block_read;
    p->upstream.connection->write->handler = ngx_mail_proxy_dummy_handler;

    pcf = ngx_mail_get_module_srv_conf(s, ngx_mail_proxy_module);

    s->proxy->buffer = ngx_create_temp_buf(s->connection->pool,
                                           pcf->buffer_size);
    if (s->proxy->buffer == NULL) {
        ngx_mail_proxy_internal_server_error(s);
        return;
    }

    s->out.len = 0;

    switch (s->protocol) {

    case NGX_MAIL_POP3_PROTOCOL:
        p->upstream.connection->read->handler = ngx_mail_proxy_pop3_handler;
        s->mail_state = ngx_pop3_start;
        break;

    case NGX_MAIL_IMAP_PROTOCOL:
        p->upstream.connection->read->handler = ngx_mail_proxy_imap_handler;
        s->mail_state = ngx_imap_start;
        break;

    default: /* NGX_MAIL_SMTP_PROTOCOL */
        p->upstream.connection->read->handler = ngx_mail_proxy_smtp_handler;
        s->mail_state = ngx_smtp_start;
        break;
    }
}


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

    ngx_log_debug0(NGX_LOG_DEBUG_MAIL, rev->log, 0, "mail proxy block read");

    if (ngx_handle_read_event(rev, 0) == NGX_ERROR) {
        c = rev->data;
        s = c->data;

        ngx_mail_proxy_close_session(s);
    }
}


static void
ngx_mail_proxy_pop3_handler(ngx_event_t *rev)
{
    u_char                 *p;
    ngx_int_t               rc;
    ngx_str_t               line;
    ngx_connection_t       *c;
    ngx_mail_session_t     *s;
    ngx_mail_proxy_conf_t  *pcf;

    ngx_log_debug0(NGX_LOG_DEBUG_MAIL, rev->log, 0,
                   "mail proxy pop3 auth handler");

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

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

    rc = ngx_mail_proxy_read_response(s, 0);

    if (rc == NGX_AGAIN) {
        return;
    }

    if (rc == NGX_ERROR) {
        ngx_mail_proxy_upstream_error(s);
        return;
    }

    switch (s->mail_state) {

    case ngx_pop3_start:
        ngx_log_debug0(NGX_LOG_DEBUG_MAIL, rev->log, 0, "mail proxy send user");

        s->connection->log->action = "sending user name to upstream";

        line.len = sizeof("USER ")  - 1 + s->login.len + 2;
        line.data = ngx_palloc(c->pool, line.len);
        if (line.data == NULL) {
            ngx_mail_proxy_internal_server_error(s);
            return;
        }

        p = ngx_cpymem(line.data, "USER ", sizeof("USER ") - 1);
        p = ngx_cpymem(p, s->login.data, s->login.len);
        *p++ = CR; *p = LF;

        s->mail_state = ngx_pop3_user;
        break;

    case ngx_pop3_user:
        ngx_log_debug0(NGX_LOG_DEBUG_MAIL, rev->log, 0, "mail proxy send pass");

        s->connection->log->action = "sending password to upstream";

        line.len = sizeof("PASS ")  - 1 + s->passwd.len + 2;
        line.data = ngx_palloc(c->pool, line.len);
        if (line.data == NULL) {
            ngx_mail_proxy_internal_server_error(s);
            return;
        }

        p = ngx_cpymem(line.data, "PASS ", sizeof("PASS ") - 1);
        p = ngx_cpymem(p, s->passwd.data, s->passwd.len);
        *p++ = CR; *p = LF;

        s->mail_state = ngx_pop3_passwd;
        break;

    case ngx_pop3_passwd:
        s->connection->read->handler = ngx_mail_proxy_handler;
        s->connection->write->handler = ngx_mail_proxy_handler;
        rev->handler = ngx_mail_proxy_handler;
        c->write->handler = ngx_mail_proxy_handler;

        pcf = ngx_mail_get_module_srv_conf(s, ngx_mail_proxy_module);
        ngx_add_timer(s->connection->read, pcf->timeout);
        ngx_del_timer(c->read);

        c->log->action = NULL;
        ngx_log_error(NGX_LOG_INFO, c->log, 0, "client logged in");

        ngx_mail_proxy_handler(s->connection->write);

        return;

    default:
#if (NGX_SUPPRESS_WARN)
        line.len = 0;
        line.data = NULL;
#endif
        break;
    }

    if (c->send(c, line.data, line.len) < (ssize_t) line.len) {
        /*
         * we treat the incomplete sending as NGX_ERROR
         * because it is very strange here
         */
        ngx_mail_proxy_internal_server_error(s);
        return;
    }

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


static void
ngx_mail_proxy_imap_handler(ngx_event_t *rev)
{
    u_char                 *p;
    ngx_int_t               rc;
    ngx_str_t               line;
    ngx_connection_t       *c;
    ngx_mail_session_t     *s;
    ngx_mail_proxy_conf_t  *pcf;

    ngx_log_debug0(NGX_LOG_DEBUG_MAIL, rev->log, 0,
                   "mail proxy imap auth handler");

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

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

    rc = ngx_mail_proxy_read_response(s, s->mail_state);

    if (rc == NGX_AGAIN) {
        return;
    }

    if (rc == NGX_ERROR) {
        ngx_mail_proxy_upstream_error(s);
        return;
    }

    switch (s->mail_state) {

    case ngx_imap_start:
        ngx_log_debug0(NGX_LOG_DEBUG_MAIL, rev->log, 0,
                       "mail proxy send login");

        s->connection->log->action = "sending LOGIN command to upstream";

        line.len = s->tag.len + sizeof("LOGIN ") - 1
                   + 1 + NGX_SIZE_T_LEN + 1 + 2;
        line.data = ngx_palloc(c->pool, line.len);
        if (line.data == NULL) {
            ngx_mail_proxy_internal_server_error(s);
            return;
        }

        line.len = ngx_sprintf(line.data, "%VLOGIN {%uz}" CRLF,
                               &s->tag, s->login.len)
                   - line.data;

        s->mail_state = ngx_imap_login;
        break;

    case ngx_imap_login:
        ngx_log_debug0(NGX_LOG_DEBUG_MAIL, rev->log, 0, "mail proxy send user");

        s->connection->log->action = "sending user name to upstream";

        line.len = s->login.len + 1 + 1 + NGX_SIZE_T_LEN + 1 + 2;
        line.data = ngx_palloc(c->pool, line.len);
        if (line.data == NULL) {
            ngx_mail_proxy_internal_server_error(s);
            return;
        }

        line.len = ngx_sprintf(line.data, "%V {%uz}" CRLF,
                               &s->login, s->passwd.len)
                   - line.data;

        s->mail_state = ngx_imap_user;
        break;

    case ngx_imap_user:
        ngx_log_debug0(NGX_LOG_DEBUG_MAIL, rev->log, 0,
                       "mail proxy send passwd");

        s->connection->log->action = "sending password to upstream";

        line.len = s->passwd.len + 2;
        line.data = ngx_palloc(c->pool, line.len);
        if (line.data == NULL) {
            ngx_mail_proxy_internal_server_error(s);
            return;
        }

        p = ngx_cpymem(line.data, s->passwd.data, s->passwd.len);
        *p++ = CR; *p = LF;

        s->mail_state = ngx_imap_passwd;
        break;

    case ngx_imap_passwd:
        s->connection->read->handler = ngx_mail_proxy_handler;
        s->connection->write->handler = ngx_mail_proxy_handler;
        rev->handler = ngx_mail_proxy_handler;
        c->write->handler = ngx_mail_proxy_handler;

        pcf = ngx_mail_get_module_srv_conf(s, ngx_mail_proxy_module);
        ngx_add_timer(s->connection->read, pcf->timeout);
        ngx_del_timer(c->read);

        c->log->action = NULL;
        ngx_log_error(NGX_LOG_INFO, c->log, 0, "client logged in");

        ngx_mail_proxy_handler(s->connection->write);

        return;

    default:
#if (NGX_SUPPRESS_WARN)
        line.len = 0;
        line.data = NULL;
#endif
        break;
    }

    if (c->send(c, line.data, line.len) < (ssize_t) line.len) {
        /*
         * we treat the incomplete sending as NGX_ERROR
         * because it is very strange here
         */
        ngx_mail_proxy_internal_server_error(s);
        return;
    }

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


static void
ngx_mail_proxy_smtp_handler(ngx_event_t *rev)
{
    u_char                    *p;
    ngx_int_t                  rc;
    ngx_str_t                  line;
    ngx_connection_t          *c;
    ngx_mail_session_t        *s;
    ngx_mail_proxy_conf_t     *pcf;
    ngx_mail_core_srv_conf_t  *cscf;

    ngx_log_debug0(NGX_LOG_DEBUG_MAIL, rev->log, 0,
                   "mail proxy smtp auth handler");

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

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

    rc = ngx_mail_proxy_read_response(s, s->mail_state);

    if (rc == NGX_AGAIN) {
        return;
    }

    if (rc == NGX_ERROR) {
        ngx_mail_proxy_upstream_error(s);
        return;
    }

    switch (s->mail_state) {

    case ngx_smtp_start: