new file mode 100644
--- /dev/null
+++ b/src/imap/ngx_imap_auth_http_module.c
@@ -0,0 +1,421 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_event.h>
+#include <ngx_event_connect.h>
+#include <ngx_imap.h>
+
+
+typedef struct {
+    ngx_peers_t            *peers;
+
+    ngx_msec_t              timeout;
+
+    ngx_str_t               host_header;
+    ngx_str_t               uri;
+} ngx_imap_auth_http_conf_t;
+
+
+typedef struct {
+    ngx_buf_t              *request;
+    ngx_peer_connection_t   peer;
+} ngx_imap_auth_http_ctx_t;
+
+
+static void ngx_imap_auth_http_write_handler(ngx_event_t *wev);
+static void ngx_imap_auth_http_read_handler(ngx_event_t *rev);
+static void ngx_imap_auth_http_block_read(ngx_event_t *rev);
+static void ngx_imap_auth_http_dummy_handler(ngx_event_t *ev);
+static ngx_buf_t *ngx_imap_auth_http_create_request(ngx_imap_session_t *s,
+    ngx_imap_auth_http_conf_t *ahcf);
+
+static void *ngx_imap_auth_http_create_conf(ngx_conf_t *cf);
+static char *ngx_imap_auth_http_merge_conf(ngx_conf_t *cf, void *parent,
+    void *child);
+static char *ngx_imap_auth_http(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
+
+
+static ngx_command_t  ngx_imap_auth_http_commands[] = {
+
+    { ngx_string("auth_http"),
+      NGX_IMAP_MAIN_CONF|NGX_IMAP_SRV_CONF|NGX_CONF_TAKE1,
+      ngx_imap_auth_http,
+      NGX_IMAP_SRV_CONF_OFFSET,
+      0,
+      NULL },
+
+    { ngx_string("auth_http_timeout"),
+      NGX_IMAP_MAIN_CONF|NGX_IMAP_SRV_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_msec_slot,
+      NGX_IMAP_SRV_CONF_OFFSET,
+      offsetof(ngx_imap_auth_http_conf_t, timeout),
+      NULL },
+
+      ngx_null_command
+};
+
+
+static ngx_imap_module_t  ngx_imap_auth_http_module_ctx = {
+    NULL,                                  /* create main configuration */
+    NULL,                                  /* init main configuration */
+
+    ngx_imap_auth_http_create_conf,        /* create server configuration */
+    ngx_imap_auth_http_merge_conf          /* merge server configuration */
+};
+
+
+ngx_module_t  ngx_imap_auth_http_module = {
+    NGX_MODULE_V1,
+    &ngx_imap_auth_http_module_ctx,        /* module context */
+    ngx_imap_auth_http_commands,           /* module directives */
+    NGX_IMAP_MODULE,                       /* module type */
+    NULL,                                  /* init module */
+    NULL                                   /* init process */
+};
+
+
+static char *ngx_imap_auth_http_protocol[] = { "pop3", "imap" };
+
+
+void
+ngx_imap_auth_http_init(ngx_imap_session_t *s)
+{
+    ngx_int_t                   rc;
+    ngx_imap_auth_http_ctx_t   *ctx;
+    ngx_imap_auth_http_conf_t  *ahcf;
+
+    ctx = ngx_pcalloc(s->connection->pool, sizeof(ngx_imap_auth_http_ctx_t));
+    if (ctx == NULL) {
+        ngx_imap_close_connection(s->connection);
+        return;
+    }
+
+    ahcf = ngx_imap_get_module_srv_conf(s, ngx_imap_auth_http_module);
+
+    ctx->request = ngx_imap_auth_http_create_request(s, ahcf);
+    if (ctx->request == NULL) {
+        ngx_imap_close_connection(s->connection);
+        return;
+    }
+
+    ngx_imap_set_ctx(s, ctx, ngx_imap_auth_http_module);
+
+    ctx->peer.peers = ahcf->peers;
+    ctx->peer.log = s->connection->log;
+    ctx->peer.log_error = NGX_ERROR_ERR;
+
+    rc = ngx_event_connect_peer(&ctx->peer);
+
+    if (rc == NGX_ERROR) {
+        ngx_imap_close_connection(s->connection);
+        return;
+    }
+
+    ctx->peer.connection->data = s;
+    ctx->peer.connection->pool = s->connection->pool;
+
+    s->connection->read->handler = ngx_imap_auth_http_block_read;
+    ctx->peer.connection->read->handler = ngx_imap_auth_http_read_handler;
+    ctx->peer.connection->write->handler = ngx_imap_auth_http_write_handler;
+
+    if (rc == NGX_OK) {
+        ngx_imap_auth_http_write_handler(ctx->peer.connection->write);
+        return;
+    }
+
+    ngx_add_timer(ctx->peer.connection->read, ahcf->timeout);
+    ngx_add_timer(ctx->peer.connection->write, ahcf->timeout);
+}
+
+
+static void
+ngx_imap_auth_http_write_handler(ngx_event_t *wev)
+{
+    ssize_t                     n, size;
+    ngx_connection_t           *c;
+    ngx_imap_session_t         *s;
+    ngx_imap_auth_http_ctx_t   *ctx;
+    ngx_imap_auth_http_conf_t  *ahcf;
+
+    c = wev->data;
+    s = c->data;
+
+    ctx = ngx_imap_get_module_ctx(s, ngx_imap_auth_http_module);
+
+    ngx_log_debug0(NGX_LOG_DEBUG_IMAP, wev->log, 0,
+                   "imap auth http write handler");
+
+    if (wev->timedout) {  
+        ngx_log_error(NGX_LOG_ERR, wev->log, NGX_ETIMEDOUT,
+                      "auth http server timed out");
+        ngx_imap_close_connection(ctx->peer.connection);
+        ngx_imap_close_connection(s->connection);
+        return;
+    }
+
+    size = ctx->request->last - ctx->request->pos;
+
+    n = ngx_send(c, ctx->request->pos, size);
+
+    if (n == NGX_ERROR) {
+        ngx_imap_close_connection(ctx->peer.connection);
+        ngx_imap_close_connection(s->connection);
+        return;
+    }
+
+    if (n > 0) {
+        ctx->request->pos += n;
+
+        if (n == size) {
+            wev->handler = ngx_imap_auth_http_dummy_handler;
+
+            if (wev->timer_set) {
+                ngx_del_timer(wev);
+            }
+
+            return;
+        }
+    }
+
+    if (!wev->timer_set) {
+        ahcf = ngx_imap_get_module_srv_conf(s, ngx_imap_auth_http_module);
+        ngx_add_timer(wev, ahcf->timeout);
+    }
+}
+
+
+static void
+ngx_imap_auth_http_read_handler(ngx_event_t *rev)
+{
+    ngx_peers_t                *peers;
+    ngx_connection_t          *c;
+    ngx_imap_session_t        *s;
+#if 0
+    ngx_imap_auth_http_ctx_t  *ctx;
+#endif
+
+    c = rev->data;
+    s = c->data;
+
+#if 0
+    ctx = ngx_imap_get_module_ctx(s, ngx_imap_auth_http_module);
+#endif
+
+    ngx_log_debug0(NGX_LOG_DEBUG_IMAP, rev->log, 0,
+                   "imap auth http read handler");
+
+    peers = NULL;
+
+    ngx_imap_proxy_init(s, peers);
+}
+
+
+static void
+ngx_imap_auth_http_block_read(ngx_event_t *rev)
+{
+    ngx_connection_t          *c;
+    ngx_imap_session_t        *s;
+    ngx_imap_auth_http_ctx_t  *ctx;
+
+    ngx_log_debug0(NGX_LOG_DEBUG_IMAP, rev->log, 0,
+                   "imap auth http block read");
+
+    if (ngx_handle_read_event(rev, 0) == NGX_ERROR) {
+        c = rev->data;
+        s = c->data;
+
+        ctx = ngx_imap_get_module_ctx(s, ngx_imap_auth_http_module);
+
+        ngx_imap_close_connection(ctx->peer.connection);
+        ngx_imap_close_connection(s->connection);
+    }
+}
+
+
+static void
+ngx_imap_auth_http_dummy_handler(ngx_event_t *ev)
+{
+    ngx_log_debug0(NGX_LOG_DEBUG_IMAP, ev->log, 0,
+                   "imap auth http dummy handler");
+}
+
+
+static ngx_buf_t *
+ngx_imap_auth_http_create_request(ngx_imap_session_t *s,
+    ngx_imap_auth_http_conf_t *ahcf)
+{
+    size_t      len;
+    ngx_buf_t  *b;
+
+    len = sizeof("GET ") - 1 + ahcf->uri.len + sizeof(" HTTP/1.0" CRLF) - 1
+          + sizeof("Host: ") - 1 + ahcf->host_header.len + sizeof(CRLF) - 1
+          + sizeof("Auth-Method: plain" CRLF) - 1
+          + sizeof("Auth-User: ") - 1 + s->login.len + sizeof(CRLF) - 1
+          + sizeof("Auth-Pass: ") - 1 + s->passwd.len + sizeof(CRLF) - 1
+          + sizeof("Auth-Protocol: imap" CRLF) - 1
+          + sizeof("Client-IP: ") - 1 + s->connection->addr_text.len
+                + sizeof(CRLF) - 1
+          + sizeof(CRLF) - 1;
+
+    b = ngx_create_temp_buf(s->connection->pool, len);
+    if (b == NULL) {
+        return NULL;
+    }
+
+    b->last = ngx_cpymem(b->last, "GET ", sizeof("GET ") - 1);
+    b->last = ngx_cpymem(b->last, ahcf->uri.data, ahcf->uri.len);
+    b->last = ngx_cpymem(b->last, " HTTP/1.0" CRLF,
+                         sizeof(" HTTP/1.0" CRLF) - 1);
+
+    b->last = ngx_cpymem(b->last, "Host: ", sizeof("Host: ") - 1);
+    b->last = ngx_cpymem(b->last, ahcf->host_header.data,
+                         ahcf->host_header.len);
+    *b->last++ = CR; *b->last++ = LF;
+
+    b->last = ngx_cpymem(b->last, "Auth-Method: plain" CRLF,
+                         sizeof("Auth-Method: plain" CRLF) - 1);
+
+    b->last = ngx_cpymem(b->last, "Auth-User: ", sizeof("Auth-User: ") - 1);
+    b->last = ngx_cpymem(b->last, s->login.data, s->login.len);
+    *b->last++ = CR; *b->last++ = LF;
+
+    b->last = ngx_cpymem(b->last, "Auth-Pass: ", sizeof("Auth-Pass: ") - 1);
+    b->last = ngx_cpymem(b->last, s->passwd.data, s->passwd.len);
+    *b->last++ = CR; *b->last++ = LF;
+
+    b->last = ngx_cpymem(b->last, "Auth-Protocol: ",
+                         sizeof("Auth-Protocol: ") - 1);
+    b->last = ngx_cpymem(b->last, ngx_imap_auth_http_protocol[s->protocol],
+                         sizeof("imap") - 1);
+    *b->last++ = CR; *b->last++ = LF;
+
+    b->last = ngx_cpymem(b->last, "Client-IP: ", sizeof("Client-IP: ") - 1);
+    b->last = ngx_cpymem(b->last, s->connection->addr_text.data,
+                         s->connection->addr_text.len);
+    *b->last++ = CR; *b->last++ = LF;
+
+    /* add "\r\n" at the header end */
+    *b->last++ = CR; *b->last++ = LF;
+
+#if (NGX_DEBUG)
+    {
+    ngx_str_t  l;
+
+    l.len = b->last - b->pos;
+    l.data = b->pos;
+    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, s->connection->log, 0,
+                   "imap auth http header:\n\"%V\"", &l);
+    }
+#endif
+
+    return b;
+}
+
+
+static void *
+ngx_imap_auth_http_create_conf(ngx_conf_t *cf)
+{           
+    ngx_imap_auth_http_conf_t  *ahcf;
+            
+    ahcf = ngx_pcalloc(cf->pool, sizeof(ngx_imap_auth_http_conf_t));
+    if (ahcf == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    ahcf->timeout = NGX_CONF_UNSET_MSEC;
+
+    return ahcf;
+}
+
+
+static char *
+ngx_imap_auth_http_merge_conf(ngx_conf_t *cf, void *parent, void *child)
+{
+    ngx_imap_auth_http_conf_t *prev = parent;
+    ngx_imap_auth_http_conf_t *conf = child;
+
+    if (conf->peers == NULL) {
+        conf->peers = prev->peers;
+        conf->host_header = prev->host_header;
+        conf->uri = prev->uri;
+    }
+
+    ngx_conf_merge_msec_value(conf->timeout, prev->timeout, 60000);
+
+    return NGX_CONF_OK;
+}
+
+
+static char *
+ngx_imap_auth_http(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{   
+    ngx_imap_auth_http_conf_t *ahcf = conf;
+
+    ngx_uint_t                   i;
+    ngx_str_t                   *value, *url;
+    ngx_inet_upstream_t          inet_upstream;
+#if (NGX_HAVE_UNIX_DOMAIN)
+    ngx_unix_domain_upstream_t   unix_upstream;
+#endif
+    
+    value = cf->args->elts;
+
+    url = &value[1];
+
+    if (ngx_strncasecmp(url->data, "unix:", 5) == 0) {
+
+#if (NGX_HAVE_UNIX_DOMAIN)
+
+        ngx_memzero(&unix_upstream, sizeof(ngx_unix_domain_upstream_t));
+
+        unix_upstream.name = *url;
+        unix_upstream.url = *url;
+        unix_upstream.uri_part = 1;
+
+        ahcf->peers = ngx_unix_upstream_parse(cf, &unix_upstream);
+        if (ahcf->peers == NULL) {
+            return NGX_CONF_ERROR;
+        }
+
+        ahcf->peers->peer[0].uri_separator = ":";
+
+        ahcf->host_header.len = sizeof("localhost") - 1;
+        ahcf->host_header.data = (u_char *) "localhost";
+        ahcf->uri = unix_upstream.uri;
+    
+#else
+        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                           "the unix domain sockets are not supported "
+                           "on this platform");
+        return NGX_CONF_ERROR;
+    
+#endif
+
+    } else {
+        ngx_memzero(&inet_upstream, sizeof(ngx_inet_upstream_t));
+
+        inet_upstream.name = *url;
+        inet_upstream.url = *url;
+        inet_upstream.default_port_value = 80;
+        inet_upstream.uri_part = 1;
+
+        ahcf->peers = ngx_inet_upstream_parse(cf, &inet_upstream);
+        if (ahcf->peers == NULL) {
+            return NGX_CONF_ERROR;
+        }
+
+        for (i = 0; i < ahcf->peers->number; i++) {
+            ahcf->peers->peer[i].uri_separator = ":";
+        }
+
+        ahcf->host_header = inet_upstream.host_header;
+        ahcf->uri = inet_upstream.uri;
+    }
+
+    return NGX_CONF_OK;
+}