new file mode 100644
--- /dev/null
+++ b/src/mail/ngx_mail_pop3_handler.c
@@ -0,0 +1,501 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_event.h>
+#include <ngx_mail.h>
+#include <ngx_mail_pop3_module.h>
+
+
+static ngx_int_t ngx_mail_pop3_user(ngx_mail_session_t *s, ngx_connection_t *c);
+static ngx_int_t ngx_mail_pop3_pass(ngx_mail_session_t *s, ngx_connection_t *c);
+static ngx_int_t ngx_mail_pop3_capa(ngx_mail_session_t *s, ngx_connection_t *c,
+    ngx_int_t stls);
+static ngx_int_t ngx_mail_pop3_stls(ngx_mail_session_t *s, ngx_connection_t *c);
+static ngx_int_t ngx_mail_pop3_apop(ngx_mail_session_t *s, ngx_connection_t *c);
+static ngx_int_t ngx_mail_pop3_auth(ngx_mail_session_t *s, ngx_connection_t *c);
+
+
+static u_char  pop3_greeting[] = "+OK POP3 ready" CRLF;
+static u_char  pop3_ok[] = "+OK" CRLF;
+static u_char  pop3_next[] = "+ " CRLF;
+static u_char  pop3_username[] = "+ VXNlcm5hbWU6" CRLF;
+static u_char  pop3_password[] = "+ UGFzc3dvcmQ6" CRLF;
+static u_char  pop3_invalid_command[] = "-ERR invalid command" CRLF;
+
+
+void
+ngx_mail_pop3_init_session(ngx_mail_session_t *s, ngx_connection_t *c)
+{
+    u_char                    *p;
+    ngx_mail_core_srv_conf_t  *cscf;
+    ngx_mail_pop3_srv_conf_t  *pscf;
+
+    pscf = ngx_mail_get_module_srv_conf(s, ngx_mail_pop3_module);
+    cscf = ngx_mail_get_module_srv_conf(s, ngx_mail_core_module);
+
+    if (pscf->auth_methods
+        & (NGX_MAIL_AUTH_APOP_ENABLED|NGX_MAIL_AUTH_CRAM_MD5_ENABLED))
+    {
+        if (ngx_mail_salt(s, c, cscf) != NGX_OK) {
+            ngx_mail_session_internal_server_error(s);
+            return;
+        }
+
+        s->out.data = ngx_palloc(c->pool, sizeof(pop3_greeting) + s->salt.len);
+        if (s->out.data == NULL) {
+            ngx_mail_session_internal_server_error(s);
+            return;
+        }
+
+        p = ngx_cpymem(s->out.data, pop3_greeting, sizeof(pop3_greeting) - 3);
+        *p++ = ' ';
+        p = ngx_cpymem(p, s->salt.data, s->salt.len);
+
+        s->out.len = p - s->out.data;
+
+    } else {
+        s->out.len = sizeof(pop3_greeting) - 1;
+        s->out.data = pop3_greeting;
+    }
+
+    c->read->handler = ngx_mail_pop3_init_protocol;
+
+    ngx_add_timer(c->read, cscf->timeout);
+
+    if (ngx_handle_read_event(c->read, 0) == NGX_ERROR) {
+        ngx_mail_close_connection(c);
+    }
+
+    ngx_mail_send(c->write);
+}
+
+
+void
+ngx_mail_pop3_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_array_init(&s->args, c->pool, 2, sizeof(ngx_str_t))
+            == NGX_ERROR)
+        {
+            ngx_mail_session_internal_server_error(s);
+            return;
+        }
+
+        s->buffer = ngx_create_temp_buf(c->pool, 128);
+        if (s->buffer == NULL) {
+            ngx_mail_session_internal_server_error(s);
+            return;
+        }
+    }
+
+    s->mail_state = ngx_pop3_start;
+    c->read->handler = ngx_mail_pop3_auth_state;
+
+    ngx_mail_pop3_auth_state(rev);
+}
+
+
+void
+ngx_mail_pop3_auth_state(ngx_event_t *rev)
+{
+    ngx_int_t            rc;
+    ngx_connection_t    *c;
+    ngx_mail_session_t  *s;
+
+    c = rev->data;
+    s = c->data;
+
+    ngx_log_debug0(NGX_LOG_DEBUG_MAIL, c->log, 0, "pop3 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, "pop3 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(pop3_ok) - 1;
+    s->out.data = pop3_ok;
+
+    if (rc == NGX_OK) {
+        switch (s->mail_state) {
+
+        case ngx_pop3_start:
+
+            switch (s->command) {
+
+            case NGX_POP3_USER:
+                rc = ngx_mail_pop3_user(s, c);
+                break;
+
+            case NGX_POP3_CAPA:
+                rc = ngx_mail_pop3_capa(s, c, 1);
+                break;
+
+            case NGX_POP3_APOP:
+                rc = ngx_mail_pop3_apop(s, c);
+                break;
+
+            case NGX_POP3_AUTH:
+                rc = ngx_mail_pop3_auth(s, c);
+                break;
+
+            case NGX_POP3_QUIT:
+                s->quit = 1;
+                break;
+
+            case NGX_POP3_NOOP:
+                break;
+
+            case NGX_POP3_STLS:
+                rc = ngx_mail_pop3_stls(s, c);
+                break;
+
+            default:
+                rc = NGX_MAIL_PARSE_INVALID_COMMAND;
+                s->mail_state = ngx_pop3_start;
+                break;
+            }
+
+            break;
+
+        case ngx_pop3_user:
+
+            switch (s->command) {
+
+            case NGX_POP3_PASS:
+                rc = ngx_mail_pop3_pass(s, c);
+                break;
+
+            case NGX_POP3_CAPA:
+                rc = ngx_mail_pop3_capa(s, c, 0);
+                break;
+
+            case NGX_POP3_QUIT:
+                s->quit = 1;
+                break;
+
+            case NGX_POP3_NOOP:
+                break;
+
+            default:
+                rc = NGX_MAIL_PARSE_INVALID_COMMAND;
+                s->mail_state = ngx_pop3_start;
+                break;
+            }
+
+            break;
+
+        /* suppress warinings */
+        case ngx_pop3_passwd:
+            break;
+
+        case ngx_pop3_auth_login_username:
+            rc = ngx_mail_auth_login_username(s, c);
+
+            s->out.len = sizeof(pop3_password) - 1;
+            s->out.data = pop3_password;
+            s->mail_state = ngx_pop3_auth_login_password;
+            break;
+
+        case ngx_pop3_auth_login_password:
+            rc = ngx_mail_auth_login_password(s, c);
+            break;
+
+        case ngx_pop3_auth_plain:
+            rc = ngx_mail_auth_plain(s, c, 0);
+            break;
+
+        case ngx_pop3_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_pop3_start;
+        s->state = 0;
+
+        s->out.len = sizeof(pop3_invalid_command) - 1;
+        s->out.data = pop3_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_pop3_user(ngx_mail_session_t *s, ngx_connection_t *c)
+{
+    ngx_str_t            *arg;
+
+#if (NGX_MAIL_SSL)
+    if (ngx_mail_starttls_only(s, c)) {
+        return NGX_MAIL_PARSE_INVALID_COMMAND;
+    }
+#endif
+
+    if (s->args.nelts != 1) {
+        return NGX_MAIL_PARSE_INVALID_COMMAND;
+    }
+
+    arg = s->args.elts;
+    s->login.len = arg[0].len;
+    s->login.data = ngx_palloc(c->pool, s->login.len);
+    if (s->login.data == NULL) {
+        return NGX_ERROR;
+    }
+
+    ngx_memcpy(s->login.data, arg[0].data, s->login.len);
+
+    ngx_log_debug1(NGX_LOG_DEBUG_MAIL, c->log, 0,
+                   "pop3 login: \"%V\"", &s->login);
+
+    s->mail_state = ngx_pop3_user;
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_mail_pop3_pass(ngx_mail_session_t *s, ngx_connection_t *c)
+{
+    ngx_str_t  *arg;
+
+    if (s->args.nelts != 1) {
+        return NGX_MAIL_PARSE_INVALID_COMMAND;
+    }
+
+    arg = s->args.elts;
+    s->passwd.len = arg[0].len;
+    s->passwd.data = ngx_palloc(c->pool, s->passwd.len);
+    if (s->passwd.data == NULL) {
+        return NGX_ERROR;
+    }
+
+    ngx_memcpy(s->passwd.data, arg[0].data, s->passwd.len);
+
+#if (NGX_DEBUG_MAIL_PASSWD)
+    ngx_log_debug1(NGX_LOG_DEBUG_MAIL, c->log, 0,
+                   "pop3 passwd: \"%V\"", &s->passwd);
+#endif
+
+    return NGX_DONE;
+}
+
+
+static ngx_int_t
+ngx_mail_pop3_capa(ngx_mail_session_t *s, ngx_connection_t *c, ngx_int_t stls)
+{
+    ngx_mail_pop3_srv_conf_t  *pscf;
+#if (NGX_MAIL_SSL)
+    ngx_mail_ssl_conf_t       *sslcf;
+#endif
+
+    pscf = ngx_mail_get_module_srv_conf(s, ngx_mail_pop3_module);
+
+#if (NGX_MAIL_SSL)
+
+    if (stls && c->ssl == NULL) {
+        sslcf = ngx_mail_get_module_srv_conf(s, ngx_mail_ssl_module);
+
+        if (sslcf->starttls == NGX_MAIL_STARTTLS_ON) {
+            s->out = pscf->starttls_capability;
+            return NGX_OK;
+        }
+
+        if (sslcf->starttls == NGX_MAIL_STARTTLS_ONLY) {
+            s->out = pscf->starttls_only_capability;
+            return NGX_OK;
+        }
+    }
+
+#endif
+
+    s->out = pscf->capability;
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_mail_pop3_stls(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) {
+            c->read->handler = ngx_mail_starttls_handler;
+            return NGX_OK;
+        }
+    }
+
+#endif
+
+    return NGX_MAIL_PARSE_INVALID_COMMAND;
+}
+
+
+static ngx_int_t
+ngx_mail_pop3_apop(ngx_mail_session_t *s, ngx_connection_t *c)
+{
+    ngx_str_t                 *arg;
+    ngx_mail_pop3_srv_conf_t  *pscf;
+
+#if (NGX_MAIL_SSL)
+    if (ngx_mail_starttls_only(s, c)) {
+        return NGX_MAIL_PARSE_INVALID_COMMAND;
+    }
+#endif
+
+    if (s->args.nelts != 2) {
+        return NGX_MAIL_PARSE_INVALID_COMMAND;
+    }
+
+    pscf = ngx_mail_get_module_srv_conf(s, ngx_mail_pop3_module);
+
+    if (!(pscf->auth_methods & NGX_MAIL_AUTH_APOP_ENABLED)) {
+        return NGX_MAIL_PARSE_INVALID_COMMAND;
+    }
+
+    arg = s->args.elts;
+
+    s->login.len = arg[0].len;
+    s->login.data = ngx_palloc(c->pool, s->login.len);
+    if (s->login.data == NULL) {
+        return NGX_ERROR;
+    }
+
+    ngx_memcpy(s->login.data, arg[0].data, s->login.len);
+
+    s->passwd.len = arg[1].len;
+    s->passwd.data = ngx_palloc(c->pool, s->passwd.len);
+    if (s->passwd.data == NULL) {
+        return NGX_ERROR;
+    }
+
+    ngx_memcpy(s->passwd.data, arg[1].data, s->passwd.len);
+
+    ngx_log_debug2(NGX_LOG_DEBUG_MAIL, c->log, 0,
+                   "pop3 apop: \"%V\" \"%V\"", &s->login, &s->passwd);
+
+    s->auth_method = NGX_MAIL_AUTH_APOP;
+
+    return NGX_DONE;
+}
+
+
+static ngx_int_t
+ngx_mail_pop3_auth(ngx_mail_session_t *s, ngx_connection_t *c)
+{
+    ngx_int_t                  rc;
+    ngx_mail_pop3_srv_conf_t  *pscf;
+
+#if (NGX_MAIL_SSL)
+    if (ngx_mail_starttls_only(s, c)) {
+        return NGX_MAIL_PARSE_INVALID_COMMAND;
+    }
+#endif
+
+    pscf = ngx_mail_get_module_srv_conf(s, ngx_mail_pop3_module);
+
+    if (s->args.nelts == 0) {
+        s->out = pscf->auth_capability;
+        s->state = 0;
+
+        return NGX_OK;
+    }
+
+    rc = ngx_mail_auth_parse(s, c);
+
+    switch (rc) {
+
+    case NGX_MAIL_AUTH_LOGIN:
+
+        s->out.len = sizeof(pop3_username) - 1;
+        s->out.data = pop3_username;
+        s->mail_state = ngx_pop3_auth_login_username;
+
+        return NGX_OK;
+
+    case NGX_MAIL_AUTH_PLAIN:
+
+        s->out.len = sizeof(pop3_next) - 1;
+        s->out.data = pop3_next;
+        s->mail_state = ngx_pop3_auth_plain;
+
+        return NGX_OK;
+
+    case NGX_MAIL_AUTH_CRAM_MD5:
+
+        if (!(pscf->auth_methods & NGX_MAIL_AUTH_CRAM_MD5_ENABLED)) {
+            return NGX_MAIL_PARSE_INVALID_COMMAND;
+        }
+
+        if (ngx_mail_auth_cram_md5_salt(s, c, "+ ", 2) == NGX_OK) {
+            s->mail_state = ngx_pop3_auth_cram_md5;
+            return NGX_OK;
+        }
+
+        return NGX_ERROR;
+    }
+
+    return rc;
+}