new file mode 100644
--- /dev/null
+++ b/src/imap/ngx_imap_parse.c
@@ -0,0 +1,68 @@
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_event.h>
+#include <ngx_imap.h>
+
+
+ngx_int_t ngx_pop3_parse_command(ngx_imap_request_t *r)
+{
+    u_char  ch, *p, *c;
+    enum {
+        sw_start = 0,
+        sw_done
+    } state;
+
+    while (p < r->buf->last && state < sw_done) {
+        ch = *p++;
+
+        switch (state) {
+
+        /* POP3 commands */
+        case sw_start:
+            if (ch == ' ') {
+                c = r->buf->start;
+
+                if (p - 1 - m == 4) {
+
+                    if (*c == 'U' && *(c + 1) == 'S'
+                        && *(c + 2) == 'E' && *(c + 3) == 'R')
+                    {
+                        r->command = NGX_POP3_USER;
+
+                    } else if (*c == 'P' && *(c + 1) == 'A'
+                               && *(c + 2) == 'A' && *(c + 3) == 'S')
+                    {
+                        r->method = NGX_POP3_PASS;
+
+                    } else if (*c == 'Q' && *(c + 1) == 'U'
+                               && *(c + 2) == 'I' && *(c + 3) == 'T')
+                    {
+                        r->method = NGX_POP3_QUIT;
+
+                    } else if (*c == 'N' && *(c + 1) == 'O'
+                               && *(c + 2) == 'O' && *(c + 3) == 'P')
+                    {
+                        r->method = NGX_POP3_NOOP;
+                    }
+                }
+
+                state = sw_spaces_before_arg;
+                break;
+            }
+
+            if (ch < 'A' || ch > 'Z') {
+                return NGX_IMAP_PARSE_INVALID_COMMAND;
+            }
+
+            break;
+        }
+
+        /* suppress warning */
+        case sw_done:
+            break;
+        }
+    }
+
+    return NGX_OK;
+}