Add a parser for ovpn config files

- This will be used for reading the management i/f
parameters for externally started (persistent) openpvn.exe

TODO: replace the parsing of config file in passphrase.c
using this.

Signed-off-by: Selva Nair <selva.nair@gmail.com>

CMakeLists.txt

@@ -29,6 +29,7 @@ add_executable(${PROJECT_NAME} WIN32
     viewlog.c
     as.c
     pkcs11.c
+    config_parser.c
     res/openvpn-gui-res.rc)
 
 find_package(OpenSSL REQUIRED)

Makefile.am

@@ -96,6 +96,7 @@ openvpn_gui_SOURCES = \
 	echo.c echo.h \
 	as.c as.h \
 	pkcs11.c pkcs11.h \
+	config_parser.c config_parser.h \
 	openvpn-gui-res.h
 
 openvpn_gui_LDFLAGS = -mwindows

config_parser.c

@@ -0,0 +1,180 @@
+/*
+ *  This file is a part of OpenVPN-GUI -- A Windows GUI for OpenVPN.
+ *
+ *  Copyright (C) 2016 Selva Nair <selva.nair@gmail.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program (see the file COPYING included with this
+ *  distribution); if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <windows.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <wchar.h>
+#include "main.h"
+#include "config_parser.h"
+
+static int
+legal_escape(wchar_t c)
+{
+    wchar_t *escapes = L"\"\' \\"; /* space, ", ' or backslash */
+    return (wcschr(escapes, c) != NULL);
+}
+
+static int
+copy_token(wchar_t **dest, wchar_t **src, wchar_t* delim)
+{
+    wchar_t *p = *src;
+    wchar_t *s = *dest;
+
+    /* copy src to dest until delim character with escaped chars converted */
+    for ( ; *p != L'\0' && wcschr(delim, *p) == NULL; p++, s++)
+    {
+        if (*p == L'\\' && legal_escape(*(p+1)))
+        {
+            *s = *(++p);
+        }
+        else if (*p == L'\\')
+        {
+            return -1; /* parse error -- illegal backslash in input */
+        }
+        else
+            *s = *p;
+    }
+    /* at this point p is one of the delimiters or null */
+    *s = L'\0';
+    *src = p;
+    *dest = s;
+    return 0;
+}
+
+static int
+tokenize(config_entry_t *ce)
+{
+    wchar_t *p, *s;
+    p = ce->line;
+    s = ce->sline;
+    unsigned int i = 0;
+    int status;
+
+    for ( ; *p != L'\0';  p++, s++)
+    {
+        if (*p == L' ' || *p == L'\t') continue;
+
+        if (_countof(ce->tokens) <= i)
+        {
+            return -1;
+        }
+        ce->tokens[i++] = s;
+
+        if (*p == L'\'' )
+        {
+            int len = wcscspn(++p, L"\'");
+            wcsncpy(s, p, len);
+            s += len;
+            p += len;
+        }
+        else if (*p == L'\"')
+        {
+            p++;
+            status = copy_token(&s, &p, L"\"");
+        }
+        else
+            status = copy_token(&s, &p, L" \t");
+        if (status != 0) return status;
+
+        if (*p == L'\0') break;
+    }
+    ce->ntokens = i;
+    return 0;
+}
+
+config_entry_t *
+config_readline(FILE *fd, int first)
+{
+    int len;
+    char tmp[MAX_LINE_LENGTH];
+    int offset = 0;
+
+    if (fgets(tmp, _countof(tmp)-1, fd) == NULL)
+    {
+        return NULL;
+    }
+    /* remove UTF-8 BOM */
+    if (first && strncmp(tmp, "\xEF\xBB\xBF", 3) == 0)
+    {
+        offset = 3;
+    }
+
+    config_entry_t *ce = calloc(sizeof(*ce), 1);
+    if (!ce)
+    {
+       MsgToEventLog(EVENTLOG_ERROR_TYPE, L"Out of memory in tokenize");
+       return NULL;
+    }
+
+    mbstowcs(ce->line, &tmp[offset], _countof(ce->line)-1);
+
+    len = wcscspn(ce->line, L"\n\r");
+    ce->line[len] = L'\0';
+
+    if (tokenize(ce) != 0)
+    {
+        free(ce);
+        return NULL;
+    }
+
+    return ce;
+}
+
+config_entry_t *
+config_parse(wchar_t *fname)
+{
+    FILE *fd = NULL;
+    config_entry_t *head, *tail;
+
+    if (fname)
+    {
+        fd = _wfopen(fname, L"r");
+    }
+    if (!fd)
+    {
+        MsgToEventLog(EVENTLOG_ERROR_TYPE, L"Error opening <%ls> in config_parse", fname);
+        return NULL;
+    }
+    head = tail = config_readline(fd, 1);
+
+    while (tail)
+    {
+        tail->next = config_readline(fd, 0);
+        tail = tail->next;
+    }
+    fclose(fd);
+    return head;
+}
+
+void
+config_list_free(config_entry_t *head)
+{
+    config_entry_t *next;
+    while (head)
+    {
+        next = head->next;
+        free(head);
+        head = next;
+    }
+    return;
+}

config_parser.h

@@ -0,0 +1,54 @@
+/*
+ *  This file is a part of OpenVPN-GUI -- A Windows GUI for OpenVPN.
+ *
+ *  Copyright (C) 2016 Selva Nair <selva.nair@gmail.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program (see the file COPYING included with this
+ *  distribution); if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef CONFIG_PARSER_H
+#define CONFIG_PARSER_H
+
+#define MAX_LINE_LENGTH 256
+
+typedef struct config_entry config_entry_t;
+
+struct config_entry {
+    wchar_t line[MAX_LINE_LENGTH];
+    wchar_t sline[MAX_LINE_LENGTH];
+    wchar_t *tokens[16];
+    int ntokens;
+    config_entry_t *next;
+};
+
+/**
+ * Parse an ovpn file into a list of tokenized
+ * structs.
+ * @param fname : filename of the config to parse
+ * @returns the pointer to the head of a list of
+ *          config_entry_t structs.
+ *          The called must free it after use by calling
+ *          config_list_free()
+ */
+config_entry_t *config_parse(wchar_t *fname);
+
+/**
+ * Free a list of config_entry_t structs
+ * @param head : list head returned by config_parse()
+ */
+void config_list_free(config_entry_t *head);
+
+#endif