Merge pull request #173 from ecotarobles/master

Command line options for example server client

examples/client/CMakeLists.txt

@@ -3,7 +3,11 @@ if(POLICY CMP0079)
 	cmake_policy(SET CMP0079 NEW)
 endif()
 
-add_executable(datachannel-client main.cpp)
+if(WIN32)
+add_executable(datachannel-client main.cpp parse_cl.cpp parse_cl.h getopt.cpp getopt.h)
+else()
+add_executable(datachannel-client main.cpp parse_cl.cpp parse_cl.h)
+endif()
 set_target_properties(datachannel-client PROPERTIES
 	CXX_STANDARD 17
 	OUTPUT_NAME client)

examples/client/README-getopt-for-windows.md

@@ -0,0 +1,4 @@
+# getopt-for-windows
+getopt.h and getopt.c is very often used in linux, to make it easy for windows user, two files were extracted from glibc. In order to make it works properly in windows, some modification was done and you may compare the change using original source files. Enjoy it!
+
+Source: https://github.com/Chunde/getopt-for-windows.  IMPORTANT: getopt.[ch] are likely not safe for Linux due to conflict with existing getopt.[ch].  They are thus NOT in CMakeFiles.txt and instead both files are #include only on Windows.

examples/client/getopt.cpp

@@ -0,0 +1,973 @@
+/* Getopt for Microsoft C
+This code is a modification of the Free Software Foundation, Inc.
+Getopt library for parsing command line argument the purpose was
+to provide a Microsoft Visual C friendly derivative. This code
+provides functionality for both Unicode and Multibyte builds.
+
+Date: 02/03/2011 - Ludvik Jerabek - Initial Release
+Version: 1.0
+Comment: Supports getopt, getopt_long, and getopt_long_only
+and POSIXLY_CORRECT environment flag
+License: LGPL
+
+Revisions:
+
+02/03/2011 - Ludvik Jerabek - Initial Release
+02/20/2011 - Ludvik Jerabek - Fixed compiler warnings at Level 4
+07/05/2011 - Ludvik Jerabek - Added no_argument, required_argument, optional_argument defs
+08/03/2011 - Ludvik Jerabek - Fixed non-argument runtime bug which caused runtime exception
+08/09/2011 - Ludvik Jerabek - Added code to export functions for DLL and LIB
+02/15/2012 - Ludvik Jerabek - Fixed _GETOPT_THROW definition missing in implementation file
+08/01/2012 - Ludvik Jerabek - Created separate functions for char and wchar_t characters so single dll can do both unicode and ansi
+10/15/2012 - Ludvik Jerabek - Modified to match latest GNU features
+06/19/2015 - Ludvik Jerabek - Fixed maximum option limitation caused by option_a (255) and option_w (65535) structure val variable
+
+**DISCLAIMER**
+THIS MATERIAL IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
+EITHER EXPRESS OR IMPLIED, INCLUDING, BUT Not LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+PURPOSE, OR NON-INFRINGEMENT. SOME JURISDICTIONS DO NOT ALLOW THE
+EXCLUSION OF IMPLIED WARRANTIES, SO THE ABOVE EXCLUSION MAY NOT
+APPLY TO YOU. IN NO EVENT WILL I BE LIABLE TO ANY PARTY FOR ANY
+DIRECT, INDIRECT, SPECIAL OR OTHER CONSEQUENTIAL DAMAGES FOR ANY
+USE OF THIS MATERIAL INCLUDING, WITHOUT LIMITATION, ANY LOST
+PROFITS, BUSINESS INTERRUPTION, LOSS OF PROGRAMS OR OTHER DATA ON
+YOUR INFORMATION HANDLING SYSTEM OR OTHERWISE, EVEN If WE ARE
+EXPRESSLY ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+*/
+#define _CRT_SECURE_NO_WARNINGS
+#include <stdlib.h>
+#include <stdio.h>
+#include <malloc.h>
+#include "getopt.h"
+
+#ifdef __cplusplus
+	#define _GETOPT_THROW throw()
+#else
+	#define _GETOPT_THROW
+#endif
+
+int optind = 1;
+int opterr = 1;
+int optopt = '?';
+enum ENUM_ORDERING { REQUIRE_ORDER, PERMUTE, RETURN_IN_ORDER };
+
+//
+//
+//		Ansi structures and functions follow
+// 
+//
+
+static struct _getopt_data_a
+{
+	int optind;
+	int opterr;
+	int optopt;
+	char *optarg;
+	int __initialized;
+	char *__nextchar;
+	enum ENUM_ORDERING __ordering;
+	int __posixly_correct;
+	int __first_nonopt;
+	int __last_nonopt;
+} getopt_data_a;
+char *optarg_a;
+
+static void exchange_a(char **argv, struct _getopt_data_a *d)
+{
+	int bottom = d->__first_nonopt;
+	int middle = d->__last_nonopt;
+	int top = d->optind;
+	char *tem;
+	while (top > middle && middle > bottom)
+	{
+		if (top - middle > middle - bottom)
+		{
+			int len = middle - bottom;
+			register int i;
+			for (i = 0; i < len; i++)
+			{
+				tem = argv[bottom + i];
+				argv[bottom + i] = argv[top - (middle - bottom) + i];
+				argv[top - (middle - bottom) + i] = tem;
+			}
+			top -= len;
+		}
+		else
+		{
+			int len = top - middle;
+			register int i;
+			for (i = 0; i < len; i++)
+			{
+				tem = argv[bottom + i];
+				argv[bottom + i] = argv[middle + i];
+				argv[middle + i] = tem;
+			}
+			bottom += len;
+		}
+	}
+	d->__first_nonopt += (d->optind - d->__last_nonopt);
+	d->__last_nonopt = d->optind;
+}
+static const char *_getopt_initialize_a (const char *optstring, struct _getopt_data_a *d, int posixly_correct)
+{
+	d->__first_nonopt = d->__last_nonopt = d->optind;
+	d->__nextchar = NULL;
+	d->__posixly_correct = posixly_correct | !!getenv("POSIXLY_CORRECT");
+	if (optstring[0] == '-')
+	{
+		d->__ordering = RETURN_IN_ORDER;
+		++optstring;
+	}
+	else if (optstring[0] == '+')
+	{
+		d->__ordering = REQUIRE_ORDER;
+		++optstring;
+	}
+	else if (d->__posixly_correct)
+		d->__ordering = REQUIRE_ORDER;
+	else
+		d->__ordering = PERMUTE;
+	return optstring;
+}
+int _getopt_internal_r_a (int argc, char *const *argv, const char *optstring, const struct option_a *longopts, int *longind, int long_only, struct _getopt_data_a *d, int posixly_correct)
+{
+	int print_errors = d->opterr;
+	if (argc < 1)
+		return -1;
+	d->optarg = NULL;
+	if (d->optind == 0 || !d->__initialized)
+	{
+		if (d->optind == 0)
+			d->optind = 1;
+		optstring = _getopt_initialize_a (optstring, d, posixly_correct);
+		d->__initialized = 1;
+	}
+	else if (optstring[0] == '-' || optstring[0] == '+')
+		optstring++;
+	if (optstring[0] == ':')
+		print_errors = 0;
+	if (d->__nextchar == NULL || *d->__nextchar == '\0')
+	{
+		if (d->__last_nonopt > d->optind)
+			d->__last_nonopt = d->optind;
+		if (d->__first_nonopt > d->optind)
+			d->__first_nonopt = d->optind;
+		if (d->__ordering == PERMUTE)
+		{
+			if (d->__first_nonopt != d->__last_nonopt && d->__last_nonopt != d->optind)
+				exchange_a ((char **) argv, d);
+			else if (d->__last_nonopt != d->optind)
+				d->__first_nonopt = d->optind;
+			while (d->optind < argc && (argv[d->optind][0] != '-' || argv[d->optind][1] == '\0'))
+				d->optind++;
+			d->__last_nonopt = d->optind;
+		}
+		if (d->optind != argc && !strcmp(argv[d->optind], "--"))
+		{
+			d->optind++;
+			if (d->__first_nonopt != d->__last_nonopt && d->__last_nonopt != d->optind)
+				exchange_a((char **) argv, d);
+			else if (d->__first_nonopt == d->__last_nonopt)
+				d->__first_nonopt = d->optind;
+			d->__last_nonopt = argc;
+			d->optind = argc;
+		}
+		if (d->optind == argc)
+		{
+			if (d->__first_nonopt != d->__last_nonopt)
+				d->optind = d->__first_nonopt;
+			return -1;
+		}
+		if ((argv[d->optind][0] != '-' || argv[d->optind][1] == '\0'))
+		{
+			if (d->__ordering == REQUIRE_ORDER)
+				return -1;
+			d->optarg = argv[d->optind++];
+			return 1;
+		}
+		d->__nextchar = (argv[d->optind] + 1 + (longopts != NULL && argv[d->optind][1] == '-'));
+	}
+	if (longopts != NULL && (argv[d->optind][1] == '-' || (long_only && (argv[d->optind][2] || !strchr(optstring, argv[d->optind][1])))))
+	{
+		char *nameend;
+		unsigned int namelen;
+		const struct option_a *p;
+		const struct option_a *pfound = NULL;
+		struct option_list
+		{
+			const struct option_a *p;
+			struct option_list *next;
+		} *ambig_list = NULL;
+		int exact = 0;
+		int indfound = -1;
+		int option_index;
+		for (nameend = d->__nextchar; *nameend && *nameend != '='; nameend++);
+		namelen = (unsigned int)(nameend - d->__nextchar);
+		for (p = longopts, option_index = 0; p->name; p++, option_index++)
+			if (!strncmp(p->name, d->__nextchar, namelen))
+			{
+				if (namelen == (unsigned int)strlen(p->name))
+				{
+					pfound = p;
+					indfound = option_index;
+					exact = 1;
+					break;
+				}
+				else if (pfound == NULL)
+				{
+					pfound = p;
+					indfound = option_index;
+				}
+				else if (long_only || pfound->has_arg != p->has_arg || pfound->flag != p->flag || pfound->val != p->val)
+				{
+					struct option_list *newp = (struct option_list*)alloca(sizeof(*newp));
+					newp->p = p;
+					newp->next = ambig_list;
+					ambig_list = newp;
+				}
+			}
+			if (ambig_list != NULL && !exact)
+			{
+				if (print_errors)
+				{
+					struct option_list first;
+					first.p = pfound;
+					first.next = ambig_list;
+					ambig_list = &first;
+					fprintf (stderr, "%s: option '%s' is ambiguous; possibilities:", argv[0], argv[d->optind]);
+					do
+					{
+						fprintf (stderr, " '--%s'", ambig_list->p->name);
+						ambig_list = ambig_list->next;
+					}
+					while (ambig_list != NULL);
+					fputc ('\n', stderr);
+				}
+				d->__nextchar += strlen(d->__nextchar);
+				d->optind++;
+				d->optopt = 0;
+				return '?';
+			}
+			if (pfound != NULL)
+			{
+				option_index = indfound;
+				d->optind++;
+				if (*nameend)
+				{
+					if (pfound->has_arg)
+						d->optarg = nameend + 1;
+					else
+					{
+						if (print_errors)
+						{
+							if (argv[d->optind - 1][1] == '-')
+							{
+								fprintf(stderr, "%s: option '--%s' doesn't allow an argument\n",argv[0], pfound->name);
+							}
+							else
+							{
+								fprintf(stderr, "%s: option '%c%s' doesn't allow an argument\n",argv[0], argv[d->optind - 1][0],pfound->name);
+							}
+						}
+						d->__nextchar += strlen(d->__nextchar);
+						d->optopt = pfound->val;
+						return '?';
+					}
+				}
+				else if (pfound->has_arg == 1)
+				{
+					if (d->optind < argc)
+						d->optarg = argv[d->optind++];
+					else
+					{
+						if (print_errors)
+						{
+							fprintf(stderr,"%s: option '--%s' requires an argument\n",argv[0], pfound->name);
+						}
+						d->__nextchar += strlen(d->__nextchar);
+						d->optopt = pfound->val;
+						return optstring[0] == ':' ? ':' : '?';
+					}
+				}
+				d->__nextchar += strlen(d->__nextchar);
+				if (longind != NULL)
+					*longind = option_index;
+				if (pfound->flag)
+				{
+					*(pfound->flag) = pfound->val;
+					return 0;
+				}
+				return pfound->val;
+			}
+			if (!long_only || argv[d->optind][1] == '-' || strchr(optstring, *d->__nextchar) == NULL)
+			{
+				if (print_errors)
+				{
+					if (argv[d->optind][1] == '-')
+					{
+						fprintf(stderr, "%s: unrecognized option '--%s'\n",argv[0], d->__nextchar);
+					}
+					else
+					{
+						fprintf(stderr, "%s: unrecognized option '%c%s'\n",argv[0], argv[d->optind][0], d->__nextchar);
+					}
+				}
+				d->__nextchar = (char *)"";
+				d->optind++;
+				d->optopt = 0;
+				return '?';
+			}
+	}
+	{
+		char c = *d->__nextchar++;
+		char *temp = (char*)strchr(optstring, c);
+		if (*d->__nextchar == '\0')
+			++d->optind;
+		if (temp == NULL || c == ':' || c == ';')
+		{
+			if (print_errors)
+			{
+				fprintf(stderr, "%s: invalid option -- '%c'\n", argv[0], c);
+			}
+			d->optopt = c;
+			return '?';
+		}
+		if (temp[0] == 'W' && temp[1] == ';')
+		{
+			char *nameend;
+			const struct option_a *p;
+			const struct option_a *pfound = NULL;
+			int exact = 0;
+			int ambig = 0;
+			int indfound = 0;
+			int option_index;
+			if (longopts == NULL)
+				goto no_longs;
+			if (*d->__nextchar != '\0')
+			{
+				d->optarg = d->__nextchar;
+				d->optind++;
+			}
+			else if (d->optind == argc)
+			{
+				if (print_errors)
+				{
+					fprintf(stderr,"%s: option requires an argument -- '%c'\n",argv[0], c);
+				}
+				d->optopt = c;
+				if (optstring[0] == ':')
+					c = ':';
+				else
+					c = '?';
+				return c;
+			}
+			else
+				d->optarg = argv[d->optind++];
+			for (d->__nextchar = nameend = d->optarg; *nameend && *nameend != '='; nameend++);
+			for (p = longopts, option_index = 0; p->name; p++, option_index++)
+				if (!strncmp(p->name, d->__nextchar, nameend - d->__nextchar))
+				{
+					if ((unsigned int) (nameend - d->__nextchar) == strlen(p->name))
+					{
+						pfound = p;
+						indfound = option_index;
+						exact = 1;
+						break;
+					}
+					else if (pfound == NULL)
+					{
+						pfound = p;
+						indfound = option_index;
+					}
+					else if (long_only || pfound->has_arg != p->has_arg || pfound->flag != p->flag || pfound->val != p->val)
+						ambig = 1;
+				}
+				if (ambig && !exact)
+				{
+					if (print_errors)
+					{
+						fprintf(stderr, "%s: option '-W %s' is ambiguous\n",argv[0], d->optarg);
+					}
+					d->__nextchar += strlen(d->__nextchar);
+					d->optind++;
+					return '?';
+				}
+				if (pfound != NULL)
+				{
+					option_index = indfound;
+					if (*nameend)
+					{
+						if (pfound->has_arg)
+							d->optarg = nameend + 1;
+						else
+						{
+							if (print_errors)
+							{
+								fprintf(stderr, "%s: option '-W %s' doesn't allow an argument\n",argv[0], pfound->name);
+							}
+							d->__nextchar += strlen(d->__nextchar);
+							return '?';
+						}
+					}
+					else if (pfound->has_arg == 1)
+					{
+						if (d->optind < argc)
+							d->optarg = argv[d->optind++];
+						else
+						{
+							if (print_errors)
+							{
+								fprintf(stderr, "%s: option '-W %s' requires an argument\n",argv[0], pfound->name);
+							}
+							d->__nextchar += strlen(d->__nextchar);
+							return optstring[0] == ':' ? ':' : '?';
+						}
+					}
+					else
+						d->optarg = NULL;
+					d->__nextchar += strlen(d->__nextchar);
+					if (longind != NULL)
+						*longind = option_index;
+					if (pfound->flag)
+					{
+						*(pfound->flag) = pfound->val;
+						return 0;
+					}
+					return pfound->val;
+				}
+no_longs:
+				d->__nextchar = NULL;
+				return 'W';
+		}
+		if (temp[1] == ':')
+		{
+			if (temp[2] == ':')
+			{
+				if (*d->__nextchar != '\0')
+				{
+					d->optarg = d->__nextchar;
+					d->optind++;
+				}
+				else
+					d->optarg = NULL;
+				d->__nextchar = NULL;
+			}
+			else
+			{
+				if (*d->__nextchar != '\0')
+				{
+					d->optarg = d->__nextchar;
+					d->optind++;
+				}
+				else if (d->optind == argc)
+				{
+					if (print_errors)
+					{
+						fprintf(stderr,"%s: option requires an argument -- '%c'\n",argv[0], c);
+					}
+					d->optopt = c;
+					if (optstring[0] == ':')
+						c = ':';
+					else
+						c = '?';
+				}
+				else
+					d->optarg = argv[d->optind++];
+				d->__nextchar = NULL;
+			}
+		}
+		return c;
+	}
+}
+int _getopt_internal_a (int argc, char *const *argv, const char *optstring, const struct option_a *longopts, int *longind, int long_only, int posixly_correct)
+{
+	int result;
+	getopt_data_a.optind = optind;
+	getopt_data_a.opterr = opterr;
+	result = _getopt_internal_r_a (argc, argv, optstring, longopts,longind, long_only, &getopt_data_a,posixly_correct);
+	optind = getopt_data_a.optind;
+	optarg_a = getopt_data_a.optarg;
+	optopt = getopt_data_a.optopt;
+	return result;
+}
+int getopt_a (int argc, char *const *argv, const char *optstring) _GETOPT_THROW
+{
+	return _getopt_internal_a (argc, argv, optstring, (const struct option_a *) 0, (int *) 0, 0, 0);
+}
+int getopt_long_a (int argc, char *const *argv, const char *options, const struct option_a *long_options, int *opt_index) _GETOPT_THROW
+{
+	return _getopt_internal_a (argc, argv, options, long_options, opt_index, 0, 0);
+}
+int getopt_long_only_a (int argc, char *const *argv, const char *options, const struct option_a *long_options, int *opt_index) _GETOPT_THROW
+{
+	return _getopt_internal_a (argc, argv, options, long_options, opt_index, 1, 0);
+}
+int _getopt_long_r_a (int argc, char *const *argv, const char *options, const struct option_a *long_options, int *opt_index, struct _getopt_data_a *d)
+{
+	return _getopt_internal_r_a (argc, argv, options, long_options, opt_index,0, d, 0);
+}
+int _getopt_long_only_r_a (int argc, char *const *argv, const char *options, const struct option_a *long_options, int *opt_index, struct _getopt_data_a *d)
+{
+	return _getopt_internal_r_a (argc, argv, options, long_options, opt_index, 1, d, 0);
+}
+
+//
+//
+//	Unicode Structures and Functions
+// 
+//
+
+static struct _getopt_data_w
+{
+	int optind;
+	int opterr;
+	int optopt;
+	wchar_t *optarg;
+	int __initialized;
+	wchar_t *__nextchar;
+	enum ENUM_ORDERING __ordering;
+	int __posixly_correct;
+	int __first_nonopt;
+	int __last_nonopt;
+} getopt_data_w;
+wchar_t *optarg_w;
+
+static void exchange_w(wchar_t **argv, struct _getopt_data_w *d)
+{
+	int bottom = d->__first_nonopt;
+	int middle = d->__last_nonopt;
+	int top = d->optind;
+	wchar_t *tem;
+	while (top > middle && middle > bottom)
+	{
+		if (top - middle > middle - bottom)
+		{
+			int len = middle - bottom;
+			register int i;
+			for (i = 0; i < len; i++)
+			{
+				tem = argv[bottom + i];
+				argv[bottom + i] = argv[top - (middle - bottom) + i];
+				argv[top - (middle - bottom) + i] = tem;
+			}
+			top -= len;
+		}
+		else
+		{
+			int len = top - middle;
+			register int i;
+			for (i = 0; i < len; i++)
+			{
+				tem = argv[bottom + i];
+				argv[bottom + i] = argv[middle + i];
+				argv[middle + i] = tem;
+			}
+			bottom += len;
+		}
+	}
+	d->__first_nonopt += (d->optind - d->__last_nonopt);
+	d->__last_nonopt = d->optind;
+}
+static const wchar_t *_getopt_initialize_w (const wchar_t *optstring, struct _getopt_data_w *d, int posixly_correct)
+{
+	d->__first_nonopt = d->__last_nonopt = d->optind;
+	d->__nextchar = NULL;
+	d->__posixly_correct = posixly_correct | !!_wgetenv(L"POSIXLY_CORRECT");
+	if (optstring[0] == L'-')
+	{
+		d->__ordering = RETURN_IN_ORDER;
+		++optstring;
+	}
+	else if (optstring[0] == L'+')
+	{
+		d->__ordering = REQUIRE_ORDER;
+		++optstring;
+	}
+	else if (d->__posixly_correct)
+		d->__ordering = REQUIRE_ORDER;
+	else
+		d->__ordering = PERMUTE;
+	return optstring;
+}
+int _getopt_internal_r_w (int argc, wchar_t *const *argv, const wchar_t *optstring, const struct option_w *longopts, int *longind, int long_only, struct _getopt_data_w *d, int posixly_correct)
+{
+	int print_errors = d->opterr;
+	if (argc < 1)
+		return -1;
+	d->optarg = NULL;
+	if (d->optind == 0 || !d->__initialized)
+	{
+		if (d->optind == 0)
+			d->optind = 1;
+		optstring = _getopt_initialize_w (optstring, d, posixly_correct);
+		d->__initialized = 1;
+	}
+	else if (optstring[0] == L'-' || optstring[0] == L'+')
+		optstring++;
+	if (optstring[0] == L':')
+		print_errors = 0;
+	if (d->__nextchar == NULL || *d->__nextchar == L'\0')
+	{
+		if (d->__last_nonopt > d->optind)
+			d->__last_nonopt = d->optind;
+		if (d->__first_nonopt > d->optind)
+			d->__first_nonopt = d->optind;
+		if (d->__ordering == PERMUTE)
+		{
+			if (d->__first_nonopt != d->__last_nonopt && d->__last_nonopt != d->optind)
+				exchange_w((wchar_t **) argv, d);
+			else if (d->__last_nonopt != d->optind)
+				d->__first_nonopt = d->optind;
+			while (d->optind < argc && (argv[d->optind][0] != L'-' || argv[d->optind][1] == L'\0'))
+				d->optind++;
+			d->__last_nonopt = d->optind;
+		}
+		if (d->optind != argc && !wcscmp(argv[d->optind], L"--"))
+		{
+			d->optind++;
+			if (d->__first_nonopt != d->__last_nonopt && d->__last_nonopt != d->optind)
+				exchange_w((wchar_t **) argv, d);
+			else if (d->__first_nonopt == d->__last_nonopt)
+				d->__first_nonopt = d->optind;
+			d->__last_nonopt = argc;
+			d->optind = argc;
+		}
+		if (d->optind == argc)
+		{
+			if (d->__first_nonopt != d->__last_nonopt)
+				d->optind = d->__first_nonopt;
+			return -1;
+		}
+		if ((argv[d->optind][0] != L'-' || argv[d->optind][1] == L'\0'))
+		{
+			if (d->__ordering == REQUIRE_ORDER)
+				return -1;
+			d->optarg = argv[d->optind++];
+			return 1;
+		}
+		d->__nextchar = (argv[d->optind] + 1 + (longopts != NULL && argv[d->optind][1] == L'-'));
+	}
+	if (longopts != NULL && (argv[d->optind][1] == L'-' || (long_only && (argv[d->optind][2] || !wcschr(optstring, argv[d->optind][1])))))
+	{
+		wchar_t *nameend;
+		unsigned int namelen;
+		const struct option_w *p;
+		const struct option_w *pfound = NULL;
+		struct option_list
+		{
+			const struct option_w *p;
+			struct option_list *next;
+		} *ambig_list = NULL;
+		int exact = 0;
+		int indfound = -1;
+		int option_index;
+		for (nameend = d->__nextchar; *nameend && *nameend != L'='; nameend++);
+		namelen = (unsigned int)(nameend - d->__nextchar);
+		for (p = longopts, option_index = 0; p->name; p++, option_index++)
+			if (!wcsncmp(p->name, d->__nextchar, namelen))
+			{
+				if (namelen == (unsigned int)wcslen(p->name))
+				{
+					pfound = p;
+					indfound = option_index;
+					exact = 1;
+					break;
+				}
+				else if (pfound == NULL)
+				{
+					pfound = p;
+					indfound = option_index;
+				}
+				else if (long_only || pfound->has_arg != p->has_arg || pfound->flag != p->flag || pfound->val != p->val)
+				{
+					struct option_list *newp = (struct option_list*)alloca(sizeof(*newp));
+					newp->p = p;
+					newp->next = ambig_list;
+					ambig_list = newp;
+				}
+			}
+			if (ambig_list != NULL && !exact)
+			{
+				if (print_errors)
+				{						
+					struct option_list first;
+					first.p = pfound;
+					first.next = ambig_list;
+					ambig_list = &first;
+					fwprintf(stderr, L"%s: option '%s' is ambiguous; possibilities:", argv[0], argv[d->optind]);
+					do
+					{
+						fwprintf (stderr, L" '--%s'", ambig_list->p->name);
+						ambig_list = ambig_list->next;
+					}
+					while (ambig_list != NULL);
+					fputwc (L'\n', stderr);
+				}
+				d->__nextchar += wcslen(d->__nextchar);
+				d->optind++;
+				d->optopt = 0;
+				return L'?';
+			}
+			if (pfound != NULL)
+			{
+				option_index = indfound;
+				d->optind++;
+				if (*nameend)
+				{
+					if (pfound->has_arg)
+						d->optarg = nameend + 1;
+					else
+					{
+						if (print_errors)
+						{
+							if (argv[d->optind - 1][1] == L'-')
+							{
+								fwprintf(stderr, L"%s: option '--%s' doesn't allow an argument\n",argv[0], pfound->name);
+							}
+							else
+							{
+								fwprintf(stderr, L"%s: option '%c%s' doesn't allow an argument\n",argv[0], argv[d->optind - 1][0],pfound->name);
+							}
+						}
+						d->__nextchar += wcslen(d->__nextchar);
+						d->optopt = pfound->val;
+						return L'?';
+					}
+				}
+				else if (pfound->has_arg == 1)
+				{
+					if (d->optind < argc)
+						d->optarg = argv[d->optind++];
+					else
+					{
+						if (print_errors)
+						{
+							fwprintf(stderr,L"%s: option '--%s' requires an argument\n",argv[0], pfound->name);
+						}
+						d->__nextchar += wcslen(d->__nextchar);
+						d->optopt = pfound->val;
+						return optstring[0] == L':' ? L':' : L'?';
+					}
+				}
+				d->__nextchar += wcslen(d->__nextchar);
+				if (longind != NULL)
+					*longind = option_index;
+				if (pfound->flag)
+				{
+					*(pfound->flag) = pfound->val;
+					return 0;
+				}
+				return pfound->val;
+			}
+			if (!long_only || argv[d->optind][1] == L'-' || wcschr(optstring, *d->__nextchar) == NULL)
+			{
+				if (print_errors)
+				{
+					if (argv[d->optind][1] == L'-')
+					{
+						fwprintf(stderr, L"%s: unrecognized option '--%s'\n",argv[0], d->__nextchar);
+					}
+					else
+					{
+						fwprintf(stderr, L"%s: unrecognized option '%c%s'\n",argv[0], argv[d->optind][0], d->__nextchar);
+					}
+				}
+				d->__nextchar = (wchar_t *)L"";
+				d->optind++;
+				d->optopt = 0;
+				return L'?';
+			}
+	}
+	{
+		wchar_t c = *d->__nextchar++;
+		wchar_t *temp = (wchar_t*)wcschr(optstring, c);
+		if (*d->__nextchar == L'\0')
+			++d->optind;
+		if (temp == NULL || c == L':' || c == L';')
+		{
+			if (print_errors)
+			{
+				fwprintf(stderr, L"%s: invalid option -- '%c'\n", argv[0], c);
+			}
+			d->optopt = c;
+			return L'?';
+		}
+		if (temp[0] == L'W' && temp[1] == L';')
+		{
+			wchar_t *nameend;
+			const struct option_w *p;
+			const struct option_w *pfound = NULL;
+			int exact = 0;
+			int ambig = 0;
+			int indfound = 0;
+			int option_index;
+			if (longopts == NULL)
+				goto no_longs;
+			if (*d->__nextchar != L'\0')
+			{
+				d->optarg = d->__nextchar;
+				d->optind++;
+			}
+			else if (d->optind == argc)
+			{
+				if (print_errors)
+				{
+					fwprintf(stderr,L"%s: option requires an argument -- '%c'\n",argv[0], c);
+				}
+				d->optopt = c;
+				if (optstring[0] == L':')
+					c = L':';
+				else
+					c = L'?';
+				return c;
+			}
+			else
+				d->optarg = argv[d->optind++];
+			for (d->__nextchar = nameend = d->optarg; *nameend && *nameend != L'='; nameend++);
+			for (p = longopts, option_index = 0; p->name; p++, option_index++)
+				if (!wcsncmp(p->name, d->__nextchar, nameend - d->__nextchar))
+				{
+					if ((unsigned int) (nameend - d->__nextchar) == wcslen(p->name))
+					{
+						pfound = p;
+						indfound = option_index;
+						exact = 1;
+						break;
+					}
+					else if (pfound == NULL)
+					{
+						pfound = p;
+						indfound = option_index;
+					}
+					else if (long_only || pfound->has_arg != p->has_arg || pfound->flag != p->flag || pfound->val != p->val)
+						ambig = 1;
+				}
+				if (ambig && !exact)
+				{
+					if (print_errors)
+					{
+						fwprintf(stderr, L"%s: option '-W %s' is ambiguous\n",argv[0], d->optarg);
+					}
+					d->__nextchar += wcslen(d->__nextchar);
+					d->optind++;
+					return L'?';
+				}
+				if (pfound != NULL)
+				{
+					option_index = indfound;
+					if (*nameend)
+					{
+						if (pfound->has_arg)
+							d->optarg = nameend + 1;
+						else
+						{
+							if (print_errors)
+							{
+								fwprintf(stderr, L"%s: option '-W %s' doesn't allow an argument\n",argv[0], pfound->name);
+							}
+							d->__nextchar += wcslen(d->__nextchar);
+							return L'?';
+						}
+					}
+					else if (pfound->has_arg == 1)
+					{
+						if (d->optind < argc)
+							d->optarg = argv[d->optind++];
+						else
+						{
+							if (print_errors)
+							{
+								fwprintf(stderr, L"%s: option '-W %s' requires an argument\n",argv[0], pfound->name);
+							}
+							d->__nextchar += wcslen(d->__nextchar);
+							return optstring[0] == L':' ? L':' : L'?';
+						}
+					}
+					else
+						d->optarg = NULL;
+					d->__nextchar += wcslen(d->__nextchar);
+					if (longind != NULL)
+						*longind = option_index;
+					if (pfound->flag)
+					{
+						*(pfound->flag) = pfound->val;
+						return 0;
+					}
+					return pfound->val;
+				}
+no_longs:
+				d->__nextchar = NULL;
+				return L'W';
+		}
+		if (temp[1] == L':')
+		{
+			if (temp[2] == L':')
+			{
+				if (*d->__nextchar != L'\0')
+				{
+					d->optarg = d->__nextchar;
+					d->optind++;
+				}
+				else
+					d->optarg = NULL;
+				d->__nextchar = NULL;
+			}
+			else
+			{
+				if (*d->__nextchar != L'\0')
+				{
+					d->optarg = d->__nextchar;
+					d->optind++;
+				}
+				else if (d->optind == argc)
+				{
+					if (print_errors)
+					{
+						fwprintf(stderr,L"%s: option requires an argument -- '%c'\n",argv[0], c);
+					}
+					d->optopt = c;
+					if (optstring[0] == L':')
+						c = L':';
+					else
+						c = L'?';
+				}
+				else
+					d->optarg = argv[d->optind++];
+				d->__nextchar = NULL;
+			}
+		}
+		return c;
+	}
+}
+int _getopt_internal_w (int argc, wchar_t *const *argv, const wchar_t *optstring, const struct option_w *longopts, int *longind, int long_only, int posixly_correct)
+{
+	int result;
+	getopt_data_w.optind = optind;
+	getopt_data_w.opterr = opterr;
+	result = _getopt_internal_r_w (argc, argv, optstring, longopts,longind, long_only, &getopt_data_w,posixly_correct);
+	optind = getopt_data_w.optind;
+	optarg_w = getopt_data_w.optarg;
+	optopt = getopt_data_w.optopt;
+	return result;
+}
+int getopt_w (int argc, wchar_t *const *argv, const wchar_t *optstring) _GETOPT_THROW
+{
+	return _getopt_internal_w (argc, argv, optstring, (const struct option_w *) 0, (int *) 0, 0, 0);
+}
+int getopt_long_w (int argc, wchar_t *const *argv, const wchar_t *options, const struct option_w *long_options, int *opt_index) _GETOPT_THROW
+{
+	return _getopt_internal_w (argc, argv, options, long_options, opt_index, 0, 0);
+}
+int getopt_long_only_w (int argc, wchar_t *const *argv, const wchar_t *options, const struct option_w *long_options, int *opt_index) _GETOPT_THROW
+{
+	return _getopt_internal_w (argc, argv, options, long_options, opt_index, 1, 0);
+}
+int _getopt_long_r_w (int argc, wchar_t *const *argv, const wchar_t *options, const struct option_w *long_options, int *opt_index, struct _getopt_data_w *d)
+{
+	return _getopt_internal_r_w (argc, argv, options, long_options, opt_index,0, d, 0);
+}
+int _getopt_long_only_r_w (int argc, wchar_t *const *argv, const wchar_t *options, const struct option_w *long_options, int *opt_index, struct _getopt_data_w *d)
+{
+	return _getopt_internal_r_w (argc, argv, options, long_options, opt_index, 1, d, 0);
+}

examples/client/getopt.h

@@ -0,0 +1,136 @@
+/* Getopt for Microsoft C
+This code is a modification of the Free Software Foundation, Inc.
+Getopt library for parsing command line argument the purpose was
+to provide a Microsoft Visual C friendly derivative. This code
+provides functionality for both Unicode and Multibyte builds.
+
+Date: 02/03/2011 - Ludvik Jerabek - Initial Release
+Version: 1.0
+Comment: Supports getopt, getopt_long, and getopt_long_only
+and POSIXLY_CORRECT environment flag
+License: LGPL
+
+Revisions:
+
+02/03/2011 - Ludvik Jerabek - Initial Release
+02/20/2011 - Ludvik Jerabek - Fixed compiler warnings at Level 4
+07/05/2011 - Ludvik Jerabek - Added no_argument, required_argument, optional_argument defs
+08/03/2011 - Ludvik Jerabek - Fixed non-argument runtime bug which caused runtime exception
+08/09/2011 - Ludvik Jerabek - Added code to export functions for DLL and LIB
+02/15/2012 - Ludvik Jerabek - Fixed _GETOPT_THROW definition missing in implementation file
+08/01/2012 - Ludvik Jerabek - Created separate functions for char and wchar_t characters so single dll can do both unicode and ansi
+10/15/2012 - Ludvik Jerabek - Modified to match latest GNU features
+06/19/2015 - Ludvik Jerabek - Fixed maximum option limitation caused by option_a (255) and option_w (65535) structure val variable
+
+**DISCLAIMER**
+THIS MATERIAL IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
+EITHER EXPRESS OR IMPLIED, INCLUDING, BUT Not LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+PURPOSE, OR NON-INFRINGEMENT. SOME JURISDICTIONS DO NOT ALLOW THE
+EXCLUSION OF IMPLIED WARRANTIES, SO THE ABOVE EXCLUSION MAY NOT
+APPLY TO YOU. IN NO EVENT WILL I BE LIABLE TO ANY PARTY FOR ANY
+DIRECT, INDIRECT, SPECIAL OR OTHER CONSEQUENTIAL DAMAGES FOR ANY
+USE OF THIS MATERIAL INCLUDING, WITHOUT LIMITATION, ANY LOST
+PROFITS, BUSINESS INTERRUPTION, LOSS OF PROGRAMS OR OTHER DATA ON
+YOUR INFORMATION HANDLING SYSTEM OR OTHERWISE, EVEN If WE ARE
+EXPRESSLY ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+*/
+#ifndef __GETOPT_H_
+	#define __GETOPT_H_
+
+	#ifdef _GETOPT_API
+		#undef _GETOPT_API
+	#endif
+
+	#if defined(EXPORTS_GETOPT) && defined(STATIC_GETOPT)
+		#error "The preprocessor definitions of EXPORTS_GETOPT and STATIC_GETOPT can only be used individually"
+	#elif defined(STATIC_GETOPT)
+		#pragma message("Warning static builds of getopt violate the Lesser GNU Public License")
+		#define _GETOPT_API
+	#elif defined(EXPORTS_GETOPT)
+		#pragma message("Exporting getopt library")
+		#define _GETOPT_API __declspec(dllexport)
+	#else
+		#pragma message("Importing getopt library")
+		#define _GETOPT_API __declspec(dllimport)
+	#endif
+
+	// Change behavior for C\C++
+	#ifdef __cplusplus
+		#define _BEGIN_EXTERN_C extern "C" {
+		#define _END_EXTERN_C }
+		#define _GETOPT_THROW throw()
+	#else
+		#define _BEGIN_EXTERN_C
+		#define _END_EXTERN_C
+		#define _GETOPT_THROW
+	#endif
+
+	// Standard GNU options
+	#define	null_argument		0	/*Argument Null*/
+	#define	no_argument			0	/*Argument Switch Only*/
+	#define required_argument	1	/*Argument Required*/
+	#define optional_argument	2	/*Argument Optional*/	
+
+	// Shorter Options
+	#define ARG_NULL	0	/*Argument Null*/
+	#define ARG_NONE	0	/*Argument Switch Only*/
+	#define ARG_REQ		1	/*Argument Required*/
+	#define ARG_OPT		2	/*Argument Optional*/
+
+	#include <string.h>
+	#include <wchar.h>
+
+_BEGIN_EXTERN_C
+
+	extern _GETOPT_API int optind;
+	extern _GETOPT_API int opterr;
+	extern _GETOPT_API int optopt;
+
+	// Ansi
+	struct option_a
+	{
+		const char* name;
+		int has_arg;
+		int *flag;
+		int val;
+	};
+	extern _GETOPT_API char *optarg_a;
+	extern _GETOPT_API int getopt_a(int argc, char *const *argv, const char *optstring) _GETOPT_THROW;
+	extern _GETOPT_API int getopt_long_a(int argc, char *const *argv, const char *options, const struct option_a *long_options, int *opt_index) _GETOPT_THROW;
+	extern _GETOPT_API int getopt_long_only_a(int argc, char *const *argv, const char *options, const struct option_a *long_options, int *opt_index) _GETOPT_THROW;
+
+	// Unicode
+	struct option_w
+	{
+		const wchar_t* name;
+		int has_arg;
+		int *flag;
+		int val;
+	};
+	extern _GETOPT_API wchar_t *optarg_w;
+	extern _GETOPT_API int getopt_w(int argc, wchar_t *const *argv, const wchar_t *optstring) _GETOPT_THROW;
+	extern _GETOPT_API int getopt_long_w(int argc, wchar_t *const *argv, const wchar_t *options, const struct option_w *long_options, int *opt_index) _GETOPT_THROW;
+	extern _GETOPT_API int getopt_long_only_w(int argc, wchar_t *const *argv, const wchar_t *options, const struct option_w *long_options, int *opt_index) _GETOPT_THROW;	
+	
+_END_EXTERN_C
+
+	#undef _BEGIN_EXTERN_C
+	#undef _END_EXTERN_C
+	#undef _GETOPT_THROW
+	#undef _GETOPT_API
+
+	#ifdef _UNICODE
+		#define getopt getopt_w
+		#define getopt_long getopt_long_w
+		#define getopt_long_only getopt_long_only_w
+		#define option option_w
+		#define optarg optarg_w
+	#else
+		#define getopt getopt_a
+		#define getopt_long getopt_long_a
+		#define getopt_long_only getopt_long_only_a
+		#define option option_a
+		#define optarg optarg_a
+	#endif
+#endif  // __GETOPT_H_

examples/client/main.cpp

@@ -5,6 +5,7 @@
  * Copyright (c) 2020 Will Munn
  * Copyright (c) 2020 Nico Chatzi
  * Copyright (c) 2020 Lara Mackey
+ * Copyright (c) 2020 Erik Cota-Robles
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -30,6 +31,7 @@
 #include <random>
 #include <thread>
 #include <unordered_map>
+#include "parse_cl.h"
 
 using namespace rtc;
 using namespace std;
@@ -43,20 +45,42 @@ unordered_map<string, shared_ptr<PeerConnection>> peerConnectionMap;
 unordered_map<string, shared_ptr<DataChannel>> dataChannelMap;
 
 string localId;
+bool echoDataChannelMessages = false;
 
 shared_ptr<PeerConnection> createPeerConnection(const Configuration &config,
                                                 weak_ptr<WebSocket> wws, string id);
+
+void confirmOnStdout(bool echoed, string id, string type, int length);
 string randomId(size_t length);
 
 int main(int argc, char **argv) {
+	Cmdline *params = nullptr;
+	try {
+		params = new Cmdline(argc, argv);
+	} catch (const std::range_error&e) {
+		std::cout<< e.what() << '\n';
+		delete params;
+		return -1;
+	}
+
 	rtc::InitLogger(LogLevel::Debug);
 
 	Configuration config;
-	config.iceServers.emplace_back("stun:stun.l.google.com:19302"); // change to your STUN server
+	string stunServer = "";
+	if (params->stunServer().substr(0,5).compare("stun:") != 0) {
+		stunServer = "stun:";
+	}
+	stunServer += params->stunServer() + ":" + to_string(params->stunPort());
+	cout << "Stun server is " << stunServer << endl;
+	config.iceServers.emplace_back(stunServer);
 
 	localId = randomId(4);
 	cout << "The local ID is: " << localId << endl;
 
+	echoDataChannelMessages = params->echoDataChannelMessages();
+	cout << "Received data channel messages will be "
+	     << (echoDataChannelMessages ? "echoed back to sender" : "printed to stdout") << endl;
+
 	auto ws = make_shared<WebSocket>();
 
 	ws->onOpen([]() { cout << "WebSocket connected, signaling ready" << endl; });
@@ -101,7 +125,13 @@ int main(int argc, char **argv) {
 		}
 	});
 
-	const string url = "ws://localhost:8000/" + localId;
+	string wsPrefix = "";
+	if (params->webSocketServer().substr(0,5).compare("ws://") != 0) {
+		wsPrefix = "ws://";
+	}
+	const string url = wsPrefix + params->webSocketServer() + ":" +
+		to_string(params->webSocketPort()) + "/" + localId;
+	cout << "Url is " << url << endl;
 	ws->open(url);
 
 	cout << "Waiting for signaling to be connected..." << endl;
@@ -137,11 +167,20 @@ int main(int argc, char **argv) {
 
 		dc->onClosed([id]() { cout << "DataChannel from " << id << " closed" << endl; });
 
-		dc->onMessage([id](const variant<binary, string> &message) {
-			if (!holds_alternative<string>(message))
-				return;
-
-			cout << "Message from " << id << " received: " << get<string>(message) << endl;
+		dc->onMessage([id, wdc = make_weak_ptr(dc)](const variant<binary, string> &message) {
+			static bool firstMessage = true;
+			if (holds_alternative<string>(message) && (!echoDataChannelMessages || firstMessage)) {
+				cout << "Message from " << id << " received: " << get<string>(message) << endl;
+				firstMessage = false;
+			} else if (echoDataChannelMessages) {
+				bool echoed = false;
+				if (auto dc = wdc.lock()) {
+					dc->send(message);
+					echoed = true;
+				}
+				confirmOnStdout(echoed, id, (holds_alternative<string>(message) ? "text" : "binary"),
+						get<string>(message).length());
+			}
 		});
 
 		dataChannelMap.emplace(id, dc);
@@ -153,6 +192,7 @@ int main(int argc, char **argv) {
 
 	dataChannelMap.clear();
 	peerConnectionMap.clear();
+	delete params;
 	return 0;
 }
 
@@ -190,11 +230,20 @@ shared_ptr<PeerConnection> createPeerConnection(const Configuration &config,
 
 		dc->onClosed([id]() { cout << "DataChannel from " << id << " closed" << endl; });
 
-		dc->onMessage([id](const variant<binary, string> &message) {
-			if (!holds_alternative<string>(message))
-				return;
-
-			cout << "Message from " << id << " received: " << get<string>(message) << endl;
+		dc->onMessage([id, wdc = make_weak_ptr(dc)](const variant<binary, string> &message) {
+			static bool firstMessage = true;
+			if (holds_alternative<string>(message) && (!echoDataChannelMessages || firstMessage)) {
+				cout << "Message from " << id << " received: " << get<string>(message) << endl;
+				firstMessage = false;
+			} else if (echoDataChannelMessages) {
+				bool echoed = false;
+				if (auto dc = wdc.lock()) {
+					dc->send(message);
+					echoed = true;
+				}
+				confirmOnStdout(echoed, id, (holds_alternative<string>(message) ? "text" : "binary"),
+						get<string>(message).length());
+			}
 		});
 
 		dc->send("Hello from " + localId);
@@ -206,6 +255,19 @@ shared_ptr<PeerConnection> createPeerConnection(const Configuration &config,
 	return pc;
 };
 
+void confirmOnStdout(bool echoed, string id, string type, int length) {
+	static long count = 0;
+	static long freq = 100;
+	if (!(++count%freq)) {
+		cout << "Received " << count << " pings in total from host " << id << ", most recent of type "
+		     << type << " and " << (echoed ? "" : "un") << "successfully echoed most recent ping of size "
+		     << length << " back to " << id << endl;
+		if (count >= (freq * 10) && freq < 1000000) {
+			freq *= 10;
+		}
+	}
+}
+
 // Helper function to generate a random ID
 string randomId(size_t length) {
 	static const string characters(

examples/client/parse_cl.cpp

@@ -0,0 +1,173 @@
+/******************************************************************************
+**
+** parse_cl.cpp
+**
+** Thu Aug  6 19:42:25 2020
+** Linux 5.4.0-42-generic (#46-Ubuntu SMP Fri Jul 10 00:24:02 UTC 2020) x86_64
+** cerik@Erik-VBox-Ubuntu (Erik Cota-Robles)
+**
+** Copyright (c) 2020 Erik Cota-Robles
+**
+** Definition of command line parser class
+**
+** Automatically created by genparse v0.9.3
+**
+** See http://genparse.sourceforge.net for details and updates
+**
+**
+******************************************************************************/
+
+#include <stdlib.h>
+
+#if defined(_WIN32) || defined(WIN32)
+#include "getopt.h"
+#else
+#include <getopt.h>
+#endif
+
+#include "parse_cl.h"
+
+/*----------------------------------------------------------------------------
+**
+** Cmdline::Cmdline ()
+**
+** Constructor method.
+**
+**--------------------------------------------------------------------------*/
+
+Cmdline::Cmdline (int argc, char *argv[]) // ISO C++17 not allowed: throw (std::string )
+{
+  extern char *optarg;
+  extern int optind;
+  int c;
+
+  static struct option long_options[] =
+  {
+    {"stunServer", required_argument, NULL, 's'},
+    {"stunPort", required_argument, NULL, 't'},
+    {"webSocketServer", required_argument, NULL, 'w'},
+    {"webSocketPort", required_argument, NULL, 'x'},
+    {"help", no_argument, NULL, 'h'},
+    {"version", no_argument, NULL, 'v'},
+    {NULL, 0, NULL, 0}
+  };
+
+  _program_name += argv[0];
+
+  /* default values */
+  _s = "stun.l.google.com";
+  _t = 19302;
+  _w = "localhost";
+  _x = 8000;
+  _e = false;
+  _h = false;
+  _v = false;
+
+  optind = 0;
+  while ((c = getopt_long (argc, argv, "s:t:w:x:ehv", long_options, &optind)) != - 1)
+    {
+      switch (c)
+        {
+        case 's': 
+          _s = optarg;
+          break;
+
+        case 't': 
+          _t = atoi (optarg);
+          if (_t < 0)
+            {
+              std::string err;
+              err += "parameter range error: t must be >= 0";
+              throw (std::range_error(err));
+            }
+          if (_t > 65535)
+            {
+              std::string err;
+              err += "parameter range error: t must be <= 65535";
+              throw (std::range_error(err));
+            }
+          break;
+
+        case 'w': 
+          _w = optarg;
+          break;
+
+        case 'x': 
+          _x = atoi (optarg);
+          if (_x < 0)
+            {
+              std::string err;
+              err += "parameter range error: x must be >= 0";
+              throw (std::range_error(err));
+            }
+          if (_x > 65535)
+            {
+              std::string err;
+              err += "parameter range error: x must be <= 65535";
+              throw (std::range_error(err));
+            }
+          break;
+
+        case 'e': 
+          _e = true;
+          break;
+
+        case 'h': 
+          _h = true;
+          this->usage (EXIT_SUCCESS);
+          break;
+
+        case 'v': 
+          _v = true;
+          this->version (EXIT_SUCCESS);
+          break;
+
+        default:
+          this->usage (EXIT_FAILURE);
+
+        }
+    } /* while */
+
+  _optind = optind;
+}
+
+/*----------------------------------------------------------------------------
+**
+** Cmdline::usage () and version()
+**
+** Print out usage (or version) information, then exit.
+**
+**--------------------------------------------------------------------------*/
+
+void Cmdline::usage (int status)
+{
+  if (status != EXIT_SUCCESS)
+    std::cerr << "Try `" << _program_name << " --help' for more information.\n";
+  else
+    {
+      std::cout << "\
+usage: " << _program_name << " [ -estwxhv ] \n\
+libdatachannel client implementing WebRTC Data Channels with WebSocket signaling\n\
+   [ -e ] [ --echo ] (type=FLAG)\n\
+          Echo data channel messages back to sender rather than putting to stdout.\n\
+   [ -s ] [ --stunServer ] (type=STRING, default=stun.l.google.com)\n\
+          Stun server URL or IP address.\n\
+   [ -t ] [ --stunPort ] (type=INTEGER, range=0...65535, default=19302)\n\
+          Stun server port.\n\
+   [ -w ] [ --webSocketServer ] (type=STRING, default=localhost)\n\
+          Web socket server URL or IP address.\n\
+   [ -x ] [ --webSocketPort ] (type=INTEGER, range=0...65535, default=8000)\n\
+          Web socket server port.\n\
+   [ -h ] [ --help ] (type=FLAG)\n\
+          Display this help and exit.\n\
+   [ -v ] [ --version ] (type=FLAG)\n\
+          Output version information and exit.\n";
+    }
+  exit (status);
+}
+
+void Cmdline::version (int status)
+{
+  std::cout << _program_name << " v0.5\n";
+  exit (status);
+}

examples/client/parse_cl.h

@@ -0,0 +1,72 @@
+/******************************************************************************
+**
+** parse_cl.h
+**
+** Thu Aug  6 19:42:25 2020
+** Linux 5.4.0-42-generic (#46-Ubuntu SMP Fri Jul 10 00:24:02 UTC 2020) x86_64
+** cerik@Erik-VBox-Ubuntu (Erik Cota-Robles)
+**
+** Copyright (c) 2020 Erik Cota-Robles
+**
+** Header file for command line parser class
+**
+** Automatically created by genparse v0.9.3
+**
+** See http://genparse.sourceforge.net for details and updates
+**
+******************************************************************************/
+
+#ifndef CMDLINE_H
+#define CMDLINE_H
+
+#include <iostream>
+#include <string>
+
+/*----------------------------------------------------------------------------
+**
+** class Cmdline
+**
+** command line parser class
+**
+**--------------------------------------------------------------------------*/
+
+class Cmdline
+{
+private:
+  /* parameters */
+  std::string _s;
+  int _t;
+  std::string _w;
+  int _x;
+  bool _e;
+  bool _h;
+  bool _v;
+
+  /* other stuff to keep track of */
+  std::string _program_name;
+  int _optind;
+
+public:
+  /* constructor and destructor */
+  Cmdline (int, char **); // ISO C++17 not allowed: throw (std::string);
+  ~Cmdline (){}
+
+  /* usage function */
+  void usage (int status);
+
+  /* version function */
+  void version (int status);
+
+  /* return next (non-option) parameter */
+  int next_param () { return _optind; }
+
+  std::string stunServer () const { return _s; }
+  int stunPort () const { return _t; }
+  std::string webSocketServer () const { return _w; }
+  int webSocketPort () const { return _x; }
+  bool echoDataChannelMessages () const { return _e; }
+  bool h () const { return _h; }
+  bool v () const { return _v; }
+};
+
+#endif