From 26ee2eacc7d60aa379c9e4b9b9c6b8bcdcd4bc6b Mon Sep 17 00:00:00 2001
From: cbdev <cb@cbcdn.com>
Date: Sat, 27 Jul 2019 19:31:21 +0200
Subject: Refactor OSC backend, implement pattern matching

---
 README.md                 |   4 +-
 TODO                      |   1 -
 backends/Makefile         |   4 +-
 backends/osc.c            | 635 ++++++++++++++++++++++++++++++++--------------
 backends/osc.h            |  25 +-
 backends/osc.md           |  21 +-
 configs/flying-faders.cfg |  24 ++
 configs/flying-faders.lua |  10 +
 configs/osc-xy.cfg        |  26 ++
 9 files changed, 543 insertions(+), 207 deletions(-)
 create mode 100644 configs/flying-faders.cfg
 create mode 100644 configs/flying-faders.lua
 create mode 100644 configs/osc-xy.cfg

diff --git a/README.md b/README.md
index 3704f5f..9647d4f 100644
--- a/README.md
+++ b/README.md
@@ -7,8 +7,8 @@ Currently, the MIDIMonster supports the following protocols:
 
 * MIDI (Linux, via ALSA)
 * ArtNet
-* sACN / E1.31
-* OSC
+* Streaming ACN (sACN / E1.31)
+* OpenSoundControl (OSC)
 * evdev input devices (Linux)
 * Open Lighting Architecture (OLA)
 
diff --git a/TODO b/TODO
index d114640..2a97c30 100644
--- a/TODO
+++ b/TODO
@@ -3,6 +3,5 @@ Note source in channel value struct
 Optimize core channel search (store backend offset)
 Printing backend / Verbose mode
 
-document example configs
 evdev relative axis size
 mm_managed_fd.impl is not freed currently
diff --git a/backends/Makefile b/backends/Makefile
index fe88669..22cb95b 100644
--- a/backends/Makefile
+++ b/backends/Makefile
@@ -6,8 +6,8 @@ BACKEND_LIB = libmmbackend.o
 
 SYSTEM := $(shell uname -s)
 
-CFLAGS += -fPIC -I../
-CPPFLAGS += -fPIC -I../
+CFLAGS += -g -fPIC -I../
+CPPFLAGS += -g -fPIC -I../
 LDFLAGS += -shared
 
 # Build Linux backends if possible
diff --git a/backends/osc.c b/backends/osc.c
index 36b0993..3f19abf 100644
--- a/backends/osc.c
+++ b/backends/osc.c
@@ -13,6 +13,14 @@
 #define osc_align(a) ((((a) / 4) + (((a) % 4) ? 1 : 0)) * 4)
 #define BACKEND_NAME "osc"
 
+typedef union {
+	struct {
+		uint32_t channel;
+		uint32_t parameter;
+	} fields;
+	uint64_t label;
+} osc_channel_ident;
+
 static struct {
 	uint8_t detect;
 } osc_global_config = {
@@ -41,6 +49,7 @@ int init(){
 }
 
 static size_t osc_data_length(osc_parameter_type t){
+	//binary representation lengths for osc data types
 	switch(t){
 		case int32:
 		case float32:
@@ -55,6 +64,7 @@ static size_t osc_data_length(osc_parameter_type t){
 }
 
 static inline void osc_defaults(osc_parameter_type t, osc_parameter_value* max, osc_parameter_value* min){
+	//data type default ranges
 	memset(max, 0, sizeof(osc_parameter_value));
 	memset(min, 0, sizeof(osc_parameter_value));
 	switch(t){
@@ -77,6 +87,7 @@ static inline void osc_defaults(osc_parameter_type t, osc_parameter_value* max,
 }
 
 static inline osc_parameter_value osc_parse(osc_parameter_type t, uint8_t* data){
+	//read value from binary representation
 	osc_parameter_value v = {0};
 	switch(t){
 		case int32:
@@ -94,6 +105,7 @@ static inline osc_parameter_value osc_parse(osc_parameter_type t, uint8_t* data)
 }
 
 static inline int osc_deparse(osc_parameter_type t, osc_parameter_value v, uint8_t* data){
+	//write value to binary representation
 	uint64_t u64 = 0;
 	uint32_t u32 = 0;
 	switch(t){
@@ -115,6 +127,7 @@ static inline int osc_deparse(osc_parameter_type t, osc_parameter_value v, uint8
 }
 
 static inline osc_parameter_value osc_parse_value_spec(osc_parameter_type t, char* value){
+	//read value from string
 	osc_parameter_value v = {0};
 	switch(t){
 		case int32:
@@ -136,6 +149,7 @@ static inline osc_parameter_value osc_parse_value_spec(osc_parameter_type t, cha
 }
 
 static inline channel_value osc_parameter_normalise(osc_parameter_type t, osc_parameter_value min, osc_parameter_value max, osc_parameter_value cur){
+	//normalise osc value wrt given min/max
 	channel_value v = {
 		.raw = {0},
 		.normalised = 0
@@ -179,6 +193,7 @@ static inline channel_value osc_parameter_normalise(osc_parameter_type t, osc_pa
 }
 
 static inline osc_parameter_value osc_parameter_denormalise(osc_parameter_type t, osc_parameter_value min, osc_parameter_value max, channel_value cur){
+	//convert normalised value to osc value wrt given min/max
 	osc_parameter_value v = {0};
 
 	union {
@@ -212,45 +227,192 @@ static inline osc_parameter_value osc_parameter_denormalise(osc_parameter_type t
 	return v;
 }
 
-static int osc_generate_event(channel* c, osc_channel* info, char* fmt, uint8_t* data, size_t data_len){
-	size_t p, off = 0;
-	if(!c || !info){
-		return 0;
+static int osc_path_validate(char* path, uint8_t allow_patterns){
+	//validate osc path or pattern
+	char illegal_chars[] = " #,";
+	char pattern_chars[] = "?[]{}*";
+	size_t u, c;
+	uint8_t square_open = 0, curly_open = 0;
+	
+	if(path[0] != '/'){
+		fprintf(stderr, "%s is not a valid OSC path: Missing root /\n", path);
+		return 1;
 	}
 
-	osc_parameter_value min, max, cur;
-	channel_value evt;
+	for(u = 0; u < strlen(path); u++){
+		for(c = 0; c < sizeof(illegal_chars); c++){
+			if(path[u] == illegal_chars[c]){
+				fprintf(stderr, "%s is not a valid OSC path: Illegal '%c' at %lu\n", path, illegal_chars[c], u);
+				return 1;
+			}
+		}
 
-	if(!fmt || !data || data_len % 4 || !*fmt){
-		fprintf(stderr, "Invalid OSC packet, data length %zu\n", data_len);
-		return 1;
-	}
+		if(!isgraph(path[u])){
+			fprintf(stderr, "%s is not a valid OSC path: Illegal '%c' at %lu\n", path, pattern_chars[c], u);
+			return 1;
+		}
 
-	//find offset for this parameter
-	for(p = 0; p < info->param_index; p++){
-		off += osc_data_length(fmt[p]);
-	}
+		if(!allow_patterns){
+			for(c = 0; c < sizeof(pattern_chars); c++){
+				if(path[u] == pattern_chars[c]){
+					fprintf(stderr, "%s is not a valid OSC path: Illegal '%c' at %lu\n", path, pattern_chars[c], u);
+					return 1;
+				}
+			}
+		}
 
-	if(info->type != not_set){
-		max = info->max;
-		min = info->min;
+		switch(path[u]){
+			case '{':
+				if(square_open || curly_open){
+					fprintf(stderr, "%s is not a valid OSC path: Illegal '%c' at %lu\n", path, pattern_chars[c], u);
+					return 1;
+				}
+				curly_open = 1;
+				break;
+			case '[':
+				if(square_open || curly_open){
+					fprintf(stderr, "%s is not a valid OSC path: Illegal '%c' at %lu\n", path, pattern_chars[c], u);
+					return 1;
+				}
+				square_open = 1;
+				break;
+			case '}':
+				curly_open = 0;
+				break;
+			case ']':
+				square_open = 0;
+				break;
+			case '/':
+				if(square_open || curly_open){
+					fprintf(stderr, "%s is not a valid OSC path: Pattern across part boundaries\n", path);
+					return 1;
+				}
+		}
 	}
-	else{
-		osc_defaults(fmt[info->param_index], &max, &min);
+
+	if(square_open || curly_open){
+		fprintf(stderr, "%s is not a valid OSC path: Unterminated pattern expression\n", path);
+		return 1;
 	}
+	return 0;
+}
 
-	cur = osc_parse(fmt[info->param_index], data + off);
-	evt = osc_parameter_normalise(fmt[info->param_index], min, max, cur);
+static int osc_path_match(char* pattern, char* path){
+	size_t u, p = 0, match_begin, match_end;
+	uint8_t match_any = 0, inverted, match;
 
-	return mm_channel_event(c, evt);
-}
+	for(u = 0; u < strlen(path); u++){
+		switch(pattern[p]){
+			case '/':
+				if(match_any){
+					for(; path[u] && path[u] != '/'; u++){
+					}
+				}
+				if(path[u] != '/'){
+					return 0;
+				}
+				match_any = 0;
+				p++;
+				break;
+			case '?':
+				match_any = 0;
+				p++;
+				break;
+			case '*':
+				match_any = 1;
+				p++;
+				break;
+			case '[':
+				inverted = (pattern[p + 1] == '!') ? 1 : 0;
+				match_end = match_begin = inverted ? p + 2 : p + 1;
+				match = 0;
+				for(; pattern[match_end] != ']'; match_end++){
+					if(pattern[match_end] == path[u]){
+						match = 1;
+						break;
+					}
 
-static int osc_validate_path(char* path){
-	if(path[0] != '/'){
-		fprintf(stderr, "%s is not a valid OSC path: Missing root /\n", path);
-		return 1;
+					if(pattern[match_end + 1] == '-' && pattern[match_end + 2] != ']'){
+						if((pattern[match_end] > pattern[match_end + 2] 
+									&& path[u] >= pattern[match_end + 2]
+									&& path[u] <= pattern[match_end])
+								|| (pattern[match_end] <= pattern[match_end + 2]
+									&& path[u] >= pattern[match_end]
+									&& path[u] <= pattern[match_end + 2])){
+							match = 1;
+							break;
+						}
+						match_end += 2;
+					}
+
+					if(pattern[match_end + 1] == ']' && match_any && !match
+							&& path[u + 1] && path[u + 1] != '/'){
+						match_end = match_begin - 1;
+						u++;
+					}
+				}
+
+				if(match == inverted){
+					return 0;
+				}
+
+				match_any = 0;
+				//advance to end of pattern
+				for(; pattern[p] != ']'; p++){
+				}
+				p++;
+				break;
+			case '{':
+				for(match_begin = p + 1; pattern[match_begin] != '}'; match_begin++){
+					//find end
+					for(match_end = match_begin; pattern[match_end] != ',' && pattern[match_end] != '}'; match_end++){
+					}
+
+					if(!strncmp(path + u, pattern + match_begin, match_end - match_begin)){
+						//advance pattern
+						for(; pattern[p] != '}'; p++){
+						}
+						p++;
+						//advance path
+						u += match_end - match_begin - 1;
+						break;
+					}
+
+					if(pattern[match_end] == '}'){
+						//retry with next if in match_any
+						if(match_any && path[u + 1] && path[u + 1] != '/'){
+							u++;
+							match_begin = p;
+							continue;
+						}
+						return 0;
+					}
+					match_begin = match_end;
+				}
+				match_any = 0;
+				break;
+			case 0:
+				if(match_any){
+					for(; path[u] && path[u] != '/'; u++){
+					}
+				}
+				if(path[u]){
+					return 0;
+				}
+				break;
+			default:
+				if(match_any){
+					for(; path[u] && path[u] != '/' && path[u] != pattern[p]; u++){
+					}
+				}
+				if(pattern[p] != path[u]){
+					return 0;
+				}
+				p++;
+				break;
+		}
 	}
-	return 0;
+	return 1;
 }
 
 static int osc_configure(char* option, char* value){
@@ -266,13 +428,81 @@ static int osc_configure(char* option, char* value){
 	return 1;
 }
 
+static int osc_register_pattern(osc_instance_data* data, char* pattern_path, char* configuration){
+	size_t u, pattern;
+	char* format = NULL, *token = NULL;
+
+	if(osc_path_validate(pattern_path, 1)){
+		fprintf(stderr, "Not a valid OSC pattern: %s\n", pattern_path);
+		return 1;
+	}
+
+	//tokenize configuration
+	format = strtok(configuration, " ");
+	if(!format || strlen(format) < 1){
+		fprintf(stderr, "Not a valid format specification for OSC pattern %s\n", pattern_path);
+		return 1;
+	}
+
+	//create pattern
+	data->pattern = realloc(data->pattern, (data->patterns + 1) * sizeof(osc_channel));
+	if(!data->pattern){
+		fprintf(stderr, "Failed to allocate memory\n");
+		return 1;
+	}
+	pattern = data->patterns;
+
+	data->pattern[pattern].params = strlen(format);
+	data->pattern[pattern].path = strdup(pattern_path);
+	data->pattern[pattern].type = calloc(strlen(format), sizeof(osc_parameter_type));
+	data->pattern[pattern].max = calloc(strlen(format), sizeof(osc_parameter_value));
+	data->pattern[pattern].min = calloc(strlen(format), sizeof(osc_parameter_value));
+
+	if(!data->pattern[pattern].path
+			|| !data->pattern[pattern].type
+			|| !data->pattern[pattern].max
+			|| !data->pattern[pattern].min){
+		//this should fail config parsing and thus call the shutdown function,
+		//which should properly free the rest of the data
+		fprintf(stderr, "Failed to allocate memory\n");
+		return 1;
+	}
+
+	//check format validity and store min/max values
+	for(u = 0; u < strlen(format); u++){
+		if(!osc_data_length(format[u])){
+			fprintf(stderr, "Invalid format specifier %c for pattern %s\n", format[u], pattern_path);
+			return 1;
+		}
+
+		data->pattern[pattern].type[u] = format[u];
+
+		//parse min/max values
+		token = strtok(NULL, " ");
+		if(!token){
+			fprintf(stderr, "Missing minimum specification for parameter %zu of OSC pattern %s\n", u, pattern_path);
+			return 1;
+		}
+		data->pattern[pattern].min[u] = osc_parse_value_spec(format[u], token);
+
+		token = strtok(NULL, " ");
+		if(!token){
+			fprintf(stderr, "Missing maximum specification for parameter %zu of OSC pattern %s\n", u, pattern_path);
+			return 1;
+		}
+		data->pattern[pattern].max[u] = osc_parse_value_spec(format[u], token);
+	}
+
+	data->patterns++;
+	return 0;
+}
+
 static int osc_configure_instance(instance* inst, char* option, char* value){
 	osc_instance_data* data = (osc_instance_data*) inst->impl;
-	char* host = NULL, *port = NULL, *token = NULL, *format = NULL;
-	size_t u, p;
+	char* host = NULL, *port = NULL, *token = NULL;
 
 	if(!strcmp(option, "root")){
-		if(osc_validate_path(value)){
+		if(osc_path_validate(value, 0)){
 			fprintf(stderr, "Not a valid OSC root: %s\n", value);
 			return 1;
 		}
@@ -326,76 +556,7 @@ static int osc_configure_instance(instance* inst, char* option, char* value){
 		return 0;
 	}
 	else if(*option == '/'){
-		//pre-configure channel
-		if(osc_validate_path(option)){
-			fprintf(stderr, "Not a valid OSC path: %s\n", option);
-			return 1;
-		}
-
-		for(u = 0; u < data->channels; u++){
-			if(!strcmp(option, data->channel[u].path)){
-				fprintf(stderr, "OSC channel %s already configured\n", option);
-				return 1;
-			}
-		}
-
-		//tokenize configuration
-		format = strtok(value, " ");
-		if(!format || strlen(format) < 1){
-			fprintf(stderr, "Not a valid format for OSC path %s\n", option);
-			return 1;
-		}
-
-		//check format validity, create subchannels
-		for(p = 0; p < strlen(format); p++){
-			if(!osc_data_length(format[p])){
-				fprintf(stderr, "Invalid format specifier %c for path %s, ignoring\n", format[p], option);
-				continue;
-			}
-
-			//register new sub-channel
-			data->channel = realloc(data->channel, (data->channels + 1) * sizeof(osc_channel));
-			if(!data->channel){
-				fprintf(stderr, "Failed to allocate memory\n");
-				return 1;
-			}
-
-			memset(data->channel + data->channels, 0, sizeof(osc_channel));
-			data->channel[data->channels].params = strlen(format);
-			data->channel[data->channels].param_index = p;
-			data->channel[data->channels].type = format[p];
-			data->channel[data->channels].path = strdup(option);
-
-			if(!data->channel[data->channels].path){
-				fprintf(stderr, "Failed to allocate memory\n");
-				return 1;
-			}
-
-			//parse min/max values
-			token = strtok(NULL, " ");
-			if(!token){
-				fprintf(stderr, "Missing minimum specification for parameter %zu of %s\n", p, option);
-				return 1;
-			}
-			data->channel[data->channels].min = osc_parse_value_spec(format[p], token);
-
-			token = strtok(NULL, " ");
-			if(!token){
-				fprintf(stderr, "Missing maximum specification for parameter %zu of %s\n", p, option);
-				return 1;
-			}
-			data->channel[data->channels].max = osc_parse_value_spec(format[p], token);
-
-			//allocate channel from core
-			if(!mm_channel(inst, data->channels, 1)){
-				fprintf(stderr, "Failed to register core channel\n");
-				return 1;
-			}
-
-			//increase channel count
-			data->channels++;
-		}
-		return 0;
+		return osc_register_pattern(data, option, value);
 	}
 
 	fprintf(stderr, "Unknown configuration parameter %s for OSC instance %s\n", option, inst->name);
@@ -420,31 +581,38 @@ static instance* osc_instance(){
 }
 
 static channel* osc_map_channel(instance* inst, char* spec){
-	size_t u;
+	size_t u, p;
 	osc_instance_data* data = (osc_instance_data*) inst->impl;
-	size_t param_index = 0;
+	osc_channel_ident ident = {
+		.label = 0
+	};
 
 	//check spec for correctness
-	if(osc_validate_path(spec)){
+	if(osc_path_validate(spec, 0)){
 		return NULL;
 	}
 
 	//parse parameter offset
 	if(strrchr(spec, ':')){
-		param_index = strtoul(strrchr(spec, ':') + 1, NULL, 10);
+		ident.fields.parameter = strtoul(strrchr(spec, ':') + 1, NULL, 10);
 		*(strrchr(spec, ':')) = 0;
 	}
 
 	//find matching channel
 	for(u = 0; u < data->channels; u++){
-		if(!strcmp(spec, data->channel[u].path) && data->channel[u].param_index == param_index){
-			//fprintf(stderr, "Reusing previously created channel %s parameter %zu\n", data->channel[u].path, data->channel[u].param_index);
+		if(!strcmp(spec, data->channel[u].path)){
 			break;
 		}
 	}
 
 	//allocate new channel
 	if(u == data->channels){
+		for(p = 0; p < data->patterns; p++){
+			if(osc_path_match(data->pattern[p].path, spec)){
+				break;
+			}
+		}
+
 		data->channel = realloc(data->channel, (u + 1) * sizeof(osc_channel));
 		if(!data->channel){
 			fprintf(stderr, "Failed to allocate memory\n");
@@ -452,22 +620,100 @@ static channel* osc_map_channel(instance* inst, char* spec){
 		}
 
 		memset(data->channel + u, 0, sizeof(osc_channel));
-		data->channel[u].param_index = param_index;
 		data->channel[u].path = strdup(spec);
+		if(p != data->patterns){
+			fprintf(stderr, "Matched pattern %s for %s\n", data->pattern[p].path, spec);
+			data->channel[u].params = data->pattern[p].params;
+			//just reuse the pointers from the pattern
+			data->channel[u].type = data->pattern[p].type;
+			data->channel[u].max = data->pattern[p].max;
+			data->channel[u].min = data->pattern[p].min;
+
+			//these are per channel
+			data->channel[u].in = calloc(data->channel[u].params, sizeof(osc_parameter_value));
+			data->channel[u].out = calloc(data->channel[u].params, sizeof(osc_parameter_value));
+		}
+		else if(data->patterns){
+			fprintf(stderr, "No pattern match found for %s\n", spec);
+		}
 
-		if(!data->channel[u].path){
+		if(!data->channel[u].path
+				|| (data->channel[u].params && (!data->channel[u].in || !data->channel[u].out))){
 			fprintf(stderr, "Failed to allocate memory\n");
 			return NULL;
 		}
 		data->channels++;
 	}
 
-	return mm_channel(inst, u, 1);
+	ident.fields.channel = u;
+	return mm_channel(inst, ident.label, 1);
+}
+
+static int osc_output_channel(instance* inst, size_t channel){
+	osc_instance_data* data = (osc_instance_data*) inst->impl;
+	uint8_t xmit_buf[OSC_XMIT_BUF] = "", *format = NULL;
+	size_t offset = 0, p;
+
+	//fix destination rport if required
+	if(data->forced_rport){
+		//cheating a bit because both IPv4 and IPv6 have the port at the same offset
+		struct sockaddr_in* sockadd = (struct sockaddr_in*) &(data->dest);
+		sockadd->sin_port = htobe16(data->forced_rport);
+	}
+
+	//determine minimum packet size
+	if(osc_align((data->root ? strlen(data->root) : 0) + strlen(data->channel[channel].path) + 1) + osc_align(data->channel[channel].params + 2)  >= sizeof(xmit_buf)){
+		fprintf(stderr, "Insufficient buffer size for OSC transmitting channel %s.%s\n", inst->name, data->channel[channel].path);
+		return 1;
+	}
+
+	//copy osc target path
+	if(data->root){
+		memcpy(xmit_buf, data->root, strlen(data->root));
+		offset += strlen(data->root);
+	}
+	
+	memcpy(xmit_buf + offset, data->channel[channel].path, strlen(data->channel[channel].path));
+	offset += strlen(data->channel[channel].path) + 1;
+	offset = osc_align(offset);
+
+	//get format string offset, initialize
+	format = xmit_buf + offset;
+	offset += osc_align(data->channel[channel].params + 2);
+	*format = ',';
+	format++;
+
+	for(p = 0; p < data->channel[channel].params; p++){
+		//write format specifier
+		format[p] = data->channel[channel].type[p];
+
+		//write data
+		if(offset + osc_data_length(data->channel[channel].type[p]) >= sizeof(xmit_buf)){
+			fprintf(stderr, "Insufficient buffer size for OSC transmitting channel %s.%s at parameter %zu\n", inst->name, data->channel[channel].path, p);
+			return 1;
+		}
+
+		osc_deparse(data->channel[channel].type[p],
+				data->channel[channel].out[p],
+				xmit_buf + offset);
+		offset += osc_data_length(data->channel[channel].type[p]);
+	}
+
+	//output packet
+	if(sendto(data->fd, xmit_buf, offset, 0, (struct sockaddr*) &(data->dest), data->dest_len) < 0){
+		fprintf(stderr, "Failed to transmit OSC packet: %s\n", strerror(errno));
+	}
+	return 0;
 }
 
 static int osc_set(instance* inst, size_t num, channel** c, channel_value* v){
-	uint8_t xmit_buf[OSC_XMIT_BUF], *format = NULL;
-	size_t evt = 0, off, members, p;
+	size_t evt = 0, mark = 0;
+	int rv;
+	osc_channel_ident ident = {
+		.label = 0
+	};
+	osc_parameter_value current;
+
 	if(!num){
 		return 0;
 	}
@@ -479,95 +725,97 @@ static int osc_set(instance* inst, size_t num, channel** c, channel_value* v){
 	}
 
 	for(evt = 0; evt < num; evt++){
-		off = c[evt]->ident;
+		ident.label = c[evt]->ident;
 
 		//sanity check
-		if(off >= data->channels){
+		if(ident.fields.channel >= data->channels
+				|| ident.fields.parameter >= data->channel[ident.fields.channel].params){
 			fprintf(stderr, "OSC channel identifier out of range\n");
 			return 1;
 		}
 
 		//if the format is unknown, don't output
-		if(data->channel[off].type == not_set || data->channel[off].params == 0){
-			fprintf(stderr, "OSC channel %s.%s requires format specification for output\n", inst->name, data->channel[off].path);
+		if(!data->channel[ident.fields.channel].params){
+			fprintf(stderr, "OSC channel %s.%s requires format specification for output\n", inst->name, data->channel[ident.fields.channel].path);
 			continue;
 		}
 
-		//update current value
-		data->channel[off].current = osc_parameter_denormalise(data->channel[off].type, data->channel[off].min, data->channel[off].max, v[evt]);
-		//mark channel
-		data->channel[off].mark = 1;
+		//only output on change
+		current = osc_parameter_denormalise(data->channel[ident.fields.channel].type[ident.fields.parameter],
+				data->channel[ident.fields.channel].min[ident.fields.parameter],
+				data->channel[ident.fields.channel].max[ident.fields.parameter],
+				v[evt]);
+		if(memcmp(&current, &data->channel[ident.fields.channel].out[ident.fields.parameter], sizeof(current))){
+			//update current value
+			data->channel[ident.fields.channel].out[ident.fields.parameter] = current;
+			//mark channel
+			data->channel[ident.fields.channel].mark = 1;
+			mark = 1;
+		}
 	}
-
-	//fix destination rport if required
-	if(data->forced_rport){
-		//cheating a bit because both IPv4 and IPv6 have the port at the same offset
-		struct sockaddr_in* sockadd = (struct sockaddr_in*) &(data->dest);
-		sockadd->sin_port = htobe16(data->forced_rport);
+	
+	if(mark){
+		//output all marked channels
+		for(evt = 0; !rv && evt < num; evt++){
+			ident.label = c[evt]->ident;
+			if(data->channel[ident.fields.channel].mark){
+				rv |= osc_output_channel(inst, ident.fields.channel);
+				data->channel[ident.fields.channel].mark = 0;
+			}
+		}
 	}
+	return rv;
+}
 
-	//find all marked channels
-	for(evt = 0; evt < data->channels; evt++){
-		//zero output buffer
-		memset(xmit_buf, 0, sizeof(xmit_buf));
-		if(data->channel[evt].mark){
-			//determine minimum packet size
-			if(osc_align((data->root ? strlen(data->root) : 0) + strlen(data->channel[evt].path) + 1) + osc_align(data->channel[evt].params + 2)  >= sizeof(xmit_buf)){
-				fprintf(stderr, "Insufficient buffer size for OSC transmitting channel %s.%s\n", inst->name, data->channel[evt].path);
-				return 1;
-			}
+static int osc_process_packet(instance* inst, char* local_path, char* format, uint8_t* payload, size_t payload_len){
+	osc_instance_data* data = (osc_instance_data*) inst->impl;
+	size_t c, p, offset = 0;
+	osc_parameter_value min, max, cur;
+	channel_value evt;
+	osc_channel_ident ident = {
+		.label = 0
+	};
+	channel* chan = NULL;
 
-			off = 0;
-			//copy osc target path
-			if(data->root){
-				memcpy(xmit_buf, data->root, strlen(data->root));
-				off += strlen(data->root);
-			}
-			memcpy(xmit_buf + off, data->channel[evt].path, strlen(data->channel[evt].path));
-			off += strlen(data->channel[evt].path) + 1;
-			off = osc_align(off);
-
-			//get format string offset, initialize
-			format = xmit_buf + off;
-			off += osc_align(data->channel[evt].params + 2);
-			*format = ',';
-			format++;
-
-			//gather subchannels, unmark
-			members = 0;
-			for(p = 0; p < data->channels && members < data->channel[evt].params; p++){
-				if(!strcmp(data->channel[evt].path, data->channel[p].path)){
-					//unmark channel
-					data->channel[p].mark = 0;
-
-					//sanity check
-					if(data->channel[p].param_index >= data->channel[evt].params){
-						fprintf(stderr, "OSC channel %s.%s has multiple parameter offset definitions\n", inst->name, data->channel[evt].path);
-						return 1;
-					}
+	if(payload_len % 4){
+		fprintf(stderr, "Invalid OSC packet, data length %zu\n", payload_len);
+		return 0;
+	}
 
-					//write format specifier
-					format[data->channel[p].param_index] = data->channel[p].type;
+	for(c = 0; c < data->channels; c++){
+		if(!strcmp(local_path, data->channel[c].path)){
+			ident.fields.channel = c;
+			//unconfigured input should work without errors (using default limits)
+			if(data->channel[c].params && strlen(format) != data->channel[c].params){
+				fprintf(stderr, "OSC message %s.%s had format %s, internal representation has %lu parameters\n", inst->name, local_path, format, data->channel[c].params);
+				continue;
+			}
 
-					//write data
-					//FIXME this currently depends on all channels being registered in the correct order, since it just appends data
-					if(off + osc_data_length(data->channel[p].type) >= sizeof(xmit_buf)){
-						fprintf(stderr, "Insufficient buffer size for OSC transmitting channel %s.%s at parameter %zu\n", inst->name, data->channel[evt].path, members);
-						return 1;
+			for(p = 0; p < strlen(format); p++){
+				ident.fields.parameter = p;
+				if(data->channel[c].params){
+					max = data->channel[c].max[p];
+					min = data->channel[c].min[p];
+				}
+				else{
+					osc_defaults(format[p], &max, &min);
+				}
+				cur = osc_parse(format[p], payload + offset);
+				if(!data->channel[c].params || memcmp(&cur, &data->channel[c].in, sizeof(cur))){
+					evt = osc_parameter_normalise(format[p], min, max, cur);
+					chan = mm_channel(inst, ident.label, 0);
+					if(chan){
+						mm_channel_event(chan, evt);
 					}
-
-					osc_deparse(data->channel[p].type, data->channel[p].current, xmit_buf + off);
-					off += osc_data_length(data->channel[p].type);
-					members++;
 				}
-			}
 
-			//output packet
-			if(sendto(data->fd, xmit_buf, off, 0, (struct sockaddr*) &(data->dest), data->dest_len) < 0){
-				fprintf(stderr, "Failed to transmit OSC packet: %s\n", strerror(errno));
+				//skip to next parameter data
+				offset += osc_data_length(format[p]);
+				//TODO check offset against payload length
 			}
 		}
 	}
+
 	return 0;
 }
 
@@ -577,7 +825,6 @@ static int osc_handle(size_t num, managed_fd* fds){
 	instance* inst = NULL;
 	osc_instance_data* data = NULL;
 	ssize_t bytes_read = 0;
-	size_t c;
 	char* osc_fmt = NULL;
 	char* osc_local = NULL;
 	uint8_t* osc_data = NULL;
@@ -600,7 +847,7 @@ static int osc_handle(size_t num, managed_fd* fds){
 				bytes_read = recv(fds[fd].fd, recv_buf, sizeof(recv_buf), 0);
 			}
 
-			if(bytes_read < 0){
+			if(bytes_read <= 0){
 				break;
 			}
 
@@ -622,20 +869,11 @@ static int osc_handle(size_t num, managed_fd* fds){
 				fprintf(stderr, "Incoming OSC data: Path %s.%s Format %s\n", inst->name, osc_local, osc_fmt);
 			}
 
-			osc_data = (uint8_t*) osc_fmt + (osc_align(strlen(osc_fmt) + 2) - 1);
 			//FIXME check supplied data length
+			osc_data = (uint8_t*) osc_fmt + (osc_align(strlen(osc_fmt) + 2) - 1);
 
-			for(c = 0; c < data->channels; c++){
-				//FIXME implement proper OSC path match
-				//prefix match
-				if(!strcmp(osc_local, data->channel[c].path)){
-					if(strlen(osc_fmt) > data->channel[c].param_index){
-						//fprintf(stderr, "Taking parameter %zu of %s (%s), %zd bytes, data offset %zu\n", data->channel[c].param_index, recv_buf, osc_fmt, bytes_read, (osc_data - (uint8_t*)recv_buf));
-						if(osc_generate_event(mm_channel(inst, c, 0), data->channel + c, osc_fmt, osc_data, bytes_read - (osc_data - (uint8_t*) recv_buf))){
-							fprintf(stderr, "Failed to generate OSC channel event\n");
-						}
-					}
-				}
+			if(osc_process_packet(inst, osc_local, osc_fmt, osc_data, bytes_read - (osc_data - (uint8_t*) recv_buf))){
+				return 1;
 			}
 		} while(bytes_read > 0);
 
@@ -706,14 +944,25 @@ static int osc_shutdown(){
 		data = (osc_instance_data*) inst[u]->impl;
 		for(c = 0; c < data->channels; c++){
 			free(data->channel[c].path);
+			free(data->channel[c].in);
+			free(data->channel[c].out);
 		}
 		free(data->channel);
+		for(c = 0; c < data->patterns; c++){
+			free(data->pattern[c].path);
+			free(data->pattern[c].type);
+			free(data->pattern[c].min);
+			free(data->pattern[c].max);
+		}
+		free(data->pattern);
+
 		free(data->root);
 		if(data->fd >= 0){
 			close(data->fd);
 		}
 		data->fd = -1;
 		data->channels = 0;
+		data->patterns = 0;
 		free(inst[u]->impl);
 	}
 
diff --git a/backends/osc.h b/backends/osc.h
index dc6cb3a..4e9dec5 100644
--- a/backends/osc.h
+++ b/backends/osc.h
@@ -34,22 +34,33 @@ typedef union {
 typedef struct /*_osc_channel*/ {
 	char* path;
 	size_t params;
-	size_t param_index;
 	uint8_t mark;
 
-	osc_parameter_type type;
-	osc_parameter_value max;
-	osc_parameter_value min;
-	osc_parameter_value current;
+	osc_parameter_type* type;
+	osc_parameter_value* max;
+	osc_parameter_value* min;
+	osc_parameter_value* in;
+	osc_parameter_value* out;
 } osc_channel;
 
 typedef struct /*_osc_instance_data*/ {
+	//pre-configured channel patterns
+	size_t patterns;
+	osc_channel* pattern;
+
+	//actual channel registry
 	size_t channels;
 	osc_channel* channel;
+
+	//instance config
 	char* root;
+	uint8_t learn;
+
+	//peer addressing
 	socklen_t dest_len;
 	struct sockaddr_storage dest;
-	int fd;
-	uint8_t learn;
 	uint16_t forced_rport;
+
+	//peer fd
+	int fd;
 } osc_instance_data;
diff --git a/backends/osc.md b/backends/osc.md
index e9aa4d5..b7ce527 100644
--- a/backends/osc.md
+++ b/backends/osc.md
@@ -23,13 +23,21 @@ it are ignored early in processing.
 Channels that are to be output or require a value range different from the default ranges (see below)
 require special configuration, as their types and limits have to be set.
 
-This is done in the instance configuration using an assignment of the syntax
+This is done by specifying *patterns* in the instance configuration using an assignment of the syntax
 
 ```
 /local/osc/path = <format> <min> <max> <min> <max> ...
 ```
 
-The OSC path to be configured must only be the local part (omitting a configured instance root).
+The pattern will be matched only against the local part (that is, the path excluding any configured instance root).
+Patterns may contain the following expressions (conforming to the [OSC pattern matching specification](http://opensoundcontrol.org/spec-1_0)):
+* `?` matches any single legal character
+* `*` matches zero or more legal characters
+* A comma-separated list of strings inside curly braces `{}` matches any of the strings
+* A string of characters within square brackets `[]` matches any character in the string
+	* Two characters with a `-` between them specify a range of characters
+	* An exclamation mark immediately after the opening `[` negates the meaning of the expression (ie. it matches characters not in the range)
+* Any other legal character matches only itself
 
 **format** may be any sequence of valid OSC type characters. See below for a table of supported
 OSC types.
@@ -44,6 +52,12 @@ a range between 0.0 and 2.0 (for example, an X-Y control), would look as follows
 /1/xy1 = ff 0.0 2.0 0.0 2.0
 ```
 
+To configure a range of faders, an expression similar to the following line could be used
+
+```
+/1/fader* = f 0.0 1.0
+```
+
 #### Channel specification
 
 A channel may be any valid OSC path, to which the instance root will be prepended if
@@ -80,4 +94,7 @@ The default ranges are:
 
 #### Known bugs / problems
 
+The OSC path match currently works on the unit of characters. This may lead to some unexpected results
+when matching expressions of the form `*<expr>`.
+
 Ping requests are not yet answered. There may be some problems using broadcast output and input.
diff --git a/configs/flying-faders.cfg b/configs/flying-faders.cfg
new file mode 100644
index 0000000..4197581
--- /dev/null
+++ b/configs/flying-faders.cfg
@@ -0,0 +1,24 @@
+; Create a 'flying faders' effect using lua and output
+; it onto TouchOSC (Layout 'Mix16', Multifader view on page 4)
+
+[osc touch]
+bind = * 8000
+dest = learn@9000
+
+; Pre-declare the fader values so the range mapping is correct
+/*/fader* = f 0.0 1.0
+/*/toggle* = f 0.0 1.0
+/*/push* = f 0.0 1.0
+/*/multifader*/* = f 0.0 1.0
+/1/xy = ff 0.0 1.0 0.0 1.0
+
+[lua generator]
+script = configs/flying-faders.lua
+
+[map]
+
+generator.wave{1..24} > touch./4/multifader1/{1..24}
+;generator.wave{1..24} > touch./4/multifader2/{1..24}
+
+touch./4/multifader2/1 > generator.magnitude
+
diff --git a/configs/flying-faders.lua b/configs/flying-faders.lua
new file mode 100644
index 0000000..0b0faef
--- /dev/null
+++ b/configs/flying-faders.lua
@@ -0,0 +1,10 @@
+step = 0
+
+function wave()
+	for chan=1,24 do
+		output("wave" .. chan, (math.sin(math.rad((step + chan * 360 / 24) % 360)) + 1) / 2)
+	end
+	step = (step + 5) % 360
+end
+
+interval(wave, 100)
diff --git a/configs/osc-xy.cfg b/configs/osc-xy.cfg
new file mode 100644
index 0000000..fc5c5f3
--- /dev/null
+++ b/configs/osc-xy.cfg
@@ -0,0 +1,26 @@
+; Test for bi-directional OSC with an XY pad (TouchOSC Layout 'Mix16', Page 1)
+
+[backend osc]
+detect = on
+
+[osc touch]
+bind = 0.0.0.0 8000
+dest = learn@9000
+
+; Pre-declare the fader values so the range mapping is correct
+/*/xy = ff 0.0 1.0 0.0 1.0
+
+[evdev xbox]
+device = /dev/input/event16
+
+[midi launch]
+
+[map]
+xbox.EV_ABS.ABS_X > touch./1/xy:1
+xbox.EV_ABS.ABS_Y > touch./1/xy:0
+
+xbox.EV_ABS.ABS_X > launch.ch0.note2
+;xbox.EV_ABS.ABS_Y > launch.ch0.note3
+
+launch.ch0.note0 <> touch./1/xy:0
+launch.ch0.note1 <> touch./1/xy:1
-- 
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