Move backend implementations to subdirectory

1 files changed, 813 insertions, 0 deletions

diff --git a/backends/osc.c b/backends/osc.c
new file mode 100644
index 0000000..adc91f5
--- /dev/null
+++ b/backends/osc.c
@@ -0,0 +1,813 @@
+#include <string.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <netdb.h>
+#include <errno.h>
+#include <fcntl.h>
+#include "osc.h"
+
+/*
+ * TODO
+ * ping method
+ */
+
+#define osc_align(a) ((((a) / 4) + (((a) % 4) ? 1 : 0)) * 4)
+#define BACKEND_NAME "osc"
+
+int init(){
+	backend osc = {
+		.name = BACKEND_NAME,
+		.conf = backend_configure,
+		.create = backend_instance,
+		.conf_instance = backend_configure_instance,
+		.channel = backend_channel,
+		.handle = backend_set,
+		.process = backend_handle,
+		.start = backend_start,
+		.shutdown = backend_shutdown
+	};
+
+	//register backend
+	if(mm_backend_register(osc)){
+		fprintf(stderr, "Failed to register OSC backend\n");
+		return 1;
+	}
+	return 0;
+}
+
+static size_t osc_data_length(osc_parameter_type t){
+	switch(t){
+		case int32:
+		case float32:
+			return 4;
+		case int64:
+		case double64:
+			return 8;
+		default:
+			fprintf(stderr, "Invalid OSC format specified %c\n", t);
+			return 0;
+	}
+}
+
+static inline void osc_defaults(osc_parameter_type t, osc_parameter_value* max, osc_parameter_value* min){
+	memset(max, 0, sizeof(osc_parameter_value));
+	memset(min, 0, sizeof(osc_parameter_value));
+	switch(t){
+		case int32:
+			max->i32 = 255;
+			return;
+		case float32:
+			max->f = 1.0;
+			return;
+		case int64:
+			max->i64 = 1024;
+			return;
+		case double64:
+			max->d = 1.0;
+			return;
+		default:
+			fprintf(stderr, "Invalid OSC type, not setting any sane defaults\n");
+			return;
+	}
+}
+
+static inline osc_parameter_value osc_parse(osc_parameter_type t, uint8_t* data){
+	osc_parameter_value v = {0};
+	switch(t){
+		case int32:
+		case float32:
+			v.i32 = be32toh(*((int32_t*) data));
+			break;
+		case int64:
+		case double64:
+			v.i64 = be64toh(*((int64_t*) data));
+			break;
+		default:
+			fprintf(stderr, "Invalid OSC type passed to parsing routine\n");
+	}
+	return v;
+}
+
+static inline int osc_deparse(osc_parameter_type t, osc_parameter_value v, uint8_t* data){
+	uint64_t u64 = 0;
+	uint32_t u32 = 0;
+	switch(t){
+		case int32:
+		case float32:
+			u32 = htobe32(v.i32);
+			memcpy(data, &u32, sizeof(u32));
+			break;
+		case int64:
+		case double64:
+			u64 = htobe64(v.i64);
+			memcpy(data, &u64, sizeof(u64));
+			break;
+		default:
+			fprintf(stderr, "Invalid OSC type passed to parsing routine\n");
+			return 1;
+	}
+	return 0;
+}
+
+static inline osc_parameter_value osc_parse_value_spec(osc_parameter_type t, char* value){
+	osc_parameter_value v = {0};
+	switch(t){
+		case int32:
+			v.i32 = strtol(value, NULL, 0);
+			break;
+		case float32:
+			v.f = strtof(value, NULL);
+			break;
+		case int64:
+			v.i64 = strtoll(value, NULL, 0);
+			break;
+		case double64:
+			v.d = strtod(value, NULL);
+			break;
+		default:
+			fprintf(stderr, "Invalid OSC type passed to value parser\n");
+	}
+	return v;
+}
+
+static inline channel_value osc_parameter_normalise(osc_parameter_type t, osc_parameter_value min, osc_parameter_value max, osc_parameter_value cur){
+	channel_value v = {
+		.raw = {0},
+		.normalised = 0
+	};
+
+	union {
+		uint32_t u32;
+		float f32;
+		uint64_t u64;
+		double d64;
+	} range;
+
+	switch(t){
+		case int32:
+			range.u32 = max.i32 - min.i32;
+			v.raw.u64 = cur.i32 - min.i32;
+			v.normalised = v.raw.u64 / range.u32;
+			break;
+		case float32:
+			range.f32 = max.f - min.f;
+			v.raw.dbl = cur.f - min.f;
+			v.normalised = v.raw.dbl / range.f32;
+			break;
+		case int64:
+			range.u64 = max.i64 - min.i64;
+			v.raw.u64 = cur.i64 - min.i64;
+			v.normalised = v.raw.u64 / range.u64;
+			break;
+		case double64:
+			range.d64 = max.d - min.d;
+			v.raw.dbl = cur.d - min.d;
+			v.normalised = v.raw.dbl / range.d64;
+			break;
+		default:
+			fprintf(stderr, "Invalid OSC type passed to interpolation routine\n");
+	}
+
+	//fix overshoot
+	if(v.normalised > 1.0){
+		v.normalised = 1.0;
+	}
+	else if(v.normalised < 0.0){
+		v.normalised = 0.0;
+	}
+
+	return v;
+}
+
+static inline osc_parameter_value osc_parameter_denormalise(osc_parameter_type t, osc_parameter_value min, osc_parameter_value max, channel_value cur){
+	osc_parameter_value v = {0};
+
+	union {
+		uint32_t u32;
+		float f32;
+		uint64_t u64;
+		double d64;
+	} range;
+
+	switch(t){
+		case int32:
+			range.u32 = max.i32 - min.i32;
+			v.i32 = (range.u32 * cur.normalised) + min.i32;
+			break;
+		case float32:
+			range.f32 = max.f - min.f;
+			v.f = (range.f32 * cur.normalised) + min.f;
+			break;
+		case int64:
+			range.u64 = max.i64 - min.i64;
+			v.i64 = (range.u64 * cur.normalised) + min.i64;
+			break;
+		case double64:
+			range.d64 = max.d - min.d;
+			v.d = (range.d64 * cur.normalised) + min.d;
+			break;
+		default:
+			fprintf(stderr, "Invalid OSC type passed to interpolation routine\n");
+	}
+
+	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;
+	}
+
+	osc_parameter_value min, max, cur;
+	channel_value evt;
+
+	if(!fmt || !data || data_len % 4 || !*fmt){
+		fprintf(stderr, "Invalid OSC packet, data length %zu\n", data_len);
+		return 1;
+	}
+
+	//find offset for this parameter
+	for(p = 0; p < info->param_index; p++){
+		off += osc_data_length(fmt[p]);
+	}
+
+	if(info->type != not_set){
+		max = info->max;
+		min = info->min;
+	}
+	else{
+		osc_defaults(fmt[info->param_index], &max, &min);
+	}
+
+	cur = osc_parse(fmt[info->param_index], data + off);
+	evt = osc_parameter_normalise(fmt[info->param_index], min, max, cur);
+
+	return mm_channel_event(c, evt);
+}
+
+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;
+	}
+	return 0;
+}
+
+static int osc_separate_hostspec(char* in, char** host, char** port){
+	size_t u;
+
+	if(!in || !host || !port){
+		return 1;
+	}
+
+	for(u = 0; in[u] && !isspace(in[u]); u++){
+	}
+
+	//guess
+	*host = in;
+
+	if(in[u]){
+		in[u] = 0;
+		*port = in + u + 1;
+	}
+	else{
+		//no port given
+		*port = NULL;
+	}
+	return 0;
+}
+
+static int osc_listener(char* host, char* port){
+	int fd = -1, status, yes = 1, flags;
+	struct addrinfo hints = {
+		.ai_family = AF_UNSPEC,
+		.ai_socktype = SOCK_DGRAM,
+		.ai_flags = AI_PASSIVE
+	};
+	struct addrinfo* info;
+	struct addrinfo* addr_it;
+
+	status = getaddrinfo(host, port, &hints, &info);
+	if(status){
+		fprintf(stderr, "Failed to get socket info for %s port %s: %s\n", host, port, gai_strerror(status));
+		return -1;
+	}
+
+	for(addr_it = info; addr_it != NULL; addr_it = addr_it->ai_next){
+		fd = socket(addr_it->ai_family, addr_it->ai_socktype, addr_it->ai_protocol);
+		if(fd < 0){
+			continue;
+		}
+
+		yes = 1;
+		if(setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (void*)&yes, sizeof(yes)) < 0){
+			fprintf(stderr, "Failed to set SO_REUSEADDR on socket\n");
+		}
+
+		yes = 1;
+		if(setsockopt(fd, SOL_SOCKET, SO_BROADCAST, (void*)&yes, sizeof(yes)) < 0){
+			fprintf(stderr, "Failed to set SO_BROADCAST on socket\n");
+		}
+
+		yes = 0;
+		if(setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, (void*)&yes, sizeof(yes)) < 0){
+			fprintf(stderr, "Failed to unset IP_MULTICAST_LOOP option: %s\n", strerror(errno));
+		}
+
+		status = bind(fd, addr_it->ai_addr, addr_it->ai_addrlen);
+		if(status < 0){
+			close(fd);
+			continue;
+		}
+
+		break;
+	}
+
+	freeaddrinfo(info);
+
+	if(!addr_it){
+		fprintf(stderr, "Failed to create listening socket for %s port %s\n", host, port);
+		return -1;
+	}
+
+	//set nonblocking
+	flags = fcntl(fd, F_GETFL, 0);
+	if(fcntl(fd, F_SETFL, flags | O_NONBLOCK) < 0){
+		fprintf(stderr, "Failed to set OSC descriptor nonblocking\n");
+		return -1;
+	}
+
+	return fd;
+}
+
+static int osc_parse_addr(char* host, char* port, struct sockaddr_storage* addr, socklen_t* len){
+	struct addrinfo* head;
+	struct addrinfo hints = {
+		.ai_family = AF_UNSPEC,
+		.ai_socktype = SOCK_DGRAM
+	};
+
+	int error = getaddrinfo(host, port, &hints, &head);
+	if(error || !head){
+		fprintf(stderr, "Failed to parse address %s port %s: %s\n", host, port, gai_strerror(error));
+		return 1;
+	}
+
+	memcpy(addr, head->ai_addr, head->ai_addrlen);
+	*len = head->ai_addrlen;
+
+	freeaddrinfo(head);
+	return 0;
+}
+
+static int backend_configure(char* option, char* value){
+	fprintf(stderr, "The OSC backend does not take any global configuration\n");
+	return 1;
+}
+
+static int backend_configure_instance(instance* inst, char* option, char* value){
+	osc_instance* data = (osc_instance*) inst->impl;
+	char* host = NULL, *port = NULL, *token = NULL, *format = NULL;
+	size_t u, p;
+
+	if(!strcmp(option, "root")){
+		if(osc_validate_path(value)){
+			fprintf(stderr, "Not a valid OSC root: %s\n", value);
+			return 1;
+		}
+
+		if(data->root){
+			free(data->root);
+		}
+		data->root = strdup(value);
+
+		if(!data->root){
+			fprintf(stderr, "Failed to allocate memory\n");
+			return 1;
+		}
+		return 0;
+	}
+	else if(!strcmp(option, "bind")){
+		if(osc_separate_hostspec(value, &host, &port)){
+			fprintf(stderr, "Invalid bind address for instance %s\n", inst->name);
+			return 1;
+		}
+
+		data->fd = osc_listener(host, port);
+		if(data->fd < 0){
+			fprintf(stderr, "Failed to bind for instance %s\n", inst->name);
+			return 1;
+		}
+		return 0;
+	}
+	else if(!strcmp(option, "dest") || !strcmp(option, "destination")){
+		if(!strncmp(value, "learn", 5)){
+			data->learn = 1;
+
+			//check if a forced port was provided
+			if(value[5] == '@'){
+				data->forced_rport = strtoul(value + 6, NULL, 0);
+			}
+			return 0;
+		}
+
+		if(osc_separate_hostspec(value, &host, &port)){
+			fprintf(stderr, "Invalid destination address for instance %s\n", inst->name);
+			return 1;
+		}
+
+		if(osc_parse_addr(host, port, &data->dest, &data->dest_len)){
+			fprintf(stderr, "Failed to parse destination address for instance %s\n", inst->name);
+			return 1;
+		}
+		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;
+	}
+
+	fprintf(stderr, "Unknown configuration parameter %s for OSC backend\n", option);
+	return 1;
+}
+
+static instance* backend_instance(){
+	instance* inst = mm_instance();
+	if(!inst){
+		return NULL;
+	}
+
+	osc_instance* data = calloc(1, sizeof(osc_instance));
+	if(!data){
+		fprintf(stderr, "Failed to allocate memory\n");
+		return NULL;
+	}
+
+	data->fd = -1;
+	inst->impl = data;
+	return inst;
+}
+
+static channel* backend_channel(instance* inst, char* spec){
+	size_t u;
+	osc_instance* data = (osc_instance*) inst->impl;
+	size_t param_index = 0;
+
+	//check spec for correctness
+	if(osc_validate_path(spec)){
+		return NULL;
+	}
+
+	//parse parameter offset
+	if(strrchr(spec, ':')){
+		param_index = 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);
+			break;
+		}
+	}
+
+	//allocate new channel
+	if(u == data->channels){
+		data->channel = realloc(data->channel, (u + 1) * sizeof(osc_channel));
+		if(!data->channel){
+			fprintf(stderr, "Failed to allocate memory\n");
+			return NULL;
+		}
+
+		memset(data->channel + u, 0, sizeof(osc_channel));
+		data->channel[u].param_index = param_index;
+		data->channel[u].path = strdup(spec);
+
+		if(!data->channel[u].path){
+			fprintf(stderr, "Failed to allocate memory\n");
+			return NULL;
+		}
+		data->channels++;
+	}
+
+	return mm_channel(inst, u, 1);
+}
+
+static int backend_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;
+	if(!num){
+		return 0;
+	}
+
+	osc_instance* data = (osc_instance*) inst->impl;
+	if(!data->dest_len){
+		fprintf(stderr, "OSC instance %s does not have a destination, output is disabled (%zu channels)\n", inst->name, num);
+		return 0;
+	}
+
+	for(evt = 0; evt < num; evt++){
+		off = c[evt]->ident;
+
+		//sanity check
+		if(off >= data->channels){
+			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);
+			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;
+	}
+
+	//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);
+	}
+
+	//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;
+			}
+
+			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;
+					}
+
+					//write format specifier
+					format[data->channel[p].param_index] = data->channel[p].type;
+
+					//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;
+					}
+
+					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));
+			}
+		}
+	}
+	return 0;
+}
+
+static int backend_handle(size_t num, managed_fd* fds){
+	size_t fd;
+	char recv_buf[OSC_RECV_BUF];
+	instance* inst = NULL;
+	osc_instance* data = NULL;
+	ssize_t bytes_read = 0;
+	size_t c;
+	char* osc_fmt = NULL;
+	char* osc_local = NULL;
+	uint8_t* osc_data = NULL;
+
+	for(fd = 0; fd < num; fd++){
+		inst = (instance*) fds[fd].impl;
+		if(!inst){
+			fprintf(stderr, "OSC backend signaled for unknown fd\n");
+			continue;
+		}
+
+		data = (osc_instance*) inst->impl;
+
+		do{
+			if(data->learn){
+				data->dest_len = sizeof(data->dest);
+				bytes_read = recvfrom(fds[fd].fd, recv_buf, sizeof(recv_buf), 0, (struct sockaddr*) &(data->dest), &(data->dest_len));
+			}
+			else{
+				bytes_read = recv(fds[fd].fd, recv_buf, sizeof(recv_buf), 0);
+			}
+			if(data->root && strncmp(recv_buf, data->root, strlen(data->root))){
+				//ignore packet for different root
+				continue;
+			}
+			osc_local = recv_buf + (data->root ? strlen(data->root) : 0);
+
+			if(bytes_read < 0){
+				break;
+			}
+
+			osc_fmt = recv_buf + osc_align(strlen(recv_buf) + 1);
+			if(*osc_fmt != ','){
+				//invalid format string
+				fprintf(stderr, "Invalid OSC format string in packet\n");
+				continue;
+			}
+			osc_fmt++;
+
+			osc_data = (uint8_t*) osc_fmt + (osc_align(strlen(osc_fmt) + 2) - 1);
+			//FIXME check supplied data length
+
+			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");
+						}
+					}
+				}
+			}
+		} while(bytes_read > 0);
+
+		if(bytes_read < 0 && errno != EAGAIN){
+			fprintf(stderr, "OSC failed to receive data for instance %s: %s\n", inst->name, strerror(errno));
+		}
+
+		if(bytes_read == 0){
+			fprintf(stderr, "OSC descriptor for instance %s closed\n", inst->name);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+static int backend_start(){
+	size_t n, u, fds = 0;
+	instance** inst = NULL;
+	osc_instance* data = NULL;
+
+	//fetch all instances
+	if(mm_backend_instances(BACKEND_NAME, &n, &inst)){
+		fprintf(stderr, "Failed to fetch instance list\n");
+		return 1;
+	}
+
+	if(!n){
+		free(inst);
+		return 0;
+	}
+
+	//update instance identifiers
+	for(u = 0; u < n; u++){
+		data = (osc_instance*) inst[u]->impl;
+
+		if(data->fd >= 0){
+			inst[u]->ident = data->fd;
+			if(mm_manage_fd(data->fd, BACKEND_NAME, 1, inst[u])){
+				fprintf(stderr, "Failed to register OSC descriptor for instance %s\n", inst[u]->name);
+				free(inst);
+				return 1;
+			}
+			fds++;
+		}
+		else{
+			inst[u]->ident = -1;
+		}
+	}
+
+	fprintf(stderr, "OSC backend registered %zu descriptors to core\n", fds);
+
+	free(inst);
+	return 0;
+}
+
+static int backend_shutdown(){
+	size_t n, u, c;
+	instance** inst = NULL;
+	osc_instance* data = NULL;
+
+	if(mm_backend_instances(BACKEND_NAME, &n, &inst)){
+		fprintf(stderr, "Failed to fetch instance list\n");
+		return 1;
+	}
+
+	for(u = 0; u < n; u++){
+		data = (osc_instance*) inst[u]->impl;
+		for(c = 0; c < data->channels; c++){
+			free(data->channel[c].path);
+		}
+		free(data->channel);
+		free(data->root);
+		close(data->fd);
+		data->fd = -1;
+		data->channels = 0;
+		free(inst[u]->impl);
+	}
+
+	free(inst);
+	return 0;
+}