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-rw-r--r--backends/rtpmidi.c246
-rw-r--r--backends/rtpmidi.h33
-rw-r--r--backends/rtpmidi.md4
3 files changed, 237 insertions, 46 deletions
diff --git a/backends/rtpmidi.c b/backends/rtpmidi.c
index 2eec871..97364cf 100644
--- a/backends/rtpmidi.c
+++ b/backends/rtpmidi.c
@@ -11,9 +11,9 @@
#include "rtpmidi.h"
//TODO learn peer ssrcs
-//TODO default session join?
//TODO default mode?
//TODO internal loop mode
+//FIXME what qualifies an instance to be announced via mdns?
static struct /*_rtpmidi_global*/ {
int mdns_fd;
@@ -41,6 +41,7 @@ MM_PLUGIN_API int init(){
.conf_instance = rtpmidi_configure_instance,
.channel = rtpmidi_channel,
.handle = rtpmidi_set,
+ .interval = rtpmidi_interval,
.process = rtpmidi_handle,
.start = rtpmidi_start,
.shutdown = rtpmidi_shutdown
@@ -59,38 +60,90 @@ MM_PLUGIN_API int init(){
return 0;
}
-static int rtpmidi_configure(char* option, char* value){
- char* host = NULL, *port = NULL;
+static int dns_decode_name(uint8_t* buffer, size_t len, size_t start, dns_name* out){
+ size_t offset = 0, output_offset = 0;
+ uint8_t current_label = 0;
+ uint16_t ptr_target = 0;
- if(!strcmp(option, "mdns-name")){
- if(cfg.mdns_name){
- LOG("Duplicate mdns-name assignment");
- return 1;
+ //reset output data length and terminate null name
+ out->length = 0;
+ if(out->name){
+ out->name[0] = 0;
+ }
+
+ while(start + offset < len){
+ current_label = buffer[start + offset];
+
+ //if we're at a pointer, move there and stop counting data length
+ if(DNS_POINTER(current_label)){
+ if(start + offset + 1 >= len){
+ LOG("mDNS internal pointer out of bounds");
+ return 1;
+ }
+
+ //do this before setting the target
+ if(!ptr_target){
+ out->length += 2;
+ }
+
+ //calculate pointer target
+ ptr_target = DNS_LABEL_LENGTH(current_label) << 8 | buffer[start + offset + 1];
+
+ if(ptr_target >= len){
+ LOG("mDNS internal pointer target out of bounds");
+ return 1;
+ }
+ start = ptr_target;
+ offset = 0;
}
+ else{
+ if(DNS_LABEL_LENGTH(current_label) == 0){
+ if(!ptr_target){
+ out->length++;
+ }
+ break;
+ }
- cfg.mdns_name = strdup(value);
- if(!cfg.mdns_name){
- LOG("Failed to allocate memory");
- return 1;
+ //check whether we have the bytes we need
+ if(start + offset + DNS_LABEL_LENGTH(current_label) > len){
+ LOG("mDNS bytes missing");
+ return 1;
+ }
+
+ //check whether we have space in the output
+ if(output_offset + DNS_LABEL_LENGTH(current_label) > out->alloc){
+ out->name = realloc(out->name, (output_offset + DNS_LABEL_LENGTH(current_label) + 2) * sizeof(uint8_t));
+ out->alloc = output_offset + DNS_LABEL_LENGTH(current_label);
+ }
+
+ //copy data from this label to output buffer
+ memcpy(out->name + output_offset, buffer + start + offset + 1, DNS_LABEL_LENGTH(current_label));
+ output_offset += DNS_LABEL_LENGTH(current_label) + 1;
+ offset += DNS_LABEL_LENGTH(current_label) + 1;
+ out->name[output_offset - 1] = '.';
+ out->name[output_offset] = 0;
+ if(!ptr_target){
+ out->length = offset;
+ }
}
- return 0;
}
- else if(!strcmp(option, "mdns-bind")){
- if(cfg.mdns_fd >= 0){
- LOG( "Only one mDNS discovery bind is supported");
- return 1;
- }
+ return 0;
+}
- mmbackend_parse_hostspec(value, &host, &port, NULL);
+static uint32_t rtpmidi_interval(){
+ return max(0, RTPMIDI_SERVICE_INTERVAL - (mm_timestamp() - cfg.last_service));
+}
- if(!host){
- LOGPF("Not a valid mDNS bind address: %s", value);
+static int rtpmidi_configure(char* option, char* value){
+ if(!strcmp(option, "mdns-name")){
+ if(cfg.mdns_name){
+ LOG("Duplicate mdns-name assignment");
return 1;
}
- cfg.mdns_fd = mmbackend_socket(host, (port ? port : RTPMIDI_MDNS_PORT), SOCK_DGRAM, 1, 1);
- if(cfg.mdns_fd < 0){
- LOGPF("Failed to bind mDNS interface: %s", value);
+ cfg.mdns_name = strdup(value);
+ if(!cfg.mdns_name){
+ LOG("Failed to allocate memory");
return 1;
}
return 0;
@@ -925,6 +978,79 @@ static int rtpmidi_service(){
return 0;
}
+static int rtpmidi_handle_mdns(){
+ uint8_t buffer[RTPMIDI_PACKET_BUFFER];
+ dns_header* hdr = (dns_header*) buffer;
+ dns_rr* rr = NULL;
+ dns_name name = {
+ .alloc = 0
+ };
+ ssize_t bytes = 0;
+ size_t u = 0, offset = sizeof(dns_header);
+
+ for(bytes = recv(cfg.mdns_fd, buffer, sizeof(buffer), 0); bytes > 0; bytes = recv(cfg.mdns_fd, buffer, sizeof(buffer), 0)){
+ if(bytes < sizeof(dns_header)){
+ continue;
+ }
+ LOGPF("%" PRIsize_t " bytes of mDNS data", bytes);
+
+ hdr->id = be16toh(hdr->id);
+ hdr->questions = be16toh(hdr->questions);
+ hdr->answers = be16toh(hdr->answers);
+ hdr->servers = be16toh(hdr->servers);
+ hdr->additional = be16toh(hdr->additional);
+
+ //TODO Check for ._apple-midi._udp.local.
+ LOGPF("ID %d, Opcode %d, %s, %d questions, %d answers, %d servers, %d additional", hdr->id, DNS_OPCODE(hdr->flags[0]), DNS_RESPONSE(hdr->flags[0]) ? "response" : "query", hdr->questions, hdr->answers, hdr->servers, hdr->additional);
+ for(u = 0; u < hdr->questions; u++){
+ dns_decode_name(buffer, bytes, offset, &name);
+ offset += name.length;
+ offset += sizeof(dns_question);
+
+ LOGPF("Question: %s", name.name);
+ }
+
+ for(u = 0; u < hdr->answers; u++){
+ dns_decode_name(buffer, bytes, offset, &name);
+ offset += name.length;
+ rr = (dns_rr*) (buffer + offset);
+ offset += sizeof(dns_rr) + be16toh(rr->data);
+
+ LOGPF("Answer (%d): %s, %d bytes of data", be16toh(rr->rtype), name.name, be16toh(rr->data));
+ }
+
+ for(u = 0; u < hdr->servers; u++){
+ dns_decode_name(buffer, bytes, offset, &name);
+ offset += name.length;
+ rr = (dns_rr*) (buffer + offset);
+ offset += sizeof(dns_rr) + be16toh(rr->data);
+
+ LOGPF("Authority (%d): %s, %d bytes of data", be16toh(rr->rtype), name.name, be16toh(rr->data));
+ }
+
+ for(u = 0; u < hdr->additional; u++){
+ dns_decode_name(buffer, bytes, offset, &name);
+ offset += name.length;
+ rr = (dns_rr*) (buffer + offset);
+ offset += sizeof(dns_rr) + be16toh(rr->data);
+
+ LOGPF("Additional (%d): %s, %d bytes of data", be16toh(rr->rtype), name.name, be16toh(rr->data));
+ }
+ }
+
+ free(name.name);
+ if(bytes <= 0){
+ if(errno == EAGAIN){
+ return 0;
+ }
+
+ LOGPF("Error reading from mDNS descriptor: %s", strerror(errno));
+ return 1;
+ }
+
+ return 0;
+}
+
static int rtpmidi_handle(size_t num, managed_fd* fds){
size_t u;
int rv = 0;
@@ -933,7 +1059,7 @@ static int rtpmidi_handle(size_t num, managed_fd* fds){
//handle service tasks (mdns, clock sync, peer connections)
if(mm_timestamp() - cfg.last_service > RTPMIDI_SERVICE_INTERVAL){
- DBGPF("Performing service tasks, delta %" PRIu64, mm_timestamp() - cfg.last_service);
+ //DBGPF("Performing service tasks, delta %" PRIu64, mm_timestamp() - cfg.last_service);
if(rtpmidi_service()){
return 1;
}
@@ -942,7 +1068,8 @@ static int rtpmidi_handle(size_t num, managed_fd* fds){
for(u = 0; u < num; u++){
if(!fds[u].impl){
- //TODO handle mDNS discovery input
+ //handle mDNS discovery input
+ rtpmidi_handle_mdns();
}
else{
//handle rtp/control input
@@ -963,30 +1090,53 @@ static int rtpmidi_handle(size_t num, managed_fd* fds){
return rv;
}
-static int rtpmidi_start(size_t n, instance** inst){
- size_t u, p, fds = 0;
- rtpmidi_instance_data* data = NULL;
+static int rtpmidi_start_mdns(){
+ struct ip_mreq mcast_req = {
+ .imr_multiaddr.s_addr = htobe32(((uint32_t) 0xe00000fb)),
+ .imr_interface.s_addr = INADDR_ANY
+ };
- //if mdns name defined and no socket, bind default values
- if(cfg.mdns_name && cfg.mdns_fd < 0){
- cfg.mdns_fd = mmbackend_socket(RTPMIDI_DEFAULT_HOST, RTPMIDI_MDNS_PORT, SOCK_DGRAM, 1, 1);
- if(cfg.mdns_fd < 0){
- return 1;
- }
+ struct ipv6_mreq mcast6_req = {
+ .ipv6mr_multiaddr.s6_addr = {0xff, 0x02, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0xfb},
+ .ipv6mr_interface = 0
+ };
+
+ if(!cfg.mdns_name){
+ LOG("No mDNS name set, disabling AppleMIDI discovery");
+ return 0;
}
- //register mdns fd to core
- if(cfg.mdns_fd >= 0){
- if(mm_manage_fd(cfg.mdns_fd, BACKEND_NAME, 1, NULL)){
- LOG("Failed to register mDNS socket with core");
- return 1;
- }
- fds++;
+ //FIXME might try passing NULL as host here to work around possible windows ipv6 handicaps
+ cfg.mdns_fd = mmbackend_socket(RTPMIDI_DEFAULT_HOST, RTPMIDI_MDNS_PORT, SOCK_DGRAM, 1, 1);
+ if(cfg.mdns_fd < 0){
+ LOG("Failed to create requested mDNS descriptor");
+ return 1;
}
- else{
- LOG("No mDNS discovery interface bound, AppleMIDI session discovery disabled");
+
+ //join ipv4 multicast group
+ if(setsockopt(cfg.mdns_fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, (uint8_t*) &mcast_req, sizeof(mcast_req))){
+ LOGPF("Failed to join IPv4 multicast group for mDNS: %s", strerror(errno));
+ return 1;
+ }
+
+ //join ipv6 multicast group
+ if(setsockopt(cfg.mdns_fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, (uint8_t*) &mcast6_req, sizeof(mcast6_req))){
+ LOGPF("Failed to join IPv6 multicast group for mDNS: %s", strerror(errno));
+ return 1;
}
+ //register mdns fd to core
+ return mm_manage_fd(cfg.mdns_fd, BACKEND_NAME, 1, NULL);
+}
+
+static int rtpmidi_start(size_t n, instance** inst){
+ size_t u, p, fds = 0;
+ rtpmidi_instance_data* data = NULL;
+ uint8_t mdns_required = 0;
+
for(u = 0; u < n; u++){
data = (rtpmidi_instance_data*) inst[u]->impl;
//check whether instances are explicitly configured to a mode
@@ -1013,6 +1163,9 @@ static int rtpmidi_start(size_t n, instance** inst){
data->peer[p].connected = 1;
}
}
+ else if(data->mode == apple){
+ mdns_required = 1;
+ }
//register fds to core
if(mm_manage_fd(data->fd, BACKEND_NAME, 1, inst[u]) || (data->control_fd >= 0 && mm_manage_fd(data->control_fd, BACKEND_NAME, 1, inst[u]))){
@@ -1022,6 +1175,13 @@ static int rtpmidi_start(size_t n, instance** inst){
fds += (data->control_fd >= 0) ? 2 : 1;
}
+ if(mdns_required && rtpmidi_start_mdns()){
+ return 1;
+ }
+ else{
+ fds++;
+ }
+
LOGPF("Registered %" PRIsize_t " descriptors to core", fds);
return 0;
}
diff --git a/backends/rtpmidi.h b/backends/rtpmidi.h
index a08cf0f..b1fe26a 100644
--- a/backends/rtpmidi.h
+++ b/backends/rtpmidi.h
@@ -8,6 +8,7 @@ static int rtpmidi_configure(char* option, char* value);
static int rtpmidi_configure_instance(instance* instance, char* option, char* value);
static int rtpmidi_instance(instance* inst);
static channel* rtpmidi_channel(instance* instance, char* spec, uint8_t flags);
+static uint32_t rtpmidi_interval();
static int rtpmidi_set(instance* inst, size_t num, channel** c, channel_value* v);
static int rtpmidi_handle(size_t num, managed_fd* fds);
static int rtpmidi_start(size_t n, instance** inst);
@@ -22,6 +23,11 @@ static int rtpmidi_shutdown(size_t n, instance** inst);
#define RTPMIDI_DEFAULT_NAME "MIDIMonster"
#define RTPMIDI_SERVICE_INTERVAL 1000
+#define DNS_POINTER(a) (((a) & 0xC0) == 0xC0)
+#define DNS_LABEL_LENGTH(a) ((a) & 0x3F)
+#define DNS_OPCODE(a) (((a) & 0x78) >> 3)
+#define DNS_RESPONSE(a) ((a) & 0x80)
+
enum /*_rtpmidi_channel_type*/ {
none = 0,
note = 0x90,
@@ -90,6 +96,12 @@ enum applemidi_command {
apple_feedback = 0x5253 //RS
};
+typedef struct /*_dns_name*/ {
+ size_t alloc;
+ char* name;
+ size_t length;
+} dns_name;
+
#pragma pack(push, 1)
typedef struct /*_apple_session_command*/ {
uint16_t res1;
@@ -128,4 +140,25 @@ typedef struct /*_rtp_midi_command*/ {
uint8_t flags;
uint8_t length;
} rtpmidi_command_header;
+
+typedef struct /*_dns_header*/ {
+ uint16_t id;
+ uint8_t flags[2];
+ uint16_t questions;
+ uint16_t answers;
+ uint16_t servers;
+ uint16_t additional;
+} dns_header;
+
+typedef struct /*_dns_question*/ {
+ uint16_t qtype;
+ uint16_t qclass;
+} dns_question;
+
+typedef struct /*_dns_rr*/ {
+ uint16_t rtype;
+ uint16_t rclass;
+ uint32_t ttl;
+ uint16_t data;
+} dns_rr;
#pragma pack(pop)
diff --git a/backends/rtpmidi.md b/backends/rtpmidi.md
index e857a5a..c188039 100644
--- a/backends/rtpmidi.md
+++ b/backends/rtpmidi.md
@@ -25,7 +25,6 @@ stream, which may lead to inconsistencies during playback.
| Option | Example value | Default value | Description |
|---------------|-----------------------|-----------------------|-----------------------|
| `detect` | `on` | `off` | Output channel specifications for any events coming in on configured instances to help with configuration |
-| `mdns-bind` | `10.1.2.1 5353` | `:: 5353` | Bind host for the mDNS discovery server |
| `mdns-name` | `computer1` | none | mDNS hostname to announce, also used as AppleMIDI peer name |
#### Instance configuration
@@ -51,9 +50,8 @@ Common instance configuration parameters
|---------------|-----------------------|-----------------------|-----------------------|
| `bind` | `10.1.2.1 9001` | `:: <random>` | Local network address to bind to (note that AppleMIDI requires two consecutive port numbers to be allocated) |
| `session` | `Just Jamming` | `MIDIMonster` | Session name to announce via mDNS |
-| `invite` | `pad` | none | Devices to send invitations to when discovered (the special value `*` invites all discovered peers). Setting this option makes the instance a session initiator. May be specified multiple times |
+| `invite` | `pad` | none | Devices to send invitations to when discovered (the special value `*` invites all discovered peers). Setting this option makes the instance a session initiator. May be specified multiple times. |
| `join` | `Just Jamming` | none | Session for which to accept invitations (the special value `*` accepts the first invitation seen). Setting this option makes the instance a session participant |
-| `peer` | `10.1.2.3 9001` | none | Configure a direct session peer, bypassing AppleMIDI discovery. May be specified multiple times |
Note that AppleMIDI session discovery requires mDNS functionality, thus the `mdns-name` global parameter
(and, depending on your setup, the `mdns-bind` parameter) need to be configured properly.
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-31 09:57:12 +0000