diff options
| -rw-r--r-- | backends/rtpmidi.c | 265 | ||||
| -rw-r--r-- | backends/rtpmidi.h | 8 | ||||
| -rw-r--r-- | backends/rtpmidi.md | 21 |
3 files changed, 190 insertions, 104 deletions
diff --git a/backends/rtpmidi.c b/backends/rtpmidi.c index 9e0a4d4..7ad3eca 100644 --- a/backends/rtpmidi.c +++ b/backends/rtpmidi.c @@ -15,7 +15,6 @@ //TODO learn peer ssrcs //TODO default mode? //TODO internal loop mode -//FIXME what qualifies an instance to be announced via mdns? static struct /*_rtpmidi_global*/ { int mdns_fd; @@ -173,6 +172,48 @@ static int dns_encode_name(char* name, dns_name* out){ return 0; } +static ssize_t dns_push_rr(uint8_t* buffer, size_t length, dns_rr** out, char* name, uint16_t type, uint16_t class, uint32_t ttl, uint16_t len){ + dns_rr* rr = NULL; + size_t offset = 0; + dns_name encode = { + .alloc = 0 + }; + + //if requested, encode name + if(name && dns_encode_name(name, &encode)){ + LOGPF("Failed to encode DNS name %s", name); + goto bail; + } + + if(encode.length + sizeof(dns_rr) > length){ + LOGPF("Failed to encode DNS name %s, insufficient space", name); + goto bail; + } + + if(name){ + //copy encoded name to buffer + memcpy(buffer, encode.name, encode.length); + offset += encode.length; + } + + rr = (dns_rr*) (buffer + offset); + rr->rtype = htobe16(type); + rr->rclass = htobe16(class); + rr->ttl = htobe32(ttl); + rr->data = htobe16(len); + offset += sizeof(dns_rr); + if(out){ + *out = rr; + } + + free(encode.name); + return offset; + +bail: + free(encode.name); + return -1; +} + static uint32_t rtpmidi_interval(){ return max(0, RTPMIDI_SERVICE_INTERVAL - (mm_timestamp() - cfg.last_service)); } @@ -421,14 +462,18 @@ static int rtpmidi_configure_instance(instance* inst, char* option, char* value) return rtpmidi_push_peer(data, sock_addr, sock_len, 0, 0); } - else if(!strcmp(option, "session")){ + else if(!strcmp(option, "title")){ if(data->mode != apple){ - LOG("'session' option is only valid for apple mode instances"); + LOG("'title' option is only valid for apple mode instances"); return 1; } - free(data->session_name); - data->session_name = strdup(value); - if(!data->session_name){ + if(strchr(value, '.')){ + LOGPF("Invalid instance title %s on %s: titles may not contain periods", value, inst->name); + return 1; + } + free(data->title); + data->title = strdup(value); + if(!data->title){ LOG("Failed to allocate memory"); return 1; } @@ -684,10 +729,10 @@ static int rtpmidi_handle_applemidi(instance* inst, int fd, uint8_t* frame, size invite->version = htobe32(2); invite->token = command->token; invite->ssrc = htobe32(data->ssrc); - memcpy(response + sizeof(apple_command), data->session_name ? data->session_name : RTPMIDI_DEFAULT_NAME, strlen((data->session_name ? data->session_name : RTPMIDI_DEFAULT_NAME)) + 1); + memcpy(response + sizeof(apple_command), data->title ? data->title : RTPMIDI_DEFAULT_NAME, strlen((data->title ? data->title : RTPMIDI_DEFAULT_NAME)) + 1); //calculate data port ((struct sockaddr_in*) peer)->sin_port = be16toh(htobe16(((struct sockaddr_in*) peer)->sin_port) + 1); - sendto(data->fd, response, sizeof(apple_command) + strlen(data->session_name ? data->session_name : RTPMIDI_DEFAULT_NAME) + 1, 0, (struct sockaddr*) peer, peer_len); + sendto(data->fd, response, sizeof(apple_command) + strlen(data->title ? data->title : RTPMIDI_DEFAULT_NAME) + 1, 0, (struct sockaddr*) peer, peer_len); } return 0; } @@ -961,15 +1006,7 @@ static int rtpmidi_handle_control(instance* inst){ return 0; } -int rtpmidi_mdns_announce(rtpmidi_instance_data* data){ - uint8_t frame[RTPMIDI_PACKET_BUFFER] = ""; - dns_header* hdr = (dns_header*) frame; - dns_rr* rr = NULL; - dns_rr_srv* srv = NULL; - dns_name name = { - .alloc = 0 - }; - size_t offset = 0; +static int rtpmidi_mdns_broadcast(uint8_t* frame, size_t len){ struct sockaddr_in mcast = { .sin_family = AF_INET, .sin_port = htobe16(5353), @@ -984,6 +1021,63 @@ int rtpmidi_mdns_announce(rtpmidi_instance_data* data){ 0x00, 0x00, 0x00, 0xfb} }; + //send to ipv4 and ipv6 mcasts + sendto(cfg.mdns_fd, frame, len, 0, (struct sockaddr*) &mcast6, sizeof(mcast6)); + sendto(cfg.mdns_fd, frame, len, 0, (struct sockaddr*) &mcast, sizeof(mcast)); + return 0; +} + +static int rtpmidi_mdns_detach(rtpmidi_instance_data* data){ + uint8_t frame[RTPMIDI_PACKET_BUFFER] = ""; + dns_header* hdr = (dns_header*) frame; + dns_rr* rr = NULL; + dns_name name = { + .alloc = 0 + }; + size_t offset = 0; + ssize_t bytes = 0; + + hdr->id = 0; + hdr->flags[0] = 0x84; + hdr->flags[1] = 0; + hdr->questions = hdr->servers = hdr->additional = 0; + hdr->answers = htobe16(1); + offset = sizeof(dns_header); + + //answer 1: _apple-midi PTR FQDN + snprintf((char*) frame + offset, sizeof(frame) - offset, "%s", RTPMIDI_MDNS_DOMAIN); + bytes = dns_push_rr(frame + offset, sizeof(frame) - offset, &rr, (char*) frame + offset, 12, 1, 0, 0); + if(bytes < 0){ + goto bail; + } + offset += bytes; + + //TODO length-checks here + frame[offset++] = strlen(data->title); + memcpy(frame + offset, data->title, strlen(data->title)); + offset += strlen(data->title); + frame[offset++] = 0xC0; + frame[offset++] = sizeof(dns_header); + rr->data = htobe16(1 + strlen(data->title) + 2); + + free(name.name); + return rtpmidi_mdns_broadcast(frame, offset); +bail: + free(name.name); + return 1; +} + +static int rtpmidi_mdns_announce(rtpmidi_instance_data* data){ + uint8_t frame[RTPMIDI_PACKET_BUFFER] = ""; + dns_header* hdr = (dns_header*) frame; + dns_rr* rr = NULL; + dns_rr_srv* srv = NULL; + dns_name name = { + .alloc = 0 + }; + size_t offset = 0; + ssize_t bytes = 0; + hdr->id = 0; hdr->flags[0] = 0x84; hdr->flags[1] = 0; @@ -993,20 +1087,12 @@ int rtpmidi_mdns_announce(rtpmidi_instance_data* data){ offset = sizeof(dns_header); //answer 1: SRV FQDN - snprintf((char*) frame + offset, sizeof(frame) - offset, "%s.%s", data->session_name, RTPMIDI_MDNS_DOMAIN); - if(dns_encode_name((char*) frame + offset, &name)){ - LOGPF("Failed to encode name for %s", frame); - return 1; + snprintf((char*) frame + offset, sizeof(frame) - offset, "%s.%s", data->title, RTPMIDI_MDNS_DOMAIN); + bytes = dns_push_rr(frame + offset, sizeof(frame) - offset, &rr, (char*) frame + offset, 33, 1, 120, 0); + if(bytes < 0){ + goto bail; } - - memcpy(frame + offset, name.name, name.length); - offset += name.length; - - rr = (dns_rr*) (frame + offset); - rr->rtype = htobe16(33); //SRV RR - rr->rclass = htobe16(1); //INADDR - rr->ttl = htobe32(120); - offset += sizeof(dns_rr); + offset += bytes; srv = (dns_rr_srv*) (frame + offset); srv->priority = 0; @@ -1017,7 +1103,7 @@ int rtpmidi_mdns_announce(rtpmidi_instance_data* data){ snprintf((char*) frame + offset, sizeof(frame) - offset, "%s.local", cfg.mdns_name); if(dns_encode_name((char*) frame + offset, &name)){ LOGPF("Failed to encode name for %s", frame + offset); - return 1; + goto bail; } memcpy(frame + offset, name.name, name.length); offset += name.length; @@ -1026,29 +1112,21 @@ int rtpmidi_mdns_announce(rtpmidi_instance_data* data){ //answer 2: empty TXT (apple asks for it otherwise) frame[offset++] = 0xC0; frame[offset++] = sizeof(dns_header); - rr = (dns_rr*) (frame + offset); - rr->rtype = htobe16(16); //TXT RR - rr->rclass = htobe16(1); //INADDR - rr->ttl = htobe32(4500); - rr->data = htobe16(1); - offset += sizeof(dns_rr); + + bytes = dns_push_rr(frame + offset, sizeof(frame) - offset, &rr, NULL, 16, 1, 4500, 1); + if(bytes < 0){ + goto bail; + } + offset += bytes; frame[offset++] = 0x00; //zero-length TXT //answer 3: dns-sd PTR _applemidi snprintf((char*) frame + offset, sizeof(frame) - offset, "%s", RTPMIDI_DNSSD_DOMAIN); - if(dns_encode_name((char*) frame + offset, &name)){ - LOGPF("Failed to encode name for %s", frame + offset); - return 1; + bytes = dns_push_rr(frame + offset, sizeof(frame) - offset, &rr, (char*) frame + offset, 12, 1, 4500, 2); + if(bytes < 0){ + goto bail; } - memcpy(frame + offset, name.name, name.length); - offset += name.length; - - rr = (dns_rr*) (frame + offset); - rr->rtype = htobe16(12); //PTR RR - rr->rclass = htobe16(1); //INADDR - rr->ttl = htobe32(4500); - rr->data = htobe16(2); - offset += sizeof(dns_rr); + offset += bytes; //add backref for PTR frame[offset++] = 0xC0; @@ -1058,12 +1136,11 @@ int rtpmidi_mdns_announce(rtpmidi_instance_data* data){ frame[offset++] = 0xC0; frame[offset++] = sizeof(dns_header) + frame[sizeof(dns_header)] + 1; - rr = (dns_rr*) (frame + offset); - rr->rtype = htobe16(12); //PTR RR - rr->rclass = htobe16(1); //INADDR - rr->ttl = htobe32(4500); - rr->data = htobe16(2); - offset += sizeof(dns_rr); + bytes = dns_push_rr(frame + offset, sizeof(frame) - offset, &rr, NULL, 12, 1, 4500, 2); + if(bytes < 0){ + goto bail; + } + offset += bytes; //add backref for PTR frame[offset++] = 0xC0; @@ -1071,19 +1148,11 @@ int rtpmidi_mdns_announce(rtpmidi_instance_data* data){ //additional 1: A host snprintf((char*) frame + offset, sizeof(frame) - offset, "%s.local", cfg.mdns_name); - if(dns_encode_name((char*) frame + offset, &name)){ - LOGPF("Failed to encode name for %s", frame + offset); + bytes = dns_push_rr(frame + offset, sizeof(frame) - offset, &rr, (char*) frame + offset, 1, 1, 120, 4); + if(bytes < 0){ return 1; } - memcpy(frame + offset, name.name, name.length); - offset += name.length; - - rr = (dns_rr*) (frame + offset); - rr->rtype = htobe16(1); //A RR - rr->rclass = htobe16(1); //INADDR - rr->ttl = htobe32(120); - rr->data = htobe16(4); - offset += sizeof(dns_rr); + offset += bytes; //TODO get local addresses here frame[offset++] = 0x0A; @@ -1091,12 +1160,11 @@ int rtpmidi_mdns_announce(rtpmidi_instance_data* data){ frame[offset++] = 0x01; frame[offset++] = 0x07; - //send to ipv4 and ipv6 mcasts - sendto(cfg.mdns_fd, frame, offset, 0, (struct sockaddr*) &mcast6, sizeof(mcast6)); - sendto(cfg.mdns_fd, frame, offset, 0, (struct sockaddr*) &mcast, sizeof(mcast)); - free(name.name); - return 0; + return rtpmidi_mdns_broadcast(frame, offset); +bail: + free(name.name); + return 1; } static int rtpmidi_service(){ @@ -1127,13 +1195,13 @@ static int rtpmidi_service(){ return 1; } - for(u = 0; u < n; u++){ data = (rtpmidi_instance_data*) inst[u]->impl; if(data->mode == apple){ //mdns discovery - if(cfg.mdns_fd >= 0){ + //TODO time-out this properly + if(cfg.mdns_fd >= 0 && data->title){ rtpmidi_mdns_announce(data); } @@ -1156,9 +1224,9 @@ static int rtpmidi_service(){ memcpy(&control_peer, &(data->peer[u].dest), sizeof(control_peer)); ((struct sockaddr_in*) &control_peer)->sin_port = be16toh(htobe16(((struct sockaddr_in*) &control_peer)->sin_port) - 1); //append session name to packet - memcpy(frame + sizeof(apple_command), data->session_name ? data->session_name : RTPMIDI_DEFAULT_NAME, strlen((data->session_name ? data->session_name : RTPMIDI_DEFAULT_NAME)) + 1); + memcpy(frame + sizeof(apple_command), data->title ? data->title : RTPMIDI_DEFAULT_NAME, strlen((data->title ? data->title : RTPMIDI_DEFAULT_NAME)) + 1); - sendto(data->control_fd, (char*) invite, sizeof(apple_command) + strlen((data->session_name ? data->session_name : RTPMIDI_DEFAULT_NAME)) + 1, 0, (struct sockaddr*) &control_peer, data->peer[u].dest_len); + sendto(data->control_fd, (char*) invite, sizeof(apple_command) + strlen((data->title ? data->title : RTPMIDI_DEFAULT_NAME)) + 1, 0, (struct sockaddr*) &control_peer, data->peer[u].dest_len); } } } @@ -1182,7 +1250,6 @@ static int rtpmidi_handle_mdns(){ if(bytes < sizeof(dns_header)){ continue; } - LOGPF("%" PRIsize_t " bytes of mDNS data", bytes); hdr->id = be16toh(hdr->id); hdr->questions = be16toh(hdr->questions); @@ -1193,42 +1260,53 @@ static int rtpmidi_handle_mdns(){ //rfc6762 18.3: opcode != 0 -> ignore //rfc6762 18.11: response code != 0 -> ignore - //TODO Check for ._apple-midi._udp.local. offset = sizeof(dns_header); - 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); + DBGPF("%" PRIsize_t " bytes, ID %d, Opcode %d, %s, %d questions, %d answers, %d servers, %d additional", bytes, 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); + if(dns_decode_name(buffer, bytes, offset, &name)){ + LOG("Failed to decode DNS label"); + return 1; + } offset += name.length; offset += sizeof(dns_question); - - LOGPF("Question (%d bytes): %s", name.length, name.name); } + //look for a SRV answer for ._apple-midi._udp.local. for(u = 0; u < hdr->answers; u++){ - dns_decode_name(buffer, bytes, offset, &name); + if(dns_decode_name(buffer, bytes, offset, &name)){ + LOG("Failed to decode DNS label"); + return 1; + } 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)); + if(be16toh(rr->rtype) == 33 + && strlen(name.name) > strlen(RTPMIDI_MDNS_DOMAIN) + && !strcmp(name.name + (strlen(name.name) - strlen(RTPMIDI_MDNS_DOMAIN)), RTPMIDI_MDNS_DOMAIN)){ + LOGPF("Found possible peer: %s", name.name); + } } for(u = 0; u < hdr->servers; u++){ - dns_decode_name(buffer, bytes, offset, &name); + if(dns_decode_name(buffer, bytes, offset, &name)){ + LOG("Failed to decode DNS label"); + return 1; + } 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)); } + //find a matching A/AAAA record in the additional records for(u = 0; u < hdr->additional; u++){ - dns_decode_name(buffer, bytes, offset, &name); + if(dns_decode_name(buffer, bytes, offset, &name)){ + LOG("Failed to decode DNS label"); + return 1; + } 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)); } } @@ -1386,6 +1464,11 @@ static int rtpmidi_shutdown(size_t n, instance** inst){ for(u = 0; u < n; u++){ data = (rtpmidi_instance_data*) inst[u]->impl; + + if(cfg.mdns_fd >= 0 && data->mode == apple && data->title){ + rtpmidi_mdns_detach(data); + } + if(data->fd >= 0){ close(data->fd); } @@ -1394,8 +1477,8 @@ static int rtpmidi_shutdown(size_t n, instance** inst){ close(data->control_fd); } - free(data->session_name); - data->session_name = NULL; + free(data->title); + data->title = NULL; free(data->accept); data->accept = NULL; diff --git a/backends/rtpmidi.h b/backends/rtpmidi.h index f55b543..f240586 100644 --- a/backends/rtpmidi.h +++ b/backends/rtpmidi.h @@ -22,8 +22,8 @@ static int rtpmidi_shutdown(size_t n, instance** inst); #define RTPMIDI_GET_TYPE(a) ((a) & 0x7F) #define RTPMIDI_DEFAULT_NAME "MIDIMonster" #define RTPMIDI_SERVICE_INTERVAL 1000 -#define RTPMIDI_MDNS_DOMAIN "_apple-midi._udp.local" -#define RTPMIDI_DNSSD_DOMAIN "_services._dns-sd._udp.local" +#define RTPMIDI_MDNS_DOMAIN "_apple-midi._udp.local." +#define RTPMIDI_DNSSD_DOMAIN "_services._dns-sd._udp.local." #define DNS_POINTER(a) (((a) & 0xC0) == 0xC0) #define DNS_LABEL_LENGTH(a) ((a) & 0x3F) @@ -77,8 +77,8 @@ typedef struct /*_rtmidi_instance_data*/ { uint16_t sequence; //apple-midi config - char* session_name; /* initiator only */ - char* accept; /* participant only */ + char* title; + char* accept; //direct mode config uint8_t learn_peers; diff --git a/backends/rtpmidi.md b/backends/rtpmidi.md index c188039..64978ae 100644 --- a/backends/rtpmidi.md +++ b/backends/rtpmidi.md @@ -24,8 +24,8 @@ 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-name` | `computer1` | none | mDNS hostname to announce, also used as AppleMIDI peer name | +| `detect` | `on` | `off` | Output channel specifications for any events coming in on configured instances to help with configuration. | +| `mdns-name` | `computer1` | none | mDNS hostname to announce (`<mdns-name>.local`). Apple-mode instances with `title` configuration will be announced via mDNS if set. | #### Instance configuration @@ -48,13 +48,10 @@ Common instance configuration parameters | Option | Example value | Default value | Description | |---------------|-----------------------|-----------------------|-----------------------| -| `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. | -| `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 | - -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. +| `bind` | `10.1.2.1 9001` | `:: <random>` | Local network address to bind to (note that AppleMIDI requires two consecutive port numbers to be allocated). | +| `title` | `Just Jamming` | none | Session/device name to announce via mDNS. If unset, the instance will not be announced. | +| `invite` | `pad` | none | Devices to send invitations to when discovered (the special value `*` invites all discovered peers). May be specified multiple times. | +| `join` | `Just Jamming` | none | Session for which to accept invitations (the special value `*` accepts the first invitation seen). | #### Channel specification @@ -85,3 +82,9 @@ rmidi1.ch0.pitch > rmidi2.ch1.pitch ``` #### Known bugs / problems + +The mDNS and DNS-SD implementations in this backends are extremely terse, to the point of violating the +specifications in multiple cases. Due to the complexity involved in supporting these protocols, problems +arising from this will be considered a bug only in cases where they hinder normal operation of the backend. + +mDNS discovery may announce flawed records when run on a host with multiple active interface. |