Add ohm, an OpenHome Songcast sender audio backend

Streams AirPlay audio to OpenHome/Songcast receivers as OHU unicast PCM
(16/24-bit). Sends are paced on the PTP master clock so receivers slave
to the AirPlay group clock through their buffer-fill servo; MediaLatency
carries the phase, matching the wire behaviour of Linn's own sender
(zero flags and timestamps). delay() reports the newest frame's playtime
lead so shairport feeds a receiver latency ahead. Handles Join, Listen,
Leave and Resend with a frame history, and forwards track metadata and
metatext from the metadata hub.

Makefile.am

@@ -113,7 +113,7 @@ shairport_sync_SOURCES += audio_dummy.c
 endif
 
 if USE_OHM
-shairport_sync_SOURCES += audio_ohm.c ohm_upnp.c
+shairport_sync_SOURCES += audio_ohm.c
 endif
 
 if USE_AO

audio_ohm.c

@@ -36,8 +36,6 @@
 #include "config.h"
 #endif
 
-#include "ohm_upnp.h"
-
 #include <arpa/inet.h>
 #include <errno.h>
 #include <ifaddrs.h>
@@ -248,14 +246,11 @@ static struct {
   char *name; /* sender display name, default "Shairport Sync" */
   int max_receivers;
   int history_size;
-  char *receiver_name; /* UPnP-control the receiver with this friendly name */
-  int standby_min;
 } cfg = {
   .port = OHM_DEFAULT_PORT,
   .latency_ms = OHM_DEFAULT_LATENCY_MS,
   .max_receivers = OHM_DEFAULT_MAX_RECEIVERS,
   .history_size = OHM_DEFAULT_HISTORY,
-  .standby_min = 15,
 };
 
 /* Socket and thread lifecycle. */
@@ -267,9 +262,6 @@ static struct {
   pthread_t sender_thread;
   int sender_running;
   int sender_created;
-  pthread_t upnp_thread;
-  int upnp_running;
-  int upnp_created;
   int watcher_registered;
 } rt = {
   .sock = -1,
@@ -459,11 +451,6 @@ static size_t ohm_build_audio(uint8_t *buf, uint32_t samples, uint32_t frame, ui
 static size_t ohm_build_track(uint8_t *buf, uint32_t seq, const char *uri, const char *metadata) {
   size_t uri_len = uri ? strlen(uri) : 0;
   size_t md_len = metadata ? strlen(metadata) : 0;
-  size_t cap = OHM_MAX_MSG - OHM_HEADER_BYTES - 12;
-  if (uri_len > cap)
-    uri_len = cap;
-  if (md_len > cap - uri_len)
-    md_len = cap - uri_len;
   size_t total = OHM_HEADER_BYTES + 12 + uri_len + md_len;
   ohm_write_header(buf, OHM_MSG_TRACK, (uint16_t)total);
   uint8_t *p = buf + OHM_HEADER_BYTES;
@@ -479,9 +466,6 @@ static size_t ohm_build_track(uint8_t *buf, uint32_t seq, const char *uri, const
 
 static size_t ohm_build_metatext(uint8_t *buf, uint32_t seq, const char *text) {
   size_t t_len = text ? strlen(text) : 0;
-  size_t cap = OHM_MAX_MSG - OHM_HEADER_BYTES - 8;
-  if (t_len > cap)
-    t_len = cap;
   size_t total = OHM_HEADER_BYTES + 8 + t_len;
   ohm_write_header(buf, OHM_MSG_METATEXT, (uint16_t)total);
   uint8_t *p = buf + OHM_HEADER_BYTES;
@@ -499,6 +483,40 @@ static size_t ohm_build_control(uint8_t *buf, uint8_t type) {
 
 /* ---- DIDL-Lite / metatext from the metadata hub ---- */
 
+/* XML-escape src into dst (NUL-terminated). Returns chars written (excluding NUL). */
+static size_t ohm_xml_escape(char *dst, size_t dst_cap, const char *src) {
+  size_t w = 0;
+  if (dst == NULL || dst_cap == 0)
+    return 0;
+  dst[0] = '\0';
+  if (!src)
+    return 0;
+  for (const char *s = src; *s && w + 8 < dst_cap; s++) {
+    switch (*s) {
+    case '&':
+      memcpy(dst + w, "&amp;", 5);
+      w += 5;
+      break;
+    case '<':
+      memcpy(dst + w, "&lt;", 4);
+      w += 4;
+      break;
+    case '>':
+      memcpy(dst + w, "&gt;", 4);
+      w += 4;
+      break;
+    case '"':
+      memcpy(dst + w, "&quot;", 6);
+      w += 6;
+      break;
+    default:
+      dst[w++] = *s;
+    }
+  }
+  dst[w] = '\0';
+  return w;
+}
+
 /* Build a DIDL-Lite metadata string from the current track. Caller frees. */
 static char *ohm_build_didl_lite_locked(void) {
   /* Called under the metadata hub write lock (from the watcher) or not at all.
@@ -592,8 +610,6 @@ static void ohm_send_metatext_to_all_locked(void) {
 /* ---- Metadata watcher (runs under the hub write lock) ---- */
 
 static void ohm_metadata_watcher(struct metadata_bundle *md, __attribute__((unused)) void *userdata) {
-  if (!rt.control_running)
-    return;
   /* Decide whether this is a track-identity change worth re-sending. */
   int track_changed = md->track_name_changed || md->artist_name_changed || md->album_name_changed ||
                       md->item_id_changed || md->songtime_in_milliseconds_changed ||
@@ -621,7 +637,6 @@ static void ohm_metadata_watcher(struct metadata_bundle *md, __attribute__((unus
   pthread_mutex_unlock(&control.lock);
 }
 
-
 /* ---- Control thread: Join / Listen / Leave / Resend + expiry ---- */
 
 static void ohm_handle_resend_locked(const uint8_t *payload, size_t payload_len,
@@ -740,19 +755,6 @@ static void *ohm_control_thread(__attribute__((unused)) void *arg) {
   return NULL;
 }
 
-/* UPnP receiver control runs on its own thread: discovery and SOAP block for
- * seconds and must never stall Join/Listen/Resend handling. */
-#define OHM_UPNP_TICK_MS 250
-
-static void *ohm_upnp_thread(__attribute__((unused)) void *arg) {
-  const struct timespec interval = {.tv_nsec = OHM_UPNP_TICK_MS * 1000000L};
-  while (rt.upnp_running) {
-    ohm_upnp_tick();
-    nanosleep(&interval, NULL);
-  }
-  return NULL;
-}
-
 /* ---- Paced sender thread ---- */
 
 static void ohm_audio_unlock_cleanup(__attribute__((unused)) void *arg) {
@@ -1067,14 +1069,6 @@ static int ohm_start_socket(void) {
   setsockopt(rt.sock, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
 
   ohm_print_uris(bound_port);
-  ohm_upnp_config_t upnp = {
-      .receiver_name = cfg.receiver_name,
-      .interface_ip = cfg.interface_ip,
-      .display_name = cfg.name,
-      .standby_minutes = cfg.standby_min,
-      .ohu_port = bound_port,
-  };
-  ohm_upnp_configure(&upnp);
   return 0;
 }
 
@@ -1089,8 +1083,6 @@ static void help(void) {
   printf("  -m <n>               max simultaneous receivers (default %d)\n",
          OHM_DEFAULT_MAX_RECEIVERS);
   printf("  -H <n>               resend history frames (default %d)\n", OHM_DEFAULT_HISTORY);
-  printf("  -r <name>            control the receiver with this friendly name (UPnP)\n");
-  printf("  -S <min>             minutes after stop before receiver standby (default 15, 0 = never)\n");
 }
 
 static int init(__attribute__((unused)) int argc, __attribute__((unused)) char **argv) {
@@ -1101,9 +1093,43 @@ static int init(__attribute__((unused)) int argc, __attribute__((unused)) char *
   cfg.history_size = OHM_DEFAULT_HISTORY;
   cfg.name = strdup("Shairport Sync");
 
+  /* command line (shairport passes this backend's arguments as a slice) */
+  optind = 1; /* optind=0 is equivalent to optind=1 plus special behaviour */
+  argv--;     /* shift so getopt() sees a conventional argv[0..argc-1] */
+  argc++;
+  opterr = 0;
+  int opt;
+  while ((opt = getopt(argc, argv, "o:i:l:n:m:H:")) > 0) {
+    switch (opt) {
+    case 'o':
+      cfg.port = atoi(optarg);
+      break;
+    case 'i':
+      free(cfg.interface_ip);
+      cfg.interface_ip = strdup(optarg);
+      break;
+    case 'l':
+      cfg.latency_ms = atoi(optarg);
+      break;
+    case 'n':
+      free(cfg.name);
+      cfg.name = strdup(optarg);
+      break;
+    case 'm':
+      cfg.max_receivers = atoi(optarg);
+      break;
+    case 'H':
+      cfg.history_size = atoi(optarg);
+      break;
+    default:
+      warn("ohm: invalid audio option \"-%c\" specified -- ignored.", optopt);
+      help();
+      break;
+    }
+  }
+
   /* settings file (libconfig), stanza "ohm". config.cfg may be NULL if no
-   * configuration file was supplied / readable, so guard every lookup.
-   * Command-line options are parsed afterwards and take priority. */
+   * configuration file was supplied / readable, so guard every lookup. */
   if (config.cfg != NULL) {
     const char *str;
     int value;
@@ -1129,55 +1155,6 @@ static int init(__attribute__((unused)) int argc, __attribute__((unused)) char *
     if (config_lookup_int(config.cfg, "ohm.history", &value)) {
       cfg.history_size = value;
     }
-    if (config_lookup_non_empty_string(config.cfg, "ohm.receiver", &str)) {
-      free(cfg.receiver_name);
-      cfg.receiver_name = strdup(str);
-    }
-    if (config_lookup_int(config.cfg, "ohm.standby_minutes", &value)) {
-      cfg.standby_min = value;
-    }
-  }
-
-  /* command line (shairport passes this backend's arguments as a slice) */
-  optind = 1; /* optind=0 is equivalent to optind=1 plus special behaviour */
-  argv--;     /* shift so getopt() sees a conventional argv[0..argc-1] */
-  argc++;
-  opterr = 0;
-  int opt;
-  while ((opt = getopt(argc, argv, "o:i:l:n:m:H:r:S:")) > 0) {
-    switch (opt) {
-    case 'o':
-      cfg.port = atoi(optarg);
-      break;
-    case 'i':
-      free(cfg.interface_ip);
-      cfg.interface_ip = strdup(optarg);
-      break;
-    case 'l':
-      cfg.latency_ms = atoi(optarg);
-      break;
-    case 'n':
-      free(cfg.name);
-      cfg.name = strdup(optarg);
-      break;
-    case 'm':
-      cfg.max_receivers = atoi(optarg);
-      break;
-    case 'H':
-      cfg.history_size = atoi(optarg);
-      break;
-    case 'r':
-      free(cfg.receiver_name);
-      cfg.receiver_name = strdup(optarg);
-      break;
-    case 'S':
-      cfg.standby_min = atoi(optarg);
-      break;
-    default:
-      warn("ohm: invalid audio option \"-%c\" specified -- ignored.", optopt);
-      help();
-      break;
-    }
   }
 
   if (cfg.max_receivers < 1)
@@ -1185,13 +1162,12 @@ static int init(__attribute__((unused)) int argc, __attribute__((unused)) char *
   if (cfg.history_size < 0)
     cfg.history_size = OHM_DEFAULT_HISTORY;
 
-  if (cfg.latency_ms < 1) {
-    warn("ohm: latency %dms is invalid, using %dms", cfg.latency_ms, OHM_DEFAULT_LATENCY_MS);
-    cfg.latency_ms = OHM_DEFAULT_LATENCY_MS;
-  } else if (cfg.latency_ms < 100) {
-    warn("ohm: latency %dms is below the working range of typical receivers; expect no sync",
-         cfg.latency_ms);
-  }
+  if (cfg.latency_ms < 100)
+    warn("ohm: latency %dms is below the working range of typical receivers; expect no sync", cfg.latency_ms);
+
+  /* delay() never reports less than the receiver latency, so the feed gate
+   * must sit above it; the margin is the ring's working level. */
+  config.audio_backend_buffer_desired_length += cfg.latency_ms / 1000.0;
 
 #ifndef CONFIG_AIRPLAY_2
   parse_audio_options("ohm", (1 << SPS_FORMAT_S16_BE) | (1 << SPS_FORMAT_S24_3BE),
@@ -1201,12 +1177,6 @@ static int init(__attribute__((unused)) int argc, __attribute__((unused)) char *
                       (1 << SPS_RATE_48000), (1 << 2));
 #endif
 
-  /* delay() never reports less than the receiver latency, so the feed gate
-   * must sit above it; the margin is the ring's working level.
-   * parse_audio_options() may have replaced the value, so add the latency
-   * afterwards. */
-  config.audio_backend_buffer_desired_length += cfg.latency_ms / 1000.0;
-
   control.receivers = calloc(cfg.max_receivers, sizeof(ohm_receiver_t));
   control.history = calloc(cfg.history_size > 0 ? cfg.history_size : 1, sizeof(ohm_history_entry_t));
   control.bcast_addrs = calloc(cfg.max_receivers, sizeof(struct sockaddr_storage));
@@ -1256,25 +1226,12 @@ static int init(__attribute__((unused)) int argc, __attribute__((unused)) char *
     return -1;
   }
   rt.sender_created = 1;
-
-  if (ohm_upnp_enabled()) {
-    rt.upnp_running = 1;
-    if (pthread_create(&rt.upnp_thread, NULL, ohm_upnp_thread, NULL) != 0) {
-      warn("ohm: cannot create upnp thread: %s.", strerror(errno));
-      rt.upnp_running = 0;
-      return -1;
-    }
-    rt.upnp_created = 1;
-  }
   return 0;
 }
 
 static void deinit(void) {
-  /* Cooperative shutdown: never pthread_cancel, a thread cancelled inside a
-   * lock-held region would die holding the lock. */
   rt.sender_running = 0;
   rt.control_running = 0;
-  rt.upnp_running = 0;
   pthread_mutex_lock(&audio.lock);
   pthread_cond_broadcast(&audio.cond);
   pthread_cond_broadcast(&audio.not_full);
@@ -1283,29 +1240,15 @@ static void deinit(void) {
     shutdown(rt.sock, SHUT_RDWR);
   }
   if (rt.sender_created) {
+    pthread_cancel(rt.sender_thread);
     pthread_join(rt.sender_thread, NULL);
     rt.sender_created = 0;
   }
   if (rt.control_created) {
+    pthread_cancel(rt.control_thread);
     pthread_join(rt.control_thread, NULL);
     rt.control_created = 0;
   }
-  if (rt.upnp_created) {
-    pthread_join(rt.upnp_thread, NULL);
-    rt.upnp_created = 0;
-  }
-
-  /* The metadata hub has no unregister; the watcher bails out on
-   * !control_running. Cycling the hub write lock waits out any watcher that
-   * passed that check before the flag was cleared, so the frees below cannot
-   * race it. */
-#ifndef TEST_OHM
-  if (rt.watcher_registered) {
-    metadata_hub_modify_prolog();
-    metadata_hub_modify_epilog(0);
-  }
-#endif
-
   if (rt.sock >= 0) {
     close(rt.sock);
     rt.sock = -1;
@@ -1328,9 +1271,6 @@ static void deinit(void) {
   cfg.interface_ip = NULL;
   free(cfg.name);
   cfg.name = NULL;
-  free(cfg.receiver_name);
-  cfg.receiver_name = NULL;
-  ohm_upnp_deinit();
 }
 
 static int prepare(void) {
@@ -1422,8 +1362,6 @@ static int play(void *buf, int samples, int sample_type,
   if (!audio.configured || samples <= 0)
     return samples;
 
-  ohm_upnp_session_begin();
-
   uint64_t wallclock = ohm_now_ns();
   if (sample_type == play_samples_are_untimed)
     debug(3, "ohm: play samples=%d untimed wall=%llums", samples,
@@ -1485,10 +1423,7 @@ static void ohm_request_halt(void) {
   pthread_mutex_unlock(&audio.lock);
 }
 
-static void stop(void) {
-  ohm_request_halt();
-  ohm_upnp_session_end();
-}
+static void stop(void) { ohm_request_halt(); }
 
 static void flush(void) { ohm_request_halt(); }
 
@@ -1501,6 +1436,8 @@ static int is_running(void) {
  * L), so the report is simply its playtime lead. Without timing marks fall
  * back to occupancy plus the receiver latency. */
 static int ohm_delay(long *the_delay) {
+  if (the_delay == NULL)
+    return -1;
   pthread_mutex_lock(&audio.lock);
   if (!audio.configured || audio.fmt.sample_rate == 0) {
     pthread_mutex_unlock(&audio.lock);
@@ -1529,14 +1466,10 @@ static int ohm_delay(long *the_delay) {
 }
 
 static void volume(double vol) {
-  if (ohm_upnp_enabled())
-    ohm_upnp_set_volume((long)vol);
-  else
-    debug(2, "ohm: volume %.2f ignored, receiver controls volume.", vol);
+  debug(2, "ohm: volume %.2f ignored, receiver controls volume.", vol);
 }
 
-static volume_range_t ohm_volume_range = {.minimum_volume_dB = -OHM_UPNP_VOLUME_RANGE_CDB,
-                                          .maximum_volume_dB = 0};
+static volume_range_t ohm_volume_range = {.minimum_volume_dB = -9630, .maximum_volume_dB = 0};
 static output_parameters_t ohm_parameters = {.volume_range = &ohm_volume_range};
 
 static output_parameters_t *parameters(void) { return &ohm_parameters; }

common.c

@@ -1948,9 +1948,6 @@ char *get_version_string() {
 #ifdef CONFIG_PIPE
     strcat(version_string, "-pipe");
 #endif
-#ifdef CONFIG_OHM
-    strcat(version_string, "-ohm");
-#endif
 #ifdef CONFIG_SOXR
     strcat(version_string, "-soxr");
 #endif

docker/Dockerfile.ohm

@@ -60,53 +60,7 @@ RUN ../configure --sysconfdir=/etc --with-alsa \
         --with-dbus-interface --with-mpris-interface \
         --with-convolution --with-soxr
 RUN make -j"$(nproc)"
-RUN make install DESTDIR=/install
 
 # Target that yields just the binary on the host filesystem via --output.
 FROM --platform=linux/arm64 scratch AS binary
 COPY --from=builder /shairport-sync/build/shairport-sync /shairport-sync
-
-# nqptp sidecar image for AirPlay 2 timing; shares /dev/shm with the
-# shairport-sync container (see k8s/shairport-ohm.yaml).
-FROM --platform=linux/arm64 debian:${DEBIAN_VERSION} AS nqptp-build
-ENV DEBIAN_FRONTEND=noninteractive
-RUN apt-get update && apt-get install -y --no-install-recommends \
-        build-essential autoconf automake libtool git ca-certificates \
-    && rm -rf /var/lib/apt/lists/*
-RUN git clone --depth=1 https://github.com/mikebrady/nqptp /nqptp
-WORKDIR /nqptp
-RUN autoreconf -i && ./configure && make
-
-FROM --platform=linux/arm64 debian:${DEBIAN_VERSION}-slim AS nqptp
-COPY --from=nqptp-build /nqptp/nqptp /usr/local/bin/nqptp
-ENTRYPOINT ["/usr/local/bin/nqptp"]
-
-# Deployable runtime image. Uses the node's avahi (host D-Bus socket mounted)
-# and the nqptp sidecar (shared /dev/shm); see k8s/shairport-ohm.yaml.
-#
-#   docker buildx build --platform linux/arm64 --target runtime \
-#     -t <registry>/shairport-sync-ohm:latest -f docker/Dockerfile.ohm --push .
-#   docker buildx build --platform linux/arm64 --target nqptp \
-#     -t <registry>/nqptp:latest -f docker/Dockerfile.ohm --push .
-FROM --platform=linux/arm64 debian:${DEBIAN_VERSION}-slim AS runtime
-ENV DEBIAN_FRONTEND=noninteractive
-RUN apt-get update && apt-get install -y --no-install-recommends \
-        libasound2 \
-        libavahi-client3 \
-        libavcodec58 \
-        libavformat58 \
-        libavutil56 \
-        libconfig9 \
-        libgcrypt20 \
-        libglib2.0-0 \
-        libplist3 \
-        libpopt0 \
-        libsndfile1 \
-        libsodium23 \
-        libsoxr0 \
-        libssl1.1 \
-        libswresample3 \
-        libuuid1 \
-    && rm -rf /var/lib/apt/lists/*
-COPY --from=builder /install/usr/local/bin/shairport-sync /usr/local/bin/shairport-sync
-ENTRYPOINT ["/usr/local/bin/shairport-sync"]

ohm_upnp.c

@@ -1,579 +0,0 @@
-/*
- * OpenHome receiver control for the ohm audio backend.
- *
- * This file is part of Shairport Sync.
- * Copyright (c) Nils Schneider 2026
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to
- * deal in the Software without restriction, including without limitation the
- * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
- * sell copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be
- * included in all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
- * DEALINGS IN THE SOFTWARE.
- */
-
-#include "ohm_upnp.h"
-
-#include <arpa/inet.h>
-#include <netinet/in.h>
-#include <stdatomic.h>
-#include <stdint.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <strings.h>
-#include <sys/socket.h>
-#include <time.h>
-#include <unistd.h>
-
-#ifdef TEST_OHM
-#include <stdarg.h>
-static void debug(int level, const char *fmt, ...) {
-  if (level > 1)
-    return;
-  va_list ap;
-  va_start(ap, fmt);
-  fprintf(stderr, "upnp: ");
-  vfprintf(stderr, fmt, ap);
-  fprintf(stderr, "\n");
-  va_end(ap);
-}
-#define inform(...) debug(1, __VA_ARGS__)
-#else
-#include "config.h"
-#include "common.h"
-#endif
-
-#define NS_PER_SEC 1000000000LL
-#define NS_PER_MIN (60LL * NS_PER_SEC)
-
-#define OHM_CTL_HTTP_MAX (128 * 1024)
-#define OHM_CTL_TIMEOUT_S 3
-#define OHM_CTL_RETRY_NS (10LL * NS_PER_SEC)
-
-#define SSDP_ADDR "239.255.255.250"
-#define SSDP_PORT 1900
-#define SSDP_LOCATIONS_MAX 8
-#define SSDP_LOCATION_LEN 192
-
-#define CDB_PER_DB 100   /* shairport volume unit: dB * 100 */
-#define BMDB_PER_DB 1024 /* OpenHome volume unit: binary milli-dB */
-
-typedef struct {
-  char type[80]; /* full urn, e.g. "urn:av-openhome-org:service:Volume:4" */
-  char url[160]; /* controlURL path */
-} ohm_svc_t;
-
-/* Settings, copied in ohm_upnp_configure(). */
-static struct {
-  char *receiver;
-  char *iface;
-  char *name;
-  int standby_min;
-  int ohu_port;
-} set;
-
-/* The discovered device, valid while .found. Tick thread only. */
-static struct {
-  int found;
-  char host[64];
-  int port;
-  ohm_svc_t receiver, volume, product;
-  int vol_limit;
-  int vol_step; /* binary milli-dB per volume step */
-} dev;
-
-/* Requests from the backend callbacks to the tick thread. */
-static struct {
-  volatile int session;
-  volatile int activate;
-  volatile int vol_dirty;
-  volatile long vol_cdb;      /* dB * 100, <= 0 */
-  _Atomic uint64_t standby_at; /* 64-bit accesses must not tear on 32-bit targets */
-} req;
-
-static char *scratch; /* HTTP response buffer, tick thread only */
-static uint64_t retry_at;
-
-size_t ohm_xml_escape(char *dst, size_t dst_cap, const char *src) {
-  size_t w = 0;
-  dst[0] = '\0';
-  if (!src)
-    return 0;
-  for (const char *s = src; *s && w + 8 < dst_cap; s++) {
-    switch (*s) {
-    case '&':
-      memcpy(dst + w, "&amp;", 5);
-      w += 5;
-      break;
-    case '<':
-      memcpy(dst + w, "&lt;", 4);
-      w += 4;
-      break;
-    case '>':
-      memcpy(dst + w, "&gt;", 4);
-      w += 4;
-      break;
-    case '"':
-      memcpy(dst + w, "&quot;", 6);
-      w += 6;
-      break;
-    default:
-      dst[w++] = *s;
-    }
-  }
-  dst[w] = '\0';
-  return w;
-}
-
-static uint64_t ohm_ctl_mono_ns(void) {
-  struct timespec t;
-  clock_gettime(CLOCK_MONOTONIC, &t);
-  return (uint64_t)t.tv_sec * NS_PER_SEC + (uint64_t)t.tv_nsec;
-}
-
-static long ohm_ctl_lround(double d) { return (long)(d < 0 ? d - 0.5 : d + 0.5); }
-
-static const char *ohm_ctl_find_ci(const char *hay, const char *needle) {
-  size_t n = strlen(needle);
-  for (; *hay; hay++)
-    if (strncasecmp(hay, needle, n) == 0)
-      return hay;
-  return NULL;
-}
-
-/* ---- XML scraping ---- */
-
-/* Copy text from p up to the next '<' into out. */
-static int ohm_ctl_span(const char *p, char *out, size_t cap) {
-  const char *e = strchr(p, '<');
-  if (!e || (size_t)(e - p) >= cap)
-    return -1;
-  memcpy(out, p, e - p);
-  out[e - p] = '\0';
-  return 0;
-}
-
-/* Copy the text content of the first <tag> into out. */
-static int ohm_ctl_tag(const char *xml, const char *tag, char *out, size_t cap) {
-  char key[96];
-  snprintf(key, sizeof(key), "<%s>", tag);
-  const char *p = strstr(xml, key);
-  return p ? ohm_ctl_span(p + strlen(key), out, cap) : -1;
-}
-
-/* Fill svc from the <service> element whose serviceType starts with prefix. */
-static int ohm_ctl_service(const char *xml, const char *prefix, ohm_svc_t *svc) {
-  const char *p = strstr(xml, prefix);
-  if (!p || ohm_ctl_span(p, svc->type, sizeof(svc->type)) != 0)
-    return -1;
-  const char *end = strstr(p, "</service>");
-  const char *cu = strstr(p, "<controlURL>");
-  if (!cu || (end && cu > end))
-    return -1;
-  return ohm_ctl_span(cu + strlen("<controlURL>"), svc->url, sizeof(svc->url));
-}
-
-/* ---- HTTP ---- */
-
-/* Collapse chunked transfer-encoding in place; a chunk boundary must never
- * split a tag. Returns the new body length. */
-static size_t ohm_ctl_dechunk(char *body, size_t body_len) {
-  char *end = body + body_len;
-  char *src = body;
-  char *dst = body;
-  while (src < end) {
-    char *num_end;
-    long sz = strtol(src, &num_end, 16);
-    if (num_end == src || sz <= 0)
-      break;
-    src = strstr(num_end, "\r\n");
-    if (src == NULL)
-      break;
-    src += 2;
-    if (src + sz > end)
-      sz = (long)(end - src);
-    memmove(dst, src, (size_t)sz);
-    dst += sz;
-    src += sz;
-    if (src + 2 <= end && src[0] == '\r')
-      src += 2;
-  }
-  *dst = '\0';
-  return (size_t)(dst - body);
-}
-
-/* One request/response exchange into scratch. Returns 0 on HTTP 200. */
-static int ohm_ctl_http(const char *host, int port, const char *req_buf, size_t req_len) {
-  int fd = socket(AF_INET, SOCK_STREAM, 0);
-  if (fd < 0)
-    return -1;
-  struct timeval tv = {.tv_sec = OHM_CTL_TIMEOUT_S};
-  setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
-  setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
-  struct sockaddr_in sin = {.sin_family = AF_INET, .sin_port = htons(port)};
-  if (inet_pton(AF_INET, host, &sin.sin_addr) != 1 ||
-      connect(fd, (struct sockaddr *)&sin, sizeof(sin)) != 0 ||
-      send(fd, req_buf, req_len, 0) != (ssize_t)req_len) {
-    close(fd);
-    return -1;
-  }
-  size_t len = 0;
-  for (;;) {
-    ssize_t n = recv(fd, scratch + len, OHM_CTL_HTTP_MAX - 1 - len, 0);
-    if (n <= 0)
-      break;
-    len += (size_t)n;
-    if (len >= OHM_CTL_HTTP_MAX - 1)
-      break;
-  }
-  close(fd);
-  scratch[len] = '\0';
-
-  const char *sp = strchr(scratch, ' ');
-  if (sp == NULL || atoi(sp + 1) != 200)
-    return -1;
-  char *body = strstr(scratch, "\r\n\r\n");
-  if (body == NULL)
-    return -1;
-  body += 4;
-
-  body[-4] = '\0'; /* terminate the headers for the search */
-  int chunked = ohm_ctl_find_ci(scratch, "transfer-encoding: chunked") != NULL;
-  body[-4] = '\r';
-  if (chunked)
-    ohm_ctl_dechunk(body, len - (size_t)(body - scratch));
-  return 0;
-}
-
-static int ohm_ctl_get(const char *host, int port, const char *path) {
-  char req_buf[256];
-  int n = snprintf(req_buf, sizeof(req_buf),
-                   "GET %s HTTP/1.1\r\nHost: %s:%d\r\nConnection: close\r\n\r\n", path, host, port);
-  return ohm_ctl_http(host, port, req_buf, (size_t)n);
-}
-
-static int ohm_ctl_soap(const ohm_svc_t *svc, const char *action, const char *args) {
-  char body[6144];
-  int blen = snprintf(body, sizeof(body),
-                      "<?xml version=\"1.0\"?>"
-                      "<s:Envelope xmlns:s=\"http://schemas.xmlsoap.org/soap/envelope/\" "
-                      "s:encodingStyle=\"http://schemas.xmlsoap.org/soap/encoding/\">"
-                      "<s:Body><u:%s xmlns:u=\"%s\">%s</u:%s></s:Body></s:Envelope>",
-                      action, svc->type, args, action);
-  char req_buf[8192];
-  int rlen = snprintf(req_buf, sizeof(req_buf),
-                      "POST %s HTTP/1.1\r\nHost: %s:%d\r\n"
-                      "Content-Type: text/xml; charset=\"utf-8\"\r\n"
-                      "SOAPACTION: \"%s#%s\"\r\nContent-Length: %d\r\nConnection: close\r\n\r\n%s",
-                      svc->url, dev.host, dev.port, svc->type, action, blen, body);
-  return ohm_ctl_http(dev.host, dev.port, req_buf, (size_t)rlen);
-}
-
-/* ---- Discovery ---- */
-
-/* M-SEARCH for OpenHome receivers; collect response LOCATION urls. */
-static int ohm_ctl_ssdp(char locations[][SSDP_LOCATION_LEN], int max) {
-  int fd = socket(AF_INET, SOCK_DGRAM, 0);
-  if (fd < 0)
-    return 0;
-  struct timeval tv = {.tv_usec = 500000};
-  setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
-  if (set.iface) {
-    struct in_addr mcast_if;
-    if (inet_pton(AF_INET, set.iface, &mcast_if) == 1)
-      setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF, &mcast_if, sizeof(mcast_if));
-  }
-  const char *msearch = "M-SEARCH * HTTP/1.1\r\nHOST: " SSDP_ADDR ":1900\r\n"
-                        "MAN: \"ssdp:discover\"\r\nMX: 1\r\n"
-                        "ST: urn:av-openhome-org:service:Receiver:1\r\n\r\n";
-  struct sockaddr_in dst = {.sin_family = AF_INET, .sin_port = htons(SSDP_PORT)};
-  inet_pton(AF_INET, SSDP_ADDR, &dst.sin_addr);
-  sendto(fd, msearch, strlen(msearch), 0, (struct sockaddr *)&dst, sizeof(dst));
-
-  int n = 0;
-  char pkt[2048];
-  for (int i = 0; i < max && n < max; i++) {
-    ssize_t r = recv(fd, pkt, sizeof(pkt) - 1, 0);
-    if (r <= 0)
-      break;
-    pkt[r] = '\0';
-    const char *l = ohm_ctl_find_ci(pkt, "location:");
-    if (!l)
-      continue;
-    l += strlen("location:");
-    while (*l == ' ')
-      l++;
-    size_t len = strcspn(l, "\r\n");
-    if (len == 0 || len >= SSDP_LOCATION_LEN)
-      continue;
-    memcpy(locations[n], l, len);
-    locations[n][len] = '\0';
-    n++;
-  }
-  close(fd);
-  return n;
-}
-
-/* Fetch one device description; on a friendly-name match fill dev. */
-static int ohm_ctl_probe(const char *location) {
-  char host[64], path[128], fname[128];
-  int port = 80;
-  if (sscanf(location, "http://%63[^:/]:%d%127s", host, &port, path) != 3 &&
-      sscanf(location, "http://%63[^:/]%127s", host, path) != 2)
-    return -1;
-  if (ohm_ctl_get(host, port, path) != 0 ||
-      ohm_ctl_tag(scratch, "friendlyName", fname, sizeof(fname)) != 0 ||
-      !ohm_ctl_find_ci(fname, set.receiver))
-    return -1;
-  if (ohm_ctl_service(scratch, "urn:av-openhome-org:service:Receiver:", &dev.receiver) != 0 ||
-      ohm_ctl_service(scratch, "urn:av-openhome-org:service:Volume:", &dev.volume) != 0 ||
-      ohm_ctl_service(scratch, "urn:av-openhome-org:service:Product:", &dev.product) != 0)
-    return -1;
-  snprintf(dev.host, sizeof(dev.host), "%s", host);
-  dev.port = port;
-  inform("ohm: controlling receiver \"%s\" at %s:%d", fname, dev.host, dev.port);
-  return 0;
-}
-
-static void ohm_ctl_read_volume_caps(void) {
-  dev.vol_limit = 100;
-  dev.vol_step = BMDB_PER_DB;
-  char v[32];
-  if (ohm_ctl_soap(&dev.volume, "Characteristics", "") == 0) {
-    if (ohm_ctl_tag(scratch, "VolumeMax", v, sizeof(v)) == 0)
-      dev.vol_limit = atoi(v);
-    if (ohm_ctl_tag(scratch, "VolumeMilliDbPerStep", v, sizeof(v)) == 0 && atoi(v) > 0)
-      dev.vol_step = atoi(v);
-  }
-  if (ohm_ctl_soap(&dev.volume, "VolumeLimit", "") == 0 &&
-      ohm_ctl_tag(scratch, "Value", v, sizeof(v)) == 0 && atoi(v) > 0)
-    dev.vol_limit = atoi(v);
-  debug(1, "ohm: receiver volume limit %d, %d mdB/step", dev.vol_limit, dev.vol_step);
-}
-
-static int ohm_ctl_discover(void) {
-  char locations[SSDP_LOCATIONS_MAX][SSDP_LOCATION_LEN];
-  int n = ohm_ctl_ssdp(locations, SSDP_LOCATIONS_MAX);
-  for (int i = 0; i < n; i++) {
-    if (ohm_ctl_probe(locations[i]) == 0) {
-      ohm_ctl_read_volume_caps();
-      dev.found = 1;
-      return 0;
-    }
-  }
-  return -1;
-}
-
-/* shairport delivers attenuation in cdB over the declared range; the device
- * runs 0..vol_limit steps. */
-static long ohm_ctl_steps_from_cdb(long cdb) {
-  double step_db = (double)dev.vol_step / BMDB_PER_DB;
-  long steps = dev.vol_limit + ohm_ctl_lround((double)cdb / CDB_PER_DB / step_db);
-  if (steps < 0)
-    steps = 0;
-  if (steps > dev.vol_limit)
-    steps = dev.vol_limit;
-  return steps;
-}
-
-/* ---- Actions ---- */
-
-/* ohu:// URI of this sender as reachable from the receiver. */
-static int ohm_ctl_our_uri(char *out, size_t cap) {
-  struct sockaddr_in sin = {.sin_family = AF_INET, .sin_port = htons(SSDP_PORT)};
-  inet_pton(AF_INET, dev.host, &sin.sin_addr);
-  int fd = socket(AF_INET, SOCK_DGRAM, 0);
-  if (fd < 0)
-    return -1;
-  struct sockaddr_in local;
-  socklen_t slen = sizeof(local);
-  int ok = connect(fd, (struct sockaddr *)&sin, sizeof(sin)) == 0 &&
-           getsockname(fd, (struct sockaddr *)&local, &slen) == 0;
-  close(fd);
-  if (!ok)
-    return -1;
-  char ip[INET_ADDRSTRLEN];
-  inet_ntop(AF_INET, &local.sin_addr, ip, sizeof(ip));
-  snprintf(out, cap, "ohu://%s:%d", ip, set.ohu_port);
-  return 0;
-}
-
-/* Switch the receiver's product to its Songcast source. The SourceXml body is
- * XML-escaped inside the SOAP response, so count escaped <Source> elements up
- * to the one of type Receiver. */
-static void ohm_ctl_select_source(void) {
-  if (ohm_ctl_soap(&dev.product, "SourceXml", "") != 0)
-    return;
-  const char *rcv = strstr(scratch, "&lt;Type&gt;Receiver&lt;/Type&gt;");
-  if (!rcv)
-    return;
-  int idx = -1;
-  for (const char *p = scratch; (p = strstr(p, "&lt;Source&gt;")) != NULL && p < rcv; p++)
-    idx++;
-  if (idx < 0)
-    return;
-  char arg[48];
-  snprintf(arg, sizeof(arg), "<Value>%d</Value>", idx);
-  ohm_ctl_soap(&dev.product, "SetSourceIndex", arg);
-}
-
-static int ohm_ctl_set_sender(const char *uri) {
-  char name[256], didl[768], meta[2304], args[2560];
-  ohm_xml_escape(name, sizeof(name), set.name ? set.name : "Shairport Sync");
-  snprintf(didl, sizeof(didl),
-           "<DIDL-Lite xmlns:dc=\"http://purl.org/dc/elements/1.1/\" "
-           "xmlns:upnp=\"urn:schemas-upnp-org:metadata-1-0/upnp/\" "
-           "xmlns=\"urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/\">"
-           "<item id=\"0\" restricted=\"True\"><dc:title>%s</dc:title>"
-           "<res protocolInfo=\"ohu:*:*:*\">%s</res>"
-           "<upnp:class>object.item.audioItem</upnp:class></item></DIDL-Lite>",
-           name, uri);
-  ohm_xml_escape(meta, sizeof(meta), didl);
-  snprintf(args, sizeof(args), "<Uri>%s</Uri><Metadata>%s</Metadata>", uri, meta);
-  return ohm_ctl_soap(&dev.receiver, "SetSender", args);
-}
-
-static int ohm_ctl_activate(void) {
-  char uri[128];
-  if (ohm_ctl_soap(&dev.product, "SetStandby", "<Value>0</Value>") != 0)
-    return -1;
-  ohm_ctl_select_source();
-  if (ohm_ctl_our_uri(uri, sizeof(uri)) != 0 || ohm_ctl_set_sender(uri) != 0 ||
-      ohm_ctl_soap(&dev.receiver, "Play", "") != 0)
-    return -1;
-  debug(1, "ohm: receiver pointed at %s and playing", uri);
-  return 0;
-}
-
-static int ohm_ctl_push_volume(void) {
-  long steps = ohm_ctl_steps_from_cdb(req.vol_cdb);
-  char arg[48];
-  snprintf(arg, sizeof(arg), "<Value>%ld</Value>", steps);
-  if (ohm_ctl_soap(&dev.volume, "SetVolume", arg) != 0)
-    return -1;
-  debug(2, "ohm: receiver volume %ld/%d", steps, dev.vol_limit);
-  return 0;
-}
-
-/* Standby only if the receiver is still pointed at us. */
-static int ohm_ctl_standby(void) {
-  char uri[128];
-  if (ohm_ctl_soap(&dev.receiver, "Sender", "") != 0)
-    return -1;
-  if (ohm_ctl_our_uri(uri, sizeof(uri)) == 0 && !strstr(scratch, uri)) {
-    debug(1, "ohm: receiver plays another sender, skipping standby");
-    return 0;
-  }
-  if (ohm_ctl_soap(&dev.product, "SetStandby", "<Value>1</Value>") != 0)
-    return -1;
-  debug(1, "ohm: receiver put into standby");
-  return 0;
-}
-
-/* Run every due request in order; -1 invalidates the device. */
-static int ohm_ctl_run(uint64_t now) {
-  if (req.activate) {
-    if (ohm_ctl_activate() != 0)
-      return -1;
-    req.activate = 0;
-  }
-  if (req.vol_dirty) {
-    req.vol_dirty = 0; /* a newer volume arriving during the push re-sets it */
-    if (ohm_ctl_push_volume() != 0) {
-      req.vol_dirty = 1;
-      return -1;
-    }
-  }
-  if (req.standby_at && now >= req.standby_at) {
-    if (ohm_ctl_standby() != 0)
-      return -1;
-    req.standby_at = 0;
-  }
-  return 0;
-}
-
-/* ---- Backend interface ---- */
-
-void ohm_upnp_configure(const ohm_upnp_config_t *config) {
-  free(set.receiver);
-  free(set.iface);
-  free(set.name);
-  set.receiver = config->receiver_name ? strdup(config->receiver_name) : NULL;
-  set.iface = config->interface_ip ? strdup(config->interface_ip) : NULL;
-  set.name = config->display_name ? strdup(config->display_name) : NULL;
-  set.standby_min = config->standby_minutes;
-  set.ohu_port = config->ohu_port;
-}
-
-int ohm_upnp_enabled(void) { return set.receiver != NULL; }
-
-void ohm_upnp_session_begin(void) {
-  if (set.receiver == NULL || req.session)
-    return;
-  req.session = 1;
-  req.standby_at = 0;
-  req.activate = 1;
-}
-
-void ohm_upnp_session_end(void) {
-  if (set.receiver == NULL)
-    return;
-  req.session = 0;
-  req.standby_at =
-      set.standby_min > 0 ? ohm_ctl_mono_ns() + (uint64_t)set.standby_min * NS_PER_MIN : 0;
-}
-
-void ohm_upnp_set_volume(long vol_cdb) {
-  req.vol_cdb = vol_cdb;
-  req.vol_dirty = 1;
-}
-
-void ohm_upnp_tick(void) {
-  if (set.receiver == NULL)
-    return;
-  uint64_t now = ohm_ctl_mono_ns();
-  int standby_due = req.standby_at && now >= req.standby_at;
-  if (!req.activate && !req.vol_dirty && !standby_due)
-    return;
-  if (now < retry_at)
-    return;
-  if (scratch == NULL && (scratch = malloc(OHM_CTL_HTTP_MAX)) == NULL)
-    return;
-  if (!dev.found && ohm_ctl_discover() != 0) {
-    retry_at = now + OHM_CTL_RETRY_NS;
-    debug(1, "ohm: receiver \"%s\" not found, retrying", set.receiver);
-    return;
-  }
-  if (ohm_ctl_run(now) != 0) {
-    dev.found = 0;
-    retry_at = now + OHM_CTL_RETRY_NS;
-  }
-}
-
-void ohm_upnp_deinit(void) {
-  free(set.receiver);
-  set.receiver = NULL;
-  free(set.iface);
-  set.iface = NULL;
-  free(set.name);
-  set.name = NULL;
-  free(scratch);
-  scratch = NULL;
-  dev.found = 0;
-  req.session = 0;
-  req.activate = 0;
-  req.vol_dirty = 0;
-  req.standby_at = 0;
-}

ohm_upnp.h

@@ -1,58 +0,0 @@
-/*
- * OpenHome receiver control for the ohm audio backend.
- *
- * This file is part of Shairport Sync.
- * Copyright (c) Nils Schneider 2026
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to
- * deal in the Software without restriction, including without limitation the
- * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
- * sell copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be
- * included in all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
- * DEALINGS IN THE SOFTWARE.
- */
-
-#pragma once
-
-#include <stddef.h>
-
-/* XML-escape src into dst (NUL-terminated). Returns chars written (excluding NUL). */
-size_t ohm_xml_escape(char *dst, size_t dst_cap, const char *src);
-
-/* The backend declares volume as attenuation -OHM_UPNP_VOLUME_RANGE_CDB..0
- * (dB * 100); shairport stretches the AirPlay slider over exactly this range. */
-#define OHM_UPNP_VOLUME_RANGE_CDB 6000
-
-typedef struct {
-  const char *receiver_name; /* friendly name to match; NULL disables the module */
-  const char *interface_ip;
-  const char *display_name;
-  int standby_minutes; /* 0 = never */
-  int ohu_port;
-} ohm_upnp_config_t;
-
-/* Strings are copied. */
-void ohm_upnp_configure(const ohm_upnp_config_t *config);
-int ohm_upnp_enabled(void);
-
-/* Callback side: cheap, thread-safe, never block. */
-void ohm_upnp_session_begin(void);
-void ohm_upnp_session_end(void);
-void ohm_upnp_set_volume(long vol_cdb); /* dB * 100, <= 0 */
-
-/* Does the network work (SSDP discovery, SOAP); call periodically from one
- * thread. */
-void ohm_upnp_tick(void);
-
-void ohm_upnp_deinit(void);