* add RTP/SAP/SDP reciever module

* use server cookie as RTP SSRC
* enable SVN keywords
* add new option "loop" for RTP sender module


git-svn-id: file:///home/lennart/svn/public/pulseaudio/trunk@716 fefdeb5f-60dc-0310-8127-8f9354f1896f

8 files changed, 1000 insertions, 48 deletions

diff --git a/src/modules/rtp/module-rtp-monitor.c b/src/modules/rtp/module-rtp-monitor.c
index c153a9d5..5ff25557 100644
--- a/src/modules/rtp/module-rtp-monitor.c
+++ b/src/modules/rtp/module-rtp-monitor.c
@@ -1,3 +1,4 @@
+/* $Id */
 
 /***
   This file is part of polypaudio.
@@ -49,16 +50,17 @@
 #include "sap.h"
 
 PA_MODULE_AUTHOR("Lennart Poettering")
-PA_MODULE_DESCRIPTION("Read data from source and send it to the network via RTP")
+PA_MODULE_DESCRIPTION("Read data from source and send it to the network via RTP/SAP/SDP")
 PA_MODULE_VERSION(PACKAGE_VERSION)
 PA_MODULE_USAGE(
-        "source=<name for the source> "
+        "source=<name of the source> "
         "format=<sample format> "
         "channels=<number of channels> "
         "rate=<sample rate> "
         "destinaton=<destination IP address> "
         "port=<port number> "
         "mtu=<maximum transfer unit> "
+        "loop=<loopback to local host?>"
 )
 
 #define DEFAULT_PORT 5004
@@ -75,6 +77,7 @@ static const char* const valid_modargs[] = {
     "rate",
     "destination",
     "port",
+    "loop",
     NULL
 };
 
@@ -125,7 +128,7 @@ static pa_usec_t source_output_get_latency (pa_source_output *o) {
     return pa_bytes_to_usec(pa_memblockq_get_length(u->memblockq), &o->sample_spec);
 }
 
-static void sap_event(pa_mainloop_api *m, pa_time_event *t, const struct timeval *tv, void *userdata) {
+static void sap_event_cb(pa_mainloop_api *m, pa_time_event *t, const struct timeval *tv, void *userdata) {
     struct userdata *u = userdata;
     struct timeval next;
     
@@ -159,6 +162,8 @@ int pa__init(pa_core *c, pa_module*m) {
     int r;
     socklen_t k;
     struct timeval tv;
+    char hn[128], *n;
+    int loop = 0;
     
     assert(c);
     assert(m);
@@ -173,6 +178,11 @@ int pa__init(pa_core *c, pa_module*m) {
         goto fail;
     }
 
+    if (pa_modargs_get_value_boolean(ma, "loop", &loop) < 0) {
+        pa_log(__FILE__": failed to parse \"loop\" parameter.");
+        goto fail;
+    }
+
     ss = s->sample_spec;
     pa_rtp_sample_spec_fixup(&ss);
     cm = s->channel_map;
@@ -189,7 +199,7 @@ int pa__init(pa_core *c, pa_module*m) {
     if (ss.channels != cm.channels)
         pa_channel_map_init_auto(&cm, ss.channels);
 
-    payload = pa_rtp_payload_type(&ss);
+    payload = pa_rtp_payload_from_sample_spec(&ss);
 
     mtu = (DEFAULT_MTU/pa_frame_size(&ss))*pa_frame_size(&ss);
     
@@ -203,21 +213,21 @@ int pa__init(pa_core *c, pa_module*m) {
         goto fail;
     }
 
-    if ((dest = pa_modargs_get_value(ma, "destination", DEFAULT_DESTINATION))) {
-        if (inet_pton(AF_INET6, dest, &sa6.sin6_addr) > 0) {
-            sa6.sin6_family = af = AF_INET6;
-            sa6.sin6_port = htons(port);
-            sap_sa6 = sa6;
-            sap_sa6.sin6_port = htons(SAP_PORT);
-        } else if (inet_pton(AF_INET, dest, &sa4.sin_addr) > 0) {
-            sa4.sin_family = af = AF_INET;
-            sa4.sin_port = htons(port);
-            sap_sa4 = sa4;
-            sap_sa4.sin_port = htons(SAP_PORT);
-        } else {
-            pa_log(__FILE__": invalid destination '%s'", dest);
-            goto fail;
-        }
+    dest = pa_modargs_get_value(ma, "destination", DEFAULT_DESTINATION);
+
+    if (inet_pton(AF_INET6, dest, &sa6.sin6_addr) > 0) {
+        sa6.sin6_family = af = AF_INET6;
+        sa6.sin6_port = htons(port);
+        sap_sa6 = sa6;
+        sap_sa6.sin6_port = htons(SAP_PORT);
+    } else if (inet_pton(AF_INET, dest, &sa4.sin_addr) > 0) {
+        sa4.sin_family = af = AF_INET;
+        sa4.sin_port = htons(port);
+        sap_sa4 = sa4;
+        sap_sa4.sin_port = htons(SAP_PORT);
+    } else {
+        pa_log(__FILE__": invalid destination '%s'", dest);
+        goto fail;
     }
     
     if ((fd = socket(af, SOCK_DGRAM, 0)) < 0) {
@@ -240,6 +250,12 @@ int pa__init(pa_core *c, pa_module*m) {
         goto fail;
     }
 
+    if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)) < 0 ||
+        setsockopt(sap_fd, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)) < 0) {
+        pa_log(__FILE__": IP_MULTICAST_LOOP failed: %s", strerror(errno));
+        goto fail;
+    }
+    
     if (!(o = pa_source_output_new(s, __FILE__, "RTP Monitor Stream", &ss, &cm, PA_RESAMPLER_INVALID))) {
         pa_log(__FILE__": failed to create source output.");
         goto fail;
@@ -273,23 +289,27 @@ int pa__init(pa_core *c, pa_module*m) {
     k = sizeof(sa_dst);
     r = getsockname(fd, (struct sockaddr*) &sa_dst, &k);
     assert(r >= 0);
+
+    n = pa_sprintf_malloc("Polypaudio RTP Stream on %s", pa_get_fqdn(hn, sizeof(hn)));
         
     p = pa_sdp_build(af,
                      af == AF_INET ? (void*) &((struct sockaddr_in*) &sa_dst)->sin_addr : (void*) &((struct sockaddr_in6*) &sa_dst)->sin6_addr,
                      af == AF_INET ? (void*) &sa4.sin_addr : (void*) &sa6.sin6_addr,
-                     "Polypaudio RTP Stream", port, payload, &ss);
+                     n, port, payload, &ss);
+
+    pa_xfree(n);
     
-    pa_rtp_context_init_send(&u->rtp_context, fd, 0, payload, pa_frame_size(&ss));
+    pa_rtp_context_init_send(&u->rtp_context, fd, c->cookie, payload, pa_frame_size(&ss));
     pa_sap_context_init_send(&u->sap_context, sap_fd, p);
 
-    pa_log_info("RTP stream initialized with mtu %u on %s:%u, SSRC=0x%08x, payload=%u, initial sequence #%u", mtu, dest, port, u->rtp_context.ssrc, payload, u->rtp_context.sequence);
-    pa_log_info("SDP-Data:\n%s\nEOF", p);
-    
+    pa_log_info(__FILE__": RTP stream initialized with mtu %u on %s:%u, SSRC=0x%08x, payload=%u, initial sequence #%u", mtu, dest, port, u->rtp_context.ssrc, payload, u->rtp_context.sequence);
+    pa_log_info(__FILE__": SDP-Data:\n%s\n"__FILE__": EOF", p);
+
     pa_sap_send(&u->sap_context, 0);
 
     pa_gettimeofday(&tv);
     pa_timeval_add(&tv, SAP_INTERVAL);
-    u->sap_event = c->mainloop->time_new(c->mainloop, &tv, sap_event, u);
+    u->sap_event = c->mainloop->time_new(c->mainloop, &tv, sap_event_cb, u);
 
     pa_modargs_free(ma);
 
diff --git a/src/modules/rtp/module-rtp-recv.c b/src/modules/rtp/module-rtp-recv.c
new file mode 100644
index 00000000..1ac057d0
--- /dev/null
+++ b/src/modules/rtp/module-rtp-recv.c
@@ -0,0 +1,469 @@
+
+/***
+  This file is part of polypaudio.
+ 
+  polypaudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as published
+  by the Free Software Foundation; either version 2 of the License,
+  or (at your option) any later version.
+ 
+  polypaudio is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+ 
+  You should have received a copy of the GNU Lesser General Public License
+  along with polypaudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <assert.h>
+#include <stdio.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <polypcore/module.h>
+#include <polypcore/llist.h>
+#include <polypcore/sink.h>
+#include <polypcore/sink-input.h>
+#include <polypcore/memblockq.h>
+#include <polypcore/log.h>
+#include <polypcore/util.h>
+#include <polypcore/xmalloc.h>
+#include <polypcore/modargs.h>
+#include <polypcore/namereg.h>
+
+#include "module-rtp-recv-symdef.h"
+
+#include "rtp.h"
+#include "sdp.h"
+#include "sap.h"
+
+PA_MODULE_AUTHOR("Lennart Poettering")
+PA_MODULE_DESCRIPTION("Recieve data from a network via RTP/SAP/SDP")
+PA_MODULE_VERSION(PACKAGE_VERSION)
+PA_MODULE_USAGE(
+        "sink=<name of the sink> "
+        "sap_address=<multicast address to listen on> "
+)
+
+#define SAP_PORT 9875
+#define DEFAULT_SAP_ADDRESS "224.0.1.2"
+#define MEMBLOCKQ_MAXLENGTH (1024*170)
+#define MAX_SESSIONS 16
+#define DEATH_TIMEOUT 20000000
+
+static const char* const valid_modargs[] = {
+    "sink",
+    "sap_address",
+    NULL
+};
+
+struct session {
+    struct userdata *userdata;
+
+    pa_sink_input *sink_input;
+    pa_memblockq *memblockq;
+
+    pa_time_event *death_event;
+
+    int first_packet;
+    uint32_t ssrc;
+    uint32_t offset;
+
+    struct pa_sdp_info sdp_info;
+
+    pa_rtp_context rtp_context;
+    pa_io_event* rtp_event;
+};
+
+struct userdata {
+    pa_module *module;
+    pa_core *core;
+
+    pa_sap_context sap_context;
+    pa_io_event* sap_event;
+
+    pa_hashmap *by_origin;
+
+    char *sink_name;
+};
+
+static void session_free(struct session *s, int from_hash);
+
+static int sink_input_peek(pa_sink_input *i, pa_memchunk *chunk) {
+    struct session *s;
+    assert(i);
+    s = i->userdata;
+
+    return pa_memblockq_peek(s->memblockq, chunk);
+}
+
+static void sink_input_drop(pa_sink_input *i, const pa_memchunk *chunk, size_t length) {
+    struct session *s;
+    assert(i);
+    s = i->userdata;
+
+    pa_memblockq_drop(s->memblockq, chunk, length);
+}
+
+static void sink_input_kill(pa_sink_input* i) {
+    struct session *s;
+    assert(i);
+    s = i->userdata;
+
+    session_free(s, 1);
+}
+
+static pa_usec_t sink_input_get_latency(pa_sink_input *i) {
+    struct session *s;
+    assert(i);
+    s = i->userdata;
+
+    return pa_bytes_to_usec(pa_memblockq_get_length(s->memblockq), &i->sample_spec);
+}
+
+static void rtp_event_cb(pa_mainloop_api *m, pa_io_event *e, int fd, pa_io_event_flags_t flags, void *userdata) {
+    struct session *s = userdata;
+    pa_memchunk chunk;
+    int64_t k, j, delta;
+    struct timeval tv;
+    
+    assert(m);
+    assert(e);
+    assert(s);
+    assert(fd == s->rtp_context.fd);
+    assert(flags == PA_IO_EVENT_INPUT);
+
+    if (pa_rtp_recv(&s->rtp_context, &chunk, s->userdata->core->memblock_stat) < 0)
+        return;
+
+    if (s->sdp_info.payload != s->rtp_context.payload) {
+        pa_memblock_unref(chunk.memblock);
+        return;
+    }
+    
+    if (!s->first_packet) {
+        s->first_packet = 1;
+
+        s->ssrc = s->rtp_context.ssrc;
+        s->offset = s->rtp_context.timestamp;
+    } else {
+        if (s->ssrc != s->rtp_context.ssrc) {
+            pa_memblock_unref(chunk.memblock);
+            return;
+        }
+    }
+
+    /* Check wheter there was a timestamp overflow */
+    k = (int64_t) s->rtp_context.timestamp - (int64_t) s->offset;
+    j = (int64_t) 0x100000000 - (int64_t) s->offset + (int64_t) s->rtp_context.timestamp;
+
+    if ((k < 0 ? -k : k) < (j < 0 ? -j : j))
+        delta = k;
+    else
+        delta = j;
+    
+    pa_memblockq_seek(s->memblockq, delta * s->rtp_context.frame_size, PA_SEEK_RELATIVE);
+    pa_memblockq_push(s->memblockq, &chunk);
+    
+    /* The next timestamp we expect */
+    s->offset = s->rtp_context.timestamp + (chunk.length / s->rtp_context.frame_size);
+    
+    pa_memblock_unref(chunk.memblock);
+
+    /* Reset death timer */
+    pa_gettimeofday(&tv);
+    pa_timeval_add(&tv, DEATH_TIMEOUT);
+    m->time_restart(s->death_event, &tv);
+}
+
+static void death_event_cb(pa_mainloop_api *m, pa_time_event *t, const struct timeval *tv, void *userdata) {
+    struct session *s = userdata;
+    
+    assert(m);
+    assert(t);
+    assert(tv);
+    assert(s);
+
+    session_free(s, 1);
+}
+
+static int mcast_socket(const struct sockaddr* sa, socklen_t salen) {
+    int af, fd = -1, r, one;
+    
+    af = sa->sa_family;
+    if ((fd = socket(af, SOCK_DGRAM, 0)) < 0) {
+        pa_log(__FILE__": Failed to create socket: %s", strerror(errno));
+        goto fail;
+    }
+
+    one = 1;
+    if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) < 0) {
+        pa_log(__FILE__": SO_REUSEADDR failed: %s", strerror(errno));
+        goto fail;
+    }
+    
+    if (af == AF_INET) {
+        struct ip_mreq mr4;
+        memset(&mr4, 0, sizeof(mr4));
+        mr4.imr_multiaddr = ((const struct sockaddr_in*) sa)->sin_addr;
+        r = setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mr4, sizeof(mr4));
+    } else {
+        struct ipv6_mreq mr6;
+        memset(&mr6, 0, sizeof(mr6));
+        mr6.ipv6mr_multiaddr = ((const struct sockaddr_in6*) sa)->sin6_addr;
+        r = setsockopt(fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mr6, sizeof(mr6));
+    }
+
+    if (r < 0) {
+        pa_log_info(__FILE__": Joining mcast group failed: %s", strerror(errno));
+        goto fail;
+    }
+    
+    if (bind(fd, sa, salen) < 0) {
+        pa_log(__FILE__": bind() failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    return fd;
+    
+fail:
+    if (fd >= 0)
+        close(fd);
+
+    return -1;
+}
+
+static struct session *session_new(struct userdata *u, const pa_sdp_info *sdp_info) {
+    struct session *s = NULL;
+    struct timeval tv;
+    char *c;
+    pa_sink *sink;
+    int fd = -1;
+
+    if (!(sink = pa_namereg_get(u->core, u->sink_name, PA_NAMEREG_SINK, 1))) {
+        pa_log(__FILE__": sink does not exist.");
+        goto fail;
+    }
+
+    s = pa_xnew0(struct session, 1);
+    s->userdata = u;
+    s->first_packet = 0;
+    s->sdp_info = *sdp_info;
+
+    if ((fd = mcast_socket((const struct sockaddr*) &sdp_info->sa, sdp_info->salen)) < 0)
+        goto fail;
+
+    c = pa_sprintf_malloc("RTP Stream%s%s%s",
+                          sdp_info->session_name ? " (" : "",
+                          sdp_info->session_name ? sdp_info->session_name : "", 
+                          sdp_info->session_name ? ")" : "");
+
+    s->sink_input = pa_sink_input_new(sink, __FILE__, c, &sdp_info->sample_spec, NULL, 0, PA_RESAMPLER_INVALID);
+    pa_xfree(c);
+        
+    if (!s->sink_input) {
+        pa_log(__FILE__": failed to create sink input.");
+        goto fail;
+    }
+
+    s->sink_input->userdata = s;
+    s->sink_input->owner = u->module;
+
+    s->sink_input->peek = sink_input_peek;
+    s->sink_input->drop = sink_input_drop;
+    s->sink_input->kill = sink_input_kill;
+    s->sink_input->get_latency = sink_input_get_latency;
+    
+    s->memblockq = pa_memblockq_new(
+            0,
+            MEMBLOCKQ_MAXLENGTH,
+            MEMBLOCKQ_MAXLENGTH,
+            pa_frame_size(&s->sink_input->sample_spec),
+            1,
+            0,
+            NULL,
+            u->core->memblock_stat);
+
+    s->rtp_event = u->core->mainloop->io_new(u->core->mainloop, fd, PA_IO_EVENT_INPUT, rtp_event_cb, s);
+
+    pa_gettimeofday(&tv);
+    pa_timeval_add(&tv, DEATH_TIMEOUT);
+    s->death_event = u->core->mainloop->time_new(u->core->mainloop, &tv, death_event_cb, s);
+
+    pa_hashmap_put(s->userdata->by_origin, s->sdp_info.origin, s);
+
+    pa_rtp_context_init_recv(&s->rtp_context, fd, pa_frame_size(&s->sdp_info.sample_spec));
+
+    pa_log_info(__FILE__": Found new session '%s'", s->sdp_info.session_name);
+    
+    return s;
+
+fail:
+    if (s) {
+        if (fd >= 0)
+            close(fd);
+        
+        pa_xfree(s);
+    }
+
+    return NULL;
+}
+
+static void session_free(struct session *s, int from_hash) {
+    assert(s);
+
+    pa_log_info(__FILE__": Freeing session '%s'", s->sdp_info.session_name);
+
+    s->userdata->core->mainloop->time_free(s->death_event);
+    s->userdata->core->mainloop->io_free(s->rtp_event);
+
+    if (from_hash)
+        pa_hashmap_remove(s->userdata->by_origin, s->sdp_info.origin);
+
+    pa_sink_input_disconnect(s->sink_input);
+    pa_sink_input_unref(s->sink_input);
+
+    pa_memblockq_free(s->memblockq);
+    pa_sdp_info_destroy(&s->sdp_info);
+    pa_rtp_context_destroy(&s->rtp_context);
+    
+    pa_xfree(s);
+}
+
+static void sap_event_cb(pa_mainloop_api *m, pa_io_event *e, int fd, pa_io_event_flags_t flags, void *userdata) {
+    struct userdata *u = userdata;
+    int goodbye;
+    pa_sdp_info info;
+    struct session *s;
+    
+    assert(m);
+    assert(e);
+    assert(u);
+    assert(fd == u->sap_context.fd);
+    assert(flags == PA_IO_EVENT_INPUT);
+
+    if (pa_sap_recv(&u->sap_context, &goodbye) < 0)
+        return;
+
+    if (!pa_sdp_parse(u->sap_context.sdp_data, &info, goodbye))
+        return;
+
+    if (goodbye) {
+
+        if ((s = pa_hashmap_get(u->by_origin, info.origin)))
+            session_free(s, 1);
+
+        pa_sdp_info_destroy(&info);
+    } else {
+
+        if (!(s = pa_hashmap_get(u->by_origin, info.origin))) {
+            if (!(s = session_new(u, &info)))
+                pa_sdp_info_destroy(&info);
+            
+        } else {
+            struct timeval tv;
+            
+            pa_gettimeofday(&tv);
+            pa_timeval_add(&tv, DEATH_TIMEOUT);
+            m->time_restart(s->death_event, &tv);
+            
+            pa_sdp_info_destroy(&info);
+        }
+    }
+}
+
+int pa__init(pa_core *c, pa_module*m) {
+    struct userdata *u;
+    pa_modargs *ma = NULL;
+    struct sockaddr_in sa4;
+    struct sockaddr_in6 sa6;
+    struct sockaddr *sa;
+    socklen_t salen;
+    const char *sap_address;
+    int fd = -1;
+    
+    assert(c);
+    assert(m);
+
+    if (!(ma = pa_modargs_new(m->argument, valid_modargs))) {
+        pa_log(__FILE__": failed to parse module arguments");
+        goto fail;
+    }
+
+    sap_address = pa_modargs_get_value(ma, "sap_address", DEFAULT_SAP_ADDRESS);
+    
+    if (inet_pton(AF_INET6, sap_address, &sa6.sin6_addr) > 0) {
+        sa6.sin6_family = AF_INET6;
+        sa6.sin6_port = htons(SAP_PORT);
+        sa = (struct sockaddr*) &sa6;
+        salen = sizeof(sa6);
+    } else if (inet_pton(AF_INET, sap_address, &sa4.sin_addr) > 0) {
+        sa4.sin_family = AF_INET;
+        sa4.sin_port = htons(SAP_PORT);
+        sa = (struct sockaddr*) &sa4;
+        salen = sizeof(sa4);
+    } else {
+        pa_log(__FILE__": invalid SAP address '%s'", sap_address);
+        goto fail;
+    }
+
+    if ((fd = mcast_socket(sa, salen)) < 0)
+        goto fail;
+
+    u = pa_xnew(struct userdata, 1);
+    m->userdata = u;
+    u->module = m;
+    u->core = c;
+    u->sink_name = pa_xstrdup(pa_modargs_get_value(ma, "sink", NULL));
+
+    u->sap_event = c->mainloop->io_new(c->mainloop, fd, PA_IO_EVENT_INPUT, sap_event_cb, u);
+
+    u->by_origin = pa_hashmap_new(pa_idxset_string_hash_func, pa_idxset_string_compare_func);
+    
+    pa_sap_context_init_recv(&u->sap_context, fd);
+    
+    pa_modargs_free(ma);
+
+    return 0;
+
+fail:
+    if (ma)
+        pa_modargs_free(ma);
+
+    if (fd >= 0)
+        close(fd);
+    
+    return -1;
+}
+
+static void free_func(void *p, void *userdata) {
+    session_free(p, 0);
+}
+
+void pa__done(pa_core *c, pa_module*m) {
+    struct userdata *u;
+    assert(c);
+    assert(m);
+
+    if (!(u = m->userdata))
+        return;
+
+    c->mainloop->io_free(u->sap_event);
+    pa_sap_context_destroy(&u->sap_context);
+
+    pa_hashmap_free(u->by_origin, free_func, NULL);
+    
+    pa_xfree(u->sink_name);
+    pa_xfree(u);
+}
diff --git a/src/modules/rtp/rtp.c b/src/modules/rtp/rtp.c
index a3bce38b..ccd3b6c3 100644
--- a/src/modules/rtp/rtp.c
+++ b/src/modules/rtp/rtp.c
@@ -30,6 +30,7 @@
 #include <errno.h>
 #include <arpa/inet.h>
 #include <unistd.h>
+#include <sys/ioctl.h>
 
 #include <polypcore/log.h>
 
@@ -135,27 +136,114 @@ int pa_rtp_send(pa_rtp_context *c, size_t size, pa_memblockq *q) {
     return 0;
 }
 
-pa_rtp_context* pa_rtp_context_init_recv(pa_rtp_context *c, int fd) {
+pa_rtp_context* pa_rtp_context_init_recv(pa_rtp_context *c, int fd, size_t frame_size) {
     assert(c);
 
     c->fd = fd;
+    c->frame_size = frame_size;
     return c;
 }
 
-int pa_rtp_recv(pa_rtp_context *c, pa_memchunk *chunk) {
+int pa_rtp_recv(pa_rtp_context *c, pa_memchunk *chunk, pa_memblock_stat *st) {
+    int size;
+    struct msghdr m;
+    struct iovec iov;
+    uint32_t header;
+    int cc;
+    ssize_t r;
+    
     assert(c);
     assert(chunk);
 
+    chunk->memblock = NULL;
+
+    if (ioctl(c->fd, FIONREAD, &size) < 0) {
+        pa_log(__FILE__": FIONREAD failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    if (!size)
+        return 0;
+
+    chunk->memblock = pa_memblock_new(size, st);
+
+    iov.iov_base = chunk->memblock->data;
+    iov.iov_len = size;
+
+    m.msg_name = NULL;
+    m.msg_namelen = 0;
+    m.msg_iov = &iov;
+    m.msg_iovlen = 1;
+    m.msg_control = NULL;
+    m.msg_controllen = 0;
+    m.msg_flags = 0;
+    
+    if ((r = recvmsg(c->fd, &m, 0)) != size) {
+        pa_log(__FILE__": recvmsg() failed: %s", r < 0 ? strerror(errno) : "size mismatch");
+        goto fail;
+    }
+
+    if (size < 12) {
+        pa_log(__FILE__": RTP packet too short.");
+        goto fail;
+    }
+
+    memcpy(&header, chunk->memblock->data, sizeof(uint32_t));
+    memcpy(&c->timestamp, (uint8_t*) chunk->memblock->data + 4, sizeof(uint32_t));
+    memcpy(&c->ssrc, (uint8_t*) chunk->memblock->data + 8, sizeof(uint32_t));
+    
+    header = ntohl(header);
+    c->timestamp = ntohl(c->timestamp);
+    c->ssrc = ntohl(c->ssrc);
+
+    if ((header >> 30) != 2) {
+        pa_log(__FILE__": Unsupported RTP version.");
+        goto fail;
+    }
+
+    if ((header >> 29) & 1) {
+        pa_log(__FILE__": RTP padding not supported.");
+        goto fail;
+    }
+
+    if ((header >> 28) & 1) {
+        pa_log(__FILE__": RTP header extensions not supported.");
+        goto fail;
+    }
+
+    cc = (header >> 24) & 0xF;
+    c->payload = (header >> 16) & 127;
+    c->sequence = header & 0xFFFF;
+
+    if (12 + cc*4 > size) {
+        pa_log(__FILE__": RTP packet too short. (CSRC)");
+        goto fail;
+    }
+
+    chunk->index = 12 + cc*4;
+    chunk->length = size - chunk->index;
+
+    if (chunk->length % c->frame_size != 0) {
+        pa_log(__FILE__": Vad RTP packet size.");
+        goto fail;
+    }
+    
     return 0;
+
+fail:
+    if (chunk->memblock)
+        pa_memblock_unref(chunk->memblock);
+
+    return -1;
 }
 
-uint8_t pa_rtp_payload_type(const pa_sample_spec *ss) {
+uint8_t pa_rtp_payload_from_sample_spec(const pa_sample_spec *ss) {
     assert(ss);
 
     if (ss->format == PA_SAMPLE_ULAW && ss->rate == 8000 && ss->channels == 1)
         return 0;
     if (ss->format == PA_SAMPLE_ALAW && ss->rate == 8000 && ss->channels == 1)
-        return 0;
+        return 8;
     if (ss->format == PA_SAMPLE_S16BE && ss->rate == 44100 && ss->channels == 2)
         return 10;
     if (ss->format == PA_SAMPLE_S16BE && ss->rate == 44100 && ss->channels == 1)
@@ -164,6 +252,41 @@ uint8_t pa_rtp_payload_type(const pa_sample_spec *ss) {
     return 127;
 }
 
+pa_sample_spec *pa_rtp_sample_spec_from_payload(uint8_t payload, pa_sample_spec *ss) {
+    assert(ss);
+
+    switch (payload) {
+        case 0:
+            ss->channels = 1;
+            ss->format = PA_SAMPLE_ULAW;
+            ss->rate = 8000;
+            break;
+
+        case 8:
+            ss->channels = 1;
+            ss->format = PA_SAMPLE_ALAW;
+            ss->rate = 8000;
+            break;
+
+        case 10:
+            ss->channels = 2;
+            ss->format = PA_SAMPLE_S16BE;
+            ss->rate = 44100;
+            break;
+            
+        case 11:
+            ss->channels = 1;
+            ss->format = PA_SAMPLE_S16BE;
+            ss->rate = 44100;
+            break;
+
+        default:
+            return NULL;
+    }
+
+    return ss;
+}
+
 pa_sample_spec *pa_rtp_sample_spec_fixup(pa_sample_spec * ss) {
     assert(ss);
 
@@ -192,3 +315,34 @@ void pa_rtp_context_destroy(pa_rtp_context *c) {
 
     close(c->fd);
 }
+
+const char* pa_rtp_format_to_string(pa_sample_format_t f) {
+    switch (f) {
+        case PA_SAMPLE_S16BE:
+            return "L16";
+        case PA_SAMPLE_U8:
+            return "L8";
+        case PA_SAMPLE_ALAW:
+            return "PCMA";
+        case PA_SAMPLE_ULAW:
+            return "PCMU";
+        default:
+            return NULL;
+    }
+}
+
+pa_sample_format_t pa_rtp_string_to_format(const char *s) {
+    assert(s);
+    
+    if (!(strcmp(s, "L16")))
+        return PA_SAMPLE_S16BE;
+    else if (!strcmp(s, "L8"))
+        return PA_SAMPLE_U8;
+    else if (!strcmp(s, "PCMA"))
+        return PA_SAMPLE_ALAW;
+    else if (!strcmp(s, "PCMU"))
+        return PA_SAMPLE_ULAW;
+    else
+        return PA_SAMPLE_INVALID;
+}
+
diff --git a/src/modules/rtp/rtp.h b/src/modules/rtp/rtp.h
index 39288158..49da155b 100644
--- a/src/modules/rtp/rtp.h
+++ b/src/modules/rtp/rtp.h
@@ -40,13 +40,18 @@ typedef struct pa_rtp_context {
 pa_rtp_context* pa_rtp_context_init_send(pa_rtp_context *c, int fd, uint32_t ssrc, uint8_t payload, size_t frame_size);
 int pa_rtp_send(pa_rtp_context *c, size_t size, pa_memblockq *q);
 
-pa_rtp_context* pa_rtp_context_init_recv(pa_rtp_context *c, int fd);
-int pa_rtp_recv(pa_rtp_context *c, pa_memchunk *chunk);
+pa_rtp_context* pa_rtp_context_init_recv(pa_rtp_context *c, int fd, size_t frame_size);
+int pa_rtp_recv(pa_rtp_context *c, pa_memchunk *chunk, pa_memblock_stat *st);
+
+void pa_rtp_context_destroy(pa_rtp_context *c);
 
-uint8_t pa_rtp_payload_type(const pa_sample_spec *ss);
 pa_sample_spec* pa_rtp_sample_spec_fixup(pa_sample_spec *ss);
 int pa_rtp_sample_spec_valid(const pa_sample_spec *ss);
 
-void pa_rtp_context_destroy(pa_rtp_context *c);
+uint8_t pa_rtp_payload_from_sample_spec(const pa_sample_spec *ss);
+pa_sample_spec *pa_rtp_sample_spec_from_payload(uint8_t payload, pa_sample_spec *ss);
+
+const char* pa_rtp_format_to_string(pa_sample_format_t f);
+pa_sample_format_t pa_rtp_string_to_format(const char *s);
 
 #endif
diff --git a/src/modules/rtp/sap.c b/src/modules/rtp/sap.c
index ebf20bc4..0c12322e 100644
--- a/src/modules/rtp/sap.c
+++ b/src/modules/rtp/sap.c
@@ -32,12 +32,16 @@
 #include <errno.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/ioctl.h>
 
 #include <polypcore/util.h>
 #include <polypcore/log.h>
 #include <polypcore/xmalloc.h>
 
 #include "sap.h"
+#include "sdp.h"
+
+#define MIME_TYPE "application/sdp"
 
 pa_sap_context* pa_sap_context_init_send(pa_sap_context *c, int fd, char *sdp_data) {
     assert(c);
@@ -60,7 +64,6 @@ void pa_sap_context_destroy(pa_sap_context *c) {
 
 int pa_sap_send(pa_sap_context *c, int goodbye) {
     uint32_t header;
-    const char mime[] = "application/sdp";
     struct sockaddr_storage sa_buf;
     struct sockaddr *sa = (struct sockaddr*) &sa_buf;
     socklen_t salen = sizeof(sa_buf);
@@ -86,8 +89,8 @@ int pa_sap_send(pa_sap_context *c, int goodbye) {
     iov[1].iov_base = sa->sa_family == AF_INET ? (void*) &((struct sockaddr_in*) sa)->sin_addr : (void*) &((struct sockaddr_in6*) sa)->sin6_addr;
     iov[1].iov_len = sa->sa_family == AF_INET ? 4 : 16;
 
-    iov[2].iov_base = (char*) mime;
-    iov[2].iov_len = sizeof(mime);
+    iov[2].iov_base = (char*) MIME_TYPE;
+    iov[2].iov_len = sizeof(MIME_TYPE);
 
     iov[3].iov_base = c->sdp_data;
     iov[3].iov_len = strlen(c->sdp_data);
@@ -105,3 +108,110 @@ int pa_sap_send(pa_sap_context *c, int goodbye) {
 
     return k;
 }
+
+pa_sap_context* pa_sap_context_init_recv(pa_sap_context *c, int fd) {
+    assert(c);
+    assert(fd >= 0);
+
+    c->fd = fd;
+    c->sdp_data = NULL;
+    return c;
+}
+
+int pa_sap_recv(pa_sap_context *c, int *goodbye) {
+    struct msghdr m;
+    struct iovec iov;
+    int size, k;
+    char *buf = NULL, *e;
+    uint32_t header;
+    int six, ac;
+    ssize_t r;
+    
+    assert(c);
+    assert(goodbye);
+
+    if (ioctl(c->fd, FIONREAD, &size) < 0) {
+        pa_log(__FILE__": FIONREAD failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    if (!size)
+        return 0;
+
+    buf = pa_xnew(char, size+1);
+    buf[size] = 0;
+    
+    iov.iov_base = buf;
+    iov.iov_len = size;
+
+    m.msg_name = NULL;
+    m.msg_namelen = 0;
+    m.msg_iov = &iov;
+    m.msg_iovlen = 1;
+    m.msg_control = NULL;
+    m.msg_controllen = 0;
+    m.msg_flags = 0;
+    
+    if ((r = recvmsg(c->fd, &m, 0)) != size) {
+        pa_log(__FILE__": recvmsg() failed: %s", r < 0 ? strerror(errno) : "size mismatch");
+        goto fail;
+    }
+
+    if (size < 4) {
+        pa_log(__FILE__": SAP packet too short.");
+        goto fail;
+    }
+
+    memcpy(&header, buf, sizeof(uint32_t));
+    header = ntohl(header);
+
+    if (header >> 29 != 1) {
+        pa_log(__FILE__": Unsupported SAP version.");
+        goto fail;
+    }
+
+    if ((header >> 25) & 1) {
+        pa_log(__FILE__": Encrypted SAP not supported.");
+        goto fail;
+    }
+
+    if ((header >> 24) & 1) {
+        pa_log(__FILE__": Compressed SAP not supported.");
+        goto fail;
+    }
+
+    six = (header >> 28) & 1;
+    ac = (header >> 16) & 0xFF;
+
+    k = 4 + (six ? 16 : 4) + ac*4;
+    if (size < k) {
+        pa_log(__FILE__": SAP packet too short (AD).");
+        goto fail;
+    }
+
+    e = buf + k;
+    size -= k;
+
+    if ((unsigned) size >= sizeof(MIME_TYPE) && !strcmp(e, MIME_TYPE)) {
+        e += sizeof(MIME_TYPE);
+        size -= sizeof(MIME_TYPE);
+    } else if ((unsigned) size < sizeof(PA_SDP_HEADER)-1 || strncmp(e, PA_SDP_HEADER, sizeof(PA_SDP_HEADER)-1)) {
+        pa_log(__FILE__": Invalid SDP header.");
+        goto fail;
+    }
+
+    if (c->sdp_data)
+        pa_xfree(c->sdp_data);
+    
+    c->sdp_data = pa_xstrndup(e, size);
+    pa_xfree(buf);
+    
+    *goodbye = !!((header >> 26) & 1);
+    
+    return 0;
+
+fail:
+    pa_xfree(buf);
+
+    return -1;
+}
diff --git a/src/modules/rtp/sap.h b/src/modules/rtp/sap.h
index 787b39f7..b11b1dd7 100644
--- a/src/modules/rtp/sap.h
+++ b/src/modules/rtp/sap.h
@@ -40,4 +40,7 @@ void pa_sap_context_destroy(pa_sap_context *c);
 
 int pa_sap_send(pa_sap_context *c, int goodbye);
 
+pa_sap_context* pa_sap_context_init_recv(pa_sap_context *c, int fd);
+int pa_sap_recv(pa_sap_context *c, int *goodbye);
+
 #endif
diff --git a/src/modules/rtp/sdp.c b/src/modules/rtp/sdp.c
index 99e8c12b..9dca15ba 100644
--- a/src/modules/rtp/sdp.c
+++ b/src/modules/rtp/sdp.c
@@ -29,21 +29,15 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <arpa/inet.h>
+#include <string.h>
 
 #include <polypcore/util.h>
+#include <polypcore/log.h>
+#include <polypcore/xmalloc.h>
 
 #include "sdp.h"
+#include "rtp.h"
 
-static const char* map_format(pa_sample_format_t f) {
-    switch (f) {
-        case PA_SAMPLE_S16BE: return "L16";
-        case PA_SAMPLE_U8: return "L8";
-        case PA_SAMPLE_ALAW: return "PCMA";
-        case PA_SAMPLE_ULAW: return "PCMU";
-        default:
-            return NULL;
-    }
-}
 
 char *pa_sdp_build(int af, const void *src, const void *dst, const char *name, uint16_t port, uint8_t payload, const pa_sample_spec *ss) {
     uint32_t ntp;
@@ -54,7 +48,7 @@ char *pa_sdp_build(int af, const void *src, const void *dst, const char *name, u
     assert(dst);
     assert(af == AF_INET || af == AF_INET6);
 
-    f = map_format(ss->format);
+    f = pa_rtp_format_to_string(ss->format);
     assert(f);
     
     if (!(u = getenv("USER")))
@@ -69,7 +63,7 @@ char *pa_sdp_build(int af, const void *src, const void *dst, const char *name, u
     assert(a);
     
     return pa_sprintf_malloc(
-            "v=0\n"
+            PA_SDP_HEADER
             "o=%s %lu 0 IN %s %s\n"
             "s=%s\n"
             "c=IN %s %s\n"
@@ -85,3 +79,183 @@ char *pa_sdp_build(int af, const void *src, const void *dst, const char *name, u
             port, payload,
             payload, f, ss->rate, ss->channels);
 }
+
+static pa_sample_spec *parse_sdp_sample_spec(pa_sample_spec *ss, char *c) {
+    unsigned rate, channels;
+    assert(ss);
+    assert(c);
+
+    if (pa_startswith(c, "L16/")) {
+        ss->format = PA_SAMPLE_S16BE;
+        c += 4;
+    } else if (pa_startswith(c, "L8/")) {
+        ss->format = PA_SAMPLE_U8;
+        c += 3;
+    } else if (pa_startswith(c, "PCMA/")) {
+        ss->format = PA_SAMPLE_ALAW;
+        c += 5;
+    } else if (pa_startswith(c, "PCMU/")) {
+        ss->format = PA_SAMPLE_ULAW;
+        c += 5;
+    } else
+        return NULL;
+
+    if (sscanf(c, "%u/%u", &rate, &channels) == 2) {
+        ss->rate = rate;
+        ss->channels = channels;
+    } else if (sscanf(c, "%u", &rate) == 2) {
+        ss->rate = rate;
+        ss->channels = 1;
+    } else
+        return NULL;
+
+    if (!pa_sample_spec_valid(ss))
+        return NULL;
+
+    return ss;
+}
+
+pa_sdp_info *pa_sdp_parse(const char *t, pa_sdp_info *i, int is_goodbye) {
+    uint16_t port = 0;
+    int ss_valid = 0;
+
+    assert(t);
+    assert(i);
+    
+    i->origin = i->session_name = NULL;
+    i->salen = 0;
+    i->payload = 255;
+    
+    if (!pa_startswith(t, PA_SDP_HEADER)) {
+        pa_log(__FILE__": Failed to parse SDP data: invalid header.");
+        goto fail;
+    }
+
+    t += sizeof(PA_SDP_HEADER)-1;
+
+    while (*t) {
+        size_t l;
+
+        l = strcspn(t, "\n");
+
+        if (l <= 2) {
+            pa_log(__FILE__": Failed to parse SDP data: line too short: >%s<.", t);
+            goto fail;
+        }
+
+        if (pa_startswith(t, "o="))
+            i->origin = pa_xstrndup(t+2, l-2);
+        else if (pa_startswith(t, "s="))
+            i->session_name = pa_xstrndup(t+2, l-2);
+        else if (pa_startswith(t, "c=IN IP4 ")) {
+            char a[64];
+            size_t k;
+
+            k = l-8 > sizeof(a) ? sizeof(a) : l-8;
+            
+            pa_strlcpy(a, t+9, k);
+            a[strcspn(a, "/")] = 0;
+
+            if (inet_pton(AF_INET, a, &((struct sockaddr_in*) &i->sa)->sin_addr) <= 0) {
+                pa_log(__FILE__": Failed to parse SDP data: bad address: >%s<.", a);
+                goto fail;
+            }
+
+            ((struct sockaddr_in*) &i->sa)->sin_family = AF_INET;
+            ((struct sockaddr_in*) &i->sa)->sin_port = 0;
+            i->salen = sizeof(struct sockaddr_in);
+        } else if (pa_startswith(t, "c=IN IP6 ")) {
+            char a[64];
+            size_t k;
+
+            k = l-8 > sizeof(a) ? sizeof(a) : l-8;
+            
+            pa_strlcpy(a, t+9, k);
+            a[strcspn(a, "/")] = 0;
+
+            if (inet_pton(AF_INET6, a, &((struct sockaddr_in6*) &i->sa)->sin6_addr) <= 0) {
+                pa_log(__FILE__": Failed to parse SDP data: bad address: >%s<.", a);
+                goto fail;
+            }
+
+            ((struct sockaddr_in6*) &i->sa)->sin6_family = AF_INET6;
+            ((struct sockaddr_in6*) &i->sa)->sin6_port = 0;
+            i->salen = sizeof(struct sockaddr_in6);
+        } else if (pa_startswith(t, "m=audio ")) {
+
+            if (i->payload > 127) {
+                int _port, _payload;
+                
+                if (sscanf(t+8, "%i RTP/AVP %i", &_port, &_payload) == 2) {
+
+                    if (_port <= 0 || _port > 0xFFFF) {
+                        pa_log(__FILE__": Failed to parse SDP data: invalid port %i.", _port);
+                        goto fail;
+                    }
+
+                    if (_payload < 0 || _payload > 127) {
+                        pa_log(__FILE__": Failed to parse SDP data: invalid payload %i.", _payload);
+                        goto fail;
+                    }
+
+                    port = (uint16_t) _port;
+                    i->payload = (uint8_t) _payload;
+
+                    if (pa_rtp_sample_spec_from_payload(i->payload, &i->sample_spec))
+                        ss_valid = 1;
+                }
+            }
+        } else if (pa_startswith(t, "a=rtpmap:")) {
+
+            if (i->payload <= 127) {
+                char c[64];
+                int _payload;
+
+                if (sscanf(t+9, "%i %64c", &_payload, c) == 2) {
+
+                    if (_payload < 0 || _payload > 127) {
+                        pa_log(__FILE__": Failed to parse SDP data: invalid payload %i.", _payload);
+                        goto fail;
+                    }
+                    if (_payload == i->payload) {
+
+                        c[strcspn(c, "\n")] = 0;
+                        
+                        if (parse_sdp_sample_spec(&i->sample_spec, c))
+                            ss_valid = 1;
+                    }
+                }
+            }
+        }
+        
+        t += l;
+        
+        if (*t == '\n')
+            t++;
+    }
+
+    if (!i->origin || (!is_goodbye && (!i->salen || i->payload > 127 || !ss_valid || port == 0))) {
+        pa_log(__FILE__": Failed to parse SDP data: missing data.");
+        goto fail;
+    }
+
+    if (((struct sockaddr*) &i->sa)->sa_family == AF_INET)
+        ((struct sockaddr_in*) &i->sa)->sin_port = htons(port);
+    else
+        ((struct sockaddr_in6*) &i->sa)->sin6_port = htons(port);
+    
+    return i;
+
+fail:
+    pa_xfree(i->origin);
+    pa_xfree(i->session_name);
+
+    return NULL;
+}
+
+void pa_sdp_info_destroy(pa_sdp_info *i) {
+    assert(i);
+
+    pa_xfree(i->origin);
+    pa_xfree(i->session_name);
+}
diff --git a/src/modules/rtp/sdp.h b/src/modules/rtp/sdp.h
index 10820067..2aa18056 100644
--- a/src/modules/rtp/sdp.h
+++ b/src/modules/rtp/sdp.h
@@ -28,6 +28,23 @@
 
 #include <polyp/sample.h>
 
+#define PA_SDP_HEADER "v=0\n"
+
+typedef struct pa_sdp_info {
+    char *origin;
+    char *session_name;
+
+    struct sockaddr_storage sa;
+    socklen_t salen;
+
+    pa_sample_spec sample_spec;
+    uint8_t payload;
+} pa_sdp_info;
+
 char *pa_sdp_build(int af, const void *src, const void *dst, const char *name, uint16_t port, uint8_t payload, const pa_sample_spec *ss);
 
+pa_sdp_info *pa_sdp_parse(const char *t, pa_sdp_info *info, int is_goodbye);
+
+void pa_sdp_info_destroy(pa_sdp_info *i);
+
 #endif