better UDP support - added preliminary multicast support (untested)

Originally committed as revision 793 to svn://svn.ffmpeg.org/ffmpeg/trunk

libav/udp.c

 /*
  * UDP prototype streaming system
- * Copyright (c) 2000 Fabrice Bellard.
+ * Copyright (c) 2000, 2001, 2002 Fabrice Bellard.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -25,118 +25,233 @@
 #include <netdb.h>
 
 typedef struct {
-    int udp_socket;
-    int max_payload_size; /* in bytes */
+    int udp_fd;
+    int ttl;
+    int is_multicast;
+    int local_port;
+    struct ip_mreq mreq;
+    struct sockaddr_in dest_addr;
 } UDPContext;
 
 #define UDP_TX_BUF_SIZE 32768
 
-/* put it in UDP context */
-static struct sockaddr_in dest_addr;
+/**
+ * If no filename is given to av_open_input_file because you want to
+ * get the local port first, then you must call this function to set
+ * the remote server address.
+ *
+ * url syntax: udp://host:port[?option=val...]
+ * option: 'multicast=1' : enable multicast 
+ *         'ttl=n'       : set the ttl value (for multicast only)
+ *         'localport=n' : set the local port
+ *
+ * @param s1 media file context
+ * @param uri of the remote server
+ * @return zero if no error.
+ */
+int udp_set_remote_url(URLContext *h, const char *uri)
+{
+    UDPContext *s = h->priv_data;
+    char hostname[256];
+    int port;
+    
+    url_split(NULL, 0, hostname, sizeof(hostname), &port, NULL, 0, uri);
 
+    /* set the destination address */
+    if (resolve_host(&s->dest_addr.sin_addr, hostname) < 0)
+        return -EIO;
+    s->dest_addr.sin_family = AF_INET;
+    s->dest_addr.sin_port = htons(port);
+    return 0;
+}
+
+/**
+ * Return the local port used by the UDP connexion
+ * @param s1 media file context
+ * @return the local port number
+ */
+int udp_get_local_port(URLContext *h)
+{
+    UDPContext *s = h->priv_data;
+    return s->local_port;
+}
+
+/**
+ * Return the udp file handle for select() usage to wait for several RTP
+ * streams at the same time.
+ * @param h media file context
+ */
+int udp_get_file_handle(URLContext *h)
+{
+    UDPContext *s = h->priv_data;
+    return s->udp_fd;
+}
+
+/* put it in UDP context */
 /* return non zero if error */
 static int udp_open(URLContext *h, const char *uri, int flags)
 {
-    int local_port = 0;
-    struct sockaddr_in my_addr;
-    const char *p, *q;
+    struct sockaddr_in my_addr, my_addr1;
     char hostname[1024];
-    int port, udp_socket, tmp;
-    struct hostent *hp;
-    UDPContext *s;
+    int port, udp_fd = -1, tmp;
+    UDPContext *s = NULL;
+    int is_output, len;
+    const char *p;
+    char buf[256];
 
     h->is_streamed = 1;
 
-    if (!(flags & URL_WRONLY))
-        return -EIO;
+    is_output = (flags & URL_WRONLY);
     
-    /* fill the dest addr */
-    p = uri;
-    if (!strstart(p, "udp:", &p))
-        return -1;
-    q = strchr(p, ':');
-    if (!q)
-        return -1;
-    memcpy(hostname, p, q - p);
-    hostname[q - p] = '\0';
-    port = strtol(q+1, NULL, 10);
-    if (port <= 0)
-        return -1;
-
-    dest_addr.sin_family = AF_INET;
-    dest_addr.sin_port = htons(port);
-    if ((inet_aton(hostname, &dest_addr.sin_addr)) == 0) {
-        hp = gethostbyname(hostname);
-        if (!hp)
-            return -1;
-        memcpy ((char *) &dest_addr.sin_addr, hp->h_addr, hp->h_length);
+    s = av_malloc(sizeof(UDPContext));
+    if (!s)
+        return -ENOMEM;
+
+    h->priv_data = s;
+    s->ttl = 16;
+    s->is_multicast = 0;
+    p = strchr(uri, '?');
+    if (p) {
+        s->is_multicast = find_info_tag(buf, sizeof(buf), "multicast", p);
+        if (find_info_tag(buf, sizeof(buf), "ttl", p)) {
+            s->ttl = strtol(buf, NULL, 10);
+        }
+        if (find_info_tag(buf, sizeof(buf), "localport", p)) {
+            s->local_port = strtol(buf, NULL, 10);
+        }
     }
+
+    /* fill the dest addr */
+    url_split(NULL, 0, hostname, sizeof(hostname), &port, NULL, 0, uri);
     
-    udp_socket = socket(PF_INET, SOCK_DGRAM, 0);
-    if (udp_socket < 0)
-        return -1;
+    /* XXX: fix url_split */
+    if (hostname[0] == '\0' || hostname[0] == '?') {
+        /* only accepts null hostname if input */
+        if (s->is_multicast || (flags & URL_WRONLY))
+            goto fail;
+    } else {
+        udp_set_remote_url(h, uri);
+    }
 
-    my_addr.sin_family = AF_INET;
-    my_addr.sin_port = htons(local_port);
-    my_addr.sin_addr.s_addr = htonl (INADDR_ANY);
+    udp_fd = socket(PF_INET, SOCK_DGRAM, 0);
+    if (udp_fd < 0)
+        goto fail;
+
+    if (s->is_multicast && !(h->flags & URL_WRONLY)) {
+        /* special case: the bind must be done on the multicast address */
+        my_addr = s->dest_addr;
+    } else {
+        my_addr.sin_family = AF_INET;
+        my_addr.sin_port = htons(s->local_port);
+        my_addr.sin_addr.s_addr = htonl (INADDR_ANY);
+    }
 
     /* the bind is needed to give a port to the socket now */
-    if (bind(udp_socket,(struct sockaddr *)&my_addr, sizeof(my_addr)) < 0) 
+    if (bind(udp_fd,(struct sockaddr *)&my_addr, sizeof(my_addr)) < 0) 
         goto fail;
 
-    /* limit the tx buf size to limit latency */
+    len = sizeof(my_addr1);
+    getsockname(udp_fd, (struct sockaddr *)&my_addr1, &len);
+    s->local_port = ntohs(my_addr1.sin_port);
 
-    tmp = UDP_TX_BUF_SIZE;
-    if (setsockopt(udp_socket, SOL_SOCKET, SO_SNDBUF, &tmp, sizeof(tmp)) < 0) {
-        perror("setsockopt sndbuf");
-        goto fail;
+    if (s->is_multicast) {
+        if (h->flags & URL_WRONLY) {
+            /* output */
+            if (setsockopt(udp_fd, IPPROTO_IP, IP_MULTICAST_TTL, 
+                           &s->ttl, sizeof(s->ttl)) < 0) {
+                perror("IP_MULTICAST_TTL");
+                goto fail;
+            }
+        } else {
+            /* input */
+            memset(&s->mreq, 0, sizeof(s->mreq));
+            s->mreq.imr_multiaddr = s->dest_addr.sin_addr;
+            s->mreq.imr_interface.s_addr = htonl (INADDR_ANY);
+            if (setsockopt(udp_fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, 
+                           &s->mreq, sizeof(s->mreq)) < 0) {
+                perror("rtp: IP_ADD_MEMBERSHIP");
+                goto fail;
+            }
+        }
     }
 
-    s = av_malloc(sizeof(UDPContext));
-    if (!s)
-        return -ENOMEM;
-    h->priv_data = s;
-    s->udp_socket = udp_socket;
-    h->packet_size = 1500;
+    if (is_output) {
+        /* limit the tx buf size to limit latency */
+        tmp = UDP_TX_BUF_SIZE;
+        if (setsockopt(udp_fd, SOL_SOCKET, SO_SNDBUF, &tmp, sizeof(tmp)) < 0) {
+            perror("setsockopt sndbuf");
+            goto fail;
+        }
+    }
+
+    s->udp_fd = udp_fd;
+    h->max_packet_size = 1472; /* XXX: probe it ? */
     return 0;
  fail:
+    if (udp_fd >= 0)
+        close(udp_fd);
+    av_free(s);
     return -EIO;
 }
 
-int udp_close(URLContext *h)
+static int udp_read(URLContext *h, UINT8 *buf, int size)
 {
     UDPContext *s = h->priv_data;
-    close(s->udp_socket);
-    return 0;
+    struct sockaddr_in from;
+    int from_len, len;
+
+    for(;;) {
+        from_len = sizeof(from);
+        len = recvfrom (s->udp_fd, buf, size, 0,
+                        (struct sockaddr *)&from, &from_len);
+        if (len < 0) {
+            if (errno != EAGAIN && errno != EINTR)
+                return -EIO;
+        } else {
+            break;
+        }
+    }
+    return len;
 }
 
-int udp_write(URLContext *h, UINT8 *buf, int size)
+static int udp_write(URLContext *h, UINT8 *buf, int size)
 {
     UDPContext *s = h->priv_data;
-    int ret, len, size1;
-
-    /* primitive way to avoid big packets */
-    size1 = size;
-    while (size > 0) {
-        len = size;
-        if (len > h->packet_size)
-            len = h->packet_size;
-        
-        ret = sendto (s->udp_socket, buf, len, 0, 
-                      (struct sockaddr *) &dest_addr,
-                      sizeof (dest_addr));
-        if (ret < 0)
-            perror("sendto");
-        buf += len;
-        size -= len;
+    int ret;
+
+    for(;;) {
+        ret = sendto (s->udp_fd, buf, size, 0, 
+                      (struct sockaddr *) &s->dest_addr,
+                      sizeof (s->dest_addr));
+        if (ret < 0) {
+            if (errno != EINTR && errno != EAGAIN)
+                return -EIO;
+        } else {
+            break;
+        }
     }
-    return size1 - size;
+    return size;
+}
+
+static int udp_close(URLContext *h)
+{
+    UDPContext *s = h->priv_data;
+
+    if (s->is_multicast && !(h->flags & URL_WRONLY)) {
+        if (setsockopt(s->udp_fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, 
+                       &s->mreq, sizeof(s->mreq)) < 0) {
+            perror("IP_DROP_MEMBERSHIP");
+        }
+    }
+    close(s->udp_fd);
+    av_free(s);
+    return 0;
 }
 
 URLProtocol udp_protocol = {
     "udp",
     udp_open,
-    NULL, /* read */
+    udp_read,
     udp_write,
     NULL, /* seek */
     udp_close,