GUACAMOLE-25: Implement parsing of audio mimetypes.

src/protocols/rdp/audio_input.c

@@ -30,16 +30,130 @@
 #include <guacamole/stream.h>
 #include <guacamole/user.h>
 
+#include <errno.h>
 #include <stdlib.h>
 #include <pthread.h>
 
+/**
+ * Parses the given raw audio mimetype, producing the corresponding rate,
+ * number of channels, and bytes per sample.
+ *
+ * @param mimetype
+ *     The raw auduio mimetype to parse.
+ *
+ * @param rate
+ *     A pointer to an int where the sample rate for the PCM format described
+ *     by the given mimetype should be stored.
+ *
+ * @param channels
+ *     A pointer to an int where the number of channels used by the PCM format
+ *     described by the given mimetype should be stored.
+ *
+ * @param bps
+ *     A pointer to an int where the number of bytes used the PCM format for
+ *     each sample (independent of number of channels) described by the given
+ *     mimetype should be stored.
+ *
+ * @return
+ *     Zero if the given mimetype is a raw audio mimetype and has been parsed
+ *     successfully, non-zero otherwise.
+ */
+static int guac_rdp_audio_parse_mimetype(const char* mimetype,
+        int* rate, int* channels, int* bps) {
+
+    int parsed_rate = -1;
+    int parsed_channels = 1;
+    int parsed_bps;
+
+    /* PCM audio with one byte per sample */
+    if (strncmp(mimetype, "audio/L8;", 9) == 0) {
+        mimetype += 8; /* Advance to semicolon ONLY */
+        parsed_bps = 1;
+    }
+
+    /* PCM audio with two bytes per sample */
+    else if (strncmp(mimetype, "audio/L16;", 10) == 0) {
+        mimetype += 9; /* Advance to semicolon ONLY */
+        parsed_bps = 2;
+    }
+
+    /* Unsupported mimetype */
+    else
+        return 1;
+
+    /* Parse each parameter name/value pair within the mimetype */
+    do {
+
+        /* Advance to first character of parameter (current is either a
+         * semicolon or a comma) */
+        mimetype++;
+
+        /* Parse number of channels */
+        if (strncmp(mimetype, "channels=", 9) == 0) {
+
+            mimetype += 9;
+            parsed_channels = strtol(mimetype, (char**) &mimetype, 10);
+
+            /* Fail if value invalid / out of range */
+            if (errno == EINVAL || errno == ERANGE)
+                return 1;
+
+        }
+
+        /* Parse number of rate */
+        else if (strncmp(mimetype, "rate=", 5) == 0) {
+
+            mimetype += 5;
+            parsed_rate = strtol(mimetype, (char**) &mimetype, 10);
+
+            /* Fail if value invalid / out of range */
+            if (errno == EINVAL || errno == ERANGE)
+                return 1;
+
+        }
+
+        /* Advance to next parameter */
+        mimetype = strchr(mimetype, ',');
+
+    } while (mimetype != NULL);
+
+    /* Mimetype is invalid if rate was not specified */
+    if (rate == -1)
+        return 1;
+
+    /* Parse success */
+    *rate = parsed_rate;
+    *channels = parsed_channels;
+    *bps = parsed_bps;
+
+    return 0;
+
+}
+
 int guac_rdp_audio_handler(guac_user* user, guac_stream* stream,
         char* mimetype) {
 
     guac_client* client = user->client;
     guac_rdp_client* rdp_client = (guac_rdp_client*) client->data;
 
+    int rate;
+    int channels;
+    int bps;
+
+    /* Parse mimetype, abort on parse error */
+    if (guac_rdp_audio_parse_mimetype(mimetype, &rate, &channels, &bps)) {
+        guac_user_log(user, GUAC_LOG_WARN, "Denying user audio stream with "
+                "unsupported mimetype: \"%s\"", mimetype);
+        guac_protocol_send_ack(user->socket, stream, "Unsupported audio "
+                "mimetype", GUAC_PROTOCOL_STATUS_CLIENT_BAD_TYPE);
+        return 0;
+    }
+
     /* FIXME: Assuming mimetype of "audio/L16;rate=44100,channels=2" */
+    else {
+        guac_user_log(user, GUAC_LOG_DEBUG, "rate=%i, channels=%i, bps=%i",
+                rate, channels, bps);
+    }
 
     /* Init stream data */
     stream->blob_handler = guac_rdp_audio_blob_handler;