[OpenSER-Devel] extending SDP parser to support MSRP attributes

[Denis Bilenko]

Hello,

I'm using SDP parser in openser (parser/sdp/sdp.*) for MSRP chat server.
Thus I need the parser to support additional stream attributes as defined in RFC4975
(accept-types, accept-wrapped-types, path and max-size).

The patch attached extends sdp_stream_cell with the four attrs mentioned.

I wonder 
a) if this is the right way to extend SDP parser in openser
b) what needs to be done for this patch to be accepted

thanks,
Denis.

Index: parser/sdp/sdp_helpr_funcs.c
===================================================================
--- parser/sdp/sdp_helpr_funcs.c        (revision 4057)
+++ parser/sdp/sdp_helpr_funcs.c        (working copy)
@@ -35,10 +35,12 @@


 static str sup_ptypes[] = {
-       { "udp", 3},
-       { "udptl", 5},
-       { "rtp/avp", 7},
-       { "rtp/savpf", 9},
+       str_init("udp"),
+       str_init("udptl"),
+       str_init("rtp/avp"),
+       str_init("rtp/savpf"),
+       str_init("TCP/MSRP"),
+       str_init("TCP/TLS/MSRP"),
        { NULL, 0}
 };

@@ -216,22 +218,54 @@
        return 0;
 }

-
-int extract_ptime(str *body, str *ptime)
+/* field must has format "a=attrname:" */
+int extract_field(str *body, str *value, str field)
 {
-       if (strncmp(body->s, "a=ptime:", 8) !=0) {
-               /*LM_DBG("We are not pointing to an a=rtpmap: attribute =>`%.*s'\n", body->len, body->s); */
+       if (strncmp(body->s, field.s, field.len < body->len ? field.len : body->len) !=0) {
+               /*LM_DBG("We are not pointing to an %.* attribute =>`%.*s'\n", field.len, field.s, body->len, body->s); */
                return -1;
        }

-       ptime->s = body->s + 8; /* skip `a=ptime:' */
-       ptime->len = eat_line(ptime->s, body->s + body->len -
-                 ptime->s) - ptime->s;
-       trim_len(ptime->len, ptime->s, *ptime);
+       value->s = body->s + field.len; /* skip `a=attrname:' */
+       value->len = eat_line(value->s, body->s + body->len -
+                 value->s) - value->s;
+       trim_len(value->len, value->s, *value);

        return 0;
 }

+int extract_ptime(str *body, str *ptime)
+{
+    static const str field = str_init("a=ptime:");
+    return extract_field(body, ptime, field);
+}
+
+int extract_accept_types(str *body, str *accept_types)
+{
+    static const str field = str_init("a=accept-types:");
+    return extract_field(body, accept_types, field);
+}
+
+int extract_accept_wrapped_types(str *body, str *accept_wrapped_types)
+{
+    static const str field = str_init("a=accept-wrapped-types:");
+    return extract_field(body, accept_wrapped_types, field);
+}
+
+int extract_max_size(str *body, str *max_size)
+{
+    static const str field = str_init("a=max-size:");
+    return extract_field(body, max_size, field);
+}
+
+int extract_path(str *body, str *path)
+{
+    static const str field = str_init("a=path:");
+    return extract_field(body, path, field);
+}
+
+// also fix debug print functions
+
 int extract_sendrecv_mode(str *body, str *sendrecv_mode)
 {
        char *cp1;
Index: parser/sdp/sdp_helpr_funcs.h
===================================================================
--- parser/sdp/sdp_helpr_funcs.h        (revision 4057)
+++ parser/sdp/sdp_helpr_funcs.h        (working copy)
@@ -49,6 +49,11 @@
 int extract_mediaip(str *body, str *mediaip, int *pf, char *line);
 int extract_media_attr(str *body, str *mediamedia, str *mediaport, str *mediatransport, str *mediapayload);

+int extract_accept_types(str *body, str *accept_types);
+int extract_accept_wrapped_types(str *body, str *accept_wrapped_types);
+int extract_max_size(str *body, str *max_size);
+int extract_path(str *body, str *path);
+
 char *find_sdp_line(char *p, char *plimit, char linechar);
 char *find_next_sdp_line(char *p, char *plimit, char linechar, char *defptr);

Index: parser/sdp/sdp.c
===================================================================
--- parser/sdp/sdp.c    (revision 4057)
+++ parser/sdp/sdp.c    (working copy)
@@ -534,6 +534,14 @@
                                }
                                payload_attr = (sdp_payload_attr_t*)get_sdp_payload4payload(stream, &rtp_payload);
                                set_sdp_payload_attr(payload_attr, &rtp_enc, &rtp_clock, &rtp_params);
+                       } else if (extract_accept_types(&tmpstr1, &stream->accept_types) == 0) {
+                                       a1p = stream->accept_types.s + stream->accept_types.len;
+                       } else if (extract_accept_wrapped_types(&tmpstr1, &stream->accept_wrapped_types) == 0) {
+                                       a1p = stream->accept_wrapped_types.s + stream->accept_wrapped_types.len;
+                       } else if (extract_max_size(&tmpstr1, &stream->max_size) == 0) {
+                                       a1p = stream->max_size.s + stream->max_size.len;
+                       } else if (extract_path(&tmpstr1, &stream->path) == 0) {
+                                       a1p = stream->path.s + stream->path.len;
                        /*} else { */
                        /*      LM_DBG("else: `%.*s'\n", tmpstr1.len, tmpstr1.s); */
                        }
Index: parser/sdp/sdp.h
===================================================================
--- parser/sdp/sdp.h    (revision 4057)
+++ parser/sdp/sdp.h    (working copy)
@@ -59,6 +59,12 @@
        int payloads_num;                         /**< number of payloads inside a stream */
        struct sdp_payload_attr **p_payload_attr; /**< fast access pointers to payloads */
        struct sdp_payload_attr *payload_attr;
+
+  /* these attributes are defined in RFC4975 */
+  str path;
+  str max_size;
+  str accept_types;
+  str accept_wrapped_types;
 } sdp_stream_cell_t;

 typedef struct sdp_session_cell {