Don't walk the entire protocol tree to extract the value of one field.

Instead, prime the epan_dissect_t's tree to look for rtp.ssrc, and
extract that value with proto_get_finfo_ptr_array().

Also, have the filter used to check whether the packet is a candidate
for RTP analysis to check for RTPv2 (and add a check for IPv4 or IPv6
back to the Qt version), and get rid of an unnecessary extra level of
indirection for that string.

In the Qt version, if findStreams() set the error string, don't
overwrite it with a "No streams found." indication, and fix error
handling for the "filter didn't compile" case.

Change-Id: I09d0ea37ccd4806d99e3b6394f2a8a376e974705
Reviewed-on: https://code.wireshark.org/review/13045
Reviewed-by: Guy Harris <guy@alum.mit.edu>

1 files changed, 25 insertions, 87 deletions

diff --git a/ui/qt/rtp_analysis_dialog.cpp b/ui/qt/rtp_analysis_dialog.cpp
index ae819d48ad..66ac236e94 100644
--- a/ui/qt/rtp_analysis_dialog.cpp
+++ b/ui/qt/rtp_analysis_dialog.cpp
@@ -372,7 +372,7 @@ RtpAnalysisDialog::RtpAnalysisDialog(QWidget &parent, CaptureFile &cf, struct _r
         findStreams();
     }
 
-    if (num_streams_ < 1) {
+    if (err_str_.isEmpty() && num_streams_ < 1) {
         err_str_ = tr("No streams found.");
     }
 
@@ -1366,75 +1366,6 @@ void RtpAnalysisDialog::saveCsv(RtpAnalysisDialog::StreamDirection direction)
     }
 }
 
-// Adapted from rtp_analysis.c:process_node
-guint32 RtpAnalysisDialog::processNode(proto_node *ptree_node, header_field_info *hfinformation, const gchar *proto_field, bool *ok)
-{
-    field_info         *finfo;
-    proto_node         *proto_sibling_node;
-    header_field_info  *hfssrc;
-    ipv4_addr_and_mask *ipv4;
-
-    finfo = PNODE_FINFO(ptree_node);
-
-    /* Caller passed top of the protocol tree. Expected child node */
-    g_assert(finfo);
-
-    if (hfinformation == (finfo->hfinfo)) {
-        hfssrc = proto_registrar_get_byname(proto_field);
-        if (hfssrc == NULL) {
-            return 0;
-        }
-        for (ptree_node = ptree_node->first_child;
-             ptree_node != NULL;
-             ptree_node = ptree_node->next) {
-            finfo = PNODE_FINFO(ptree_node);
-            if (hfssrc == finfo->hfinfo) {
-                guint32 result;
-                if (hfinformation->type == FT_IPv4) {
-                    ipv4 = (ipv4_addr_and_mask *)fvalue_get(&finfo->value);
-                    result = ipv4_get_net_order_addr(ipv4);
-                } else {
-                    result = fvalue_get_uinteger(&finfo->value);
-                }
-                if (ok) *ok = true;
-                return result;
-            }
-        }
-        if (!ptree_node) {
-            return 0;
-        }
-    }
-
-    proto_sibling_node = ptree_node->next;
-
-    if (proto_sibling_node) {
-        return processNode(proto_sibling_node, hfinformation, proto_field, ok);
-    } else {
-        return 0;
-    }
-}
-
-// Adapted from rtp_analysis.c:get_int_value_from_proto_tree
-guint32 RtpAnalysisDialog::getIntFromProtoTree(proto_tree *protocol_tree, const gchar *proto_name, const gchar *proto_field, bool *ok)
-{
-    proto_node *ptree_node;
-    header_field_info *hfinformation;
-
-    if (ok) *ok = false;
-
-    hfinformation = proto_registrar_get_byname(proto_name);
-    if (hfinformation == NULL) {
-        return 0;
-    }
-
-    ptree_node = ((proto_node *)protocol_tree)->first_child;
-    if (!ptree_node) {
-        return 0;
-    }
-
-    return processNode(ptree_node, hfinformation, proto_field, ok);
-}
-
 bool RtpAnalysisDialog::eventFilter(QObject *, QEvent *event)
 {
     if (event->type() != QEvent::KeyPress) return false;
@@ -1464,14 +1395,24 @@ void RtpAnalysisDialog::graphClicked(QMouseEvent *event)
 
 void RtpAnalysisDialog::findStreams()
 {
-    const gchar *filter_text = "rtp && rtp.version && rtp.ssrc";
+    const gchar filter_text[] = "rtp && rtp.version == 2 && rtp.ssrc && (ip || ipv6)";
     dfilter_t *sfcode;
     gchar *err_msg;
 
+    /* Try to get the hfid for "rtp.ssrc". */
+    int hfid_rtp_ssrc = proto_registrar_get_id_byname("rtp.ssrc");
+    if (hfid_rtp_ssrc == -1) {
+        err_str_ = tr("There is no \"rtp.ssrc\" field in this version of Wireshark.");
+        updateWidgets();
+        return;
+    }
+
+    /* Try to compile the filter. */
     if (!dfilter_compile(filter_text, &sfcode, &err_msg)) {
-        QMessageBox::warning(this, tr("No RTP packets found"), QString("%1").arg(err_msg));
+        err_str_ = QString(err_msg);
         g_free(err_msg);
-        close();
+        updateWidgets();
+        return;
     }
 
     if (!cap_file_.capFile() || !cap_file_.capFile()->current_frame) close();
@@ -1484,14 +1425,18 @@ void RtpAnalysisDialog::findStreams()
 
     epan_dissect_init(&edt, cap_file_.capFile()->epan, TRUE, FALSE);
     epan_dissect_prime_dfilter(&edt, sfcode);
+    epan_dissect_prime_hfid(&edt, hfid_rtp_ssrc);
     epan_dissect_run(&edt, cap_file_.capFile()->cd_t, &cap_file_.capFile()->phdr,
                      frame_tvbuff_new_buffer(fdata, &cap_file_.capFile()->buf), fdata, NULL);
 
-    // This shouldn't happen (the menu item should be disabled) but check anyway
+    /*
+     * Packet must be an RTPv2 packet with an SSRC; we use the filter to
+     * check.
+     */
     if (!dfilter_apply_edt(sfcode, &edt)) {
         epan_dissect_cleanup(&edt);
         dfilter_free(sfcode);
-        err_str_ = tr("Please select an RTP packet");
+        err_str_ = tr("Please select an RTPv2 packet with an SSRC value");
         updateWidgets();
         return;
     }
@@ -1510,23 +1455,16 @@ void RtpAnalysisDialog::findStreams()
     port_src_rev_ = edt.pi.destport;
     port_dst_rev_ = edt.pi.srcport;
 
-    /* Check if it is RTP Version 2 */
-    unsigned int  version_fwd;
-    bool ok;
-    version_fwd = getIntFromProtoTree(edt.tree, "rtp", "rtp.version", &ok);
-    if (!ok || version_fwd != 2) {
-        err_str_ = tr("RTP version %1 found. Only version 2 is supported.").arg(version_fwd);
-        updateWidgets();
-        return;
-    }
-
     /* now we need the SSRC value of the current frame */
-    ssrc_fwd_ = getIntFromProtoTree(edt.tree, "rtp", "rtp.ssrc", &ok);
-    if (!ok) {
+    GPtrArray *gp = proto_get_finfo_ptr_array(edt.tree, hfid_rtp_ssrc);
+    if (gp == NULL || gp->len == 0) {
+        /* XXX - should not happen, as the filter includes rtp.ssrc */
+        epan_dissect_cleanup(&edt);
         err_str_ = tr("SSRC value not found.");
         updateWidgets();
         return;
     }
+    ssrc_fwd_ = fvalue_get_uinteger(&((field_info *)gp->pdata[0])->value);
 
     /* Register the tap listener */
     memset(&tapinfo_, 0, sizeof(rtpstream_tapinfo_t));