Add a mechanism to register aliases for preference modules.

That way, we don't need a chunk of code in epan/prefs.c that knows about
various preference module mappings; individual dissectors can register
aliases as appropriate.

(The Nortel Discovery Protocol never *had* any preferences, even when
it was the SynOptics Network Management Protocol, so there's no need for
it to register an alias.)

Change-Id: I4a718dac6bb06801cc06a6ee5a28d7ed81e67e5d
Reviewed-on: https://code.wireshark.org/review/29914
Reviewed-by: Guy Harris <guy@alum.mit.edu>

10 files changed, 119 insertions, 27 deletions

diff --git a/epan/dissectors/asn1/p1/packet-p1-template.c b/epan/dissectors/asn1/p1/packet-p1-template.c
index 36b51c59d2..bd6bd06fc1 100644
--- a/epan/dissectors/asn1/p1/packet-p1-template.c
+++ b/epan/dissectors/asn1/p1/packet-p1-template.c
@@ -366,6 +366,8 @@ void proto_register_p1(void) {
   /* Register our configuration options for P1, particularly our port */
 
   p1_module = prefs_register_protocol_subtree("OSI/X.400", proto_p1, NULL);
+  /* For reading older preference files with "x411." preferences */
+  prefs_register_module_alias("x411", p1_module);
 
   prefs_register_obsolete_preference(p1_module, "tcp.port");
 
diff --git a/epan/dissectors/packet-beep.c b/epan/dissectors/packet-beep.c
index ec8ac2a18c..890ca0c126 100644
--- a/epan/dissectors/packet-beep.c
+++ b/epan/dissectors/packet-beep.c
@@ -971,6 +971,8 @@ proto_register_beep(void)
   /* Register our configuration options for BEEP, particularly our port */
 
   beep_module = prefs_register_protocol(proto_beep, apply_beep_prefs);
+  /* For reading older preference files with "bxxp." preferences */
+  prefs_register_module_alias("bxxp", beep_module);
 
   prefs_register_bool_preference(beep_module, "strict_header_terminator",
                                  "BEEP Header Requires CRLF",
diff --git a/epan/dissectors/packet-dccp.c b/epan/dissectors/packet-dccp.c
index 601a208e3c..8611bdd28a 100644
--- a/epan/dissectors/packet-dccp.c
+++ b/epan/dissectors/packet-dccp.c
@@ -1283,6 +1283,8 @@ proto_register_dccp(void)
 
     /* reg preferences */
     dccp_module = prefs_register_protocol(proto_dccp, NULL);
+    /* For reading older preference files with "dcp." preferences */
+    prefs_register_module_alias("dcp", dccp_module);
     prefs_register_bool_preference(
         dccp_module, "summary_in_tree",
         "Show DCCP summary in protocol tree",
diff --git a/epan/dissectors/packet-diameter.c b/epan/dissectors/packet-diameter.c
index 136e401bb0..f2d9467254 100644
--- a/epan/dissectors/packet-diameter.c
+++ b/epan/dissectors/packet-diameter.c
@@ -2332,6 +2332,8 @@ proto_register_diameter(void)
 
 	/* Register configuration options for ports */
 	diameter_module = prefs_register_protocol(proto_diameter, proto_reg_handoff_diameter);
+	/* For reading older preference files with "Diameter." preferences */
+	prefs_register_module_alias("Diameter", diameter_module);
 
 	prefs_register_range_preference(diameter_module, "sctp.ports",
 					"Diameter SCTP Ports",
diff --git a/epan/dissectors/packet-gsm_sms_ud.c b/epan/dissectors/packet-gsm_sms_ud.c
index 56c8981029..0b24a2023f 100644
--- a/epan/dissectors/packet-gsm_sms_ud.c
+++ b/epan/dissectors/packet-gsm_sms_ud.c
@@ -686,6 +686,8 @@ proto_register_gsm_sms_ud(void)
 
     /* Preferences for GSM SMS UD */
     gsm_sms_ud_module = prefs_register_protocol(proto_gsm_sms_ud, NULL);
+    /* For reading older preference files with "smpp-gsm-sms." preferences */
+    prefs_register_module_alias("smpp-gsm-sms", gsm_sms_ud_module);
     prefs_register_bool_preference(gsm_sms_ud_module,
         "port_number_udh_means_wsp",
         "Port Number IE in UDH always triggers CL-WSP dissection",
diff --git a/epan/dissectors/packet-gtp.c b/epan/dissectors/packet-gtp.c
index c3b1b8a2b2..2acb60fcaa 100644
--- a/epan/dissectors/packet-gtp.c
+++ b/epan/dissectors/packet-gtp.c
@@ -10990,6 +10990,9 @@ proto_register_gtp(void)
     expert_register_field_array(expert_gtp, ei, array_length(ei));
 
     gtp_module = prefs_register_protocol(proto_gtp, proto_reg_handoff_gtp);
+    /* For reading older preference files with "gtpv0." or "gtpv1." preferences */
+    prefs_register_module_alias("gtpv0", gtp_module);
+    prefs_register_module_alias("gtpv1", gtp_module);
 
     prefs_register_uint_preference(gtp_module, "v0_port", "GTPv0 and GTP' port", "GTPv0 and GTP' port (default 3386)", 10, &g_gtpv0_port);
     prefs_register_uint_preference(gtp_module, "v1c_port", "GTPv1 or GTPv2 control plane (GTP-C, GTPv2-C) port", "GTPv1 and GTPv2 control plane port (default 2123)", 10,
diff --git a/epan/dissectors/packet-nsip.c b/epan/dissectors/packet-nsip.c
index 7a20f7408e..d6adef63d8 100644
--- a/epan/dissectors/packet-nsip.c
+++ b/epan/dissectors/packet-nsip.c
@@ -1138,6 +1138,8 @@ proto_register_nsip(void)
 
   /* Register configuration options */
   nsip_module = prefs_register_protocol(proto_nsip, NULL);
+  /* For reading older preference files with "nsip." preferences */
+  prefs_register_module_alias("nsip", nsip_module);
   prefs_register_obsolete_preference(nsip_module, "udp.port1");
   prefs_register_obsolete_preference(nsip_module, "udp.port2");
 }
diff --git a/epan/dissectors/packet-x25.c b/epan/dissectors/packet-x25.c
index ae67efb9af..c09a4158aa 100644
--- a/epan/dissectors/packet-x25.c
+++ b/epan/dissectors/packet-x25.c
@@ -2351,6 +2351,8 @@ proto_register_x25(void)
 
     /* Preferences */
     x25_module = prefs_register_protocol(proto_x25, NULL);
+    /* For reading older preference files with "x.25." preferences */
+    prefs_register_module_alias("x.25", x25_module);
     prefs_register_obsolete_preference(x25_module, "non_q_bit_is_sna");
     prefs_register_bool_preference(x25_module, "payload_is_qllc_sna",
             "Default to QLLC/SNA",
diff --git a/epan/prefs.c b/epan/prefs.c
index 0b8a383c79..34c05d3075 100644
--- a/epan/prefs.c
+++ b/epan/prefs.c
@@ -42,12 +42,21 @@
 #include "epan/wmem/wmem.h"
 #include <epan/stats_tree.h>
 
+/*
+ * Module alias.
+ */
+typedef struct pref_module_alias {
+    const char *name;           /**< name of module alias */
+    module_t *module;           /**< module for which it's an alias */
+} module_alias_t;
+
 /* Internal functions */
 static module_t *find_subtree(module_t *parent, const char *tilte);
 static module_t *prefs_register_module_or_subtree(module_t *parent,
     const char *name, const char *title, const char *description, gboolean is_subtree,
     void (*apply_cb)(void), gboolean use_gui);
 static void prefs_register_modules(void);
+static module_t *prefs_find_module_alias(const char *name);
 static prefs_set_pref_e set_pref(gchar*, const gchar*, void *, gboolean);
 static void free_col_info(GList *);
 static void pre_init_prefs(void);
@@ -271,6 +280,11 @@ static wmem_tree_t *prefs_modules = NULL;
  */
 static wmem_tree_t *prefs_top_level_modules = NULL;
 
+/*
+ * List of aliases for modules.
+ */
+static wmem_tree_t *prefs_module_aliases = NULL;
+
 /** Sets up memory used by proto routines. Called at program startup */
 void
 prefs_init(void)
@@ -278,6 +292,7 @@ prefs_init(void)
     memset(&prefs, 0, sizeof(prefs));
     prefs_modules = wmem_tree_new(wmem_epan_scope());
     prefs_top_level_modules = wmem_tree_new(wmem_epan_scope());
+    prefs_module_aliases = wmem_tree_new(wmem_epan_scope());
 }
 
 /*
@@ -541,6 +556,50 @@ prefs_register_module_or_subtree(module_t *parent, const char *name,
     return module;
 }
 
+void
+prefs_register_module_alias(const char *name, module_t *module)
+{
+    module_alias_t *alias;
+    const char *p;
+    guchar c;
+
+    /*
+     * Yes.
+     * Make sure that only ASCII letters, numbers, underscores, hyphens,
+     * and dots appear in the name.  We allow upper-case letters, to
+     * handle the Diameter dissector having used "Diameter" rather
+     * than "diameter" as its preference module name in the past.
+     *
+     * Crash if there is, as that's an error in the code, but the name
+     * can be used on the command line, and shouldn't require quoting,
+     * etc.
+     */
+    for (p = name; (c = *p) != '\0'; p++) {
+        if (!(g_ascii_isalpha(c) || g_ascii_isdigit(c) || c == '_' ||
+              c == '-' || c == '.'))
+            g_error("Preference module alias \"%s\" contains invalid characters", name);
+    }
+
+    /*
+     * Make sure there's not already an alias with that
+     * name.  Crash if there is, as that's an error in the
+     * code, and the code has to be fixed not to register
+     * more than one alias with the same name.
+     *
+     * We search the list of all aliases.
+     */
+    g_assert(prefs_find_module_alias(name) == NULL);
+
+    alias = wmem_new(wmem_epan_scope(), module_alias_t);
+    alias->name = name;
+    alias->module = module;
+
+    /*
+     * Insert this module in the list of all modules.
+     */
+    wmem_tree_insert_string(prefs_module_aliases, name, alias, WMEM_TREE_STRING_NOCASE);
+}
+
 /*
  * Register that a protocol has preferences.
  */
@@ -891,6 +950,17 @@ prefs_apply(module_t *module)
         call_apply_cb(NULL, module, NULL);
 }
 
+static module_t *
+prefs_find_module_alias(const char *name)
+{
+    module_alias_t *alias;
+
+    alias = (module_alias_t *)wmem_tree_lookup_string(prefs_module_aliases, name, WMEM_TREE_STRING_NOCASE);
+    if (alias == NULL)
+        return NULL;
+    return alias->module;
+}
+
 /*
  * Register a preference in a module's list of preferences.
  * If it has a title, give it an ordinal number; otherwise, it's a
@@ -2999,6 +3069,8 @@ prefs_register_modules(void)
     prefs_register_obsolete_preference(gui_module, "hex_dump_highlight_style");
 
     gui_column_module = prefs_register_subtree(gui_module, "Columns", "Columns", NULL);
+    /* For reading older preference files with "column." preferences */
+    prefs_register_module_alias("column", gui_column_module);
 
     custom_cbs.free_cb = free_string_like_preference;
     custom_cbs.reset_cb = reset_string_like_preference;
@@ -5402,38 +5474,36 @@ set_pref(gchar *pref_name, const gchar *value, void *private_data _U_,
                  * its modern name, the Nortel Discovery Protocol (NDP).
                  */
                 if (module == NULL) {
-                    if (strcmp(pref_name, "column") == 0)
-                        module = gui_column_module;
-                    else if (strcmp(pref_name, "Diameter") == 0)
-                        module = prefs_find_module("diameter");
-                    else if (strcmp(pref_name, "bxxp") == 0)
-                        module = prefs_find_module("beep");
-                    else if (strcmp(pref_name, "gtpv0") == 0 ||
-                             strcmp(pref_name, "gtpv1") == 0)
-                        module = prefs_find_module("gtp");
-                    else if (strcmp(pref_name, "smpp-gsm-sms") == 0)
-                        module = prefs_find_module("gsm-sms-ud");
-                    else if (strcmp(pref_name, "dcp") == 0)
-                        module = prefs_find_module("dccp");
-                    else if (strcmp(pref_name, "x.25") == 0)
-                        module = prefs_find_module("x25");
-                    else if (strcmp(pref_name, "x411") == 0)
-                        module = prefs_find_module("p1");
-                    else if (strcmp(pref_name, "nsip") == 0)
-                        module = prefs_find_module("gprs-ns");
-                    else if (strcmp(pref_name, "sonmp") == 0)
-                        module = prefs_find_module("ndp");
-                    else if (strcmp(pref_name, "etheric") == 0 ||
-                             strcmp(pref_name, "isup_thin") == 0) {
-                        /* This protocol was removed 7. July 2009 */
-                        return PREFS_SET_OBSOLETE;
-                    } else {
-                        /* See if the module name matches any protocol aliases. */
+                    /*
+                     * See if there's a backwards-compatibility name
+                     * that maps to this module.
+                     */
+                    module = prefs_find_module_alias(pref_name);
+                    if (module == NULL) {
+                        /*
+                         * There's no alias for the module; see if the
+                         * module name matches any protocol aliases.
+                         */
                         header_field_info *hfinfo = proto_registrar_get_byalias(pref_name);
                         if (hfinfo) {
                             module = (module_t *) wmem_tree_lookup_string(prefs_modules, hfinfo->abbrev, WMEM_TREE_STRING_NOCASE);
                         }
                     }
+                    if (module == NULL) {
+                        /*
+                         * There aren't any aliases.  Was the module
+                         * removed rather than renamed?
+                         */
+                        if (strcmp(pref_name, "etheric") == 0 ||
+                            strcmp(pref_name, "isup_thin") == 0) {
+                            /*
+                             * The dissectors for these protocols were
+                             * removed as obsolete on 2009-07-70 in change
+                             * 739bfc6ff035583abb9434e0e988048de38a8d9a.
+                             */
+                            return PREFS_SET_OBSOLETE;
+                        }
+                    }
                     if (module) {
                         g_warning ("Preference \"%s.%s\" has been converted to \"%s.%s\"\n"
                                    "Save your preferences to make this change permanent.",
diff --git a/epan/prefs.h b/epan/prefs.h
index bf560f90e8..3e38d6d7dd 100644
--- a/epan/prefs.h
+++ b/epan/prefs.h
@@ -258,6 +258,11 @@ WS_DLL_PUBLIC void prefs_set_gui_theme_is_dark(gboolean is_dark);
  */
 WS_DLL_PUBLIC module_t *prefs_register_protocol(int id, void (*apply_cb)(void));
 
+/*
+ * Register an alias for a preference module.
+ */
+WS_DLL_PUBLIC void prefs_register_module_alias(const char *name, module_t *module);
+
 /**
  * Deregister preferences from a protocol.
  */