Add ENC_APN_STR to handle APN strings

5 files changed, 28 insertions, 58 deletions

diff --git a/epan/dissectors/packet-gsm_a_gm.c b/epan/dissectors/packet-gsm_a_gm.c
index a89e97de9c..97b221fb9d 100644
--- a/epan/dissectors/packet-gsm_a_gm.c
+++ b/epan/dissectors/packet-gsm_a_gm.c
@@ -604,7 +604,6 @@ static gint ett_sm_pco = -1;
 static expert_field ei_gsm_a_gm_extraneous_data = EI_INIT;
 static expert_field ei_gsm_a_gm_not_enough_data = EI_INIT;
 static expert_field ei_gsm_a_gm_undecoded = EI_INIT;
-static expert_field ei_gsm_a_gm_apn_too_long = EI_INIT;
 static expert_field ei_gsm_a_gm_missing_mandatory_element = EI_INIT;
 
 static dissector_handle_t rrc_irat_ho_info_handle;
@@ -4392,29 +4391,10 @@ guint16
 de_sm_apn(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, guint32 offset, guint len, gchar *add_string _U_, int string_len _U_)
 {
 	guint32     curr_offset;
-	guint       curr_len;
-	guint8     *str;
-	proto_item *pi;
 
 	curr_offset = offset;
 
-	str = tvb_get_string_enc(wmem_packet_scope(), tvb, offset, len, ENC_ASCII|ENC_NA);
-
-	curr_len = 0;
-	while (curr_len < len)
-	{
-		guint step    = str[curr_len];
-		str[curr_len] = '.';
-		curr_len     += step+1;
-	}
-
-	/* Highlight bytes including the first length byte */
-	if (str[0]) {
-		pi = proto_tree_add_string(tree, hf_gsm_a_gm_apn, tvb, curr_offset, len, str+1);
-		if (len > 100) {
-			expert_add_info(pinfo, pi, &ei_gsm_a_gm_apn_too_long);
-		}
-	}
+	proto_tree_add_item(tree, hf_gsm_a_gm_apn, tvb, curr_offset, len, ENC_APN_STR | ENC_NA);
 	curr_offset += len;
 
 	EXTRANEOUS_DATA_CHECK(len, curr_offset - offset, pinfo, &ei_gsm_a_gm_extraneous_data);
@@ -9642,7 +9622,6 @@ proto_register_gsm_a_gm(void)
 		{ &ei_gsm_a_gm_extraneous_data, { "gsm_a.gm.extraneous_data", PI_PROTOCOL, PI_NOTE, "Extraneous Data, dissector bug or later version spec (report to wireshark.org)", EXPFILL }},
 		{ &ei_gsm_a_gm_not_enough_data, { "gsm_a.gm.not_enough_data", PI_PROTOCOL, PI_WARN, "Not enough data", EXPFILL }},
 		{ &ei_gsm_a_gm_undecoded, { "gsm_a.gm.undecoded", PI_UNDECODED, PI_WARN, "Not decoded", EXPFILL }},
-		{ &ei_gsm_a_gm_apn_too_long, { "gsm_a.gm.apn_to_long", PI_PROTOCOL, PI_ERROR, "APN encoding has more than 100 octets", EXPFILL }},
 		{ &ei_gsm_a_gm_missing_mandatory_element, { "gsm_a.gm.missing_mandatory_element", PI_PROTOCOL, PI_ERROR, "Missing Mandatory element, rest of dissection is suspect", EXPFILL }},
 	};
 
diff --git a/epan/dissectors/packet-gtpv2.c b/epan/dissectors/packet-gtpv2.c
index a8022775f7..d399a37561 100644
--- a/epan/dissectors/packet-gtpv2.c
+++ b/epan/dissectors/packet-gtpv2.c
@@ -2200,29 +2200,12 @@ dissect_gtpv2_mm_ctx_for_cs_to_ps_srvcc(tvbuff_t *tvb, packet_info *pinfo _U_, p
 static void
 dissect_gtpv2_apn(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, proto_item *item, guint16 length, guint8 message_type _U_, guint8 instance _U_, session_args_t * args _U_)
 {
-    int     offset = 0;
-    guint8 *apn    = NULL;
-    int     name_len, tmp;
-
-    if (length > 0) {
-        proto_item *pi;
-
-        name_len = tvb_get_guint8(tvb, offset);
-        apn = tvb_get_string_enc(wmem_packet_scope(), tvb, offset + 1, length - 1, ENC_ASCII);
-        for (;;) {
-            if (name_len >= length - 1)
-                break;
-            tmp = name_len;
-            name_len = name_len + apn[tmp] + 1;
-            apn[tmp] = '.';
-        }
-        pi = proto_tree_add_string(tree, hf_gtpv2_apn, tvb, offset, length, apn);
-        if (length > 100)
-            expert_add_info(pinfo, pi, &ei_gtpv2_apn_too_long);
-    }
+    const guint8 *apn    = NULL;
 
-    if (apn)
+    proto_tree_add_item_ret_string(tree, hf_gtpv2_apn, tvb, 0, length, ENC_APN_STR | ENC_NA, wmem_packet_scope(), &apn);
+    if (apn) {
         proto_item_append_text(item, "%s", apn);
+    }
 
 }
 
@@ -7368,8 +7351,7 @@ dissect_gtpv2_apn_and_relative_capacity(tvbuff_t *tvb, packet_info *pinfo _U_, p
 {
     int       offset = 0;
     guint8 oct, apn_length;
-    guint8 *apn    = NULL;
-    int     name_len, tmp;
+    const guint8 *apn    = NULL;
 
     oct = tvb_get_guint8(tvb, offset);
     proto_tree_add_item(tree, hf_gtpv2_relative_capacity, tvb, offset, 1, ENC_BIG_ENDIAN);
@@ -7381,18 +7363,8 @@ dissect_gtpv2_apn_and_relative_capacity(tvbuff_t *tvb, packet_info *pinfo _U_, p
     offset += 1;
 
     if (apn_length > 0) {
-        proto_item *pi;
-
-        name_len = tvb_get_guint8(tvb, offset);
-        apn = tvb_get_string_enc(wmem_packet_scope(), tvb, offset + 1, apn_length - 1, ENC_ASCII);
-        for (;;) {
-            if (name_len >= apn_length - 1)
-                break;
-            tmp = name_len;
-            name_len = name_len + apn[tmp] + 1;
-            apn[tmp] = '.';
-        }
-        pi = proto_tree_add_string(tree, hf_gtpv2_apn, tvb, offset, apn_length, apn);
+        proto_item* pi;
+        pi = proto_tree_add_item_ret_string(tree, hf_gtpv2_apn, tvb, offset, apn_length, ENC_APN_STR | ENC_NA, wmem_packet_scope(), &apn);
         if (apn_length > 100)
             expert_add_info(pinfo, pi, &ei_gtpv2_apn_too_long);
     }
diff --git a/epan/dissectors/packet-pfcp.c b/epan/dissectors/packet-pfcp.c
index 6ef8e5ffe7..05ae0fe1b4 100644
--- a/epan/dissectors/packet-pfcp.c
+++ b/epan/dissectors/packet-pfcp.c
@@ -6109,7 +6109,7 @@ dissect_pfcp_apn_dnn(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, pr
      /* NOTE: The APN/DNN field is not encoded as a dotted string as commonly used in documentation. */
 
     const guint8* string_value;
-    proto_tree_add_item_ret_string(tree, hf_pfcp_apn_dnn, tvb, offset, length, ENC_ASCII | ENC_NA, wmem_packet_scope(), &string_value);
+    proto_tree_add_item_ret_string(tree, hf_pfcp_apn_dnn, tvb, offset, length, ENC_APN_STR | ENC_NA, wmem_packet_scope(), &string_value);
     proto_item_append_text(item, "%s", string_value);
 
 }
diff --git a/epan/proto.h b/epan/proto.h
index b893db9c65..77e24617f7 100644
--- a/epan/proto.h
+++ b/epan/proto.h
@@ -426,6 +426,7 @@ void proto_report_dissector_bug(const char *format, ...)
 #define ENC_ETSI_TS_102_221_ANNEX_A       0x0000004E /* ETSI TS 102 221 Annex A */
 #define ENC_GB18030                       0x00000050
 #define ENC_EUC_KR                        0x00000052
+#define ENC_APN_STR                       0x00000054 /* The encoding the APN/DNN field follows 3GPP TS 23.003 [2] clause 9.1.*/
 /*
  * TODO:
  *
diff --git a/epan/tvbuff.c b/epan/tvbuff.c
index fce3cb8c2d..0c26a2f9f0 100644
--- a/epan/tvbuff.c
+++ b/epan/tvbuff.c
@@ -1630,6 +1630,7 @@ validate_single_byte_ascii_encoding(const guint encoding)
 	    case ENC_KEYPAD_ABC_TBCD:
 	    case ENC_KEYPAD_BC_TBCD:
 	    case ENC_ETSI_TS_102_221_ANNEX_A:
+		case ENC_APN_STR:
 		REPORT_DISSECTOR_BUG("Invalid string encoding type passed to tvb_get_string_XXX");
 		break;
 	    default:
@@ -3092,6 +3093,23 @@ tvb_get_string_enc(wmem_allocator_t *scope, tvbuff_t *tvb, const gint offset,
 	case ENC_EUC_KR:
 		strptr = tvb_get_euc_kr_string(scope, tvb, offset, length);
 		break;
+	case ENC_APN_STR:
+	{
+		int name_len, tmp;
+
+		if (length > 0) {
+			name_len = tvb_get_guint8(tvb, offset);
+			strptr = tvb_get_string_enc(wmem_packet_scope(), tvb, offset + 1, length - 1, ENC_ASCII);
+			for (;;) {
+				if (name_len >= length - 1)
+					break;
+				tmp = name_len;
+				name_len = name_len + strptr[tmp] + 1;
+				strptr[tmp] = '.';
+			}
+		}
+	}
+		break;
 	}
 	return strptr;
 }