From 04173fc961059f49192c52d3dff9b83956446e82 Mon Sep 17 00:00:00 2001
From: iceman1001 <iceman@iuse.se>
Date: Mon, 13 Mar 2023 21:36:59 +0100
Subject: [PATCH] added bit string printing in ASN1 decoder

---
 client/src/crypto/asn1dump.c | 55 +++++++++++++++++++++++++++++++++++-
 1 file changed, 54 insertions(+), 1 deletion(-)

diff --git a/client/src/crypto/asn1dump.c b/client/src/crypto/asn1dump.c
index db0b2b687..4136c002d 100644
--- a/client/src/crypto/asn1dump.c
+++ b/client/src/crypto/asn1dump.c
@@ -44,6 +44,7 @@ enum asn1_tag_t {
     ASN1_TAG_STR_TIME,
     ASN1_TAG_OBJECT_ID,
     ASN1_TAG_HEX,
+    ASN1_TAG_BIT_STRING,
 };
 
 struct asn1_tag {
@@ -62,7 +63,7 @@ static const struct asn1_tag asn1_tags[] = {
     // ASN.1
     { 0x01, "BOOLEAN",           ASN1_TAG_BOOLEAN      },
     { 0x02, "INTEGER",           ASN1_TAG_INTEGER      },
-    { 0x03, "BIT STRING",        ASN1_TAG_GENERIC      },
+    { 0x03, "BIT STRING",        ASN1_TAG_BIT_STRING   },
     { 0x04, "OCTET STRING",      ASN1_TAG_OCTET_STRING },
     { 0x05, "NULL",              ASN1_TAG_GENERIC      },
     { 0x06, "OBJECT IDENTIFIER", ASN1_TAG_OBJECT_ID    },
@@ -170,6 +171,54 @@ static void asn1_tag_dump_string(const struct tlv *tlv, const struct asn1_tag *t
     PrintAndLogEx(NORMAL, "    value: '" _GREEN_("%.*s") "' hex: '%s'", tlv->len, tlv->value, sprint_hex(tlv->value, tlv->len));
 }
 
+static void asn1_tag_dump_bitstring(const struct tlv *tlv, const struct asn1_tag *tag, int level) {
+
+    size_t len = tlv->len;
+    size_t n = (len * 8);
+    bool skip = false;
+
+    if (tlv->value[0] == 0) {
+        n -= 8;
+        len--;
+        skip = true;
+    }
+
+    uint8_t *d = calloc(n, sizeof(uint8_t));
+    if (d == NULL) {
+        return;
+    }
+
+    if (skip)
+        bytes_to_bytebits(tlv->value + 1, len, d);
+    else
+        bytes_to_bytebits(tlv->value, len, d);
+
+    level++;
+    PrintAndLogEx(NORMAL, "  (%zu bit)", n);
+    PrintAndLogEx(INFO, "%*s" NOLF, 1 + (level * 4), "");
+
+    for (int i = 0; i < n; i++) {
+
+        char c = d[i];
+        if (c < 2) {
+            c += '0';
+        } else {
+            goto out;
+        }
+
+        PrintAndLogEx(NORMAL, "%c" NOLF, c);
+
+        if (((i + 1) % 64) == 0) {
+            PrintAndLogEx(NORMAL, "");
+            PrintAndLogEx(INFO, "%*s" NOLF, 1 + (level * 4), "");
+        }
+    }
+
+out:
+    free(d);
+    PrintAndLogEx(NORMAL, "");
+}
+
 static void asn1_tag_dump_hex(const struct tlv *tlv, const struct asn1_tag *tag, int level) {
     PrintAndLogEx(NORMAL, "    value: '%s'", sprint_hex_inrow(tlv->value, tlv->len));
 }
@@ -378,6 +427,10 @@ bool asn1_tag_dump(const struct tlv *tlv, int level, bool *candump) {
             asn1_tag_dump_hex(tlv, tag, level);
             *candump = false;
             break;
+        case ASN1_TAG_BIT_STRING:
+            asn1_tag_dump_bitstring(tlv, tag, level);
+            *candump = false;
+            break;
     };
 
     return true;