internal: store a decoded boolean as 0 or 1

GetBoolean() stores any nonzero wire byte as 1, per RFC 4251 section 5,
so callers and callbacks such as hasSignature see only 0 or 1.

- tests: add test_GetBoolean covering 0, 1 and other nonzero bytes

Issue: F-12573

Author: ejohnstown

src/internal.c

@@ -5712,7 +5712,7 @@ int GetBoolean(byte* v, const byte* buf, word32 len, word32* idx)
     int result = WS_BUFFER_E;
 
     if (*idx < len) {
-        *v = buf[*idx];
+        *v = (buf[*idx] != 0);
         *idx += BOOLEAN_SZ;
         result = WS_SUCCESS;
     }

tests/unit.c

@@ -5096,6 +5096,35 @@ static int test_GetString_zeroDestSz(void)
     return result;
 }
 
+/* GetBoolean() stores any nonzero wire byte as 1 (RFC 4251 5). */
+static int test_GetBoolean(void)
+{
+    static const byte wire[] = { 0x00, 0x01, 0x02, 0x80, 0xFF };
+    static const byte expect[] = { 0, 1, 1, 1, 1 };
+    word32 idx = 0;
+    word32 i;
+    byte v;
+
+    for (i = 0; i < (word32)sizeof(wire); i++) {
+        v = 0xAA;
+        if (GetBoolean(&v, wire, (word32)sizeof(wire), &idx) != WS_SUCCESS)
+            return -1;
+        if (v != expect[i])
+            return -2;
+        if (idx != i + 1)
+            return -3;
+    }
+
+    /* past the end */
+    v = 0xAA;
+    if (GetBoolean(&v, wire, (word32)sizeof(wire), &idx) != WS_BUFFER_E)
+        return -4;
+    if (v != 0xAA || idx != (word32)sizeof(wire))
+        return -5;
+
+    return 0;
+}
+
 /* DoChannelWindowAdjust adds the peer's advertised bytes to peerWindowSz.
  * A crafted bytesToAdd that would wrap the word32 must be rejected with
  * WS_OVERFLOW_E and leave the window untouched; a value that fits must be
@@ -24101,6 +24130,10 @@ int wolfSSH_UnitTest(int argc, char** argv)
            (unitResult == 0 ? "SUCCESS" : "FAILED"));
     testResult = testResult || unitResult;
 
+    unitResult = test_GetBoolean();
+    printf("GetBoolean: %s\n", (unitResult == 0 ? "SUCCESS" : "FAILED"));
+    testResult = testResult || unitResult;
+
     unitResult = test_GetString_zeroDestSz();
     printf("GetString_zeroDestSz: %s\n",
            (unitResult == 0 ? "SUCCESS" : "FAILED"));