fix(bencode): fix #342, support signed ints

- add inf/NaN checks - add tests
thi-ng · Apr 7, 2022 · 66615be · 66615be
1 parent 5a51f7d
commit 66615be
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diff --git a/packages/bencode/README.md b/packages/bencode/README.md
@@ -30,7 +30,7 @@ decoder for structured data.
 
 #### Booleans
 
-Will be converted to `0` or `1`.
+Will be converted to `0` or `1` integers.
 
 #### String handling
 
@@ -40,13 +40,14 @@ Bencode strings (e.g. `len:xxx...`), but are used as is.
 
 #### Floating point values
 
-This implementation has optional (non-standard) support for floating
-point values. If these are not desired (e.g. for compatibility reasons),
-all numeric values MUST be pre-rounded to integers. The encoder only
-chooses the custom float encoding iff a number has a fractional part.
-Floats are encoded similarly to standard ints (i.e. as text), but using
-`f` as prefix. Furthermore, only floats with an absolute value in the
-semi-open `[1e-6,1e21)` interval can be encoded.
+This implementation has optional (non-standard) support for floating point
+values. If these are not desired (e.g. for compatibility reasons), all numeric
+values MUST be pre-rounded to integers. The encoder only chooses the custom
+float encoding iff a number has a fractional part. Floats are encoded similarly
+to standard ints (i.e. as text), but using `f` as prefix. Furthermore, only
+floats with an absolute value in the semi-open `[1e-6,1e21)` interval can be
+encoded. Float values requiring exponential notation will throw an error during
+encoding.
 
 ### Status
 
@@ -77,7 +78,7 @@ node --experimental-repl-await
 > const bencode = await import("@thi.ng/bencode");
 ```
 
-Package sizes (gzipped, pre-treeshake): ESM: 1.22 KB
+Package sizes (gzipped, pre-treeshake): ESM: 1.30 KB
 
 ## Dependencies
 

diff --git a/packages/bencode/src/decode.ts b/packages/bencode/src/decode.ts
@@ -118,12 +118,16 @@ const collect = (stack: any[], x: any, utf8 = false) => {
 const readInt = (iter: Iterator<number>, acc: number, end = Lit.END) => {
     let i: IteratorResult<number>;
     let x: number;
+    let isSigned = false;
     while (!(i = iter.next()).done) {
         x = i.value;
         if (x >= Lit.ZERO && x <= Lit.NINE) {
             acc = acc * 10 + x - Lit.ZERO;
+        } else if (x === Lit.MINUS) {
+            assert(!isSigned, `invalid int literal`);
+            isSigned = true;
         } else if (x === end) {
-            return acc;
+            return isSigned ? -acc : acc;
         } else {
             illegalState(`expected digit, got 0x${x.toString(16)}`);
         }

diff --git a/packages/bencode/src/encode.ts b/packages/bencode/src/encode.ts
@@ -53,12 +53,16 @@ const encodeBin: MultiFn1<any, BinStructItem[]> = defmulti<
             : unsupported(`unsupported data type: ${x}`),
     {},
     {
-        [Type.INT]: (x: number) => [str(`i${Math.floor(x)}e`)],
+        [Type.INT]: (x: number) => {
+            __ensureValidNumber(x);
+            return [str(`i${Math.floor(x)}e`)];
+        },
 
         [Type.FLOAT]: (x: number) => {
+            __ensureValidNumber(x);
             assert(
                 FLOAT_RE.test(x.toString()),
-                `exponential notation not allowed (${x})`
+                `values requiring exponential notation not allowed (${x})`
             );
             return [str(`f${x}e`)];
         },
@@ -86,3 +90,9 @@ const encodeBin: MultiFn1<any, BinStructItem[]> = defmulti<
         ],
     }
 );
+
+/** @internal */
+const __ensureValidNumber = (x: number) => {
+    assert(isFinite(x), `can't encode infinite value`);
+    assert(!isNaN(x), `can't encode NaN`);
+};
diff --git a/packages/bencode/test/index.ts b/packages/bencode/test/index.ts
@@ -1,7 +1,7 @@
 import { equiv } from "@thi.ng/equiv";
 import { group } from "@thi.ng/testament";
 import * as assert from "assert";
-import { decode, encode } from "../src/index.js"
+import { decode, encode } from "../src/index.js";
 
 const src = { foo: [1, "a", { bar: "baz" }, [42.123]] };
 const src2 = { foo: new Uint8Array([0, 1, 2, 3, 255, 254, 253]) };
@@ -11,11 +11,12 @@ group("bencode", {
     "roundtrip (utf8)": () => {
         let bytes;
         assert.deepStrictEqual(
-            bytes = [...encode(src)],
+            (bytes = [...encode(src)]),
             [
-                0x64, 0x33, 0x3a, 0x66, 0x6f, 0x6f, 0x6c, 0x69, 0x31, 0x65, 0x31, 0x3a, 0x61, 0x64, 0x33, 0x3a,
-                0x62, 0x61, 0x72, 0x33, 0x3a, 0x62, 0x61, 0x7a, 0x65, 0x6c, 0x66, 0x34, 0x32, 0x2e, 0x31, 0x32,
-                0x33, 0x65, 0x65, 0x65, 0x65,
+                0x64, 0x33, 0x3a, 0x66, 0x6f, 0x6f, 0x6c, 0x69, 0x31, 0x65,
+                0x31, 0x3a, 0x61, 0x64, 0x33, 0x3a, 0x62, 0x61, 0x72, 0x33,
+                0x3a, 0x62, 0x61, 0x7a, 0x65, 0x6c, 0x66, 0x34, 0x32, 0x2e,
+                0x31, 0x32, 0x33, 0x65, 0x65, 0x65, 0x65,
             ]
         );
         assert.deepStrictEqual(decode(bytes), src);
@@ -25,10 +26,20 @@ group("bencode", {
         let bytes;
         assert.ok(
             equiv(
-                bytes = encode(src2),
-                [0x64, 0x33, 0x3a, 0x66, 0x6f, 0x6f, 0x37, 0x3a, 0x00, 0x01, 0x02, 0x03, 0xff, 0xfe, 0xfd, 0x65]
+                (bytes = encode(src2)),
+                [
+                    0x64, 0x33, 0x3a, 0x66, 0x6f, 0x6f, 0x37, 0x3a, 0x00, 0x01,
+                    0x02, 0x03, 0xff, 0xfe, 0xfd, 0x65,
+                ]
             )
-        )
+        );
         assert.ok(equiv(decode(bytes, false), src2));
     },
+
+    "signed int": () => {
+        assert.ok(equiv(decode(encode(42), false), 42));
+        assert.ok(equiv(decode(encode(-42), false), -42));
+        assert.throws(() => decode([0x69, 0x2d, 0x2d, 0x31, 0x65])); // i--1e
+        assert.throws(() => decode([0x69, 0x2d, 0x31, 0x2e, 0x32, 0x65])); // i-1.2e
+    },
 });
diff --git a/packages/bencode/tpl.readme.md b/packages/bencode/tpl.readme.md
@@ -18,7 +18,7 @@ decoder for structured data.
 
 #### Booleans
 
-Will be converted to `0` or `1`.
+Will be converted to `0` or `1` integers.
 
 #### String handling
 
@@ -28,13 +28,14 @@ Bencode strings (e.g. `len:xxx...`), but are used as is.
 
 #### Floating point values
 
-This implementation has optional (non-standard) support for floating
-point values. If these are not desired (e.g. for compatibility reasons),
-all numeric values MUST be pre-rounded to integers. The encoder only
-chooses the custom float encoding iff a number has a fractional part.
-Floats are encoded similarly to standard ints (i.e. as text), but using
-`f` as prefix. Furthermore, only floats with an absolute value in the
-semi-open `[1e-6,1e21)` interval can be encoded.
+This implementation has optional (non-standard) support for floating point
+values. If these are not desired (e.g. for compatibility reasons), all numeric
+values MUST be pre-rounded to integers. The encoder only chooses the custom
+float encoding iff a number has a fractional part. Floats are encoded similarly
+to standard ints (i.e. as text), but using `f` as prefix. Furthermore, only
+floats with an absolute value in the semi-open `[1e-6,1e21)` interval can be
+encoded. Float values requiring exponential notation will throw an error during
+encoding.
 
 ${status}