Use a result for the parser

1 files changed, 36 insertions, 17 deletions

diff --git a/src/field/mod.rs b/src/field/mod.rs
index 277e7c4..a746ece 100644
--- a/src/field/mod.rs
+++ b/src/field/mod.rs
@@ -4,6 +4,13 @@ pub mod utils;
 pub use id::ID;
 
 use std::convert::TryInto;
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error("Data could not be parsed as an integer.")]
+    InvalidInteger,
+}
 
 /// Hotline defines 3 data types in the wire format:
 /// 1) "integer" (16-bit or 32-bit, determined by magnitude)
@@ -33,9 +40,23 @@ pub struct Field {
 /// - Some field IDs are definitely “integer” (e.g. user ID).
 /// - Some are definitely “string” (e.g. user name).
 /// - Others are “binary” (which might contain sub-structures).
-pub fn parse_field_value(id: ID, data: &[u8]) -> Value {
-    use Value::*;
-    use ID::*;
+#[must_use]
+pub fn parse_field_value(id: ID, data: &[u8]) -> Result<Value, Error> {
+    use Value::{Binary, Integer, Text};
+    use ID::{
+        AutomaticResponse, ChatID, ChatOptions, ChatSubject, CommunityBannerID, Data, ErrorText,
+        FileComment, FileCreateDate, FileCreatorString, FileModifyDate, FileName, FileNameWithInfo,
+        FileNewName, FileNewPath, FilePath, FileResumeData, FileSize, FileType, FileTypeString,
+        FileXferOptions, FolderItemCount, LegacyNewsCategoryListData, NewsArticle1stChildArticle,
+        NewsArticleData, NewsArticleDataFlavor, NewsArticleDate, NewsArticleFlags, NewsArticleID,
+        NewsArticleListData, NewsArticleNextArticle, NewsArticleParentArticle, NewsArticlePoster,
+        NewsArticlePrevArticle, NewsArticleRecurseDel, NewsArticleTitle, NewsCategoryGUID,
+        NewsCategoryListData, NewsCategoryName, NewsPath, NoServerAgreement, Options,
+        QuotingMessage, ReferenceNumber, ServerAgreement, ServerBanner, ServerBannerType,
+        ServerBannerUrl, ServerName, TransferSize, Unknown, UserAccess, UserAlias, UserFlags,
+        UserID, UserIconID, UserLogin, UserName, UserNameWithInfo, UserPassword, Version,
+        WaitingCount,
+    };
 
     // By default, assume "binary"
     // Then override to integer or string if the spec clearly says so.
@@ -71,20 +92,18 @@ pub fn parse_field_value(id: ID, data: &[u8]) -> Value {
 
             let len = data.len();
             if len == 2 {
-                Integer(u16::from_be_bytes(data.try_into().unwrap()) as u32)
+                data.try_into()
+                    .map(u16::from_be_bytes)
+                    .map(u32::from)
+                    .map(Integer)
+                    .map_err(|_| Error::InvalidInteger)
             } else if len == 4 {
-                Integer(u32::from_be_bytes(data.try_into().unwrap()))
-            } else if len == 0 {
-                // no data => 0
-                Integer(0)
+                data.try_into()
+                    .map(u32::from_be_bytes)
+                    .map(Integer)
+                    .map_err(|_| Error::InvalidInteger)
             } else {
-                // fallback
-                // interpret first 4 bytes, or everything as 32-bit
-                let mut buf = [0u8; 4];
-                for (i, b) in data.iter().enumerate().take(4) {
-                    buf[i] = *b;
-                }
-                Integer(u32::from_be_bytes(buf))
+                Err(Error::InvalidInteger)
             }
         }
 
@@ -106,7 +125,7 @@ pub fn parse_field_value(id: ID, data: &[u8]) -> Value {
         | NewsArticleTitle
         | NewsArticlePoster => {
             let s = String::from_utf8_lossy(data).to_string();
-            Text(s)
+            Ok(Text(s))
         }
 
         // Some are definitely “binary,” but might happen to contain text:
@@ -133,6 +152,6 @@ pub fn parse_field_value(id: ID, data: &[u8]) -> Value {
         | NewsPath
         | NewsArticleDate
         | NewsArticleData
-        | Unknown(_) => Binary(data.to_vec()),
+        | Unknown(_) => Ok(Binary(data.to_vec())),
     }
 }