From b4e1a997a22d200e42c1662a1ddc483ce64c9b6f Mon Sep 17 00:00:00 2001
From: 0xtr <oxtrr@protonmail.com>
Date: Sun, 26 Jan 2025 01:08:35 +0100
Subject: [PATCH] Refactor range header parsing logic

There was a bug in the range header parsing logic where we expected
to always get both the start and stop byte range. This has now been
refactored so that start defaults to byte index 0 if no start value
is given and stop defaults to the length of the file if not defined
in the request.
---
 src/handlers/mod.rs | 31 +++++++++++++++++++++++--------
 1 file changed, 23 insertions(+), 8 deletions(-)

diff --git a/src/handlers/mod.rs b/src/handlers/mod.rs
index abf4593..7ce2f19 100644
--- a/src/handlers/mod.rs
+++ b/src/handlers/mod.rs
@@ -125,17 +125,26 @@ where
     }
 }
 
-fn parse_range_header(header: &str) -> Option<(u64, u64)> {
+fn parse_range_header(header: &str) -> Option<(u64, Option<u64>)> {
     let parts: Vec<&str> = header.split("=").collect();
     if parts.len() != 2 || parts[0] != "bytes" {
         return None;
     }
     let range_parts: Vec<&str> = parts[1].split("-").collect();
-    if range_parts.len() != 2 {
-        return None;
-    }
-    let start = range_parts[0].parse::<u64>().ok()?;
-    let stop = range_parts[1].parse::<u64>().ok()?;
+
+    let start = match range_parts[0] {
+        "" => 0,
+        _ => range_parts[0].parse::<u64>().ok()?,
+    };
+    let stop = if range_parts.len() == 2 {
+        match range_parts[1] {
+            "" => None,
+            _ => Some(range_parts[1].parse::<u64>().ok()?),
+        }
+    } else {
+        None
+    };
+
     Some((start, stop))
 }
 
@@ -270,12 +279,18 @@ pub async fn get_blob_handler(
 
     // Check for Range header (RFC 7233)
     if let Some(range_header) = headers.get(header::RANGE) {
-        let range = parse_range_header(range_header.to_str().unwrap());
+        let range: Option<(u64, Option<u64>)> = parse_range_header(range_header.to_str().unwrap());
         match range {
             Some((start, stop)) => {
-                if start >= stop || start >= file_contents.len() as u64 {
+                if start >= file_contents.len() as u64 {
+                    return build_range_not_satisfiable_error_response("Invalid range");
+                }
+
+                let stop = stop.unwrap_or(file_contents.len() as u64 - 1);
+                if start > stop {
                     return build_range_not_satisfiable_error_response("Invalid range");
                 }
+
                 let partial_response = file_contents[start as usize..(stop as usize + 1)].to_vec();
                 let content_range = format!("bytes {}-{}/{}", start, stop, file_contents.len());
                 let content_length = stop - start + 1;