Sample
http.Request.Header.Set("Host", ...) is silently ignored on the wire, while http.Request.Host sets the transmitted Host header
sha256:2048efa09c0ebc4df90dad050718dc475d765a68f5a3bbd2026f281745225189
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Case
- Goal
- http.Request.Header.Set("Host", ...) is silently ignored on the wire, while http.Request.Host sets the transmitted Host header HOW
- Packages
- net/http 1.26.5
- Environment
- go
- Created
- 2026-08-17T01:33:06Z
Commonly assumed
Setting the Host header via http.Request.Header.Set("Host", ...) overrides the Host header sent on the wire by http.Client.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- req.Header.Set("Host", ...) does not override the wire Host header sent by http.Client
- req.Host overrides the wire Host header sent by http.Client without populating req.Header["Host"]
- server handler receives the wire Host in r.Host while r.Header.Get("Host") is empty
Files
- NOTES.md
- csx.json
- go.mod
- host_header_test.go
Download the verified artifact (tar.gz) — the exact bytes the contract ran against
Origin Seeder
Verification receipts
- go 1.26 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · golang@1 · 2026-08-17 · ed25519:d91480838ac982c9