ICAP Server & Client in Go

A minimal working ICAP server and client implementation in Go, designed for testing RESPMOD (response modification) use cases like keyword-based content filtering.

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🧰 Features

• Supports RESPMOD (response modification)
• Parses full ICAP and embedded HTTP payloads
• Blocks responses with banned keywords like drugs, sex, violence
• Returns 403 Forbidden when content matches, or 204 No Content otherwise
• Includes a CLI test client that sends an ICAP RESPMOD request with an embedded HTTP response

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🚀 Getting Started

🛠 Requirements

• Go 1.18+
• No dependencies or external libraries

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▶️ Running the Server

go run icap-server.go

You should see:

ICAP server running on :1344

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💬 Testing the Server

Create a test payload (that should be blocked):

echo "this contains drugs" > test.txt

Run the client:

go run icap-client.go localhost:1344 /respmod test.txt

Expected output:

ICAP/1.0 200 OK
Encapsulated: res-hdr=0, res-body=75

HTTP/1.1 403 Forbidden
Content-Type: text/plain

Blocked by ICAP filter.

Clean text test:

echo "hello world" > test.txt
go run icap-client.go localhost:1344 /respmod test.txt

Expected output:

ICAP/1.0 204 No Content
Encapsulated: null-body=0

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