Onchain.ENS (onchain v0.5.4)

ENS (Ethereum Name Service) resolution and namehash computation.

Does

Compute EIP-137 namehash for ENS names (namehash/1)
Normalize names (lowercase ASCII, strip trailing dot)
Validate name structure (reject empty labels, non-ASCII)
Forward resolution: ENS name → ETH address (resolve/2)
Reverse resolution: ETH address → ENS name (reverse/2)
Text record queries (text/3), contenthash, ABI, pubkey retrieval
Look up resolver contracts (resolver/2)
Configurable registry address via :registry opt

Does Not

CCIP-Read / EIP-3668 off-chain lookups (future enhancement)
Wildcard resolution (ENSIP-10)
ENS name registration or management (write operations)
Full UTS-46 / ENSIP-15 Unicode normalization (internationalized names)
Caching — consumers manage their own cache
Multi-coin address resolution (only ETH via addr(bytes32))

Functions

Function	Purpose
`namehash/1`	ENS name -> 32-byte EIP-137 node hash
`namehash!/1`	Same, raises on error
`resolver/2`	ENS name -> resolver contract address
`resolver!/2`	Same, raises on error
`resolve/2`	ENS name -> ETH address (forward resolution)
`resolve!/2`	Same, raises on error
`reverse/2`	ETH address -> ENS name (reverse resolution)
`reverse!/2`	Same, raises on error
`text/3`	Retrieve a text record (avatar, url, etc.)
`text!/3`	Same, raises on error
`contenthash/2`	Retrieve the contenthash record
`contenthash!/2`	Same, raises on error
`pubkey/2`	Retrieve the ECDSA public key
`pubkey!/2`	Same, raises on error
`abi/3`	Retrieve ABI data (ENSIP-7)
`abi!/3`	Same, raises on error

API Functions

Function	Arity	Description	Param Kinds
`abi!`	3	Retrieve ABI data. Raises on error.	`name: value`, `content_types: value`, `opts: value`
`abi`	3	Retrieve ABI data from an ENS name's resolver (ENSIP-7).	`name: value`, `content_types: value`, `opts: value`
`pubkey!`	2	Retrieve the ECDSA public key. Raises on error.	`name: value`, `opts: value`
`pubkey`	2	Retrieve the ECDSA public key from an ENS name's resolver.	`name: value`, `opts: value`
`contenthash!`	2	Retrieve the contenthash record. Raises on error.	`name: value`, `opts: value`
`contenthash`	2	Retrieve the contenthash record from an ENS name's resolver.	`name: value`, `opts: value`
`text!`	3	Retrieve a text record. Raises on error.	`name: value`, `key: value`, `opts: value`
`text`	3	Retrieve a text record from an ENS name's resolver.	`name: value`, `key: value`, `opts: value`
`reverse!`	2	Reverse-resolve an ETH address to an ENS name. Raises on error.	`address: value`, `opts: value`
`reverse`	2	Reverse-resolve an ETH address to an ENS name.	`address: value`, `opts: value`
`resolve!`	2	Resolve an ENS name to an ETH address. Raises on error.	`name: value`, `opts: value`
`resolve`	2	Resolve an ENS name to an ETH address (forward resolution).	`name: value`, `opts: value`
`resolver!`	2	Look up the resolver contract address. Raises on error.	`name: value`, `opts: value`
`resolver`	2	Look up the resolver contract address for an ENS name.	`name: value`, `opts: value`
`namehash!`	1	Compute the EIP-137 namehash. Raises on error.	`name: value`
`namehash`	1	Compute the EIP-137 namehash for an ENS name.	`name: value`

Summary

Functions

abi(name, content_types, opts \\ [])

Retrieve ABI data from an ENS name's resolver (ENSIP-7).

abi!(name, content_types, opts \\ [])

Retrieve ABI data. Raises on error.

contenthash(name, opts \\ [])

Retrieve the contenthash record from an ENS name's resolver.

contenthash!(name, opts \\ [])

Retrieve the contenthash record. Raises on error.

namehash(name)

Compute the EIP-137 namehash for an ENS name.

namehash!(name)

Compute the EIP-137 namehash. Raises on error.

pubkey(name, opts \\ [])

Retrieve the ECDSA public key from an ENS name's resolver.

pubkey!(name, opts \\ [])

Retrieve the ECDSA public key. Raises on error.

resolve(name, opts \\ [])

Resolve an ENS name to an ETH address (forward resolution).

resolve!(name, opts \\ [])

Resolve an ENS name to an ETH address. Raises on error.

resolver(name, opts \\ [])

Look up the resolver contract address for an ENS name.

resolver!(name, opts \\ [])

Look up the resolver contract address. Raises on error.

reverse(address, opts \\ [])

Reverse-resolve an ETH address to an ENS name.

reverse!(address, opts \\ [])

Reverse-resolve an ETH address to an ENS name. Raises on error.

text(name, key, opts \\ [])

Retrieve a text record from an ENS name's resolver.

text!(name, key, opts \\ [])

Retrieve a text record. Raises on error.

Functions

abi(name, content_types, opts \\ [])

@spec abi(String.t(), non_neg_integer(), keyword()) ::
  {:ok, {non_neg_integer(), binary()}} | {:error, term()}

Retrieve ABI data from an ENS name's resolver (ENSIP-7).

Parameters

name - ENS name (e.g., "vitalik.eth") (value)
content_types - Bitmask of content types: 1=JSON, 2=zlib, 4=CBOR, 8=URI (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

Tuple of {content_type, abi_data} ({:ok, {non_neg_integer(), binary()}} | {:error, term()})

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name (e.g., \"vitalik.eth\")", kind: :value},
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    },
    content_types: %{
      description: "Bitmask of content types: 1=JSON, 2=zlib, 4=CBOR, 8=URI",
      kind: :value
    }
  },
  returns: %{
    type: "{:ok, {non_neg_integer(), binary()}} | {:error, term()}",
    description: "Tuple of {content_type, abi_data}"
  }
}

abi!(name, content_types, opts \\ [])

@spec abi!(String.t(), non_neg_integer(), keyword()) :: {non_neg_integer(), binary()}

Retrieve ABI data. Raises on error.

Parameters

name - ENS name (e.g., "vitalik.eth") (value)
content_types - Bitmask of content types: 1=JSON, 2=zlib, 4=CBOR, 8=URI (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

Tuple of {content_type, abi_data} ({non_neg_integer(), binary()})

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name (e.g., \"vitalik.eth\")", kind: :value},
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    },
    content_types: %{
      description: "Bitmask of content types: 1=JSON, 2=zlib, 4=CBOR, 8=URI",
      kind: :value
    }
  },
  returns: %{
    type: "{non_neg_integer(), binary()}",
    description: "Tuple of {content_type, abi_data}"
  }
}

contenthash(name, opts \\ [])

@spec contenthash(
  String.t(),
  keyword()
) :: {:ok, binary()} | {:error, term()}

Retrieve the contenthash record from an ENS name's resolver.

Parameters

name - ENS name (e.g., "vitalik.eth") (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

Raw contenthash bytes (ENSIP-7 encoded) ({:ok, binary()} | {:error, term()})

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name (e.g., \"vitalik.eth\")", kind: :value},
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    }
  },
  returns: %{
    type: "{:ok, binary()} | {:error, term()}",
    description: "Raw contenthash bytes (ENSIP-7 encoded)"
  }
}

contenthash!(name, opts \\ [])

@spec contenthash!(
  String.t(),
  keyword()
) :: binary()

Retrieve the contenthash record. Raises on error.

Parameters

name - ENS name (e.g., "vitalik.eth") (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

Raw contenthash bytes (binary())

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name (e.g., \"vitalik.eth\")", kind: :value},
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    }
  },
  returns: %{type: "binary()", description: "Raw contenthash bytes"}
}

namehash(name)

@spec namehash(String.t()) :: {:ok, binary()} | {:error, {:invalid_name, String.t()}}

Compute the EIP-137 namehash for an ENS name.

Parameters

name - ENS name, e.g. "vitalik.eth" (value)

Returns

32-byte keccak256 node hash per EIP-137 ({:ok, <<_::256>>} | {:error, term})

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name, e.g. \"vitalik.eth\"", kind: :value}
  },
  returns: %{
    type: "{:ok, <<_::256>>} | {:error, term}",
    description: "32-byte keccak256 node hash per EIP-137"
  }
}

namehash!(name)

@spec namehash!(String.t()) :: binary()

Compute the EIP-137 namehash. Raises on error.

Parameters

name - ENS name, e.g. "vitalik.eth" (value)

Returns

32-byte keccak256 node hash (<<_::256>>)

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name, e.g. \"vitalik.eth\"", kind: :value}
  },
  returns: %{type: "<<_::256>>", description: "32-byte keccak256 node hash"}
}

pubkey(name, opts \\ [])

@spec pubkey(
  String.t(),
  keyword()
) :: {:ok, {binary(), binary()}} | {:error, term()}

Retrieve the ECDSA public key from an ENS name's resolver.

Parameters

name - ENS name (e.g., "vitalik.eth") (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

Tuple of {x, y} 32-byte coordinates ({:ok, {binary(), binary()}} | {:error, term()})

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name (e.g., \"vitalik.eth\")", kind: :value},
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    }
  },
  returns: %{
    type: "{:ok, {binary(), binary()}} | {:error, term()}",
    description: "Tuple of {x, y} 32-byte coordinates"
  }
}

pubkey!(name, opts \\ [])

@spec pubkey!(
  String.t(),
  keyword()
) :: {binary(), binary()}

Retrieve the ECDSA public key. Raises on error.

Parameters

name - ENS name (e.g., "vitalik.eth") (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

Tuple of {x, y} 32-byte coordinates ({binary(), binary()})

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name (e.g., \"vitalik.eth\")", kind: :value},
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    }
  },
  returns: %{
    type: "{binary(), binary()}",
    description: "Tuple of {x, y} 32-byte coordinates"
  }
}

resolve(name, opts \\ [])

@spec resolve(
  String.t(),
  keyword()
) :: {:ok, String.t()} | {:error, term()}

Resolve an ENS name to an ETH address (forward resolution).

Parameters

name - ENS name (e.g., "vitalik.eth") (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

EIP-55 checksummed ETH address ({:ok, String.t()} | {:error, term()})

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name (e.g., \"vitalik.eth\")", kind: :value},
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    }
  },
  returns: %{
    type: "{:ok, String.t()} | {:error, term()}",
    description: "EIP-55 checksummed ETH address"
  }
}

resolve!(name, opts \\ [])

@spec resolve!(
  String.t(),
  keyword()
) :: String.t()

Resolve an ENS name to an ETH address. Raises on error.

Parameters

name - ENS name (e.g., "vitalik.eth") (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

EIP-55 checksummed ETH address (String.t())

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name (e.g., \"vitalik.eth\")", kind: :value},
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    }
  },
  returns: %{type: "String.t()", description: "EIP-55 checksummed ETH address"}
}

resolver(name, opts \\ [])

@spec resolver(
  String.t(),
  keyword()
) :: {:ok, String.t()} | {:error, term()}

Look up the resolver contract address for an ENS name.

Parameters

name - ENS name (e.g., "vitalik.eth") (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

EIP-55 checksummed resolver address ({:ok, String.t()} | {:error, term()})

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name (e.g., \"vitalik.eth\")", kind: :value},
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    }
  },
  returns: %{
    type: "{:ok, String.t()} | {:error, term()}",
    description: "EIP-55 checksummed resolver address"
  }
}

resolver!(name, opts \\ [])

@spec resolver!(
  String.t(),
  keyword()
) :: String.t()

Look up the resolver contract address. Raises on error.

Parameters

name - ENS name (e.g., "vitalik.eth") (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

EIP-55 checksummed resolver address (String.t())

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name (e.g., \"vitalik.eth\")", kind: :value},
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    }
  },
  returns: %{
    type: "String.t()",
    description: "EIP-55 checksummed resolver address"
  }
}

reverse(address, opts \\ [])

@spec reverse(
  String.t() | binary(),
  keyword()
) :: {:ok, String.t()} | {:error, term()}

Reverse-resolve an ETH address to an ENS name.

Parameters

address - ETH address as 0x hex string or 20-byte binary (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

ENS name (e.g., "vitalik.eth") ({:ok, String.t()} | {:error, term()})

# descripex:contract
%{
  params: %{
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    },
    address: %{
      description: "ETH address as 0x hex string or 20-byte binary",
      kind: :value
    }
  },
  returns: %{
    type: "{:ok, String.t()} | {:error, term()}",
    description: "ENS name (e.g., \"vitalik.eth\")"
  }
}

reverse!(address, opts \\ [])

@spec reverse!(
  String.t() | binary(),
  keyword()
) :: String.t()

Reverse-resolve an ETH address to an ENS name. Raises on error.

Parameters

address - ETH address as 0x hex string or 20-byte binary (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

ENS name (e.g., "vitalik.eth") (String.t())

# descripex:contract
%{
  params: %{
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    },
    address: %{
      description: "ETH address as 0x hex string or 20-byte binary",
      kind: :value
    }
  },
  returns: %{
    type: "String.t()",
    description: "ENS name (e.g., \"vitalik.eth\")"
  }
}

text(name, key, opts \\ [])

@spec text(String.t(), String.t(), keyword()) :: {:ok, String.t()} | {:error, term()}

Retrieve a text record from an ENS name's resolver.

Parameters

name - ENS name (e.g., "vitalik.eth") (value)
key - Text record key (e.g., "avatar", "url", "com.twitter") (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

Text record value ({:ok, String.t()} | {:error, term()})

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name (e.g., \"vitalik.eth\")", kind: :value},
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    },
    key: %{
      description: "Text record key (e.g., \"avatar\", \"url\", \"com.twitter\")",
      kind: :value
    }
  },
  returns: %{
    type: "{:ok, String.t()} | {:error, term()}",
    description: "Text record value"
  }
}

text!(name, key, opts \\ [])

@spec text!(String.t(), String.t(), keyword()) :: String.t()

Retrieve a text record. Raises on error.

Parameters

name - ENS name (e.g., "vitalik.eth") (value)
key - Text record key (e.g., "avatar", "url", "com.twitter") (value)
opts - Options: :rpc_url, :timeout, :registry (default: [], value)

Returns

Text record value (String.t())

# descripex:contract
%{
  params: %{
    name: %{description: "ENS name (e.g., \"vitalik.eth\")", kind: :value},
    opts: %{
      default: [],
      description: "Options: :rpc_url, :timeout, :registry",
      kind: :value
    },
    key: %{
      description: "Text record key (e.g., \"avatar\", \"url\", \"com.twitter\")",
      kind: :value
    }
  },
  returns: %{type: "String.t()", description: "Text record value"}
}