py-multiaddr improvement

[acul71]

py-multiaddr Specification Compliance Analysis

Overview

This document analyzes the compliance of py-multiaddr with the libp2p addressing specifications. The analysis is based on the implementation in multiaddr/multiaddr.py and related files.

Core Requirements Compliance

1. Basic Multiaddr Format

✅ Compliant

• Implements both string and binary representations
• Supports protocol codes and values
• Handles nested addresses correctly
• Implements proper encoding/decoding

2. Protocol Support

✅ Compliant

• Uses a registry system for protocols
• Supports protocol validation
• Implements protocol code handling
• Supports variable-length protocol values

3. Binary Format

✅ Compliant

• Implements proper binary encoding
• Handles varint encoding for lengths
• Supports proper byte ordering
• Implements binary parsing

4. String Format

✅ Compliant

• Implements proper string representation
• Handles protocol names correctly
• Supports proper formatting
• Implements string parsing

Feature Implementation

1. Core Operations

✅ Implemented

• encapsulate() - Adds one multiaddr to another
• decapsulate() - Removes a multiaddr from another
• split() - Splits a multiaddr into components
• join() - Combines multiple multiaddrs

2. Protocol Operations

✅ Implemented

• Protocol validation
• Protocol code handling
• Protocol value extraction
• Protocol registry system

3. Data Access

✅ Implemented

• to_bytes() - Binary representation
• __str__() - String representation
• protocols() - Protocol list
• value_for_protocol() - Protocol value extraction

Missing or Incomplete Features

1. DNS Resolution

❌ Not Implemented

• No built-in DNS resolution support
• Missing DNSADDR protocol handling
• No resolver system

Implementation Details:

1. DNS Resolution System:

   • Create a new module multiaddr/resolvers/ to handle DNS resolution
   • Implement a base Resolver class with async resolution methods
   • Add support for DNSADDR protocol (code 56) in protocols table
   • Implement DNS TXT record parsing for DNSADDR

2. Required Changes:

   # New file: multiaddr/resolvers/__init__.py
   from typing import List, Optional
   from ..multiaddr import Multiaddr
   
   class Resolver:
       async def resolve(self, ma: Multiaddr) -> List[Multiaddr]:
           """Resolve a multiaddr that contains a resolvable protocol."""
           pass
   
   # New file: multiaddr/resolvers/dns.py
   import aiodns
   from . import Resolver
   
   class DNSResolver(Resolver):
       async def resolve(self, ma: Multiaddr) -> List[Multiaddr]:
           # Implementation for DNS resolution
           pass

3. Integration Points:

   • Add resolve() method to Multiaddr class
   • Update protocol registry to include resolvable protocols
   • Add DNS resolution configuration options

2. Thin Waist Address Validation

❌ Not Implemented

• No explicit thin waist address validation
• Missing thin waist protocol combination checks

Implementation Details:

1. Thin Waist Definition:

   • A thin waist address must follow the pattern: {ip4,ip6}/{tcp,udp}
   • Additional protocols can be added after the thin waist
   • Must validate protocol order and combinations

2. Required Changes:

   # Add to multiaddr/multiaddr.py
   def is_thin_waist(self) -> bool:
       """Check if this multiaddr is a thin waist address.
       
       A thin waist address must start with ip4/ip6 followed by tcp/udp.
       """
       protocols = list(self.protocols())
       if len(protocols) < 2:
           return False
           
       # Check first protocol is ip4/ip6
       if protocols[0].code not in (4, 41):  # ip4 or ip6
           return False
           
       # Check second protocol is tcp/udp
       if protocols[1].code not in (6, 273):  # tcp or udp
           return False
           
       return True

3. Validation Rules:

   • Implement protocol order validation
   • Add protocol combination checks
   • Add validation in constructor and encapsulate methods
   • Add helper methods for common thin waist operations

4. Integration Points:

   • Add validation in Multiaddr constructor
   • Add validation in encapsulate() method
   • Add helper methods for thin waist operations
   • Update documentation with thin waist requirements

Recommendations

1. High Priority

   • Implement DNS resolution support
   • Add thin waist address validation

2. Medium Priority

   • Add more extensive protocol validation
   • Improve error handling with specific error types
   • Add more comprehensive documentation

3. Low Priority

   • Add more utility functions
   • Improve type hints
   • Add more examples

Conclusion

The py-multiaddr implementation follows the core libp2p addressing specifications well, but lacks some advanced features present in other implementations. The core functionality is solid, but there's room for improvement in terms of additional features like DNS resolution and thin waist address validation.

[acul71]

py-multiaddr vs js-multiaddr Implementation Comparison

Overview

This document compares the Python (py-multiaddr) and JavaScript (js-multiaddr) implementations of the libp2p multiaddr specification, focusing on feature differences and implementation approaches.

Core Implementation Differences

1. Type System

• py-multiaddr:

  • Uses Python's type hints
  • Implements Python's collection protocols (Mapping, Sequence)
  • More Pythonic approach to type handling

• js-multiaddr:

  • Uses TypeScript interfaces
  • More explicit type definitions
  • Stricter type checking at compile time

2. Protocol Handling

• py-multiaddr:

  • Uses a registry system for protocols
  • Protocol validation through registry
  • More flexible protocol registration

• js-multiaddr:

  • More extensive protocol-related methods
  • Built-in protocol validation
  • More protocol utility functions

3. Data Access Methods

• py-multiaddr:

  • Basic protocol access
  • String and binary conversion
  • Protocol value extraction

• js-multiaddr:

  • More extensive protocol access methods
  • Additional utility functions
  • More comprehensive protocol information

Feature Comparison

1. Core Features (Both Implement)

✅ Both Implement:

• String and binary representations
• Protocol code handling
• Encapsulation/decapsulation
• Basic protocol validation
• Protocol value extraction

2. Additional Features in js-multiaddr

🔍 js-multiaddr Only:

DNS Resolution Support

The JavaScript implementation includes built-in DNS resolution capabilities, particularly for DNSADDR protocol.

js-multiaddr Example:

// Resolving a DNSADDR multiaddr
const ma = multiaddr('/dnsaddr/bootstrap.libp2p.io')
const resolved = await ma.resolve()
// Returns array of resolved multiaddrs

Proposed py-multiaddr Implementation:

# New file: multiaddr/resolvers/dns.py
from typing import List, Optional
import aiodns
from ..multiaddr import Multiaddr

class DNSResolver:
    def __init__(self):
        self.resolver = aiodns.DNSResolver()
    
    async def resolve(self, ma: Multiaddr) -> List[Multiaddr]:
        """Resolve a DNSADDR multiaddr to its actual addresses."""
        if not ma.protocols()[0].name == 'dnsaddr':
            return [ma]
            
        # Get the hostname
        hostname = ma.value_for_protocol('dnsaddr')
        if not hostname:
            return [ma]
            
        # Query DNS TXT records
        try:
            txt_records = await self.resolver.query(hostname, 'TXT')
            results = []
            for record in txt_records:
                # Parse TXT record and create new multiaddr
                for addr in record.text:
                    if addr.startswith('dnsaddr='):
                        results.append(Multiaddr(addr[8:]))
            return results
        except Exception as e:
            raise DNSResolutionError(f"Failed to resolve {hostname}: {str(e)}")

Thin Waist Address Validation

js-multiaddr includes explicit validation for thin waist addresses (ip4/ip6 + tcp/udp combinations).

js-multiaddr Example:

const ma = multiaddr('/ip4/127.0.0.1/tcp/4001')
ma.isThinWaistAddress() // true

const ma2 = multiaddr('/ip4/127.0.0.1/tcp/4001/ws')
ma2.isThinWaistAddress() // false

Proposed py-multiaddr Implementation:

# Add to multiaddr/multiaddr.py
def is_thin_waist(self) -> bool:
    """Check if this multiaddr is a thin waist address.
    
    A thin waist address must start with ip4/ip6 followed by tcp/udp.
    Additional protocols can be added after the thin waist.
    """
    protocols = list(self.protocols())
    if len(protocols) < 2:
        return False
        
    # Check first protocol is ip4/ip6
    if protocols[0].code not in (4, 41):  # ip4 or ip6
        return False
        
    # Check second protocol is tcp/udp
    if protocols[1].code not in (6, 273):  # tcp or udp
        return False
        
    return True

def get_thin_waist(self) -> Optional['Multiaddr']:
    """Extract the thin waist portion of this multiaddr if it exists."""
    if not self.is_thin_waist():
        return None
        
    protocols = list(self.protocols())
    return self.split(2)[0]  # Return first two protocols

Protocol Utility Methods

js-multiaddr provides more extensive protocol-related utility methods.

js-multiaddr Example:

const ma = multiaddr('/ip4/127.0.0.1/tcp/4001')

// Protocol information methods
ma.protoCodes()  // [4, 6]
ma.protoNames()  // ['ip4', 'tcp']
ma.tuples()      // [[4, <Buffer>], [6, <Buffer>]]
ma.stringTuples() // [[4, '127.0.0.1'], [6, '4001']]

// Protocol validation and extraction
ma.isThinWaistAddress() // Checks if address follows thin waist principle
ma.getPeerId()   // Returns peer ID if present
ma.getPath()     // Returns path if present

// Protocol manipulation
const addr = multiaddr('/ip4/0.0.0.0/tcp/8080/p2p/QmcgpsyWgH8Y8ajJz1Cu72KnS5uo2Aa2LpzU7kinSupNKC')
addr.decapsulateCode(421)  // Returns: Multiaddr('/ip4/0.0.0.0/tcp/8080')

Proposed py-multiaddr Implementation:

# Add to multiaddr/multiaddr.py

# Protocol information methods
def proto_codes(self) -> List[int]:
    """Return the protocol codes in order."""
    return [p.code for p in self.protocols()]

def proto_names(self) -> List[str]:
    """Return the protocol names in order."""
    return [p.name for p in self.protocols()]

def tuples(self) -> List[Tuple[int, bytes]]:
    """Return the protocol code/value pairs."""
    return [(p.code, self.value_for_protocol(p)) 
            for p in self.protocols() 
            if self.value_for_protocol(p) is not None]

def string_tuples(self) -> List[Tuple[int, str]]:
    """Return the protocol code/value pairs with string values.
    
    Example:
        >>> addr = Multiaddr('/ip4/127.0.0.1/tcp/4001')
        >>> addr.string_tuples()
        [(4, '127.0.0.1'), (6, '4001')]
    """
    return [(p.code, str(self.value_for_protocol(p))) 
            for p in self.protocols() 
            if self.value_for_protocol(p) is not None]

# Protocol validation and extraction
def is_thin_waist(self) -> bool:
    """Check if this multiaddr is a thin waist address.
    
    A thin waist address must start with ip4/ip6 followed by tcp/udp.
    Additional protocols can be added after the thin waist.
    
    Example:
        >>> addr1 = Multiaddr('/ip4/127.0.0.1/tcp/80')
        >>> addr1.is_thin_waist()  # True
        >>> addr2 = Multiaddr('/ip4/127.0.0.1/tcp/80/udp/53')
        >>> addr2.is_thin_waist()  # False
    """
    protocols = list(self.protocols())
    if len(protocols) < 2:
        return False
        
    # Check first protocol is ip4/ip6
    if protocols[0].code not in (4, 41):  # ip4 or ip6
        return False
        
    # Check second protocol is tcp/udp
    if protocols[1].code not in (6, 273):  # tcp or udp
        return False
        
    return True

def get_peer_id(self) -> Optional[str]:
    """Get the P2P peer ID if present.
    
    Example:
        >>> addr = Multiaddr('/ip4/127.0.0.1/tcp/80/p2p/QmHash')
        >>> addr.get_peer_id()  # Returns: 'QmHash'
    """
    for proto in self.protocols():
        if proto.name == 'p2p':
            return proto.value
    return None

def get_path(self) -> Optional[str]:
    """Get the path if present.
    
    Example:
        >>> addr = Multiaddr('/ip4/127.0.0.1/tcp/80/unix/tmp/p2p.sock')
        >>> addr.get_path()  # Returns: '/tmp/p2p.sock'
    """
    for proto in self.protocols():
        if proto.name == 'unix':
            return proto.value
    return None

# Protocol manipulation
def decapsulate_code(self, code: int) -> 'Multiaddr':
    """Remove the last occurrence of a protocol with the given code.
    
    This is a more reliable version of decapsulate when targeting a specific
    protocol code. The last index of the code will be removed from the Multiaddr,
    and a new instance will be returned. If the code is not present, the original
    Multiaddr is returned.
    
    Example:
        >>> addr = Multiaddr('/ip4/0.0.0.0/tcp/8080/p2p/QmcgpsyWgH8Y8ajJz1Cu72KnS5uo2Aa2LpzU7kinSupNKC')
        >>> addr.decapsulate_code(421)  # 421 is the p2p protocol code
        Multiaddr('/ip4/0.0.0.0/tcp/8080')
    """
    protocols = list(self.protocols())
    # Find the last occurrence of the protocol code
    for i in range(len(protocols) - 1, -1, -1):
        if protocols[i].code == code:
            # Split at this index and return the first part
            return self.split(i)[0]
    # If code not found, return a copy of the original
    return Multiaddr(self)

Comprehensive Error Handling

js-multiaddr has more specific error types and better error messages.

js-multiaddr Example:

try {
    const ma = multiaddr('/invalid/addr')
} catch (e) {
    // e is a specific error type with detailed message
    console.error(e.message) // "Protocol not found: invalid"
}

Proposed py-multiaddr Implementation:

# New file: multiaddr/exceptions.py
class MultiaddrError(Exception):
    """Base class for all multiaddr errors."""
    pass

class ProtocolNotFoundError(MultiaddrError):
    """Raised when a protocol is not found in the registry."""
    def __init__(self, protocol: str):
        super().__init__(f"Protocol not found: {protocol}")
        self.protocol = protocol

class InvalidMultiaddrError(MultiaddrError):
    """Raised when a multiaddr string is invalid."""
    def __init__(self, addr: str, reason: str):
        super().__init__(f"Invalid multiaddr '{addr}': {reason}")
        self.addr = addr
        self.reason = reason

class ProtocolValueError(MultiaddrError):
    """Raised when a protocol value is invalid."""
    def __init__(self, protocol: str, value: str, reason: str):
        super().__init__(
            f"Invalid value for protocol {protocol}: {value} - {reason}"
        )
        self.protocol = protocol
        self.value = value
        self.reason = reason

Protocol Information Access

js-multiaddr provides more comprehensive access to protocol information.

js-multiaddr Example:

const ma = multiaddr('/ip4/127.0.0.1/tcp/4001')
ma.protos() // Returns detailed protocol information
// [
//   {code: 4, size: 32, name: 'ip4', resolvable: false},
//   {code: 6, size: 16, name: 'tcp', resolvable: false}
// ]

Proposed py-multiaddr Implementation:

# Add to multiaddr/protocols.py
@dataclass
class ProtocolInfo:
    """Detailed information about a protocol."""
    code: int
    size: int
    name: str
    resolvable: bool = False
    path: bool = False

# Add to multiaddr/multiaddr.py
def protocol_info(self) -> List[ProtocolInfo]:
    """Return detailed information about each protocol in this multiaddr."""
    return [
        ProtocolInfo(
            code=p.code,
            size=p.size,
            name=p.name,
            resolvable=getattr(p, 'resolvable', False),
            path=getattr(p, 'path', False)
        )
        for p in self.protocols()
    ]

Missing Tests in py-multiaddr

js-multiaddr has a comprehensive test suite that covers various aspects of multiaddr functionality. Here are the key tests that should be added to py-multiaddr:

1. Basic Construction Tests:

def test_construction():
    # Create multiaddr
    udp_addr = Multiaddr('/ip4/127.0.0.1/udp/1234')
    assert is_multiaddr(udp_addr) is True

    # Clone multiaddr
    udp_addr_clone = Multiaddr(udp_addr)
    assert udp_addr_clone != udp_addr
    assert udp_addr_clone.bytes == udp_addr.bytes

    # Reconstruct with bytes
    assert Multiaddr(udp_addr.bytes).bytes != udp_addr.bytes  # Different objects
    assert Multiaddr(udp_addr.bytes).bytes == udp_addr.bytes  # Same content

    # Reconstruct with string
    assert Multiaddr(udp_addr.to_string()).bytes != udp_addr.bytes
    assert Multiaddr(udp_addr.to_string()).bytes == udp_addr.bytes

    # Empty construct
    assert Multiaddr('').to_string() == '/'

    # Invalid inputs
    with pytest.raises(ValueError):
        Multiaddr({})  # Invalid dict
    with pytest.raises(ValueError):
        Multiaddr([])  # Invalid list
    with pytest.raises(ValueError):
        Multiaddr(138)  # Invalid number

def test_construction_edge_cases():
    # Null/None handling
    assert Multiaddr(None).to_string() == '/'
    assert Multiaddr().to_string() == '/'
    
    # Empty string variations
    assert Multiaddr('').to_string() == '/'
    assert Multiaddr('/').to_string() == '/'
    
    # Whitespace handling
    with pytest.raises(ValueError):
        Multiaddr(' /ip4/127.0.0.1')  # Leading whitespace
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1 ')  # Trailing whitespace
    
    # Special characters
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1/tcp/80/')  # Trailing slash
    with pytest.raises(ValueError):
        Multiaddr('ip4/127.0.0.1')  # Missing leading slash

2. Protocol Manipulation Tests:

def test_protocol_manipulation():
    # Basic protocol operations
    udp_addr = Multiaddr('/ip4/127.0.0.1/udp/1234')
    
    assert udp_addr.proto_codes() == [4, 273]  # ip4, udp
    assert udp_addr.proto_names() == ['ip4', 'udp']
    
    # Encapsulation
    udp_addr2 = udp_addr.encapsulate('/udp/5678')
    assert udp_addr2.to_string() == '/ip4/127.0.0.1/udp/1234/udp/5678'
    
    # Decapsulation
    assert udp_addr2.decapsulate('/udp').to_string() == '/ip4/127.0.0.1/udp/1234'
    assert udp_addr2.decapsulate('/ip4').to_string() == '/'
    
    # Decapsulate code
    p2p_addr = Multiaddr('/ip4/0.0.0.0/tcp/8080/p2p/QmcgpsyWgH8Y8ajJz1Cu72KnS5uo2Aa2LpzU7kinSupNKC')
    assert p2p_addr.decapsulate_code(421).to_string() == '/ip4/0.0.0.0/tcp/8080'

def test_protocol_manipulation_edge_cases():
    # Empty encapsulation/decapsulation
    addr = Multiaddr('/ip4/127.0.0.1')
    assert addr.encapsulate('').to_string() == addr.to_string()
    assert addr.decapsulate('').to_string() == addr.to_string()
    
    # Self encapsulation
    addr = Multiaddr('/ip4/127.0.0.1')
    assert addr.encapsulate(addr).to_string() == '/ip4/127.0.0.1/ip4/127.0.0.1'
    
    # Multiple decapsulation
    addr = Multiaddr('/ip4/127.0.0.1/tcp/80/tcp/443')
    assert addr.decapsulate('/tcp').to_string() == '/ip4/127.0.0.1/tcp/80'
    
    # Non-existent protocol decapsulation
    addr = Multiaddr('/ip4/127.0.0.1')
    assert addr.decapsulate('/tcp').to_string() == addr.to_string()
    
    # Protocol code edge cases
    addr = Multiaddr('/ip4/127.0.0.1/tcp/80')
    with pytest.raises(ValueError):
        addr.decapsulate_code(-1)  # Invalid protocol code
    with pytest.raises(ValueError):
        addr.decapsulate_code(999999)  # Non-existent protocol code

3. Protocol Variant Tests:

def test_protocol_variants():
    # IP4
    ip4_addr = Multiaddr('/ip4/127.0.0.1')
    assert ip4_addr.to_string() == '/ip4/127.0.0.1'
    
    # IP6
    ip6_addr = Multiaddr('/ip6/2001:8a0:7ac5:4201:3ac9:86ff:fe31:7095')
    assert ip6_addr.to_string() == '/ip6/2001:8a0:7ac5:4201:3ac9:86ff:fe31:7095'
    
    # IP4 + TCP
    tcp_addr = Multiaddr('/ip4/127.0.0.1/tcp/5000')
    assert tcp_addr.to_string() == '/ip4/127.0.0.1/tcp/5000'

def test_protocol_variants_edge_cases():
    # IP4 edge cases
    with pytest.raises(ValueError):
        Multiaddr('/ip4/256.0.0.1')  # Invalid IP4
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0')  # Incomplete IP4
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1.1')  # Extra octet
    
    # IP6 edge cases
    with pytest.raises(ValueError):
        Multiaddr('/ip6/2001:8a0:7ac5:4201:3ac9:86ff:fe31:7095:1234')  # Extra segment
    with pytest.raises(ValueError):
        Multiaddr('/ip6/2001:8a0:7ac5:4201:3ac9:86ff:fe31')  # Incomplete IP6
    
    # TCP/UDP port edge cases
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1/tcp/70000')  # Port too large
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1/tcp/-1')  # Negative port
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1/tcp/abc')  # Non-numeric port

4. Thin Waist Tests:

def test_thin_waist():
    # Valid thin waist addresses
    valid_addr1 = Multiaddr('/ip4/127.0.0.1/tcp/80')
    assert valid_addr1.is_thin_waist() is True
    
    valid_addr2 = Multiaddr('/ip6/::1/udp/53')
    assert valid_addr2.is_thin_waist() is True
    
    # Invalid thin waist addresses
    invalid_addr1 = Multiaddr('/ip4/127.0.0.1/tcp/80/udp/53')
    assert invalid_addr1.is_thin_waist() is False
    
    invalid_addr2 = Multiaddr('/tcp/80')
    assert invalid_addr2.is_thin_waist() is False

def test_thin_waist_edge_cases():
    # Empty address
    assert Multiaddr('').is_thin_waist() is False
    
    # Single protocol
    assert Multiaddr('/ip4/127.0.0.1').is_thin_waist() is False
    assert Multiaddr('/tcp/80').is_thin_waist() is False
    
    # Wrong order
    assert Multiaddr('/tcp/80/ip4/127.0.0.1').is_thin_waist() is False
    
    # Multiple network protocols
    assert Multiaddr('/ip4/127.0.0.1/ip6/::1/tcp/80').is_thin_waist() is False
    
    # Multiple transport protocols
    assert Multiaddr('/ip4/127.0.0.1/tcp/80/tcp/443').is_thin_waist() is False
    
    # Non-standard protocols
    assert Multiaddr('/ip4/127.0.0.1/ws').is_thin_waist() is False
    assert Multiaddr('/ip4/127.0.0.1/wss').is_thin_waist() is False

5. Protocol Information Tests:

def test_protocol_information():
    addr = Multiaddr('/ip4/127.0.0.1/tcp/80/p2p/QmHash')
    
    # Get peer ID
    assert addr.get_peer_id() == 'QmHash'
    
    # Get path
    unix_addr = Multiaddr('/ip4/127.0.0.1/tcp/80/unix/tmp/p2p.sock')
    assert unix_addr.get_path() == '/tmp/p2p.sock'
    
    # Protocol tuples
    assert addr.tuples() == [(4, b'127.0.0.1'), (6, b'80'), (421, b'QmHash')]
    assert addr.string_tuples() == [(4, '127.0.0.1'), (6, '80'), (421, 'QmHash')]

def test_protocol_information_edge_cases():
    # Empty address
    addr = Multiaddr('')
    assert addr.proto_codes() == []
    assert addr.proto_names() == []
    assert addr.tuples() == []
    assert addr.string_tuples() == []
    
    # Missing peer ID
    addr = Multiaddr('/ip4/127.0.0.1/tcp/80')
    assert addr.get_peer_id() is None
    
    # Invalid peer ID format
    addr = Multiaddr('/ip4/127.0.0.1/tcp/80/p2p/invalid')
    assert addr.get_peer_id() == 'invalid'  # Should still return the value
    
    # Multiple paths
    addr = Multiaddr('/ip4/127.0.0.1/tcp/80/unix/path1/unix/path2')
    assert addr.get_path() == '/path2'  # Should return last path
    
    # Protocol with no value
    addr = Multiaddr('/ip4/127.0.0.1/tcp/80/ws')
    assert addr.tuples() == [(4, b'127.0.0.1'), (6, b'80'), (477, b'')]

6. Error Handling Tests:

def test_error_handling():
    # Invalid protocol codes
    with pytest.raises(ValueError):
        Multiaddr('/invalid/127.0.0.1')
    
    # Invalid protocol values
    with pytest.raises(ValueError):
        Multiaddr('/ip4/256.0.0.1')  # Invalid IP
    
    # Invalid decapsulation
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1').decapsulate('/')

def test_error_handling_edge_cases():
    # Protocol code validation
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1').decapsulate_code(-1)
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1').decapsulate_code(999999)
    
    # Protocol value validation
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1/tcp/abc')  # Non-numeric port
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1/tcp/-1')  # Negative port
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1/tcp/70000')  # Port too large
    
    # Protocol order validation
    with pytest.raises(ValueError):
        Multiaddr('/tcp/80/ip4/127.0.0.1')  # Wrong order
    
    # Protocol combination validation
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1/ip4/192.168.0.1')  # Multiple IP4
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1/tcp/80/tcp/443')  # Multiple TCP
    
    # Protocol value format validation
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1/tcp/80/p2p/')  # Empty peer ID
    with pytest.raises(ValueError):
        Multiaddr('/ip4/127.0.0.1/tcp/80/unix/')  # Empty path

These tests cover the core functionality of multiaddr and would help ensure that py-multiaddr maintains compatibility with js-multiaddr. The tests are organized into logical groups and cover:

1. Basic construction and validation
2. Protocol manipulation (encapsulation/decapsulation)
3. Protocol variants (different address types)
4. Thin waist validation
5. Protocol information access
6. Error handling

Each test group now includes both basic functionality tests and edge cases to ensure robust implementation.

Conclusion

The JavaScript implementation (js-multiaddr) generally offers more features and stricter validation, while the Python implementation (py-multiaddr) provides more flexibility and better integration with Python's ecosystem. The core functionality is well-implemented in both, but js-multiaddr has more additional features that could be beneficial to add to py-multiaddr.

Key areas where py-multiaddr could be enhanced:

1. DNS resolution support - Adding built-in DNS resolution capabilities for protocols like dns, dns4, dns6, and dnsaddr
2. Thin waist address validation - Implementing stricter validation of the "thin waist" principle for network and transport protocols
3. More extensive protocol utility methods - Adding more utility methods for working with protocols and their values
4. More comprehensive error handling - Implementing more specific error types and better error messages
5. Additional protocol information access methods - Providing more comprehensive access to protocol information and metadata

These enhancements would make the Python implementation more robust, easier to use, and more aligned with the JavaScript implementation's capabilities. They would also make it easier to work with multiaddrs in a type-safe and error-resistant way.

[acul71]

I'm working on DNS resolution support here multiformats/py-multiaddr#68