Fix port allocation Groundhog Day loop, expand pool to 128 ports

Port allocator would spin on the same Docker-occupied ports because
releasing a flock and re-calling allocate() restarts from port 8192.
Now holds flocks on occupied ports during the scan so allocate()
advances past them.

Also expands default pool from 32 to 128 ports (8192-8319), and
makes range configurable via MCGHIDRA_PORT_START/MCGHIDRA_PORT_END
environment variables.

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "mcghidra"
-version = "2026.2.11"
+version = "2026.3.2"
 description = "AI-assisted reverse engineering bridge: a multi-instance Ghidra plugin exposed via a HATEOAS REST API plus an MCP Python bridge for decompilation, analysis & binary manipulation"
 readme = "README.md"
 requires-python = ">=3.11"

src/mcghidra/mixins/docker.py

@@ -24,10 +24,10 @@ from fastmcp.contrib.mcp_mixin import mcp_tool
 from mcghidra.core.logging import logger
 from mcghidra.mixins.base import MCGhidraMixinBase
 
-# Port pool configuration (32 ports should handle many concurrent sessions)
-PORT_POOL_START = 8192
-PORT_POOL_END = 8223
-PORT_LOCK_DIR = Path("/tmp/mcghidra-ports")
+# Port pool configuration — 128 ports by default, configurable via env vars
+PORT_POOL_START = int(os.environ.get("MCGHIDRA_PORT_START", "8192"))
+PORT_POOL_END = int(os.environ.get("MCGHIDRA_PORT_END", "8319"))
+PORT_LOCK_DIR = Path(os.environ.get("MCGHIDRA_PORT_LOCK_DIR", "/tmp/mcghidra-ports"))
 
 
 class PortPool:
@@ -216,7 +216,7 @@ class DockerMixin(MCGhidraMixinBase):
     with the MCGhidra plugin pre-installed.
 
     Supports multi-process environments with:
-    - Dynamic port allocation from a pool (8192-8223)
+    - Dynamic port allocation from a pool ({PORT_POOL_START}-{PORT_POOL_END})
     - Session-scoped container naming with UUIDs
     - Docker label-based tracking for cross-process visibility
     - Automatic cleanup of orphaned containers
@@ -561,7 +561,7 @@ class DockerMixin(MCGhidraMixinBase):
         plugin pre-installed. The binary will be imported and analyzed,
         then the HTTP API will be available.
 
-        Ports are automatically allocated from the pool (8192-8223) to
+        Ports are automatically allocated from the pool ({PORT_POOL_START}-{PORT_POOL_END}) to
         prevent conflicts between concurrent sessions. Container names
         are auto-generated with the session ID to ensure uniqueness.
 
@@ -588,6 +588,7 @@ class DockerMixin(MCGhidraMixinBase):
         # Clean up invalid characters in container name
         name = "".join(c if c.isalnum() or c in "-_" else "-" for c in name)
 
+        port = None
         try:
             # Check if container with this name already exists
             check_result = await self._run_docker_cmd(
@@ -598,33 +599,39 @@ class DockerMixin(MCGhidraMixinBase):
                     "error": f"Container '{name}' already exists. Stop it first with docker_stop."
                 }
 
-            # Allocate a port that's both lockable AND not in use by Docker
-            # This handles external containers (not managed by MCGhidra) using ports in our range
-            port = None
-            ports_tried = []
-            for _ in range(PORT_POOL_END - PORT_POOL_START + 1):
-                candidate_port = self.port_pool.allocate(self.session_id)
-                if candidate_port is None:
-                    break  # Pool exhausted
+            # Allocate a port that's both lockable AND not in use by Docker.
+            # We HOLD flocks on Docker-occupied ports while searching, so
+            # allocate() advances past them. Release held ports after.
+            held_ports = []  # Ports we locked but can't use (Docker-occupied)
+            try:
+                for _ in range(PORT_POOL_END - PORT_POOL_START + 1):
+                    candidate_port = self.port_pool.allocate(self.session_id)
+                    if candidate_port is None:
+                        break  # Pool exhausted
 
-                # Check if this port is already in use by a Docker container
-                port_check = await self._run_docker_cmd(
-                    ["ps", "-q", "-f", f"publish={candidate_port}"], check=False
-                )
-                if port_check.stdout.strip():
-                    # Port is in use by Docker - release and try next
-                    ports_tried.append(candidate_port)
-                    self.port_pool.release(candidate_port)
-                    continue
+                    # Check if this port is already in use by a Docker container
+                    port_check = await self._run_docker_cmd(
+                        ["ps", "-q", "-f", f"publish={candidate_port}"], check=False
+                    )
+                    if port_check.stdout.strip():
+                        # Port is Docker-occupied — hold the flock so allocate()
+                        # skips it on the next iteration, then release after loop
+                        held_ports.append(candidate_port)
+                        continue
 
-                # Found a usable port!
-                port = candidate_port
-                break
+                    # Found a usable port!
+                    port = candidate_port
+                    break
+            finally:
+                # Release all the Docker-occupied ports we held during the scan
+                for held in held_ports:
+                    self.port_pool.release(held)
 
             if port is None:
                 return {
-                    "error": "Port pool exhausted (8192-8223). All ports are in use by Docker containers.",
-                    "ports_checked": ports_tried if ports_tried else "all ports locked by other MCGhidra sessions",
+                    "error": f"Port pool exhausted ({PORT_POOL_START}-{PORT_POOL_END}). All ports are in use.",
+                    "docker_occupied": held_ports if held_ports else [],
+                    "hint": "Stop some containers with docker_stop or docker_cleanup.",
                     "allocated_ports": self.port_pool.get_allocated_ports(),
                 }
 
@@ -679,7 +686,8 @@ class DockerMixin(MCGhidraMixinBase):
             }
 
         except subprocess.CalledProcessError as e:
-            self.port_pool.release(port)
+            if port is not None:
+                self.port_pool.release(port)
             return {"error": f"Failed to start container: {e.stderr or e.stdout}"}
 
     @mcp_tool(
@@ -945,7 +953,7 @@ class DockerMixin(MCGhidraMixinBase):
         2. If not, allocates a port from the pool and starts a new container
         3. Returns connection info immediately
 
-        Ports are auto-allocated from the pool (8192-8223) to prevent
+        Ports are auto-allocated from the pool ({PORT_POOL_START}-{PORT_POOL_END}) to prevent
         conflicts between concurrent sessions.
 
         After starting, poll docker_health(port) in a loop to check readiness.