feat: add agentapi endpoint to report connections for audit (#16507)

This change adds a new `ReportConnection` endpoint to the `agentapi`.

The protocol version was bumped previously, so it has been omitted here.

This allows the agent to report connection events, for example when the
user connects to the workspace via SSH or VS Code.

Updates #15139

coderd/agentapi/audit.go

@@ -0,0 +1,105 @@
+package agentapi
+
+import (
+	"context"
+	"encoding/json"
+	"strconv"
+	"sync/atomic"
+
+	"github.com/google/uuid"
+	"golang.org/x/xerrors"
+	"google.golang.org/protobuf/types/known/emptypb"
+
+	"cdr.dev/slog"
+
+	agentproto "github.com/coder/coder/v2/agent/proto"
+	"github.com/coder/coder/v2/coderd/audit"
+	"github.com/coder/coder/v2/coderd/database"
+	"github.com/coder/coder/v2/coderd/database/db2sdk"
+	"github.com/coder/coder/v2/codersdk/agentsdk"
+)
+
+type AuditAPI struct {
+	AgentFn  func(context.Context) (database.WorkspaceAgent, error)
+	Auditor  *atomic.Pointer[audit.Auditor]
+	Database database.Store
+	Log      slog.Logger
+}
+
+func (a *AuditAPI) ReportConnection(ctx context.Context, req *agentproto.ReportConnectionRequest) (*emptypb.Empty, error) {
+	// We will use connection ID as request ID, typically this is the
+	// SSH session ID as reported by the agent.
+	connectionID, err := uuid.FromBytes(req.GetConnection().GetId())
+	if err != nil {
+		return nil, xerrors.Errorf("connection id from bytes: %w", err)
+	}
+
+	action, err := db2sdk.AuditActionFromAgentProtoConnectionAction(req.GetConnection().GetAction())
+	if err != nil {
+		return nil, err
+	}
+	connectionType, err := agentsdk.ConnectionTypeFromProto(req.GetConnection().GetType())
+	if err != nil {
+		return nil, err
+	}
+
+	// Fetch contextual data for this audit event.
+	workspaceAgent, err := a.AgentFn(ctx)
+	if err != nil {
+		return nil, xerrors.Errorf("get agent: %w", err)
+	}
+	workspace, err := a.Database.GetWorkspaceByAgentID(ctx, workspaceAgent.ID)
+	if err != nil {
+		return nil, xerrors.Errorf("get workspace by agent id: %w", err)
+	}
+	build, err := a.Database.GetLatestWorkspaceBuildByWorkspaceID(ctx, workspace.ID)
+	if err != nil {
+		return nil, xerrors.Errorf("get latest workspace build by workspace id: %w", err)
+	}
+
+	// We pass the below information to the Auditor so that it
+	// can form a friendly string for the user to view in the UI.
+	type additionalFields struct {
+		audit.AdditionalFields
+
+		ConnectionType agentsdk.ConnectionType `json:"connection_type"`
+		Reason         string                  `json:"reason,omitempty"`
+	}
+	resourceInfo := additionalFields{
+		AdditionalFields: audit.AdditionalFields{
+			WorkspaceID:    workspace.ID,
+			WorkspaceName:  workspace.Name,
+			WorkspaceOwner: workspace.OwnerUsername,
+			BuildNumber:    strconv.FormatInt(int64(build.BuildNumber), 10),
+			BuildReason:    database.BuildReason(string(build.Reason)),
+		},
+		ConnectionType: connectionType,
+		Reason:         req.GetConnection().GetReason(),
+	}
+
+	riBytes, err := json.Marshal(resourceInfo)
+	if err != nil {
+		a.Log.Error(ctx, "marshal resource info for agent connection failed", slog.Error(err))
+		riBytes = []byte("{}")
+	}
+
+	audit.BackgroundAudit(ctx, &audit.BackgroundAuditParams[database.WorkspaceAgent]{
+		Audit:            *a.Auditor.Load(),
+		Log:              a.Log,
+		Time:             req.GetConnection().GetTimestamp().AsTime(),
+		OrganizationID:   workspace.OrganizationID,
+		RequestID:        connectionID,
+		Action:           action,
+		New:              workspaceAgent,
+		Old:              workspaceAgent,
+		IP:               req.GetConnection().GetIp(),
+		Status:           int(req.GetConnection().GetStatusCode()),
+		AdditionalFields: riBytes,
+
+		// It's not possible to tell which user connected. Once we have
+		// the capability, this may be reported by the agent.
+		UserID: uuid.Nil,
+	})
+
+	return &emptypb.Empty{}, nil
+}