Improve SPF validation

assets/scripts/records/SpfRecord.js

@@ -108,11 +108,19 @@ export class SpfRecord {
 
 			const term = this.constructor.fields.find(f => f.key === name);
 			if (!term) {
-				throw new ValidationError(`Unknown term: ${name}`);
+				throw new ValidationError(name ? `Unknown term: ${name}` : "Syntax error");
 			}
 
 			const [directive, value] = token.split(term.separator);
-			const [, qualifier, key] = directive.match(/^([-+?~]?)(\w*)/);
+			const [, qualifier, key] = directive.match(/^([-+?~]?)(.*)/);
+
+			if (key !== name) {
+				throw new ValidationError(`Invalid separator for term: ${name}`);
+			}
+
+			if (token.includes(term.separator) && !value) {
+				throw new ValidationError(`No value specified for term: ${name}`);
+			}
 
 			result.push({ qualifier, key, value });
 		}
@@ -135,7 +143,7 @@ export class SpfRecord {
 			const term = this.constructor.fields.find(d => d.key === input.key);
 
 			if (!term) {
-				throw new ValidationError(`Unknown term: ${input.key}`);
+				throw new ValidationError(input.key ? `Unknown term: ${input.key}` : "Syntax error");
 			}
 
 			if (term.position < lastPos) {
@@ -144,8 +152,8 @@ export class SpfRecord {
 				throw new ValidationError(`Term "${lastDirective.key}" must come after "${term.key}"`);
 			}
 
-			if (term instanceof Modifier && input.qualifier) {
-				throw new ValidationError(`Modifier "${term.key}" must not have a qualifier`)
+			if (!term.qualifierAllowed && input.qualifier) {
+				throw new ValidationError(`Term "${term.key}" must not have a qualifier`)
 			}
 
 			if (!input.value && term.valueRequirement === ValueRequirement.REQUIRED) {

assets/scripts/spf/Mechanism.js

@@ -4,6 +4,7 @@ import { ValueRequirement } from "./ValueRequirement.js";
 export class Mechanism extends Term {
 	separator = ":";
 	placeholder = null;
+	qualifierAllowed = true;
 
 	constructor(key) {
 		super(key);

assets/scripts/spf/Modifier.js

@@ -4,6 +4,7 @@ import { validateSpfDomain } from "./utils.js";
 
 export class Modifier extends Term {
 	separator = "=";
+	qualifierAllowed = false;
 
 	constructor(key) {
 		super(key);

assets/scripts/spf/VersionTerm.js

@@ -3,6 +3,7 @@ import { ValidationError } from "../ValidationError.js";
 
 export class VersionTerm extends Term {
 	separator = "=";
+	qualifierAllowed = false;
 
 	constructor(key, version) {
 		super(key);