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| 1 | +import { hit } from './hit'; |
| 2 | +import { getPropertyInChain } from './get-property-in-chain'; |
| 3 | +import { isEmptyObject } from './object-utils'; |
| 4 | +import { getDescriptorAddon } from './get-descriptor-addon'; |
| 5 | +import { matchStackTrace } from './match-stack'; |
| 6 | +import { type Source } from '../scriptlets'; |
| 7 | +import { type ChainBase } from '../../types/types'; |
| 8 | + |
| 9 | +/** |
| 10 | + * Property handler interface used by trapProp. |
| 11 | + */ |
| 12 | +interface PropHandler { |
| 13 | + /** |
| 14 | + * Actual value of the property as set by page scripts, |
| 15 | + * stored so it can be returned when the constant override does not apply. |
| 16 | + */ |
| 17 | + factValue: unknown; |
| 18 | + |
| 19 | + /** |
| 20 | + * Initializes the handler with the property's current value. |
| 21 | + * |
| 22 | + * @param a Existing value of the property at trap time. |
| 23 | + * |
| 24 | + * @returns `true` if the trap should proceed, `false` to cancel |
| 25 | + * (e.g. when `mustCancel` determines the value should not be overridden). |
| 26 | + */ |
| 27 | + init(a: unknown): boolean; |
| 28 | + |
| 29 | + /** |
| 30 | + * Getter invoked when the trapped property is read. |
| 31 | + * Depending on the handler, it may return the constant value or the factual value. |
| 32 | + * |
| 33 | + * @returns Value to expose to the caller. |
| 34 | + */ |
| 35 | + get(): unknown; |
| 36 | + |
| 37 | + /** |
| 38 | + * Setter invoked when the trapped property is written to. |
| 39 | + * Updates `factValue` and may trigger further chain traversal or constant reassignment. |
| 40 | + * |
| 41 | + * @param a New value being assigned to the property. |
| 42 | + */ |
| 43 | + set(a: unknown): void; |
| 44 | +} |
| 45 | + |
| 46 | +/** |
| 47 | + * Configuration for the setChainPropAccess factory. |
| 48 | + */ |
| 49 | +interface SetChainPropAccessConfig { |
| 50 | + /** |
| 51 | + * Scriptlet source object for logging and hit reporting. |
| 52 | + */ |
| 53 | + source: Source; |
| 54 | + |
| 55 | + /** |
| 56 | + * Stack trace pattern to match against; if falsy, constant is returned unconditionally. |
| 57 | + */ |
| 58 | + stack: string | undefined; |
| 59 | + |
| 60 | + /** |
| 61 | + * Returns true if the constant assignment should be canceled based on the incoming value type. |
| 62 | + */ |
| 63 | + mustCancel: (value: unknown) => boolean; |
| 64 | + |
| 65 | + /** |
| 66 | + * Defines a property descriptor on the base object to intercept get/set access. |
| 67 | + * |
| 68 | + * @param base Object on which to define the property. |
| 69 | + * @param prop Property name to intercept. |
| 70 | + * @param configurable Whether the property descriptor should be configurable. |
| 71 | + * @param handler Handler object containing `get` and `set` methods. |
| 72 | + * |
| 73 | + * @returns `true` if the trap was successfully defined, `false` otherwise. |
| 74 | + */ |
| 75 | + trapProp: (base: ChainBase, prop: string, configurable: boolean, handler: PropHandler) => boolean; |
| 76 | + |
| 77 | + /** |
| 78 | + * Returns the current constant value (may change if `mustCancel` triggers reassignment). |
| 79 | + * |
| 80 | + * @returns Current constant value. |
| 81 | + */ |
| 82 | + getConstantValue: () => unknown; |
| 83 | + |
| 84 | + /** |
| 85 | + * Updates the constant value when the end property setter detects a cancellation. |
| 86 | + * |
| 87 | + * @param value New constant value. |
| 88 | + */ |
| 89 | + setConstantValue: (value: unknown) => void; |
| 90 | +} |
| 91 | + |
| 92 | +/** |
| 93 | + * Creates setChainPropAccess function for set-constant and trusted-set-constant scriptlets. |
| 94 | + * |
| 95 | + * Traverses given chain to set constant value to its end prop. |
| 96 | + * Chains that yet include non-object values (e.g null) are valid and will be |
| 97 | + * traversed when appropriate chain member is set by an external script. |
| 98 | + * |
| 99 | + * @param config Configuration object with scriptlet-specific dependencies. |
| 100 | + * |
| 101 | + * @returns `setChainPropAccess` function. |
| 102 | + */ |
| 103 | +export const createSetChainPropAccessor = (config: SetChainPropAccessConfig) => { |
| 104 | + const { |
| 105 | + source, |
| 106 | + stack, |
| 107 | + mustCancel, |
| 108 | + trapProp, |
| 109 | + getConstantValue, |
| 110 | + setConstantValue, |
| 111 | + } = config; |
| 112 | + |
| 113 | + /** |
| 114 | + * Traverses the given chain to set the constant value to its end property. |
| 115 | + * |
| 116 | + * @param owner Base object of the chain. |
| 117 | + * @param property Property name to intercept. |
| 118 | + */ |
| 119 | + const setChainPropAccess = (owner: ChainBase, property: string): void => { |
| 120 | + const chainInfo = getPropertyInChain(owner, property); |
| 121 | + const { base, prop, chain } = chainInfo; |
| 122 | + |
| 123 | + // Handler method init is used to keep track of factual value |
| 124 | + // and apply mustCancel() check only on end prop |
| 125 | + const inChainPropHandler = { |
| 126 | + factValue: undefined as unknown, |
| 127 | + init(a: unknown) { |
| 128 | + this.factValue = a; |
| 129 | + return true; |
| 130 | + }, |
| 131 | + get() { |
| 132 | + return this.factValue; |
| 133 | + }, |
| 134 | + set(a: unknown) { |
| 135 | + // Prevent breakage due to loop assignments like win.obj = win.obj |
| 136 | + if (this.factValue === a) { |
| 137 | + return; |
| 138 | + } |
| 139 | + |
| 140 | + this.factValue = a; |
| 141 | + if (a instanceof Object) { |
| 142 | + setChainPropAccess(a as ChainBase, chain as string); |
| 143 | + } |
| 144 | + }, |
| 145 | + }; |
| 146 | + const endPropHandler = { |
| 147 | + factValue: undefined as unknown, |
| 148 | + descriptorAddon: getDescriptorAddon(), |
| 149 | + init(a: unknown) { |
| 150 | + if (mustCancel(a)) { |
| 151 | + return false; |
| 152 | + } |
| 153 | + this.factValue = a; |
| 154 | + return true; |
| 155 | + }, |
| 156 | + get() { |
| 157 | + if (!stack) { |
| 158 | + hit(source); |
| 159 | + return getConstantValue(); |
| 160 | + } |
| 161 | + if (!this.descriptorAddon.isAbortingSuspended) { |
| 162 | + this.descriptorAddon.isAbortingSuspended = true; |
| 163 | + let stackMatches = false; |
| 164 | + try { |
| 165 | + stackMatches = matchStackTrace(stack, new Error().stack || ''); |
| 166 | + } catch (e) { |
| 167 | + // Invalid regex or other error - return original value |
| 168 | + this.descriptorAddon.isAbortingSuspended = false; |
| 169 | + return this.factValue; |
| 170 | + } |
| 171 | + this.descriptorAddon.isAbortingSuspended = false; |
| 172 | + if (stackMatches) { |
| 173 | + hit(source); |
| 174 | + return getConstantValue(); |
| 175 | + } |
| 176 | + } |
| 177 | + return this.factValue; |
| 178 | + }, |
| 179 | + set(a: unknown) { |
| 180 | + if (mustCancel(a)) { |
| 181 | + setConstantValue(a); |
| 182 | + return; |
| 183 | + } |
| 184 | + this.factValue = a; |
| 185 | + }, |
| 186 | + }; |
| 187 | + |
| 188 | + // End prop case |
| 189 | + if (!chain) { |
| 190 | + trapProp(base, prop, false, endPropHandler); |
| 191 | + return; |
| 192 | + } |
| 193 | + |
| 194 | + // Null prop in chain |
| 195 | + if (base !== undefined && base[prop] === null) { |
| 196 | + trapProp(base, prop, true, inChainPropHandler); |
| 197 | + return; |
| 198 | + } |
| 199 | + |
| 200 | + // Empty object prop in chain |
| 201 | + if ((base instanceof Object || typeof base === 'object') && isEmptyObject(base)) { |
| 202 | + trapProp(base, prop, true, inChainPropHandler); |
| 203 | + } |
| 204 | + |
| 205 | + // Defined prop in chain |
| 206 | + const propValue = owner[prop]; |
| 207 | + if (propValue instanceof Object || (typeof propValue === 'object' && propValue !== null)) { |
| 208 | + setChainPropAccess(propValue as ChainBase, chain); |
| 209 | + } |
| 210 | + |
| 211 | + // Undefined prop in chain |
| 212 | + trapProp(base, prop, true, inChainPropHandler); |
| 213 | + }; |
| 214 | + |
| 215 | + return setChainPropAccess; |
| 216 | +}; |
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