Merge bitcoin#16821: Fix bug where duplicate PSBT keys are accepted

9743432 Fix bug where duplicate PSBT keys are accepted (John L. Jegutanis)

Pull request description:

  As per the BIP 174 spec a PSBT key cannot be duplicated,
  however the current code accepts key duplication.
  The PSBT key/value entries can be duplicated when the value
  is `empty()` or `IsNull()` for `CScript` or `CTxOut` respectively
  and if those key/value entries are serialized before the non-empty ones.

  For example, the following PSBT, included in the test vectors,
  contains a duplicate field:

  ```
  // magic
  70736274ff

  // global tx
  //// key
  0100
  //// value
  2a02000000000140420f000000000017a9146e91b72d5593e7d4391e2ff44e91e985c31641f08700000000
  //// separator
  00

  // no inputs

  // outputs
  //// key PSBT_OUT_WITNESSSCRIPT
  0101
  //// value (empty script)
  00
  //// key PSBT_OUT_WITNESSSCRIPT (same as the above)
  0101
  //// value (an OP_RETURN script)
  016a
  //// separator
  00
  ```

ACKs for top commit:
  achow101:
    ACK 9743432
  instagibbs:
    code review ACK bitcoin@9743432

Tree-SHA512: 34f4b34c8e6561c6a6ab745cdd319f6687eac6f7cecc735c94035eeca8c5157e17a27f2ae853dbaa6634fcd5a8f4e1c6cc13d1ebd7e563459665d72bb147cc1e

src/psbt.h

@@ -101,6 +101,9 @@ struct PSBTInput
 
  template <typename Stream>
  inline void Unserialize(Stream& s) {
+ // Used for duplicate key detection
+ std::set<std::vector<unsigned char>> key_lookup;
+
  // Read loop
  bool found_sep = false;
  while(!s.empty()) {
@@ -121,7 +124,7 @@ struct PSBTInput
  // Do stuff based on type
  switch(type) {
  case PSBT_IN_NON_WITNESS_UTXO:
- if (non_witness_utxo) {
+ if (!key_lookup.emplace(key).second) {
  throw std::ios_base::failure("Duplicate Key, input non-witness utxo already provided");
  } else if (key.size() != 1) {
  throw std::ios_base::failure("Non-witness utxo key is more than one byte type");
@@ -152,7 +155,7 @@ struct PSBTInput
  break;
  }
  case PSBT_IN_SIGHASH:
- if (sighash_type > 0) {
+ if (!key_lookup.emplace(key).second) {
  throw std::ios_base::failure("Duplicate Key, input sighash type already provided");
  } else if (key.size() != 1) {
  throw std::ios_base::failure("Sighash type key is more than one byte type");
@@ -161,7 +164,7 @@ struct PSBTInput
  break;
  case PSBT_IN_REDEEMSCRIPT:
  {
- if (!redeem_script.empty()) {
+ if (!key_lookup.emplace(key).second) {
  throw std::ios_base::failure("Duplicate Key, input redeemScript already provided");
  } else if (key.size() != 1) {
  throw std::ios_base::failure("Input redeemScript key is more than one byte type");
@@ -176,7 +179,7 @@ struct PSBTInput
  }
  case PSBT_IN_SCRIPTSIG:
  {
- if (!final_script_sig.empty()) {
+ if (!key_lookup.emplace(key).second) {
  throw std::ios_base::failure("Duplicate Key, input final scriptSig already provided");
  } else if (key.size() != 1) {
  throw std::ios_base::failure("Final scriptSig key is more than one byte type");
@@ -245,6 +248,9 @@ struct PSBTOutput
 
  template <typename Stream>
  inline void Unserialize(Stream& s) {
+ // Used for duplicate key detection
+ std::set<std::vector<unsigned char>> key_lookup;
+
  // Read loop
  bool found_sep = false;
  while(!s.empty()) {
@@ -266,7 +272,7 @@ struct PSBTOutput
  switch(type) {
  case PSBT_OUT_REDEEMSCRIPT:
  {
- if (!redeem_script.empty()) {
+ if (!key_lookup.emplace(key).second) {
  throw std::ios_base::failure("Duplicate Key, output redeemScript already provided");
  } else if (key.size() != 1) {
  throw std::ios_base::failure("Output redeemScript key is more than one byte type");
@@ -373,6 +379,9 @@ struct PartiallySignedTransaction
  throw std::ios_base::failure("Invalid PSBT magic bytes");
  }
 
+ // Used for duplicate key detection
+ std::set<std::vector<unsigned char>> key_lookup;
+
  // Read global data
  bool found_sep = false;
  while(!s.empty()) {
@@ -394,7 +403,7 @@ struct PartiallySignedTransaction
  switch(type) {
  case PSBT_GLOBAL_UNSIGNED_TX:
  {
- if (tx) {
+ if (!key_lookup.emplace(key).second) {
  throw std::ios_base::failure("Duplicate Key, unsigned tx already provided");
  } else if (key.size() != 1) {
  throw std::ios_base::failure("Global unsigned tx key is more than one byte type");

test/functional/data/rpc_psbt.json

@@ -17,7 +17,15 @@
  "cHNidP8BAHMCAAAAATAa6YblFqHsisW0vGVz0y+DtGXiOtdhZ9aLOOcwtNvbAAAAAAD/////AnR7AQAAAAAAF6kUA6oXrogrXQ1Usl1jEE5P/s57nqKHYEOZOwAAAAAXqRS5IbG6b3IuS/qDtlV6MTmYakLsg4cAAAAAAAEBHwDKmjsAAAAAFgAU0tlLZK4IWH7vyO6xh8YB6Tn5A3wCAwABAAAAAAEAFgAUYunpgv/zTdgjlhAxawkM0qO3R8sAAQAiACCHa62DLx0WgBXtQSMqnqZaGBXZ7xPA74dZ9ktbKyeKZQEBJVEhA7fOI6AcW0vwCmQlN836uzFbZoMyhnR471EwnSvVf4qHUa4A",
  "cHNidP8BAHMCAAAAATAa6YblFqHsisW0vGVz0y+DtGXiOtdhZ9aLOOcwtNvbAAAAAAD/////AnR7AQAAAAAAF6kUA6oXrogrXQ1Usl1jEE5P/s57nqKHYEOZOwAAAAAXqRS5IbG6b3IuS/qDtlV6MTmYakLsg4cAAAAAAAEBHwDKmjsAAAAAFgAU0tlLZK4IWH7vyO6xh8YB6Tn5A3wAAgAAFgAUYunpgv/zTdgjlhAxawkM0qO3R8sAAQAiACCHa62DLx0WgBXtQSMqnqZaGBXZ7xPA74dZ9ktbKyeKZQEBJVEhA7fOI6AcW0vwCmQlN836uzFbZoMyhnR471EwnSvVf4qHUa4A",
  "cHNidP8BAHMCAAAAATAa6YblFqHsisW0vGVz0y+DtGXiOtdhZ9aLOOcwtNvbAAAAAAD/////AnR7AQAAAAAAF6kUA6oXrogrXQ1Usl1jEE5P/s57nqKHYEOZOwAAAAAXqRS5IbG6b3IuS/qDtlV6MTmYakLsg4cAAAAAAAEBHwDKmjsAAAAAFgAU0tlLZK4IWH7vyO6xh8YB6Tn5A3wAAQAWABRi6emC//NN2COWEDFrCQzSo7dHywABACIAIIdrrYMvHRaAFe1BIyqeploYFdnvE8Dvh1n2S1srJ4plIQEAJVEhA7fOI6AcW0vwCmQlN836uzFbZoMyhnR471EwnSvVf4qHUa4A",
- "cHNidP8BAHMCAAAAAbiWoY6pOQepFsEGhUPXaulX9rvye2NH+NrdlAHg+WgpAQAAAAD/////AkBLTAAAAAAAF6kUqWwXCcLM5BN2zoNqMNT5qMlIi7+HQEtMAAAAAAAXqRSVF/in2XNxAlN1OSxkyp0z+Wtg2YcAAAAAAAEBIBNssgAAAAAAF6kUamsvautR8hRlMRY6OKNTx03DK96HAQcXFgAUo8u1LWpHprjt/uENAwBpGZD0UH0BCGsCRzBEAiAONfH3DYiw67ZbylrsxCF/XXpVwyWBRgofyRbPslzvwgIgIKCsWw5sHSIPh1icNvcVLZLHWj6NA7Dk+4Os2pOnMbQBIQPGStfYHPtyhpV7zIWtn0Q4GXv5gK1zy/tnJ+cBXu4iiwABABYAFMwmJQEz+HDpBEEabxJ5PogPsqZRAAEAFgAUyCrGc3h3FYCmiIspbv2pSTKZ5jU"
+ "cHNidP8BAHMCAAAAAbiWoY6pOQepFsEGhUPXaulX9rvye2NH+NrdlAHg+WgpAQAAAAD/////AkBLTAAAAAAAF6kUqWwXCcLM5BN2zoNqMNT5qMlIi7+HQEtMAAAAAAAXqRSVF/in2XNxAlN1OSxkyp0z+Wtg2YcAAAAAAAEBIBNssgAAAAAAF6kUamsvautR8hRlMRY6OKNTx03DK96HAQcXFgAUo8u1LWpHprjt/uENAwBpGZD0UH0BCGsCRzBEAiAONfH3DYiw67ZbylrsxCF/XXpVwyWBRgofyRbPslzvwgIgIKCsWw5sHSIPh1icNvcVLZLHWj6NA7Dk+4Os2pOnMbQBIQPGStfYHPtyhpV7zIWtn0Q4GXv5gK1zy/tnJ+cBXu4iiwABABYAFMwmJQEz+HDpBEEabxJ5PogPsqZRAAEAFgAUyCrGc3h3FYCmiIspbv2pSTKZ5jU",
+ "cHNidP8BACoCAAAAAAFAQg8AAAAAABepFG6Rty1Vk+fUOR4v9E6R6YXDFkHwhwAAAAAAAQEAAQEBagA=",
+ "cHNidP8BACoCAAAAAAFAQg8AAAAAABepFG6Rty1Vk+fUOR4v9E6R6YXDFkHwhwAAAAAAAQAAAQABagA=",
+ "cHNidP8BADMBAAAAAREREREREREREREREREREREREfrK3hERERERERERERERfwAAAAD/////AAAAAAAAAQEJ//////////8AAQEJAADK/gAAAAAAAA==",
+ "cHNidP8BADMBAAAAAREREREREREREREREREREREREfrK3hERERERERERERERfwAAAAD/////AAAAAAAAAQMErd7f7gEDBAEAAAAA",
+ "cHNidP8BADMBAAAAAREREREREREREREREREREREREfrK3hERERERERERERERfwAAAAD/////AAAAAAAAAQQAAQQBagA=",
+ "cHNidP8BADMBAAAAAREREREREREREREREREREREREfrK3hERERERERERERERfwAAAAD/////AAAAAAAAAQEJAOH1BQAAAAAAAQUAAQUBUQA=",
+ "cHNidP8BADMBAAAAAREREREREREREREREREREREREfrK3hERERERERERERERfwAAAAD/////AAAAAAAAAQcAAQcBUQA=",
+ "cHNidP8BADMBAAAAAREREREREREREREREREREREREfrK3hERERERERERERERfwAAAAD/////AAAAAAAAAQEJAOH1BQAAAAAAAQgBAAEIAwEBUQA="
  ],
  "valid" : [
  "cHNidP8BAKACAAAAAqsJSaCMWvfEm4IS9Bfi8Vqz9cM9zxU4IagTn4d6W3vkAAAAAAD+////qwlJoIxa98SbghL0F+LxWrP1wz3PFTghqBOfh3pbe+QBAAAAAP7///8CYDvqCwAAAAAZdqkUdopAu9dAy+gdmI5x3ipNXHE5ax2IrI4kAAAAAAAAGXapFG9GILVT+glechue4O/p+gOcykWXiKwAAAAAAAEHakcwRAIgR1lmF5fAGwNrJZKJSGhiGDR9iYZLcZ4ff89X0eURZYcCIFMJ6r9Wqk2Ikf/REf3xM286KdqGbX+EhtdVRs7tr5MZASEDXNxh/HupccC1AaZGoqg7ECy0OIEhfKaC3Ibi1z+ogpIAAQEgAOH1BQAAAAAXqRQ1RebjO4MsRwUPJNPuuTycA5SLx4cBBBYAFIXRNTfy4mVAWjTbr6nj3aAfuCMIAAAA",