[build] Add several util units

Adds the following util units and adds them to libbitcoin_util:

- `util/url.cpp` takes `urlDecode` from `httpserver.cpp`
- `util/error.cpp` takes `TransactionErrorString` from
  `node/transaction.cpp` and `AmountHighWarn` and `AmountErrMsg` from
  `ui_interface.cpp`
- `util/fees.cpp` takes `StringForFeeReason` and `FeeModeFromString` from `policy/fees.cpp`
- `util/rbf.cpp` takes `SignalsOptInRBF` from `policy/rbf.cpp`
- 'util/validation.cpp` takes `FormatStateMessage` and `strMessageMagic` from 'validation.cpp`

5 files changed, 1 insertions, 55 deletions

diff --git a/src/policy/fees.cpp b/src/policy/fees.cpp
index c49b9fa36b..524afd014e 100644
--- a/src/policy/fees.cpp
+++ b/src/policy/fees.cpp
@@ -27,40 +27,6 @@ std::string StringForFeeEstimateHorizon(FeeEstimateHorizon horizon) {
     return horizon_string->second;
 }
 
-std::string StringForFeeReason(FeeReason reason) {
-    static const std::map<FeeReason, std::string> fee_reason_strings = {
-        {FeeReason::NONE, "None"},
-        {FeeReason::HALF_ESTIMATE, "Half Target 60% Threshold"},
-        {FeeReason::FULL_ESTIMATE, "Target 85% Threshold"},
-        {FeeReason::DOUBLE_ESTIMATE, "Double Target 95% Threshold"},
-        {FeeReason::CONSERVATIVE, "Conservative Double Target longer horizon"},
-        {FeeReason::MEMPOOL_MIN, "Mempool Min Fee"},
-        {FeeReason::PAYTXFEE, "PayTxFee set"},
-        {FeeReason::FALLBACK, "Fallback fee"},
-        {FeeReason::REQUIRED, "Minimum Required Fee"},
-        {FeeReason::MAXTXFEE, "MaxTxFee limit"}
-    };
-    auto reason_string = fee_reason_strings.find(reason);
-
-    if (reason_string == fee_reason_strings.end()) return "Unknown";
-
-    return reason_string->second;
-}
-
-bool FeeModeFromString(const std::string& mode_string, FeeEstimateMode& fee_estimate_mode) {
-    static const std::map<std::string, FeeEstimateMode> fee_modes = {
-        {"UNSET", FeeEstimateMode::UNSET},
-        {"ECONOMICAL", FeeEstimateMode::ECONOMICAL},
-        {"CONSERVATIVE", FeeEstimateMode::CONSERVATIVE},
-    };
-    auto mode = fee_modes.find(mode_string);
-
-    if (mode == fee_modes.end()) return false;
-
-    fee_estimate_mode = mode->second;
-    return true;
-}
-
 /**
  * We will instantiate an instance of this class to track transactions that were
  * included in a block. We will lump transactions into a bucket according to their
diff --git a/src/policy/fees.h b/src/policy/fees.h
index c8472a12f5..6e61f76178 100644
--- a/src/policy/fees.h
+++ b/src/policy/fees.h
@@ -46,8 +46,6 @@ enum class FeeReason {
     MAXTXFEE,
 };
 
-std::string StringForFeeReason(FeeReason reason);
-
 /* Used to determine type of fee estimation requested */
 enum class FeeEstimateMode {
     UNSET,        //!< Use default settings based on other criteria
@@ -55,8 +53,6 @@ enum class FeeEstimateMode {
     CONSERVATIVE, //!< Force estimateSmartFee to use conservative estimates
 };
 
-bool FeeModeFromString(const std::string& mode_string, FeeEstimateMode& fee_estimate_mode);
-
 /* Used to return detailed information about a feerate bucket */
 struct EstimatorBucket
 {
diff --git a/src/policy/policy.cpp b/src/policy/policy.cpp
index f1e6aadb5a..44c23661fb 100644
--- a/src/policy/policy.cpp
+++ b/src/policy/policy.cpp
@@ -8,7 +8,6 @@
 #include <policy/policy.h>
 
 #include <consensus/validation.h>
-#include <validation.h>
 #include <coins.h>
 #include <policy/settings.h>
 #include <tinyformat.h>
diff --git a/src/policy/rbf.cpp b/src/policy/rbf.cpp
index c73a97fd7d..b4b8341d77 100644
--- a/src/policy/rbf.cpp
+++ b/src/policy/rbf.cpp
@@ -3,16 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <policy/rbf.h>
-
-bool SignalsOptInRBF(const CTransaction &tx)
-{
-    for (const CTxIn &txin : tx.vin) {
-        if (txin.nSequence <= MAX_BIP125_RBF_SEQUENCE) {
-            return true;
-        }
-    }
-    return false;
-}
+#include <util/rbf.h>
 
 RBFTransactionState IsRBFOptIn(const CTransaction& tx, const CTxMemPool& pool)
 {
diff --git a/src/policy/rbf.h b/src/policy/rbf.h
index a4f8777310..0707b0044f 100644
--- a/src/policy/rbf.h
+++ b/src/policy/rbf.h
@@ -7,18 +7,12 @@
 
 #include <txmempool.h>
 
-static const uint32_t MAX_BIP125_RBF_SEQUENCE = 0xfffffffd;
-
 enum class RBFTransactionState {
     UNKNOWN,
     REPLACEABLE_BIP125,
     FINAL
 };
 
-// Check whether the sequence numbers on this transaction are signaling
-// opt-in to replace-by-fee, according to BIP 125
-bool SignalsOptInRBF(const CTransaction &tx);
-
 // Determine whether an in-mempool transaction is signaling opt-in to RBF
 // according to BIP 125
 // This involves checking sequence numbers of the transaction, as well