Merge #9804: Fixes subscript 0 (&var[0]) where should use (var.data()) instead.

30ac7688e Fix subscript[0] potential bugs in key.cpp (Jeremy Rubin)
4b1c0f2e2 Remove unnecessary branches in utilstrencodings string constructors. (Jeremy Rubin)
e19db7b5a Fix subscript[0] in utilstrencodings.cpp (Jeremy Rubin)
bc2e7fd98 Fix subscript[0] in streams.h (Jeremy Rubin)
4cac0d1e0 Fix subscript[0] in validation.cpp (Jeremy Rubin)
ac658e55f Fix subscript[0] in torcontrol (Jeremy Rubin)
b6856ebed Fix subscript[0] in netaddress.cpp (Jeremy Rubin)
361d95265 Fix subscript[0] in base58.cpp (Jeremy Rubin)
6896dbf16 Cleanup (safe, it was checked) subscript[0] in MurmurHash3 (and cleanup MurmurHash3 to be more clear). (Jeremy Rubin)
96f2119e6 Fix subscript[0] in compressor.cpp (Jeremy Rubin)
500710bd2 Fix 2 subscript[0] bugs in pubkey.cpp, and eliminate one extra size check (Jeremy Rubin)
e0451e3e2 Fix subscript[0] bug in net.cpp if GetGroup returns a 0-sized vector (Jeremy Rubin)

Tree-SHA512: 5b9103652cf8c615bd8f4f32b3573d291d6b67c39e0308ce00100bc6625f346e8e016b4c999f4f34f5c37ae059490a83c3b513deb21f838af785227d06e02362

13 files changed, 51 insertions, 57 deletions

diff --git a/src/base58.cpp b/src/base58.cpp
index efa1beb1e4..17022a6bc1 100644
--- a/src/base58.cpp
+++ b/src/base58.cpp
@@ -110,7 +110,7 @@ std::string EncodeBase58(const unsigned char* pbegin, const unsigned char* pend)
 
 std::string EncodeBase58(const std::vector<unsigned char>& vch)
 {
-    return EncodeBase58(&vch[0], &vch[0] + vch.size());
+    return EncodeBase58(vch.data(), vch.data() + vch.size());
 }
 
 bool DecodeBase58(const std::string& str, std::vector<unsigned char>& vchRet)
@@ -160,7 +160,7 @@ void CBase58Data::SetData(const std::vector<unsigned char>& vchVersionIn, const
     vchVersion = vchVersionIn;
     vchData.resize(nSize);
     if (!vchData.empty())
-        memcpy(&vchData[0], pdata, nSize);
+        memcpy(vchData.data(), pdata, nSize);
 }
 
 void CBase58Data::SetData(const std::vector<unsigned char>& vchVersionIn, const unsigned char* pbegin, const unsigned char* pend)
@@ -180,8 +180,8 @@ bool CBase58Data::SetString(const char* psz, unsigned int nVersionBytes)
     vchVersion.assign(vchTemp.begin(), vchTemp.begin() + nVersionBytes);
     vchData.resize(vchTemp.size() - nVersionBytes);
     if (!vchData.empty())
-        memcpy(&vchData[0], &vchTemp[nVersionBytes], vchData.size());
-    memory_cleanse(&vchTemp[0], vchTemp.size());
+        memcpy(vchData.data(), vchTemp.data() + nVersionBytes, vchData.size());
+    memory_cleanse(vchTemp.data(), vchTemp.size());
     return true;
 }
 
@@ -262,7 +262,7 @@ CTxDestination CBitcoinAddress::Get() const
     if (!IsValid())
         return CNoDestination();
     uint160 id;
-    memcpy(&id, &vchData[0], 20);
+    memcpy(&id, vchData.data(), 20);
     if (vchVersion == Params().Base58Prefix(CChainParams::PUBKEY_ADDRESS))
         return CKeyID(id);
     else if (vchVersion == Params().Base58Prefix(CChainParams::SCRIPT_ADDRESS))
@@ -276,7 +276,7 @@ bool CBitcoinAddress::GetKeyID(CKeyID& keyID) const
     if (!IsValid() || vchVersion != Params().Base58Prefix(CChainParams::PUBKEY_ADDRESS))
         return false;
     uint160 id;
-    memcpy(&id, &vchData[0], 20);
+    memcpy(&id, vchData.data(), 20);
     keyID = CKeyID(id);
     return true;
 }
diff --git a/src/base58.h b/src/base58.h
index 3998283bb1..4de5cc6ce5 100644
--- a/src/base58.h
+++ b/src/base58.h
@@ -148,7 +148,7 @@ public:
         K ret;
         if (vchData.size() == Size) {
             // If base58 encoded data does not hold an ext key, return a !IsValid() key
-            ret.Decode(&vchData[0]);
+            ret.Decode(vchData.data());
         }
         return ret;
     }
diff --git a/src/compressor.cpp b/src/compressor.cpp
index 20c154fc1e..f4c12f38d2 100644
--- a/src/compressor.cpp
+++ b/src/compressor.cpp
@@ -93,7 +93,7 @@ bool CScriptCompressor::Decompress(unsigned int nSize, const std::vector<unsigne
         script[0] = OP_DUP;
         script[1] = OP_HASH160;
         script[2] = 20;
-        memcpy(&script[3], &in[0], 20);
+        memcpy(&script[3], in.data(), 20);
         script[23] = OP_EQUALVERIFY;
         script[24] = OP_CHECKSIG;
         return true;
@@ -101,7 +101,7 @@ bool CScriptCompressor::Decompress(unsigned int nSize, const std::vector<unsigne
         script.resize(23);
         script[0] = OP_HASH160;
         script[1] = 20;
-        memcpy(&script[2], &in[0], 20);
+        memcpy(&script[2], in.data(), 20);
         script[22] = OP_EQUAL;
         return true;
     case 0x02:
@@ -109,14 +109,14 @@ bool CScriptCompressor::Decompress(unsigned int nSize, const std::vector<unsigne
         script.resize(35);
         script[0] = 33;
         script[1] = nSize;
-        memcpy(&script[2], &in[0], 32);
+        memcpy(&script[2], in.data(), 32);
         script[34] = OP_CHECKSIG;
         return true;
     case 0x04:
     case 0x05:
         unsigned char vch[33] = {};
         vch[0] = nSize - 2;
-        memcpy(&vch[1], &in[0], 32);
+        memcpy(&vch[1], in.data(), 32);
         CPubKey pubkey(&vch[0], &vch[33]);
         if (!pubkey.Decompress())
             return false;
diff --git a/src/hash.cpp b/src/hash.cpp
index b361c90d16..5a15600be5 100644
--- a/src/hash.cpp
+++ b/src/hash.cpp
@@ -17,36 +17,34 @@ unsigned int MurmurHash3(unsigned int nHashSeed, const std::vector<unsigned char
 {
     // The following is MurmurHash3 (x86_32), see http://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp
     uint32_t h1 = nHashSeed;
-    if (vDataToHash.size() > 0)
-    {
-        const uint32_t c1 = 0xcc9e2d51;
-        const uint32_t c2 = 0x1b873593;
+    const uint32_t c1 = 0xcc9e2d51;
+    const uint32_t c2 = 0x1b873593;
 
-        const int nblocks = vDataToHash.size() / 4;
+    const int nblocks = vDataToHash.size() / 4;
 
-        //----------
-        // body
-        const uint8_t* blocks = &vDataToHash[0] + nblocks * 4;
+    //----------
+    // body
+    const uint8_t* blocks = vDataToHash.data();
 
-        for (int i = -nblocks; i; i++) {
-            uint32_t k1 = ReadLE32(blocks + i*4);
+    for (int i = 0; i < nblocks; ++i) {
+        uint32_t k1 = ReadLE32(blocks + i*4);
 
-            k1 *= c1;
-            k1 = ROTL32(k1, 15);
-            k1 *= c2;
+        k1 *= c1;
+        k1 = ROTL32(k1, 15);
+        k1 *= c2;
 
-            h1 ^= k1;
-            h1 = ROTL32(h1, 13);
-            h1 = h1 * 5 + 0xe6546b64;
-        }
+        h1 ^= k1;
+        h1 = ROTL32(h1, 13);
+        h1 = h1 * 5 + 0xe6546b64;
+    }
 
-        //----------
-        // tail
-        const uint8_t* tail = (const uint8_t*)(&vDataToHash[0] + nblocks * 4);
+    //----------
+    // tail
+    const uint8_t* tail = vDataToHash.data() + nblocks * 4;
 
-        uint32_t k1 = 0;
+    uint32_t k1 = 0;
 
-        switch (vDataToHash.size() & 3) {
+    switch (vDataToHash.size() & 3) {
         case 3:
             k1 ^= tail[2] << 16;
         case 2:
@@ -57,7 +55,6 @@ unsigned int MurmurHash3(unsigned int nHashSeed, const std::vector<unsigned char
             k1 = ROTL32(k1, 15);
             k1 *= c2;
             h1 ^= k1;
-        }
     }
 
     //----------
diff --git a/src/key.cpp b/src/key.cpp
index 5a75647f1a..5a991fc1d2 100644
--- a/src/key.cpp
+++ b/src/key.cpp
@@ -138,7 +138,7 @@ CPrivKey CKey::GetPrivKey() const {
     size_t privkeylen;
     privkey.resize(279);
     privkeylen = 279;
-    ret = ec_privkey_export_der(secp256k1_context_sign, (unsigned char*)&privkey[0], &privkeylen, begin(), fCompressed ? SECP256K1_EC_COMPRESSED : SECP256K1_EC_UNCOMPRESSED);
+    ret = ec_privkey_export_der(secp256k1_context_sign, (unsigned char*) privkey.data(), &privkeylen, begin(), fCompressed ? SECP256K1_EC_COMPRESSED : SECP256K1_EC_UNCOMPRESSED);
     assert(ret);
     privkey.resize(privkeylen);
     return privkey;
@@ -167,7 +167,7 @@ bool CKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig, uint32_
     secp256k1_ecdsa_signature sig;
     int ret = secp256k1_ecdsa_sign(secp256k1_context_sign, &sig, hash.begin(), begin(), secp256k1_nonce_function_rfc6979, test_case ? extra_entropy : NULL);
     assert(ret);
-    secp256k1_ecdsa_signature_serialize_der(secp256k1_context_sign, (unsigned char*)&vchSig[0], &nSigLen, &sig);
+    secp256k1_ecdsa_signature_serialize_der(secp256k1_context_sign, (unsigned char*)vchSig.data(), &nSigLen, &sig);
     vchSig.resize(nSigLen);
     return true;
 }
@@ -202,7 +202,7 @@ bool CKey::SignCompact(const uint256 &hash, std::vector<unsigned char>& vchSig)
 }
 
 bool CKey::Load(CPrivKey &privkey, CPubKey &vchPubKey, bool fSkipCheck=false) {
-    if (!ec_privkey_import_der(secp256k1_context_sign, (unsigned char*)begin(), &privkey[0], privkey.size()))
+    if (!ec_privkey_import_der(secp256k1_context_sign, (unsigned char*)begin(), privkey.data(), privkey.size()))
         return false;
     fCompressed = vchPubKey.IsCompressed();
     fValid = true;
@@ -245,8 +245,8 @@ void CExtKey::SetMaster(const unsigned char *seed, unsigned int nSeedLen) {
     static const unsigned char hashkey[] = {'B','i','t','c','o','i','n',' ','s','e','e','d'};
     std::vector<unsigned char, secure_allocator<unsigned char>> vout(64);
     CHMAC_SHA512(hashkey, sizeof(hashkey)).Write(seed, nSeedLen).Finalize(vout.data());
-    key.Set(&vout[0], &vout[32], true);
-    memcpy(chaincode.begin(), &vout[32], 32);
+    key.Set(vout.data(), vout.data() + 32, true);
+    memcpy(chaincode.begin(), vout.data() + 32, 32);
     nDepth = 0;
     nChild = 0;
     memset(vchFingerprint, 0, sizeof(vchFingerprint));
diff --git a/src/net.cpp b/src/net.cpp
index 301cf58b87..5bf3af7ea3 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -2876,5 +2876,5 @@ uint64_t CConnman::CalculateKeyedNetGroup(const CAddress& ad) const
 {
     std::vector<unsigned char> vchNetGroup(ad.GetGroup());
 
-    return GetDeterministicRandomizer(RANDOMIZER_ID_NETGROUP).Write(&vchNetGroup[0], vchNetGroup.size()).Finalize();
+    return GetDeterministicRandomizer(RANDOMIZER_ID_NETGROUP).Write(vchNetGroup.data(), vchNetGroup.size()).Finalize();
 }
diff --git a/src/netaddress.cpp b/src/netaddress.cpp
index 89f257c642..110e778fbd 100644
--- a/src/netaddress.cpp
+++ b/src/netaddress.cpp
@@ -573,7 +573,7 @@ std::vector<unsigned char> CService::GetKey() const
 {
      std::vector<unsigned char> vKey;
      vKey.resize(18);
-     memcpy(&vKey[0], ip, 16);
+     memcpy(vKey.data(), ip, 16);
      vKey[16] = port / 0x100;
      vKey[17] = port & 0x0FF;
      return vKey;
diff --git a/src/pubkey.cpp b/src/pubkey.cpp
index a16457ea4e..91af4e56f2 100644
--- a/src/pubkey.cpp
+++ b/src/pubkey.cpp
@@ -172,10 +172,7 @@ bool CPubKey::Verify(const uint256 &hash, const std::vector<unsigned char>& vchS
     if (!secp256k1_ec_pubkey_parse(secp256k1_context_verify, &pubkey, &(*this)[0], size())) {
         return false;
     }
-    if (vchSig.size() == 0) {
-        return false;
-    }
-    if (!ecdsa_signature_parse_der_lax(secp256k1_context_verify, &sig, &vchSig[0], vchSig.size())) {
+    if (!ecdsa_signature_parse_der_lax(secp256k1_context_verify, &sig, vchSig.data(), vchSig.size())) {
         return false;
     }
     /* libsecp256k1's ECDSA verification requires lower-S signatures, which have
@@ -274,7 +271,7 @@ bool CExtPubKey::Derive(CExtPubKey &out, unsigned int _nChild) const {
 
 /* static */ bool CPubKey::CheckLowS(const std::vector<unsigned char>& vchSig) {
     secp256k1_ecdsa_signature sig;
-    if (!ecdsa_signature_parse_der_lax(secp256k1_context_verify, &sig, &vchSig[0], vchSig.size())) {
+    if (!ecdsa_signature_parse_der_lax(secp256k1_context_verify, &sig, vchSig.data(), vchSig.size())) {
         return false;
     }
     return (!secp256k1_ecdsa_signature_normalize(secp256k1_context_verify, NULL, &sig));
diff --git a/src/serialize.h b/src/serialize.h
index e82ddf2c5a..8b86a07a76 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -450,7 +450,7 @@ public:
         }
         string.resize(size);
         if (size != 0)
-            s.read((char*)&string[0], size);
+            s.read((char*)string.data(), size);
     }
 
     template<typename Stream>
@@ -458,7 +458,7 @@ public:
     {
         WriteCompactSize(s, string.size());
         if (!string.empty())
-            s.write((char*)&string[0], string.size());
+            s.write((char*)string.data(), string.size());
     }
 };
 
@@ -556,7 +556,7 @@ void Serialize(Stream& os, const std::basic_string<C>& str)
 {
     WriteCompactSize(os, str.size());
     if (!str.empty())
-        os.write((char*)&str[0], str.size() * sizeof(str[0]));
+        os.write((char*)str.data(), str.size() * sizeof(C));
 }
 
 template<typename Stream, typename C>
@@ -565,7 +565,7 @@ void Unserialize(Stream& is, std::basic_string<C>& str)
     unsigned int nSize = ReadCompactSize(is);
     str.resize(nSize);
     if (nSize != 0)
-        is.read((char*)&str[0], nSize * sizeof(str[0]));
+        is.read((char*)str.data(), nSize * sizeof(C));
 }
 
 
@@ -578,7 +578,7 @@ void Serialize_impl(Stream& os, const prevector<N, T>& v, const unsigned char&)
 {
     WriteCompactSize(os, v.size());
     if (!v.empty())
-        os.write((char*)&v[0], v.size() * sizeof(T));
+        os.write((char*)v.data(), v.size() * sizeof(T));
 }
 
 template<typename Stream, unsigned int N, typename T, typename V>
@@ -646,7 +646,7 @@ void Serialize_impl(Stream& os, const std::vector<T, A>& v, const unsigned char&
 {
     WriteCompactSize(os, v.size());
     if (!v.empty())
-        os.write((char*)&v[0], v.size() * sizeof(T));
+        os.write((char*)v.data(), v.size() * sizeof(T));
 }
 
 template<typename Stream, typename T, typename A, typename V>
diff --git a/src/streams.h b/src/streams.h
index 8dc5a19ead..245fb9cd8f 100644
--- a/src/streams.h
+++ b/src/streams.h
@@ -389,7 +389,7 @@ public:
     {
         // Special case: stream << stream concatenates like stream += stream
         if (!vch.empty())
-            s.write((char*)&vch[0], vch.size() * sizeof(vch[0]));
+            s.write((char*)vch.data(), vch.size() * sizeof(value_type));
     }
 
     template<typename T>
diff --git a/src/torcontrol.cpp b/src/torcontrol.cpp
index 3665e7e770..ac13f73e70 100644
--- a/src/torcontrol.cpp
+++ b/src/torcontrol.cpp
@@ -662,7 +662,7 @@ void TorController::protocolinfo_cb(TorControlConnection& _conn, const TorContro
                 // _conn.Command("AUTHENTICATE " + HexStr(status_cookie.second), boost::bind(&TorController::auth_cb, this, _1, _2));
                 cookie = std::vector<uint8_t>(status_cookie.second.begin(), status_cookie.second.end());
                 clientNonce = std::vector<uint8_t>(TOR_NONCE_SIZE, 0);
-                GetRandBytes(&clientNonce[0], TOR_NONCE_SIZE);
+                GetRandBytes(clientNonce.data(), TOR_NONCE_SIZE);
                 _conn.Command("AUTHCHALLENGE SAFECOOKIE " + HexStr(clientNonce), boost::bind(&TorController::authchallenge_cb, this, _1, _2));
             } else {
                 if (status_cookie.first) {
diff --git a/src/utilstrencodings.cpp b/src/utilstrencodings.cpp
index 93abaec04b..2fabb8cf7a 100644
--- a/src/utilstrencodings.cpp
+++ b/src/utilstrencodings.cpp
@@ -228,7 +228,7 @@ std::vector<unsigned char> DecodeBase64(const char* p, bool* pfInvalid)
 std::string DecodeBase64(const std::string& str)
 {
     std::vector<unsigned char> vchRet = DecodeBase64(str.c_str());
-    return (vchRet.size() == 0) ? std::string() : std::string((const char*)&vchRet[0], vchRet.size());
+    return std::string((const char*)vchRet.data(), vchRet.size());
 }
 
 std::string EncodeBase32(const unsigned char* pch, size_t len)
@@ -415,7 +415,7 @@ std::vector<unsigned char> DecodeBase32(const char* p, bool* pfInvalid)
 std::string DecodeBase32(const std::string& str)
 {
     std::vector<unsigned char> vchRet = DecodeBase32(str.c_str());
-    return (vchRet.size() == 0) ? std::string() : std::string((const char*)&vchRet[0], vchRet.size());
+    return std::string((const char*)vchRet.data(), vchRet.size());
 }
 
 static bool ParsePrechecks(const std::string& str)
diff --git a/src/validation.cpp b/src/validation.cpp
index 09288be1ca..a21367848b 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -2890,7 +2890,7 @@ std::vector<unsigned char> GenerateCoinbaseCommitment(CBlock& block, const CBloc
     if (consensusParams.vDeployments[Consensus::DEPLOYMENT_SEGWIT].nTimeout != 0) {
         if (commitpos == -1) {
             uint256 witnessroot = BlockWitnessMerkleRoot(block, NULL);
-            CHash256().Write(witnessroot.begin(), 32).Write(&ret[0], 32).Finalize(witnessroot.begin());
+            CHash256().Write(witnessroot.begin(), 32).Write(ret.data(), 32).Finalize(witnessroot.begin());
             CTxOut out;
             out.nValue = 0;
             out.scriptPubKey.resize(38);