Validate port value in `SplitHostPort`

Forward the validation of the port from `ParseUInt16(...)`.
Consider port 0 as invalid.
Add suitable test for the `SplitHostPort` function.
Add doxygen description to the `SplitHostPort` function.

3 files changed, 37 insertions, 5 deletions

diff --git a/src/test/netbase_tests.cpp b/src/test/netbase_tests.cpp
index c2d2fa37b4..0e1e9ae211 100644
--- a/src/test/netbase_tests.cpp
+++ b/src/test/netbase_tests.cpp
@@ -84,12 +84,12 @@ BOOST_AUTO_TEST_CASE(netbase_properties)
 
 }
 
-bool static TestSplitHost(const std::string& test, const std::string& host, uint16_t port)
+bool static TestSplitHost(const std::string& test, const std::string& host, uint16_t port, bool validPort=true)
 {
     std::string hostOut;
     uint16_t portOut{0};
-    SplitHostPort(test, portOut, hostOut);
-    return hostOut == host && port == portOut;
+    bool validPortOut = SplitHostPort(test, portOut, hostOut);
+    return hostOut == host && portOut == port && validPortOut == validPort;
 }
 
 BOOST_AUTO_TEST_CASE(netbase_splithost)
@@ -109,6 +109,23 @@ BOOST_AUTO_TEST_CASE(netbase_splithost)
     BOOST_CHECK(TestSplitHost(":8333", "", 8333));
     BOOST_CHECK(TestSplitHost("[]:8333", "", 8333));
     BOOST_CHECK(TestSplitHost("", "", 0));
+    BOOST_CHECK(TestSplitHost(":65535", "", 65535));
+    BOOST_CHECK(TestSplitHost(":65536", ":65536", 0, false));
+    BOOST_CHECK(TestSplitHost(":-1", ":-1", 0, false));
+    BOOST_CHECK(TestSplitHost("[]:70001", "[]:70001", 0, false));
+    BOOST_CHECK(TestSplitHost("[]:-1", "[]:-1", 0, false));
+    BOOST_CHECK(TestSplitHost("[]:-0", "[]:-0", 0, false));
+    BOOST_CHECK(TestSplitHost("[]:0", "", 0, false));
+    BOOST_CHECK(TestSplitHost("[]:1/2", "[]:1/2", 0, false));
+    BOOST_CHECK(TestSplitHost("[]:1E2", "[]:1E2", 0, false));
+    BOOST_CHECK(TestSplitHost("127.0.0.1:65536", "127.0.0.1:65536", 0, false));
+    BOOST_CHECK(TestSplitHost("127.0.0.1:0", "127.0.0.1", 0, false));
+    BOOST_CHECK(TestSplitHost("127.0.0.1:", "127.0.0.1:", 0, false));
+    BOOST_CHECK(TestSplitHost("127.0.0.1:1/2", "127.0.0.1:1/2", 0, false));
+    BOOST_CHECK(TestSplitHost("127.0.0.1:1E2", "127.0.0.1:1E2", 0, false));
+    BOOST_CHECK(TestSplitHost("www.bitcoincore.org:65536", "www.bitcoincore.org:65536", 0, false));
+    BOOST_CHECK(TestSplitHost("www.bitcoincore.org:0", "www.bitcoincore.org", 0, false));
+    BOOST_CHECK(TestSplitHost("www.bitcoincore.org:", "www.bitcoincore.org:", 0, false));
 }
 
 bool static TestParse(std::string src, std::string canon)
diff --git a/src/util/strencodings.cpp b/src/util/strencodings.cpp
index b5ac151374..e28ca8e73a 100644
--- a/src/util/strencodings.cpp
+++ b/src/util/strencodings.cpp
@@ -97,8 +97,9 @@ std::vector<Byte> ParseHex(std::string_view str)
 template std::vector<std::byte> ParseHex(std::string_view);
 template std::vector<uint8_t> ParseHex(std::string_view);
 
-void SplitHostPort(std::string_view in, uint16_t& portOut, std::string& hostOut)
+bool SplitHostPort(std::string_view in, uint16_t& portOut, std::string& hostOut)
 {
+    bool valid = false;
     size_t colon = in.find_last_of(':');
     // if a : is found, and it either follows a [...], or no other : is in the string, treat it as port separator
     bool fHaveColon = colon != in.npos;
@@ -109,13 +110,18 @@ void SplitHostPort(std::string_view in, uint16_t& portOut, std::string& hostOut)
         if (ParseUInt16(in.substr(colon + 1), &n)) {
             in = in.substr(0, colon);
             portOut = n;
+            valid = (portOut != 0);
         }
+    } else {
+        valid = true;
     }
     if (in.size() > 0 && in[0] == '[' && in[in.size() - 1] == ']') {
         hostOut = in.substr(1, in.size() - 2);
     } else {
         hostOut = in;
     }
+
+    return valid;
 }
 
 std::string EncodeBase64(Span<const unsigned char> input)
diff --git a/src/util/strencodings.h b/src/util/strencodings.h
index 14867b21b2..94bc6cc2f3 100644
--- a/src/util/strencodings.h
+++ b/src/util/strencodings.h
@@ -88,7 +88,16 @@ std::string EncodeBase32(Span<const unsigned char> input, bool pad = true);
  */
 std::string EncodeBase32(std::string_view str, bool pad = true);
 
-void SplitHostPort(std::string_view in, uint16_t& portOut, std::string& hostOut);
+/**
+ * Splits socket address string into host string and port value.
+ * Validates port value.
+ *
+ * @param[in] in        The socket address string to split.
+ * @param[out] portOut  Port-portion of the input, if found and parsable.
+ * @param[out] hostOut  Host-portion of the input, if found.
+ * @return              true if port-portion is absent or within its allowed range, otherwise false
+ */
+bool SplitHostPort(std::string_view in, uint16_t& portOut, std::string& hostOut);
 
 // LocaleIndependentAtoi is provided for backwards compatibility reasons.
 //