Fixed incorrect TLS ports in the C++ library.

# Fixes
- Use the TLS port when connecting from C++
- Handle and display OpenSSL errors correctly
- Check for SSL connections with no established cipher (e.g., connected to the wrong endpoint port)

Merge pull request #34.

c/src/point_one/polaris/polaris.c

@@ -12,6 +12,7 @@
 #include <string.h>  // For memmove()
 
 #ifdef POLARIS_USE_TLS
+#include <openssl/err.h>
 #include <openssl/ssl.h>
 #endif
 
@@ -26,6 +27,66 @@
 #define P1_PrintError(x, ...) \
   P1_perror("polaris.c:" STR(__LINE__) "] " x, ##__VA_ARGS__)
 
+#if defined(POLARIS_USE_TLS)
+static void __P1_PrintWriteError(int line, PolarisContext_t* context,
+                                 const char* message, int ret) {
+  SSL_load_error_strings();
+  int ssl_error = SSL_get_error(context->ssl, ret);
+  if (ssl_error == SSL_ERROR_SYSCALL) {
+    P1_fprintf(stderr,
+               "polaris.c:%d] %s. [error=%s (syscall: errno=%d; %s)]\n",
+               line, message, strerror(errno), errno,
+               ERR_error_string(ssl_error, NULL));
+  } else {
+    // Note: OpenSSL has a function sort of like strerror(), SSL_error_string(),
+    // but in practice its output is less than helpful most of the time. We'll
+    // still print it, but we'll also print out our own error name string:
+    const char* error_name;
+    switch (ssl_error) {
+      case SSL_ERROR_NONE:
+        error_name = "SSL_ERROR_NONE";
+        break;
+      case SSL_ERROR_SSL:
+        error_name = "SSL_ERROR_SSL";
+        break;
+      case SSL_ERROR_WANT_READ:
+        error_name = "SSL_ERROR_WANT_READ";
+        break;
+      case SSL_ERROR_WANT_WRITE:
+        error_name = "SSL_ERROR_WANT_WRITE";
+        break;
+      case SSL_ERROR_WANT_X509_LOOKUP:
+        error_name = "SSL_ERROR_WANT_X509_LOOKUP";
+        break;
+      // case SSL_ERROR_SYSCALL:
+      //   error_name = "SSL_ERROR_SYSCALL";
+      //   break;
+      case SSL_ERROR_ZERO_RETURN:
+        error_name = "SSL_ERROR_ZERO_RETURN";
+        break;
+      case SSL_ERROR_WANT_CONNECT:
+        error_name = "SSL_ERROR_WANT_CONNECT";
+        break;
+      case SSL_ERROR_WANT_ACCEPT:
+        error_name = "SSL_ERROR_WANT_ACCEPT";
+        break;
+      default:
+        error_name = "<UNKNOWN>";
+        break;
+    }
+
+    P1_fprintf(stderr, "polaris.c:%d] %s. [error=%s (%d; %s)]\n", line, message,
+               error_name, ssl_error, ERR_error_string(ssl_error, NULL));
+  }
+}
+
+#define P1_PrintWriteError(context, x, ret) \
+  __P1_PrintWriteError(__LINE__, context, x, ret)
+#else
+#define P1_PrintWriteError(context, x, ret) P1_PrintError(x, ret)
+#endif
+
+
 #if defined(POLARIS_TRACE) && !defined(POLARIS_DEBUG)
 # define POLARIS_DEBUG 1
 #endif
@@ -96,7 +157,6 @@ int Polaris_Init(PolarisContext_t* context) {
 
   SSL_library_init();
   OpenSSL_add_all_algorithms();
-  SSL_load_error_strings();
 #endif
 
   return POLARIS_SUCCESS;
@@ -259,7 +319,7 @@ int Polaris_ConnectTo(PolarisContext_t* context, const char* endpoint_url,
   ret = send(context->socket, context->recv_buffer, message_size, 0);
 #endif
   if (ret != message_size) {
-    P1_PrintError("Error sending authentication token", ret);
+    P1_PrintWriteError(context, "Error sending authentication token", ret);
     CloseSocket(context, 1);
     return POLARIS_SEND_ERROR;
   }
@@ -329,7 +389,7 @@ int Polaris_SendECEFPosition(PolarisContext_t* context, double x_m, double y_m,
 #endif
 
   if (ret != message_size) {
-    P1_PrintError("Error sending ECEF position", ret);
+    P1_PrintWriteError(context, "Error sending ECEF position", ret);
     return POLARIS_SEND_ERROR;
   } else {
     return POLARIS_SUCCESS;
@@ -372,7 +432,7 @@ int Polaris_SendLLAPosition(PolarisContext_t* context, double latitude_deg,
 #endif
 
   if (ret != message_size) {
-    P1_PrintError("Error sending LLA position", ret);
+    P1_PrintWriteError(context, "Error sending LLA position", ret);
     return POLARIS_SEND_ERROR;
   } else {
     return POLARIS_SUCCESS;
@@ -403,7 +463,7 @@ int Polaris_RequestBeacon(PolarisContext_t* context, const char* beacon_id) {
 #endif
 
   if (ret != message_size) {
-    P1_PrintError("Error sending beacon request", ret);
+    P1_PrintWriteError(context, "Error sending beacon request", ret);
     return POLARIS_SEND_ERROR;
   } else {
     return POLARIS_SUCCESS;
@@ -609,7 +669,18 @@ static int OpenSocket(PolarisContext_t* context, const char* endpoint_url,
 
   // Perform SSL handhshake.
   if (SSL_connect(context->ssl) == -1) {
-    P1_Print("SSL handshake failed to %s:%d.\n", endpoint_url, endpoint_port);
+    P1_Print("SSL handshake failed to tcp://%s:%d.\n", endpoint_url,
+             endpoint_port);
+    CloseSocket(context, 1);
+    return POLARIS_ERROR;
+  }
+
+  const SSL_CIPHER* c = SSL_get_current_cipher(context->ssl);
+  if (c == NULL) {
+    P1_Print(
+        "Server failed to negotiate encryption cipher. Verify that endpoint "
+        "tcp://%s:%d supports TLS 1.2 or better.\n",
+        endpoint_url, endpoint_port);
     CloseSocket(context, 1);
     return POLARIS_ERROR;
   }
@@ -727,7 +798,7 @@ static int SendPOSTRequest(PolarisContext_t* context, const char* endpoint_url,
 #endif
 
   if (ret != message_size) {
-    P1_PrintError("Error sending POST request", ret);
+    P1_PrintWriteError(context, "Error sending POST request", ret);
     CloseSocket(context, 1);
     return POLARIS_SEND_ERROR;
   }

c/src/point_one/polaris/portability.h

@@ -52,17 +52,26 @@ static inline int P1_GetElapsedMS(const P1_TimeValue_t* start,
 
 #else // POSIX
 
+# include <errno.h>
 # include <stdio.h>
 # include <sys/time.h>
 
 # ifndef P1_printf
 #  define P1_printf printf
 # endif
+
 # ifndef P1_fprintf
 #  define P1_fprintf fprintf
 # endif
+
+// The standard POSIX perror() does not include the numeric error code in the
+// printout, which is often very useful, so we do not use it.
+//
+// Note that we ignore the ret argument here, which is meant for use with
+// FreeRTOS, and instead get the actual error value from errno on POSIX systems.
 # ifndef P1_perror
-#  define P1_perror(format, ...) perror(format)
+#  define P1_perror(format, ret) \
+  P1_fprintf(stderr, format ". [error=%s (%d)]\n", strerror(errno), errno)
 # endif
 
 typedef struct timeval P1_TimeValue_t;

examples/ntrip/ntrip_example.cc

@@ -27,10 +27,10 @@ using namespace point_one::polaris;
 
 // Options for connecting to Polaris Server:
 DEFINE_string(
-    polaris_host, POLARIS_ENDPOINT_URL,
+    polaris_host, DEFAULT_ENDPOINT_URL,
     "The Polaris corrections endpoint URL to be used.");
 
-DEFINE_int32(polaris_port, POLARIS_ENDPOINT_PORT,
+DEFINE_int32(polaris_port, DEFAULT_ENDPOINT_PORT,
              "The TCP port of the Polaris corrections endpoint.");
 
 DEFINE_string(polaris_api_key, "",

src/point_one/polaris/polaris_interface.h

@@ -15,7 +15,7 @@ namespace point_one {
 namespace polaris {
 
 extern const std::string DEFAULT_ENDPOINT_URL;
-static constexpr int DEFAULT_ENDPOINT_PORT = POLARIS_ENDPOINT_PORT;
+static constexpr int DEFAULT_ENDPOINT_PORT = POLARIS_ENDPOINT_TLS_PORT;
 
 /**
  * @brief C++ wrapper class for the Polaris Client C library.