Network: make CDN endpoint configurable either in proj.ini, PROJ_NETWORK_ENDPOINT or proj_context_set_url_endpoint()

4 files changed, 137 insertions, 10 deletions

diff --git a/src/filemanager.cpp b/src/filemanager.cpp
index d9a02632..97d7369e 100644
--- a/src/filemanager.cpp
+++ b/src/filemanager.cpp
@@ -772,6 +772,9 @@ int proj_context_set_network_callbacks(
 
 /** Enable or disable network access.
 *
+* This overrides the default endpoint in the PROJ configuration file or with
+* the PROJ_NETWORK environment variable.
+*
 * @param ctx PROJ context, or NULL
 * @param enable TRUE if network access is allowed.
 * @return TRUE if network access is possible. That is either libcurl is
@@ -781,6 +784,8 @@ int proj_context_set_enable_network(PJ_CONTEXT *ctx, int enable) {
     if (ctx == nullptr) {
         ctx = pj_get_default_ctx();
     }
+    // Load ini file, now so as to override its network settings
+    pj_load_ini(ctx);
     ctx->networking.enabled_env_variable_checked = true;
     ctx->networking.enabled = enable != FALSE;
 #ifdef CURL_ENABLED
@@ -793,6 +798,25 @@ int proj_context_set_enable_network(PJ_CONTEXT *ctx, int enable) {
 
 // ---------------------------------------------------------------------------
 
+/** Define the URL endpoint to query for remote grids.
+*
+* This overrides the default endpoint in the PROJ configuration file or with
+* the PROJ_NETWORK_ENDPOINT environment variable.
+*
+* @param ctx PROJ context, or NULL
+* @param url Endpoint URL. Must NOT be NULL.
+*/
+void proj_context_set_url_endpoint(PJ_CONTEXT *ctx, const char *url) {
+    if (ctx == nullptr) {
+        ctx = pj_get_default_ctx();
+    }
+    // Load ini file, now so as to override its network settings
+    pj_load_ini(ctx);
+    ctx->endpoint = url;
+}
+
+// ---------------------------------------------------------------------------
+
 //! @cond Doxygen_Suppress
 
 bool pj_context_is_network_enabled(PJ_CONTEXT *ctx) {
@@ -808,6 +832,7 @@ bool pj_context_is_network_enabled(PJ_CONTEXT *ctx) {
                                   ci_equal(enabled, "YES") ||
                                   ci_equal(enabled, "TRUE");
     }
+    pj_load_ini(ctx);
     ctx->networking.enabled_env_variable_checked = true;
     return ctx->networking.enabled;
 }
diff --git a/src/open_lib.cpp b/src/open_lib.cpp
index 926505ba..cde5be7b 100644
--- a/src/open_lib.cpp
+++ b/src/open_lib.cpp
@@ -366,16 +366,21 @@ std::unique_ptr<NS_PROJ::File> NS_PROJ::FileManager::open_resource_file(
         !starts_with(name, "http://") &&
         !starts_with(name, "https://") &&
         pj_context_is_network_enabled(ctx) ) {
-        std::string remote_file("https://cdn.proj.org/");
-        remote_file += name;
-        auto pos = remote_file.rfind('.');
-        if( pos + 4 == remote_file.size() ) {
-            remote_file = remote_file.substr(0, pos) + ".tif";
-            file = open(ctx, remote_file.c_str());
-            if( file ) {
-                pj_log( ctx, PJ_LOG_DEBUG_MAJOR,
-                        "Using %s", remote_file.c_str() );
-                pj_ctx_set_errno( ctx, 0 );
+        std::string remote_file(pj_context_get_url_endpoint(ctx));
+        if( !remote_file.empty() ) {
+            if( remote_file.back() != '/' ) {
+                remote_file += '/';
+            }
+            remote_file += name;
+            auto pos = remote_file.rfind('.');
+            if( pos + 4 == remote_file.size() ) {
+                remote_file = remote_file.substr(0, pos) + ".tif";
+                file = open(ctx, remote_file.c_str());
+                if( file ) {
+                    pj_log( ctx, PJ_LOG_DEBUG_MAJOR,
+                            "Using %s", remote_file.c_str() );
+                    pj_ctx_set_errno( ctx, 0 );
+                }
             }
         }
     }
@@ -433,3 +438,91 @@ int pj_find_file(projCtx ctx, const char *short_filename,
     }
     return 0;
 }
+
+/************************************************************************/
+/*                    pj_context_get_url_endpoint()                     */
+/************************************************************************/
+
+std::string pj_context_get_url_endpoint(PJ_CONTEXT* ctx)
+{
+    if( !ctx->endpoint.empty() ) {
+        return ctx->endpoint;
+    }
+    pj_load_ini(ctx);
+    return ctx->endpoint;
+}
+
+/************************************************************************/
+/*                              trim()                                  */
+/************************************************************************/
+
+static std::string trim(const std::string& s) {
+    const auto first = s.find_first_not_of(' ');
+    const auto last = s.find_last_not_of(' ');
+    if( first == std::string::npos || last == std::string::npos ) {
+        return std::string();
+    }
+    return s.substr(first, last - first + 1);
+}
+
+/************************************************************************/
+/*                            pj_load_ini()                             */
+/************************************************************************/
+
+void pj_load_ini(projCtx ctx)
+{
+    if( ctx->iniFileLoaded )
+        return;
+
+    const char* endpoint_from_env = getenv("PROJ_NETWORK_ENDPOINT");
+    if( endpoint_from_env && endpoint_from_env[0] != '\0' ) {
+        ctx->endpoint = endpoint_from_env;
+    }
+
+    ctx->iniFileLoaded = true;
+    auto file = std::unique_ptr<NS_PROJ::File>(
+        reinterpret_cast<NS_PROJ::File*>(
+               pj_open_lib_internal(ctx, "proj.ini", "rb",
+                                    pj_open_file_with_manager,
+                                    nullptr, 0)));
+    if( !file )
+        return;
+    file->seek(0, SEEK_END);
+    const auto filesize = file->tell();
+    if( filesize == 0 || filesize > 100 * 1024U )
+        return;
+    file->seek(0, SEEK_SET);
+    std::string content;
+    content.resize(static_cast<size_t>(filesize));
+    const auto nread = file->read(&content[0], content.size());
+    if( nread != content.size() )
+        return;
+    content += '\n';
+    size_t pos = 0;
+    while( pos != std::string::npos ) {
+        const auto eol = content.find_first_of("\r\n", pos);
+        if( eol == std::string::npos ) {
+            break;
+        }
+
+        const auto equal = content.find('=', pos);
+        if( equal < eol )
+        {
+            const auto key = trim(content.substr(pos, equal-pos));
+            const auto value = trim(content.substr(equal + 1,
+                                                    eol - (equal+1)));
+            if( ctx->endpoint.empty() && key == "cdn_endpoint" ) {
+                ctx->endpoint = value;
+            } else if ( key == "network" ) {
+                const char *enabled = getenv("PROJ_NETWORK");
+                if (enabled == nullptr || enabled[0] == '\0') {
+                    ctx->networking.enabled = ci_equal(value, "ON") ||
+                                                ci_equal(value, "YES") ||
+                                                ci_equal(value, "TRUE");
+                }
+            }
+        }
+
+        pos = content.find_first_not_of("\r\n", eol);
+    }
+}
diff --git a/src/proj.h b/src/proj.h
index 7210318c..3f0879bb 100644
--- a/src/proj.h
+++ b/src/proj.h
@@ -424,6 +424,8 @@ int PROJ_DLL proj_context_set_network_callbacks(
 int PROJ_DLL proj_context_set_enable_network(PJ_CONTEXT* ctx,
                                              int enabled);
 
+void PROJ_DLL proj_context_set_url_endpoint(PJ_CONTEXT* ctx, const char* url);
+
 /*! @cond Doxygen_Suppress */
 
 /* Manage the transformation definition object PJ */
diff --git a/src/proj_internal.h b/src/proj_internal.h
index 983f1c07..669fd2b5 100644
--- a/src/proj_internal.h
+++ b/src/proj_internal.h
@@ -699,6 +699,9 @@ struct projCtx_t {
     projNetworkCallbacksAndData networking{};
     bool defer_grid_opening = false; // set by pj_obj_create()
 
+    bool iniFileLoaded = false;
+    std::string endpoint{};
+
     int projStringParserCreateFromPROJStringRecursionCounter = 0; // to avoid potential infinite recursion in PROJStringParser::createFromPROJString()
 
     projCtx_t() = default;
@@ -830,6 +833,10 @@ void pj_pipeline_assign_context_to_steps( PJ* P, PJ_CONTEXT* ctx );
 // For use by projinfo
 bool PROJ_DLL pj_context_is_network_enabled(PJ_CONTEXT* ctx);
 
+std::string pj_context_get_url_endpoint(PJ_CONTEXT* ctx);
+
+void pj_load_ini(PJ_CONTEXT* ctx);
+
 /* classic public API */
 #include "proj_api.h"