1 files changed, 192 insertions, 0 deletions
diff --git a/src/common/impl/networking_common.c b/src/common/impl/networking_common.c
new file mode 100644
index 0000000..e63979b
--- /dev/null
+++ b/src/common/impl/networking_common.c
@@ -0,0 +1,192 @@
+#include "fastfetch.h"
+#include "common/library.h"
+#include "common/networking.h"
+#include "common/strutil.h"
+#include "common/debug.h"
+
+#ifdef FF_HAVE_ZLIB
+    #include <zlib.h>
+
+struct FFZlibLibrary {
+    FF_LIBRARY_SYMBOL(inflateInit2_)
+    FF_LIBRARY_SYMBOL(inflate)
+    FF_LIBRARY_SYMBOL(inflateEnd)
+
+    bool inited;
+} zlibData;
+
+const char* ffNetworkingLoadZlibLibrary(void) {
+    if (!zlibData.inited) {
+        zlibData.inited = true;
+        FF_LIBRARY_LOAD_MESSAGE(zlib,
+    #ifdef _WIN32
+            "zlib1"
+    #else
+            "libz"
+    #endif
+            FF_LIBRARY_EXTENSION,
+            2)
+        FF_LIBRARY_LOAD_SYMBOL_VAR_MESSAGE(zlib, zlibData, inflateInit2_)
+        FF_LIBRARY_LOAD_SYMBOL_VAR_MESSAGE(zlib, zlibData, inflate)
+        FF_LIBRARY_LOAD_SYMBOL_VAR_MESSAGE(zlib, zlibData, inflateEnd)
+        zlib = NULL; // don't auto dlclose
+    }
+    return zlibData.ffinflateEnd == NULL ? "Failed to load libz" : NULL;
+}
+
+// Try to pre-read gzip header to determine uncompressed size
+static uint32_t guessGzipOutputSize(const void* data, uint32_t dataSize) {
+    // gzip file format: http://www.zlib.org/rfc-gzip.html
+    if (dataSize < 10 || ((const uint8_t*) data)[0] != 0x1f || ((const uint8_t*) data)[1] != 0x8b) {
+        return 0;
+    }
+
+    // Uncompressed size in gzip format is stored in the last 4 bytes, but only valid if data is less than 4GB
+    if (dataSize > 18) {
+        // Get ISIZE value from the end of file (little endian)
+        const uint8_t* tail = (const uint8_t*) data + dataSize - 4;
+        uint32_t uncompressedSize = (uint32_t) tail[0] | ((uint32_t) tail[1] << 8u) | ((uint32_t) tail[2] << 16u) | ((uint32_t) tail[3] << 24u);
+
+        // For valid gzip files, this value is the length of the uncompressed data modulo 2^32
+        if (uncompressedSize > 0) {
+            FF_DEBUG("Read uncompressed size from GZIP trailer: %u bytes", uncompressedSize);
+            // Add some margin to the estimated size for safety
+            return uncompressedSize + 64;
+        }
+    }
+
+    // If unable to get size from trailer or size is 0, use estimated value
+    // Typically, text data compression ratio is between 3-5x, we use the larger value
+    uint32_t estimatedSize = dataSize * 5;
+    FF_DEBUG("Unable to read exact uncompressed size, estimated as 5x of compressed data: %u bytes", estimatedSize);
+    return estimatedSize;
+}
+
+// Decompress gzip content
+bool ffNetworkingDecompressGzip(FFstrbuf* buffer, char* headerEnd) {
+    assert(headerEnd != NULL && *headerEnd == '\r');
+
+    // Calculate header size
+    uint32_t headerSize = (uint32_t) (headerEnd - buffer->chars);
+
+    *headerEnd = '\0'; // Replace delimiter with null character for easier processing
+    // Ensure Content-Encoding is in response headers, not in response body
+    bool hasGzip = strcasestr(buffer->chars, "\nContent-Encoding: gzip") != NULL;
+    *headerEnd = '\r'; // Restore delimiter
+
+    if (!hasGzip) {
+        FF_DEBUG("No gzip compressed content detected, skipping decompression");
+        return true;
+    }
+
+    FF_DEBUG("Gzip compressed content detected, preparing for decompression");
+
+    const char* bodyStart = headerEnd + 4; // Skip delimiter
+
+    if (buffer->length <= headerSize + 4) {
+        // No content to decompress
+        FF_DEBUG("Compressed content size is 0, skipping decompression");
+        return true;
+    }
+
+    // Calculate compressed content size
+    uint32_t compressedSize = buffer->length - headerSize - 4;
+
+    // Check if content is actually in gzip format (gzip header magic is 0x1f 0x8b)
+    if (compressedSize < 2 || (uint8_t) bodyStart[0] != 0x1f || (uint8_t) bodyStart[1] != 0x8b) {
+        FF_DEBUG("Content is not valid gzip format, skipping decompression");
+        return false;
+    }
+
+    // Predict uncompressed size
+    uint32_t estimatedSize = guessGzipOutputSize(bodyStart, compressedSize);
+
+    // Create decompression buffer with estimated size
+    FF_STRBUF_AUTO_DESTROY decompressedBuffer = ffStrbufCreateA(estimatedSize > 0 ? estimatedSize : compressedSize * 5);
+    FF_DEBUG("Created decompression buffer: %u bytes", decompressedBuffer.allocated);
+
+    // Initialize decompression
+    z_stream zs = {
+        .zalloc = Z_NULL,
+        .zfree = Z_NULL,
+        .opaque = Z_NULL,
+        .avail_in = (uInt) compressedSize,
+        .next_in = (Bytef*) bodyStart,
+        .avail_out = (uInt) ffStrbufGetFree(&decompressedBuffer),
+        .next_out = (Bytef*) decompressedBuffer.chars,
+    };
+
+    // Initialize decompression engine
+    if (zlibData.ffinflateInit2_(&zs, 16 + MAX_WBITS, ZLIB_VERSION, (int) sizeof(z_stream)) != Z_OK) {
+        FF_DEBUG("Failed to initialize decompression engine");
+        return false;
+    }
+    uInt availableOut = zs.avail_out;
+
+    // Perform decompression
+    int result = zlibData.ffinflate(&zs, Z_FINISH);
+
+    // If output buffer is insufficient, try to extend buffer
+    while (result == Z_BUF_ERROR || (result != Z_STREAM_END && zs.avail_out == 0)) {
+        FF_DEBUG("Output buffer insufficient, trying to extend");
+
+        // Save already decompressed data amount
+        uint32_t alreadyDecompressed = (uint32_t) (availableOut - zs.avail_out);
+        decompressedBuffer.length += alreadyDecompressed;
+        decompressedBuffer.chars[decompressedBuffer.length] = '\0';
+
+        ffStrbufEnsureFree(&decompressedBuffer, decompressedBuffer.length / 2);
+
+        // Set output parameters to point to new buffer
+        zs.avail_out = (uInt) ffStrbufGetFree(&decompressedBuffer);
+        zs.next_out = (Bytef*) (decompressedBuffer.chars + decompressedBuffer.length);
+        availableOut = zs.avail_out;
+
+        // Decompress again
+        result = zlibData.ffinflate(&zs, Z_FINISH);
+    }
+
+    // Check for decompression errors before using result
+    if (result != Z_STREAM_END) {
+        FF_DEBUG("Decompression failed with zlib error: %d", result);
+        zlibData.ffinflateEnd(&zs);
+        return false;
+    }
+
+    zlibData.ffinflateEnd(&zs);
+
+    // Calculate decompressed size (from the last inflate call)
+    uint32_t decompressedSize = (uint32_t) (availableOut - zs.avail_out);
+    decompressedBuffer.length += decompressedSize;
+    decompressedBuffer.chars[decompressedBuffer.length] = '\0';
+    FF_DEBUG("Successfully decompressed %u bytes compressed data to %u bytes", compressedSize, decompressedBuffer.length);
+
+    // Modify Content-Length header and remove Content-Encoding header
+    // Use decompressedBuffer.length (total) not decompressedSize (last chunk only)
+    FF_STRBUF_AUTO_DESTROY newBuffer = ffStrbufCreateA(headerSize + decompressedBuffer.length + 64);
+
+    char* line = NULL;
+    size_t len = 0;
+    while (ffStrbufGetline(&line, &len, buffer)) {
+        if (ffStrStartsWithIgnCase(line, "Content-Encoding:")) {
+            continue;
+        } else if (ffStrStartsWithIgnCase(line, "Content-Length:")) {
+            ffStrbufAppendF(&newBuffer, "Content-Length: %u\r\n", decompressedBuffer.length);
+            continue;
+        } else if (line[0] == '\r') {
+            ffStrbufAppendS(&newBuffer, "\r\n");
+            ffStrbufGetlineRestore(&line, &len, buffer);
+            break;
+        }
+
+        ffStrbufAppendS(&newBuffer, line); // Including the trailing \r
+        ffStrbufAppendC(&newBuffer, '\n');
+    }
+
+    ffStrbufAppend(&newBuffer, &decompressedBuffer);
+    ffStrbufDestroy(buffer);
+    ffStrbufInitMove(buffer, &newBuffer);
+
+    return true;
+}
+#endif // FF_HAVE_ZLIB