Show packets as hexdump instead of text

impl/src/main.c

@@ -3,6 +3,8 @@
 #include <string.h>
 #include <assert.h>
 #include <math.h>
+#include <ctype.h>
+
 #include <liquid/liquid.h>
 
 #include <unistd.h>
@@ -34,6 +36,47 @@ void print_complex_array(const char *varname, float complex const *array, size_t
 }
 
 
+void hexdump(const uint8_t *data, size_t len)
+{
+	static const char lut[16] = "0123456789ABCDEF";
+	static const size_t BYTES_PER_LINE = 16;
+
+	size_t pos = 0;
+
+	while(pos < len) {
+		size_t bytes_in_line = len - pos;
+		if(bytes_in_line > BYTES_PER_LINE) {
+			bytes_in_line = BYTES_PER_LINE;
+		}
+
+		for(size_t i = 0; i < BYTES_PER_LINE; i++) {
+			if(i >= bytes_in_line) {
+				fputs("   ", stderr);
+			} else {
+				uint8_t byte = data[pos+i];
+
+				fprintf(stderr, "%c%c ", lut[byte >> 4], lut[byte & 0x0F]);
+			}
+		}
+
+		fputs("  ", stderr);
+
+		for(size_t i = 0; i < bytes_in_line; i++) {
+			uint8_t byte = data[pos+i];
+
+			if(isprint(byte)) {
+				putc(byte, stderr);
+			} else {
+				putc('.', stderr);
+			}
+		}
+
+		putc('\n', stderr);
+		pos += bytes_in_line;
+	}
+}
+
+
 void cb_rx(rx_evt_t evt, uint8_t *packet_data, size_t packet_len)
 {
 	int ret;
@@ -43,13 +86,13 @@ void cb_rx(rx_evt_t evt, uint8_t *packet_data, size_t packet_len)
 		case RX_EVT_CHECKSUM_ERROR:
 			fprintf(stderr, "Received a message of %zu bytes, but decoding failed.\n", packet_len);
 			//fprintf(stderr, "=== FAILED PAYLOAD ===\n");
-			//fprintf(stderr, "%s\n", packet_data);
+			//hexdump(packet_data, packet_len);
 			//fprintf(stderr, "=======================\n");
 			break;
 
 		case RX_EVT_PACKET_RECEIVED:
 			fprintf(stderr, "=== DECODED PAYLOAD (%4zu bytes) ===\n", packet_len);
-			fprintf(stderr, "%s\n", packet_data);
+			hexdump(packet_data, packet_len);
 			fprintf(stderr, "====================================\n");
 
 			ret = write(m_tunfd, packet_data, packet_len);