Well, it doesn't compile yet, but I don't want to lose it, either

examples/pcapread.c

@@ -23,7 +23,7 @@ static void usage(int argc, char **argv, const char *message, ...) {
     exit(1);
 }
 
-static int handle_block(int fd, uint32_t type, size_t len) {
+static int handle_block(int fd, uint32_t type, size_t len, int *error) {
     hexagram_pcapng_packet header;
     uint8_t packet[65535];
 
@@ -83,9 +83,13 @@ static int handle_block(int fd, uint32_t type, size_t len) {
         goto error_io;
     }
 
+    *error = HEXAGRAM_PCAPNG_ERROR_OK;
+
     return 0;
 
 error_io:
+    *error = HEXAGRAM_PCAPNG_ERROR_IO;
+
     return -1;
 }
 

include/hexagram/pcapng.h

@@ -11,20 +11,6 @@
 #include <hexagram/pcapng/if.h>
 #include <hexagram/pcapng/if_stats.h>
 #include <hexagram/pcapng/packet.h>
-
+#include <hexagram/pcapng/stream.h>
-/*
- * pcapng stream reading facilities
- */
-typedef struct _hexagram_pcapng_stream hexagram_pcapng_stream;
-
-typedef int (hexagram_pcapng_block_handler)(int fd,
-                                            uint32_t type,
-                                            size_t length);
-
-ssize_t hexagram_pcapng_stream_read(int fd,
-                                    hexagram_pcapng_block_handler *handler,
-                                    int *error);
-
-
 
 #endif /* _HEXAGRAM_PCAPNG_H */

include/hexagram/pcapng/block.h

@@ -20,4 +20,9 @@ typedef struct _hexagram_pcapng_block_footer {
     uint32_t length;
 } hexagram_pcapng_block_footer;
 
+typedef ssize_t (hexagram_pcapng_block_handler)(int fd,
+                                                uint32_t type,
+                                                size_t length,
+                                                int *error);
+
 #endif /* _HEXAGRAM_PCAPNG_BLOCK_H */

include/hexagram/pcapng/error.h

@@ -8,8 +8,7 @@ typedef enum {
     HEXAGRAM_PCAPNG_ERROR_OK        = 0,
     HEXAGRAM_PCAPNG_ERROR_IO        = 1,
     HEXAGRAM_PCAPNG_ERROR_TRUNCATED = 2,
-    HEXAGRAM_PCAPNG_ERROR_FORMAT    = 3,
+    HEXAGRAM_PCAPNG_ERROR_FORMAT    = 3
-    HEXAGRAM_PCAPNG_ERROR_HANDLER   = 4
 } hexagram_pcapng_error;
 
 #endif /* _HEXAGRAM_PCAPNG_ERROR_H */

include/hexagram/pcapng/option.h

@@ -16,4 +16,13 @@ typedef struct _hexagram_pcapng_option {
              length;
 } hexagram_pcapng_option;
 
+typedef ssize_t (hexagram_pcapng_option_handler)(int fd,
+                                                 uint16_t code,
+                                                 uint16_t length);
+
+ssize_t hexagram_pcapng_option_read(int fd,
+                                    hexagram_pcapng_option_handler *handler,
+                                    size_t len,
+                                    int *error);
+
 #endif /* _HEXAGRAM_PCAPNG_OPTION_H */

include/hexagram/pcapng/stream.h

@@ -0,0 +1,13 @@
+#ifndef _HEXAGRAM_PCAPNG_STREAM_H
+#define _HEXAGRAM_PCAPNG_STREAM_H
+
+/*
+ * pcapng stream reading facilities
+ */
+typedef struct _hexagram_pcapng_stream hexagram_pcapng_stream;
+
+ssize_t hexagram_pcapng_stream_read(int fd,
+                                    hexagram_pcapng_block_handler *handler,
+                                    int *error);
+
+#endif /* _HEXAGRAM_PCAPNG_STREAM_H */

src/pcapng.c

@@ -15,6 +15,47 @@ struct _hexagram_pcapng_stream {
     hexagram_pcapng_if_stats *stats;
 };
 
+ssize_t hexagram_pcapng_option_read(int fd,
+                                    hexagram_pcapng_option_handler *handler,
+                                    size_t len,
+                                    int *error) {
+    hexagram_pcapng_option header;
+    ssize_t total = 0;
+
+    while (total < len) {
+        size_t expected;
+        ssize_t readlen;
+
+        if ((readlen = read(fd, &header, sizeof(header))) < 0) {
+            *error = HEXAGRAM_PCAPNG_ERROR_IO;
+
+            goto error_io;
+        } else {
+            total += readlen;
+        }
+
+        expected = header.length + (header.length % sizeof(uint32_t));
+
+        if ((readlen = handler(fd, header.code, expected, error)) < 0) {
+            goto error_io;
+        } else if (readlen < expected) {
+            *error = HEXAGRAM_PCAPNG_ERROR_TRUNCATED;
+
+            goto error_io;
+        } else {
+            total += readlen;
+        }
+    }
+
+done:
+    *error = HEXAGRAM_PCAPNG_ERROR_OK;
+
+    return total;
+
+error_io:
+    return -1;
+}
+
 hexagram_pcapng_stream *hexagram_pcapng_stream_open_fd(int fd) {
     hexagram_pcapng_stream *stream;
 
@@ -56,9 +97,7 @@ ssize_t hexagram_pcapng_stream_read(fd, handler, error)
 
         total += readlen;
 
-        if (handler(fd, header.type, header.length - sizeof(header) - sizeof(footer)) < 0) {
+        if (handler(fd, header.type, header.length - sizeof(header) - sizeof(footer), error) < 0) {
-            *error = HEXAGRAM_PCAPNG_ERROR_HANDLER;
-
             goto error_io;
         }