Fix some typos

Found with codespell.

Author: fxlb

doc/pcapdump.docbook

@@ -21,7 +21,7 @@
 
   <refsect1>
     <title>DESCRIPTION</title>
-    <para><command>pcapdump</command> captures packets from a network interface and writes them to a dumpfile. The filename argument given to <option>-w</option> will be formated by <function>strftime(3)</function>.</para>
+    <para><command>pcapdump</command> captures packets from a network interface and writes them to a dumpfile. The filename argument given to <option>-w</option> will be formatted by <function>strftime(3)</function>.</para>
   </refsect1>
 
   <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="pcapnet.docbook"/>

src/pcapuc.c

@@ -185,7 +185,7 @@ static void parse_args(int argc, char **argv){
 		usage("need to specify a packet capture source");
 	int c = count_src_only + count_dst_only + count_pairs_only;
 	if(c > 1)
-		usage("mutually exclusive options selecetd");
+		usage("mutually exclusive options selected");
 	else if(c == 0)
 		usage("select a counting mode");
 }

util/net.h

@@ -213,7 +213,7 @@ struct dnshdr {
 		 /* fields in third byte */
 	unsigned qr: 1;	  /* response flag */
 	unsigned opcode: 4;      /* purpose of message */
-	unsigned aa: 1;	  /* authoritive answer */
+	unsigned aa: 1;	  /* authoritative answer */
 	unsigned tc: 1;	  /* truncated message */
 	unsigned rd: 1;	  /* recursion desired */
 		 /* fields in fourth byte */
@@ -227,7 +227,7 @@ struct dnshdr {
 			/* fields in third byte */
 	unsigned rd :1;	  /* recursion desired */
 	unsigned tc :1;	  /* truncated message */
-	unsigned aa :1;	  /* authoritive answer */
+	unsigned aa :1;	  /* authoritative answer */
 	unsigned opcode :4;      /* purpose of message */
 	unsigned qr :1;	  /* response flag */
 		 /* fields in fourth byte */