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POlibpcap Radiotap header extraction
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copied!<p>I've got some code that is using the functions <code>ieee80211_radiotap_iterator_init()</code> and <code>ieee80211_radiotap_iterator_next()</code> from <a href="http://airscan.googlecode.com/svn-history/r2/trunk/radiotap-parser.c" rel="nofollow"><code>radiotap-parser.c</code></a>, </p> <p>I'm not sure what I'm doing incorrectly, perhaps someone can educate me? I'm using the sample code from <a href="http://www.cs.fsu.edu/~baker/devices/lxr/http/source/linux/Documentation/networking/radiotap-headers.txt" rel="nofollow">the documentation</a> more or less without modification, it fits very well to what I was trying to achieve:</p> <pre><code>/* where packet is `const u_char *packet' */ struct ieee80211_radiotap_iterator rti; struct ieee80211_radiotap_header *rth = ( struct ieee80211_radiotap_header * ) packet; /* 802.11 frame starts here */ struct wi_frame *fr= ( struct wi_frame * ) ( packet + rth->it_len ); /* Set up the iteration */ int ret = ieee80211_radiotap_iterator_init(&rti, rth, rth->it_len); /* Loop until we've consumed all the fields */ while(!ret) { printf("Itteration: %d\n", count++); ret = ieee80211_radiotap_iterator_next(&rti); if(ret) { /* * The problem is here, I'm dropping into this clause with * a value of `1` consistently, that doesn't match my platform's * definition of EINVAL or ENOENT. */ continue; } switch(rti.this_arg_index) { default: printf("Constant: %d\n", *rti.this_arg); break; } } </code></pre> <p>There's limited scope for having screwed something up in that code, I think, I'm confused by the <code>1</code> being returned from <code>ieee80211_radiotap_iterator_next()</code> which according to the implenentation doesn't seem like an error condition in <a href="http://lxr.free-electrons.com/source/net/wireless/radiotap.c#L95" rel="nofollow">the implementation</a>.</p> <p>I'm filtering for packets of type <code>"(type mgt) and (not type mgt subtype beacon)"</code>, and I'm not even certain if libpcap will include these attributes when the data link is set to <code>DLT_IEEE802_11_RADIO</code>?</p>

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