Question

I have a callback function called got_packet:

void got_packet(u_char *args, const struct pcap_pkthdr *header, const u_char *packet) {
  WMShark *shark = (WMShark *)args;

  WMPacket *foundPacket = [[WMPacket alloc] init];
  foundPacket.packetNumber = [[shark capturedPackets] count];

  foundPacket.timeStamp = header.ts; // <-- PROBLEM IS HERE

  ...

  NSLog(@"%@: %s", shark, packet);
}

I get a compile error error: request for member 'ts' in something not a structure or union on the line foundPacket.timeStamp = header.ts;.

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The documentation says:

…
a const struct pcap_pkthdr pointer to a structure with the following mem-bers:

• ts — a struct timeval containing the time when the packet was captured

…

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How can I access ts? Thanks.

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For the die-hard C-developers, the square brackets are used in Objective-C, a superset of C. You can ignore this, they’re initializers in this case.

Answer 1

As you’ve the pointer to the struct, use the -> operator instead of .:

header->ts