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POiphone problem receiving UDP packets
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copied!<p>I'm using <code>sendto()</code> and <code>recvfrom()</code> to send some simple packets via UDP over WiFI.</p> <p>I've tried using two phones, and a simulator, the results I'm getting are:</p> <p>Packets sent from phones -> recieved by simulator Packets sent from simulator -> simulator recvfrom remains blocking. Packets sent from phones -> other phone recvfrom remains blocking.</p> <p>I'm not sure how to start debugging this one, since the simulator/mac is able to receive the the packets, but the phones don't appear to be getting the message.</p> <p>A slight aside, do I need to keep my packets below the MTU for my network? Or is fragmentation handled by the OS or some other lower level software?</p> <p>UPDATE: I forgot to include the packet size and structure. I'm transmitting:</p> <pre><code>typedef struct PacketForTransmission { int32_t packetTypeIdentifier; char data[64]; // size to fit my biggest struct } PacketForTransmission; </code></pre> <p>of which the char data[64] is:</p> <pre><code>typedef struct PacketHeader{ uint32_t identifier; uint32_t datatype; } PacketHeader; typedef struct BasePacket{ PacketHeader header; int32_t cardValue; char sendingDeviceID[41]; //dont forget to save room for the NULL terminator! } BasePacket; typedef struct PositionPacket{ BasePacket basePacket; int32_t x; int32_t y; } PositionPacket; </code></pre> <p>sending packet is like:</p> <pre><code>PositionPacket packet; bzero(&packet, sizeof(packet)); //fill packet with it's associated data PacketForTransmission transmissionPacket; transmissionPacket.packetTypeIdentifier = kPositionPacketType; memcpy(&transmissionPacket.data, (void*)&packet, sizeof(packet)); //put the PositionPacket into data[64] size_t sendResult = sendto(_socket, &transmissionPacket, sizeof(transmissionPacket), 0, [address bytes], [address length]); NSLog(@"packet sent of size: %i", sendResult); </code></pre> <p>and recieving packets is like:</p> <pre><code>while(1){ char dataBuffer[8192]; struct sockaddr addr; socklen_t socklen = sizeof(addr); ssize_t len = recvfrom(_socket, dataBuffer, sizeof(dataBuffer), 0, &addr, &socklen); //continues blocking here NSLog(@"packet recieved of length: %i", len); //do some more stuff } </code></pre>

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