Difference between revisions of "UDP Packet Header Formats"
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| + | <font size="+1"> | ||
| + | === Load Balancer Header === | ||
| + | : Following is the C routine to write the header that the LB reads, and eventually strips off, in order to direct the packet to the proper destination. | ||
<pre> | <pre> | ||
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* The tick goes as a single, network byte ordered, 64-bit int. | * The tick goes as a single, network byte ordered, 64-bit int. | ||
* | * | ||
| − | |||
* | * | ||
* 0 1 2 3 | * 0 1 2 3 | ||
| Line 48: | Line 50: | ||
</pre> | </pre> | ||
| + | |||
| + | : Currently the version = 2. | ||
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} | } | ||
</pre> | </pre> | ||
| + | |||
| + | </font> | ||
Revision as of 21:39, 16 November 2023
Load Balancer Header
- Following is the C routine to write the header that the LB reads, and eventually strips off, in order to direct the packet to the proper destination.
/**
* Set the Load Balancer header data.
* The first four bytes go as ordered.
* The entropy goes as a single, network byte ordered, 16-bit int.
* The tick goes as a single, network byte ordered, 64-bit int.
*
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | L | B | Version | Protocol |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* 3 4 5 6
* 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Rsvd | Entropy |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* 6 12
* 4 5 ... ... ... 0 1 2 3 4 5 6 7
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* + Tick +
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* @param buffer buffer in which to write the header.
* @param tick unsigned 64 bit tick number used to tell the load balancer
* which backend host to direct the packet to.
* @param version version of this software.
* @param protocol protocol this software uses.
* @param entropy entropy field used to determine destination port.
*/
static void setLbMetadata(char* buffer, uint64_t tick, int version, int protocol, int entropy) {
*buffer = 'L';
*(buffer+1) = 'B';
*(buffer+2) = version;
*(buffer+3) = protocol;
// Put the data in network byte order (big endian)
*((uint16_t *)(buffer + 6)) = htons(entropy);
*((uint64_t *)(buffer + 8)) = htonll(tick);
}
- Currently the version = 2.
/**
* <p>Set the Reassembly Header data.
* The first 16 bits go as ordered. The dataId is put in network byte order.
* The offset, length and tick are also put into network byte order.</p>
* Implemented <b>without</b> using C++ bit fields.
* This is the new, version 2, RE header.
*
* protocol 'Version:4, Rsvd:12, Data-ID:16, Offset:32, Length:32, Tick:64'
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |Version| Rsvd | Data-ID |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Buffer Offset |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Buffer Length |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* + Tick +
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* @param buffer buffer in which to write the header.
* @param offset byte offset into full buffer payload.
* @param length total length in bytes of full buffer payload.
* @param tick 64 bit tick number used to tell the load balancer
* which backend host to direct the packet to. Necessary to
* disentangle packets from different ticks at one destination
* as there may be overlap in time.
* @param version the version of this software.
* @param dataId the data source id number.
*/
static void setReMetadata(char* buffer, uint32_t offset, uint32_t length,
uint64_t tick, int version, uint16_t dataId) {
buffer[0] = version << 4;
*((uint16_t *)(buffer + 2)) = htons(dataId);
*((uint32_t *)(buffer + 4)) = htonl(offset);
*((uint32_t *)(buffer + 8)) = htonl(length);
*((uint64_t *)(buffer + 12)) = htonll(tick);
}