gRPC: RST_STREAM(NO_ERROR) handling (ticket #1792). As per https://tools.ietf.org/html/rfc7540#section-8.1, : A server can send a complete response prior to the client : sending an entire request if the response does not depend on : any portion of the request that has not been sent and : received. When this is true, a server MAY request that the : client abort transmission of a request without error by : sending a RST_STREAM with an error code of NO_ERROR after : sending a complete response (i.e., a frame with the : END_STREAM flag). Clients MUST NOT discard responses as a : result of receiving such a RST_STREAM, though clients can : always discard responses at their discretion for other : reasons. Previously, RST_STREAM(NO_ERROR) received from upstream after a frame with the END_STREAM flag was incorrectly treated as an error. Now, a single RST_STREAM(NO_ERROR) is properly handled. This fixes problems observed with modern grpc-c [1], as well as with the Go gRPC module. [1] https://github.com/grpc/grpc/pull/1661

/*
 * Copyright (C) Austin Appleby
 */


#include <ngx_config.h>
#include <ngx_core.h>


uint32_t
ngx_murmur_hash2(u_char *data, size_t len)
{
    uint32_t  h, k;

    h = 0 ^ len;

    while (len >= 4) {
        k  = data[0];
        k |= data[1] << 8;
        k |= data[2] << 16;
        k |= data[3] << 24;

        k *= 0x5bd1e995;
        k ^= k >> 24;
        k *= 0x5bd1e995;

        h *= 0x5bd1e995;
        h ^= k;

        data += 4;
        len -= 4;
    }

    switch (len) {
    case 3:
        h ^= data[2] << 16;
        /* fall through */
    case 2:
        h ^= data[1] << 8;
        /* fall through */
    case 1:
        h ^= data[0];
        h *= 0x5bd1e995;
    }

    h ^= h >> 13;
    h *= 0x5bd1e995;
    h ^= h >> 15;

    return h;
}