67 lines
2.2 KiB
ReStructuredText
67 lines
2.2 KiB
ReStructuredText
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nghttp2_select_next_protocol
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============================
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Synopsis
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--------
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*#include <nghttp2/nghttp2.h>*
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.. function:: int nghttp2_select_next_protocol(unsigned char **out, unsigned char *outlen, const unsigned char *in, unsigned int inlen)
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A helper function for dealing with NPN in client side or ALPN in
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server side. The *in* contains peer's protocol list in preferable
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order. The format of *in* is length-prefixed and not
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null-terminated. For example, ``h2`` and
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``http/1.1`` stored in *in* like this::
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in[0] = 2
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in[1..2] = "h2"
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in[3] = 8
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in[4..11] = "http/1.1"
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inlen = 12
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The selection algorithm is as follows:
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1. If peer's list contains HTTP/2 protocol the library supports,
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it is selected and returns 1. The following step is not taken.
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2. If peer's list contains ``http/1.1``, this function selects
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``http/1.1`` and returns 0. The following step is not taken.
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3. This function selects nothing and returns -1 (So called
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non-overlap case). In this case, *out* and *outlen* are left
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untouched.
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Selecting ``h2`` means that ``h2`` is written into *\*out* and its
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length (which is 2) is assigned to *\*outlen*.
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For ALPN, refer to https://tools.ietf.org/html/rfc7301
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See http://technotes.googlecode.com/git/nextprotoneg.html for more
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details about NPN.
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For NPN, to use this method you should do something like::
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static int select_next_proto_cb(SSL* ssl,
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unsigned char **out,
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unsigned char *outlen,
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const unsigned char *in,
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unsigned int inlen,
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void *arg)
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{
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int rv;
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rv = nghttp2_select_next_protocol(out, outlen, in, inlen);
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if (rv == -1) {
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return SSL_TLSEXT_ERR_NOACK;
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}
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if (rv == 1) {
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((MyType*)arg)->http2_selected = 1;
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}
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return SSL_TLSEXT_ERR_OK;
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}
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...
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SSL_CTX_set_next_proto_select_cb(ssl_ctx, select_next_proto_cb, my_obj);
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