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Configuration.md

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HTTP Parser Configuration

Both via::http_server and a via::http_client template classes take template parameters to control their HTTP request and response parsers respectively.

The defaults in the via::http_server and a via::http_client template classes are set to relatively relaxed values to permit most HTTP requests and all HTTP responses to be parsed successfully.
However, where it is known that HTTP request and/or response parameters will have smaller values they may be reduced, enabling the HTTP parsers to reject invalid HTTP requests and/or responses sooner.
Conversely, if an HTTP server expects requests from longer URI's or with more and/or larger headers then the request parameters can be increased.

HTTP Server Request Parameters

Parameter Description Default
MAX_URI_LENGTH The maximum length of an HTTP request URI: min 1, max 4 billion. 8190
MAX_METHOD_LENGTH The maximum length of an HTTP of an HTTP request method: min 1, max 254.
Note: "GET" is the shortest HTTP method, length = 3.		 8

MAX_URI_LENGTH

rfc7230 does not specify the maximum length of a uri, however it recommends a minimum of 8000. The default is based on rfc7230's recommendation, change it if using uris that are known to be much shorter or longer.

MAX_METHOD_LENGTH

rfc7230 does not specify the length of the method names, however the longest rfc7231 name is 7 characters long (OPTIONS).
Change this value if using only short names or non-standard names longer than 8 characters.

HTTP Client Response Parameters

Parameter Description Default/Max
MAX_STATUS_NUMBER The maximum number of an HTTP response status.
Note: "NETWORK_AUTHENTICATION_REQUIRED" is the highest standard HTTP response status = 511.		 65534
MAX_REASON_LENGTH The maximum length of a response reason string. 65534

HTTP Request/Response Common Parameters

Parameter Description Request Default
MAX_HEADER_NUMBER The maximum number of HTTP header field lines: max 65534. 100
MAX_HEADER_LENGTH The maximum cumulative length the HTTP header fields: max 4 billion. 65534
MAX_LINE_LENGTH The maximum length of an HTTP header field line: max 65534. 1024
MAX_WHITESPACE_CHARS The maximum number of consecutive whitespace characters permitted: max 254. 8
STRICT_CRLF Enforce strict parsing of CRLF in requests/responses. false

MAX_HEADER_NUMBER

The maximum number of header fields allowed in a request

MAX_HEADER_LENGTH

The maximum total size of the header fields for each request/response message.

MAX_LINE_LENGTH

This is the maximum length of a header field line, the default is 1024.
Note: cookie field lines may be longer than this.

MAX_WHITESPACE_CHARS

rfc7230 allows "optional" whitespace characters, see: rfc7230 section 3.2.3.
This value sets the maximum number of optional whitespace characters between HTTP elements: default 8, 1 is the minimum.

STRICT_CRLF

A strictly valid HTTP line must end with CRLF pair, however rfc7230 recommends that servers are tolerant so allow an LF without the CR (the default).

Enabling this value enforces strict CRLF parsing.