config: add helper to normalize and match URLs

Some http.* configuration variables need to take values customized
for the URL we are talking to.  We may want to set http.sslVerify to
true in general but to false only for a certain site, for example,
with a configuration file like this:

	[http]
		sslVerify = true
	[http "https://weak.example.com"]
		sslVerify = false

and let the configuration machinery pick up the latter only when
talking to "https://weak.example.com".  The latter needs to kick in
not only when the URL is exactly "https://weak.example.com", but
also is anything that "match" it, e.g.

	https://weak.example.com/test
	https://me@weak.example.com/test

The <url> in the configuration key consists of the following parts,
and is considered a match to the URL we are attempting to access
under certain conditions:

  . Scheme (e.g., `https` in `https://example.com/`). This field
    must match exactly between the config key and the URL.

  . Host/domain name (e.g., `example.com` in `https://example.com/`).
    This field must match exactly between the config key and the URL.

  . Port number (e.g., `8080` in `http://example.com:8080/`).  This
    field must match exactly between the config key and the URL.
    Omitted port numbers are automatically converted to the correct
    default for the scheme before matching.

  . Path (e.g., `repo.git` in `https://example.com/repo.git`). The
    path field of the config key must match the path field of the
    URL either exactly or as a prefix of slash-delimited path
    elements.  A config key with path `foo/` matches URL path
    `foo/bar`.  A prefix can only match on a slash (`/`) boundary.
    Longer matches take precedence (so a config key with path
    `foo/bar` is a better match to URL path `foo/bar` than a config
    key with just path `foo/`).

  . User name (e.g., `me` in `https://me@example.com/repo.git`). If
    the config key has a user name, it must match the user name in
    the URL exactly. If the config key does not have a user name,
    that config key will match a URL with any user name (including
    none), but at a lower precedence than a config key with a user
    name.

Longer matches take precedence over shorter matches.

This step adds two helper functions `url_normalize()` and
`match_urls()` to help implement the above semantics. The
normalization rules are based on RFC 3986 and should result in any
two equivalent urls being a match.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/urlmatch.h b/urlmatch.h
new file mode 100644
index 0000000000..b67f57f86f
--- /dev/null
+++ b/urlmatch.h
@@ -0,0 +1,36 @@
+#ifndef URL_MATCH_H
+#include "string-list.h"
+
+struct url_info {
+	/* normalized url on success, must be freed, otherwise NULL */
+	char *url;
+	/* if !url, a brief reason for the failure, otherwise NULL */
+	const char *err;
+
+	/* the rest of the fields are only set if url != NULL */
+
+	size_t url_len;		/* total length of url (which is now normalized) */
+	size_t scheme_len;	/* length of scheme name (excluding final :) */
+	size_t user_off;	/* offset into url to start of user name (0 => none) */
+	size_t user_len;	/* length of user name; if user_off != 0 but
+				   user_len == 0, an empty user name was given */
+	size_t passwd_off;	/* offset into url to start of passwd (0 => none) */
+	size_t passwd_len;	/* length of passwd; if passwd_off != 0 but
+				   passwd_len == 0, an empty passwd was given */
+	size_t host_off;	/* offset into url to start of host name (0 => none) */
+	size_t host_len;	/* length of host name; this INCLUDES any ':portnum';
+				 * file urls may have host_len == 0 */
+	size_t port_len;	/* if a portnum is present (port_len != 0), it has
+				 * this length (excluding the leading ':') at the
+				 * end of the host name (always 0 for file urls) */
+	size_t path_off;	/* offset into url to the start of the url path;
+				 * this will always point to a '/' character
+				 * after the url has been normalized */
+	size_t path_len;	/* length of path portion excluding any trailing
+				 * '?...' and '#...' portion; will always be >= 1 */
+};
+
+extern char *url_normalize(const char *, struct url_info *);
+extern int match_urls(const struct url_info *url, const struct url_info *url_prefix, int *exactusermatch);
+
+#endif /* URL_MATCH_H */