[hackers] [quark] Refactor resource-parsing and -handling heavily || Laslo Hunhold
commit 8aa213c123cbcfc2e50a77142c2206c202705e90
Author: Laslo Hunhold <dev_AT_frign.de>
AuthorDate: Wed Feb 3 18:33:51 2021 +0100
Commit: Laslo Hunhold <dev_AT_frign.de>
CommitDate: Wed Feb 3 19:05:01 2021 +0100
Refactor resource-parsing and -handling heavily
The previous approach of stripping query and fragment from the resource
was flawed and fixing this issue motivated a much deeper refactor that
was on my todo-list for a while.
First off, the resource-request (e.g. "/projects/index.html?123#eme")
is made up of the path ("/projects/index.html") and optionally the
query ("123") and fragment ("eme"). Instead of trying to break it up
or stripping it in the response-generation, we now store these three
things separately in the request-struct. Calling the resource-request
an "URI" was wrong, as the URI also includes the authority (i.e. the
host in this case) and the protocol-prefix (i.e. "http://"). To fix
this, the respective fields in the request- and response-structs had
to be renamed, as follows:
This commit adds a differentiation between a "path" (what is publicly
requested) and an "internal_path" (what we actually serve in the file
system). These two things can differ, e.g. with virtual hosts. The
cleanup and generation of these paths for the response-struct is heavily
refactored in http_prepare_response(), eliminating some deep bugs that
were due to the previously complicated approach.
Instead of doing everything by hand and having a very complicated logic
on when, after the path-cleanup, it was necessary to do a redirect, the
cleanup sections are exported to separate functions which indicate when
a redirect is necessary. This also makes more complex path-processing
possible, if desired, and definitely increases the readability.
In total, this makes the path-processing much more straightforward, and
fixes the problem where a redirect would strip queries and fragments.
Possible file-access problems for virtual hosts were also fixed while
also eliminating the pretty hacky RELPATH-macro, among other things.
Signed-off-by: Laslo Hunhold <dev_AT_frign.de>
diff --git a/data.c b/data.c
index ee43835..d794dc6 100644
--- a/data.c
+++ b/data.c
_AT_@ -104,13 +104,13 @@ data_prepare_dirlisting_buf(const struct response *res,
memset(buf, 0, sizeof(*buf));
/* read directory */
- if ((dirlen = scandir(res->path, &e, NULL, compareent)) < 0) {
+ if ((dirlen = scandir(res->internal_path, &e, NULL, compareent)) < 0) {
return S_FORBIDDEN;
}
if (*progress == 0) {
/* write listing header (sizeof(esc) >= PATH_MAX) */
- html_escape(res->uri, esc, MIN(PATH_MAX, sizeof(esc)));
+ html_escape(res->path, esc, MIN(PATH_MAX, sizeof(esc)));
if (buffer_appendf(buf,
"<!DOCTYPE html>\n<html>\n\t<head>"
"<title>Index of %s</title></head>\n"
_AT_@ -197,7 +197,7 @@ data_prepare_file_buf(const struct response *res, struct buffer *buf,
memset(buf, 0, sizeof(*buf));
/* open file */
- if (!(fp = fopen(res->path, "r"))) {
+ if (!(fp = fopen(res->internal_path, "r"))) {
s = S_FORBIDDEN;
goto cleanup;
}
diff --git a/http.c b/http.c
index 1e43035..5b9dade 100644
--- a/http.c
+++ b/http.c
_AT_@ -205,7 +205,7 @@ http_parse_header(const char *h, struct request *req)
{
struct in6_addr addr;
size_t i, mlen;
- const char *p, *q;
+ const char *p, *q, *r, *s, *t;
char *m, *n;
/* empty the request struct */
_AT_@ -235,16 +235,94 @@ http_parse_header(const char *h, struct request *req)
/* basis for next step */
p = h + mlen + 1;
- /* TARGET */
+ /* RESOURCE */
+
+ /*
+ * path?query#fragment
+ * ^ ^ ^ ^
+ * | | | |
+ * p r s q
+ *
+ */
if (!(q = strchr(p, ' '))) {
return S_BAD_REQUEST;
}
- if (q - p + 1 > PATH_MAX) {
+
+ /* search for first '?' */
+ for (r = p; r < q; r++) {
+ if (!isprint(*r)) {
+ return S_BAD_REQUEST;
+ }
+ if (*r == '?') {
+ break;
+ }
+ }
+ if (r == q) {
+ /* not found */
+ r = NULL;
+ }
+
+ /* search for first '#' */
+ for (s = p; s < q; s++) {
+ if (!isprint(*s)) {
+ return S_BAD_REQUEST;
+ }
+ if (*s == '#') {
+ break;
+ }
+ }
+ if (s == q) {
+ /* not found */
+ s = NULL;
+ }
+
+ if (r != NULL && s != NULL && s < r) {
+ /*
+ * '#' comes before '?' and thus the '?' is literal,
+ * because the query must come before the fragment
+ */
+ r = NULL;
+ }
+
+ /* write path using temporary endpointer t */
+ if (r != NULL) {
+ /* resource contains a query, path ends at r */
+ t = r;
+ } else if (s != NULL) {
+ /* resource contains only a fragment, path ends at s */
+ t = s;
+ } else {
+ /* resource contains no queries, path ends at q */
+ t = q;
+ }
+ if ((size_t)(t - p + 1) > LEN(req->path)) {
return S_REQUEST_TOO_LARGE;
}
- memcpy(req->uri, p, q - p);
- req->uri[q - p] = '\0';
- decode(req->uri, req->uri);
+ memcpy(req->path, p, t - p);
+ req->path[t - p] = '\0';
+ decode(req->path, req->path);
+
+ /* write query if present */
+ if (r != NULL) {
+ /* query ends either at s (if fragment present) or q */
+ t = (s != NULL) ? s : q;
+
+ if ((size_t)(t - (r + 1) + 1) > LEN(req->query)) {
+ return S_REQUEST_TOO_LARGE;
+ }
+ memcpy(req->query, r + 1, t - (r + 1));
+ req->query[t - (r + 1)] = '\0';
+ }
+
+ /* write fragment if present */
+ if (s != NULL) {
+ /* the fragment always starts at s + 1 and ends at q */
+ if ((size_t)(q - (s + 1) + 1) > LEN(req->fragment)) {
+ return S_REQUEST_TOO_LARGE;
+ }
+ memcpy(req->fragment, s + 1, q - (s + 1));
+ req->fragment[q - (s + 1)] = '\0';
+ }
/* basis for next step */
p = q + 1;
_AT_@ -304,7 +382,7 @@ http_parse_header(const char *h, struct request *req)
if (!(q = strstr(p, "\r\n"))) {
return S_BAD_REQUEST;
}
- if (q - p + 1 > FIELD_MAX) {
+ if ((size_t)(q - p + 1) > LEN(req->field[i])) {
return S_REQUEST_TOO_LARGE;
}
memcpy(req->field[i], p, q - p);
_AT_@ -372,24 +450,24 @@ encode(const char src[PATH_MAX], char dest[PATH_MAX])
dest[i] = '\0';
}
-static int
-normabspath(char *path)
+static enum status
+path_normalize(char *uri, int *redirect)
{
size_t len;
- int dirty = 0, last = 0;
+ int last = 0;
char *p, *q;
/* require and skip first slash */
- if (path[0] != '/') {
- return -1;
+ if (uri[0] != '/') {
+ return S_BAD_REQUEST;
}
- p = path + 1;
+ p = uri + 1;
- /* get length of path */
+ /* get length of URI */
len = strlen(p);
for (; !last; ) {
- /* bound path component within (p,q) */
+ /* bound uri component within (p,q) */
if (!(q = strchr(p, '/'))) {
q = strchr(p, '\0');
last = 1;
_AT_@ -402,9 +480,9 @@ normabspath(char *path)
goto squash;
} else if (q - p == 2 && p[0] == '.' && p[1] == '.') {
/* "../" */
- if (p != path + 1) {
+ if (p != uri + 1) {
/* place p right after the previous / */
- for (p -= 2; p > path && *p != '/'; p--);
+ for (p -= 2; p > uri && *p != '/'; p--);
p++;
}
goto squash;
_AT_@ -417,15 +495,90 @@ squash:
/* squash (p,q) into void */
if (last) {
*p = '\0';
- len = p - path;
+ len = p - uri;
} else {
- memmove(p, q + 1, len - ((q + 1) - path) + 2);
+ memmove(p, q + 1, len - ((q + 1) - uri) + 2);
len -= (q + 1) - p;
}
- dirty = 1;
+ if (redirect != NULL) {
+ *redirect = 1;
+ }
+ }
+
+ return 0;
+}
+
+static enum status
+path_add_vhost_prefix(char uri[PATH_MAX], int *redirect,
+ const struct server *srv, const struct response *res)
+{
+ if (srv->vhost && res->vhost && res->vhost->prefix) {
+ if (prepend(uri, PATH_MAX, res->vhost->prefix)) {
+ return S_REQUEST_TOO_LARGE;
+ }
+ if (redirect != NULL) {
+ *redirect = 1;
+ }
+ }
+
+ return 0;
+}
+
+static enum status
+path_apply_prefix_mapping(char uri[PATH_MAX], int *redirect,
+ const struct server *srv, const struct response *res)
+{
+ size_t i, len;
+
+ for (i = 0; i < srv->map_len; i++) {
+ len = strlen(srv->map[i].from);
+ if (!strncmp(uri, srv->map[i].from, len)) {
+ /*
+ * if vhosts are enabled only apply mappings
+ * defined for the current canonical host
+ */
+ if (srv->vhost && res->vhost && srv->map[i].chost &&
+ strcmp(srv->map[i].chost, res->vhost->chost)) {
+ continue;
+ }
+
+ /* swap out URI prefix */
+ memmove(uri, uri + len, strlen(uri) + 1);
+ if (prepend(uri, PATH_MAX, srv->map[i].to)) {
+ return S_REQUEST_TOO_LARGE;
+ }
+
+ if (redirect != NULL) {
+ *redirect = 1;
+ }
+
+ /* break so we don't possibly hit an infinite loop */
+ break;
+ }
+ }
+
+ return 0;
+}
+
+static enum status
+path_ensure_dirslash(char uri[PATH_MAX], int *redirect)
+{
+ size_t len;
+
+ /* append '/' to URI if not present */
+ len = strlen(uri);
+ if (len + 1 + 1 > PATH_MAX) {
+ return S_REQUEST_TOO_LARGE;
+ }
+ if (len > 0 && uri[len - 1] != '/') {
+ uri[len] = '/';
+ uri[len + 1] = '\0';
+ if (redirect != NULL) {
+ *redirect = 1;
+ }
}
- return dirty;
+ return 0;
}
static enum status
_AT_@ -560,60 +713,29 @@ parse_range(const char *str, size_t size, size_t *lower, size_t *upper)
return 0;
}
-#undef RELPATH
-#define RELPATH(x) ((!*(x) || !strcmp(x, "/")) ? "." : ((x) + 1))
-
void
http_prepare_response(const struct request *req, struct response *res,
const struct server *srv)
{
- enum status s;
+ enum status s, tmps;
struct in6_addr addr;
struct stat st;
struct tm tm = { 0 };
- struct vhost *vhost;
- size_t len, i;
- int dirty = 0, hasport, ipv6host;
- static char realuri[PATH_MAX], tmpuri[PATH_MAX];
+ size_t i;
+ int redirect, hasport, ipv6host;
+ static char tmppath[PATH_MAX];
char *p, *mime;
- const char *targethost;
/* empty all response fields */
memset(res, 0, sizeof(*res));
- /*
- * make a working copy of the URI, strip queries and fragments
- * (ignorable according to RFC 3986 section 3) and normalize it
- */
- memcpy(realuri, req->uri, sizeof(realuri));
-
- if ((p = strchr(realuri, '?'))) {
- *p = '\0';
- } else if ((p = strchr(realuri, '#'))) {
- *p = '\0';
- }
-
- switch (normabspath(realuri)) {
- case -1:
- s = S_BAD_REQUEST;
- goto err;
- case 0:
- /* string is unchanged */
- break;
- case 1:
- /* string was changed */
- dirty = 1;
- break;
- }
-
- /* match vhost */
- vhost = NULL;
+ /* determine virtual host */
if (srv->vhost) {
for (i = 0; i < srv->vhost_len; i++) {
- if (!regexec(&(srv->vhost[i].re), req->field[REQ_HOST],
- 0, NULL, 0)) {
+ if (!regexec(&(srv->vhost[i].re),
+ req->field[REQ_HOST], 0, NULL, 0)) {
/* we have a matching vhost */
- vhost = &(srv->vhost[i]);
+ res->vhost = &(srv->vhost[i]);
break;
}
}
_AT_@ -621,100 +743,74 @@ http_prepare_response(const struct request *req, struct response *res,
s = S_NOT_FOUND;
goto err;
}
-
- /* if we have a vhost prefix, prepend it to the URI */
- if (vhost->prefix) {
- if (prepend(realuri, LEN(realuri), vhost->prefix)) {
- s = S_REQUEST_TOO_LARGE;
- goto err;
- }
- dirty = 1;
- }
}
- /* apply URI prefix mapping */
- for (i = 0; i < srv->map_len; i++) {
- len = strlen(srv->map[i].from);
- if (!strncmp(realuri, srv->map[i].from, len)) {
- /* match canonical host if vhosts are enabled and
- * the mapping specifies a canonical host */
- if (srv->vhost && srv->map[i].chost &&
- strcmp(srv->map[i].chost, vhost->chost)) {
- continue;
- }
+ /* copy request-path to response-path and clean it up */
+ redirect = 0;
+ memcpy(res->path, req->path, MIN(sizeof(res->path), sizeof(req->path)));
+ if ((tmps = path_normalize(res->path, &redirect)) ||
+ (tmps = path_add_vhost_prefix(res->path, &redirect, srv, res)) ||
+ (tmps = path_apply_prefix_mapping(res->path, &redirect, srv, res)) ||
+ (tmps = path_normalize(res->path, &redirect))) {
+ s = tmps;
+ goto err;
+ }
- /* swap out URI prefix */
- memmove(realuri, realuri + len, strlen(realuri) + 1);
- if (prepend(realuri, LEN(realuri), srv->map[i].to)) {
- s = S_REQUEST_TOO_LARGE;
- goto err;
- }
- dirty = 1;
- break;
- }
+ /* redirect all non-canonical hosts to their canonical forms */
+ if (srv->vhost && res->vhost &&
+ strcmp(req->field[REQ_HOST], res->vhost->chost)) {
+ redirect = 1;
}
- /* normalize URI again, in case we introduced dirt */
- switch (normabspath(realuri)) {
- case -1:
- s = S_BAD_REQUEST;
+ /* reject all non-well-known hidden targets (see RFC 8615) */
+ if (strstr(res->path, "/.") && strncmp(res->path, "/.well-known/",
+ sizeof("/.well-known/") - 1)) {
+ s = S_FORBIDDEN;
goto err;
- case 0:
- /* string is unchanged */
- break;
- case 1:
- /* string was changed */
- dirty = 1;
- break;
}
- /* stat the relative path derived from the URI */
- if (stat(RELPATH(realuri), &st) < 0) {
+ /*
+ * generate and stat internal path based on the cleaned up request
+ * path and the virtual host while ignoring query and fragment
+ * (valid according to RFC 3986)
+ */
+ if (esnprintf(res->internal_path, sizeof(res->internal_path), "/%s/%s",
+ (srv->vhost && res->vhost) ? res->vhost->dir : "",
+ res->path)) {
+ s = S_REQUEST_TOO_LARGE;
+ goto err;
+ }
+ if ((tmps = path_normalize(res->internal_path, NULL))) {
+ s = tmps;
+ goto err;
+ }
+ if (stat(res->internal_path, &st) < 0) {
s = (errno == EACCES) ? S_FORBIDDEN : S_NOT_FOUND;
goto err;
}
+ /*
+ * if the path points at a directory, make sure both the path
+ * and internal path have a trailing slash
+ */
if (S_ISDIR(st.st_mode)) {
- /* append '/' to URI if not present */
- len = strlen(realuri);
- if (len + 1 + 1 > PATH_MAX) {
- s = S_REQUEST_TOO_LARGE;
+ if ((tmps = path_ensure_dirslash(res->path, &redirect)) ||
+ (tmps = path_ensure_dirslash(res->internal_path, NULL))) {
+ s = tmps;
goto err;
}
- if (len > 0 && realuri[len - 1] != '/') {
- realuri[len] = '/';
- realuri[len + 1] = '\0';
- dirty = 1;
- }
}
- /*
- * reject hidden targets, except if it is a well-known URI
- * according to RFC 8615
- */
- if (strstr(realuri, "/.") && strncmp(realuri,
- "/.well-known/", sizeof("/.well-known/") - 1)) {
- s = S_FORBIDDEN;
- goto err;
- }
-
- /*
- * redirect if the URI needs to be redirected or the requested
- * host is non-canonical
- */
- if (dirty || (srv->vhost && vhost &&
- strcmp(req->field[REQ_HOST], vhost->chost))) {
+ /* redirect if the path-cleanup necessitated it earlier */
+ if (redirect) {
res->status = S_MOVED_PERMANENTLY;
- /* encode realuri */
- encode(realuri, tmpuri);
+ /* encode path */
+ encode(res->path, tmppath);
/* determine target location */
- if (srv->vhost) {
+ if (srv->vhost && res->vhost) {
/* absolute redirection URL */
- targethost = req->field[REQ_HOST][0] ? vhost->chost ?
- vhost->chost : req->field[REQ_HOST] :
- srv->host ? srv->host : "localhost";
/* do we need to add a port to the Location? */
hasport = srv->port && strcmp(srv->port, "80");
_AT_@ -722,70 +818,83 @@ http_prepare_response(const struct request *req, struct response *res,
/* RFC 2732 specifies to use brackets for IPv6-addresses
* in URLs, so we need to check if our host is one and
* honor that later when we fill the "Location"-field */
- if ((ipv6host = inet_pton(AF_INET6, targethost,
+ if ((ipv6host = inet_pton(AF_INET6, res->vhost->chost,
&addr)) < 0) {
s = S_INTERNAL_SERVER_ERROR;
goto err;
}
- /* write location to response struct */
+ /*
+ * write location to response struct (re-including
+ * the query and fragment, if present)
+ */
if (esnprintf(res->field[RES_LOCATION],
sizeof(res->field[RES_LOCATION]),
- "//%s%s%s%s%s%s",
+ "//%s%s%s%s%s%s%s%s%s%s",
ipv6host ? "[" : "",
- targethost,
- ipv6host ? "]" : "", hasport ? ":" : "",
- hasport ? srv->port : "", tmpuri)) {
+ res->vhost->chost,
+ ipv6host ? "]" : "",
+ hasport ? ":" : "",
+ hasport ? srv->port : "",
+ tmppath,
+ req->query[0] ? "?" : "",
+ req->query,
+ req->fragment[0] ? "#" : "",
+ req->fragment)) {
s = S_REQUEST_TOO_LARGE;
goto err;
}
} else {
- /* write relative redirection URI to response struct */
+ /*
+ * write relative redirection URI to response struct
+ * (re-including the query and fragment, if present)
+ */
if (esnprintf(res->field[RES_LOCATION],
sizeof(res->field[RES_LOCATION]),
- "%s", tmpuri)) {
+ "%s%s%s%s%s",
+ tmppath,
+ req->query[0] ? "?" : "",
+ req->query,
+ req->fragment[0] ? "#" : "",
+ req->fragment)) {
s = S_REQUEST_TOO_LARGE;
goto err;
}
}
return;
- } else {
- /*
- * the URI is well-formed, we can now write the URI into
- * the response-URI and corresponding relative path
- * (optionally including the vhost servedir as a prefix)
- * into the actual response-path
- */
- if (esnprintf(res->uri, sizeof(res->uri), "%s", realuri)) {
- s = S_REQUEST_TOO_LARGE;
- goto err;
- }
- if (esnprintf(res->path, sizeof(res->path), "%s%s",
- vhost ? vhost->dir : "", RELPATH(realuri))) {
- s = S_REQUEST_TOO_LARGE;
- goto err;
- }
}
if (S_ISDIR(st.st_mode)) {
/*
- * check if the directory index exists by appending it to
- * the URI
+ * when we serve a directory, we first check if there
+ * exists a directory index. If not, we either make
+ * a directory listing (if enabled) or send an error
+ */
+
+ /*
+ * append docindex to internal_path temporarily
+ * (internal_path is guaranteed to end with '/')
*/
- if (esnprintf(tmpuri, sizeof(tmpuri), "%s%s",
- realuri, srv->docindex)) {
+ if (esnprintf(tmppath, sizeof(tmppath), "%s%s",
+ res->internal_path, srv->docindex)) {
s = S_REQUEST_TOO_LARGE;
goto err;
}
- /* stat the docindex, which must be a regular file */
- if (stat(RELPATH(tmpuri), &st) < 0 || !S_ISREG(st.st_mode)) {
+ /* stat the temporary path, which must be a regular file */
+ if (stat(tmppath, &st) < 0 || !S_ISREG(st.st_mode)) {
if (srv->listdirs) {
/* serve directory listing */
+
+ /* check if directory is accessible */
+ if (access(res->internal_path, R_OK) != 0) {
+ s = S_FORBIDDEN;
+ goto err;
+ } else {
+ res->status = S_OK;
+ }
res->type = RESTYPE_DIRLISTING;
- res->status = (access(res->path, R_OK)) ?
- S_FORBIDDEN : S_OK;
if (esnprintf(res->field[RES_CONTENT_TYPE],
sizeof(res->field[RES_CONTENT_TYPE]),
_AT_@ -802,8 +911,10 @@ http_prepare_response(const struct request *req, struct response *res,
goto err;
}
} else {
- /* docindex is valid, write tmpuri to response-path */
- if (esnprintf(res->path, sizeof(res->path), "%s", tmpuri)) {
+ /* the docindex exists; copy tmppath to internal path */
+ if (esnprintf(res->internal_path,
+ sizeof(res->internal_path), "%s",
+ tmppath)) {
s = S_REQUEST_TOO_LARGE;
goto err;
}
_AT_@ -847,7 +958,7 @@ http_prepare_response(const struct request *req, struct response *res,
/* mime */
mime = "application/octet-stream";
- if ((p = strrchr(res->path, '.'))) {
+ if ((p = strrchr(res->internal_path, '.'))) {
for (i = 0; i < LEN(mimes); i++) {
if (!strcmp(mimes[i].ext, p + 1)) {
mime = mimes[i].type;
_AT_@ -860,7 +971,7 @@ http_prepare_response(const struct request *req, struct response *res,
res->type = RESTYPE_FILE;
/* check if file is readable */
- res->status = (access(res->path, R_OK)) ? S_FORBIDDEN :
+ res->status = (access(res->internal_path, R_OK)) ? S_FORBIDDEN :
(req->field[REQ_RANGE][0] != '\0') ?
S_PARTIAL_CONTENT : S_OK;
diff --git a/http.h b/http.h
index bfaa807..9cdd97b 100644
--- a/http.h
+++ b/http.h
_AT_@ -27,7 +27,9 @@ extern const char *req_method_str[];
struct request {
enum req_method method;
- char uri[PATH_MAX];
+ char path[PATH_MAX];
+ char query[FIELD_MAX];
+ char fragment[FIELD_MAX];
char field[NUM_REQ_FIELDS][FIELD_MAX];
};
_AT_@ -73,8 +75,9 @@ struct response {
enum res_type type;
enum status status;
char field[NUM_RES_FIELDS][FIELD_MAX];
- char uri[PATH_MAX];
char path[PATH_MAX];
+ char internal_path[PATH_MAX];
+ struct vhost *vhost;
struct {
size_t lower;
size_t upper;
diff --git a/main.c b/main.c
index 28bff20..f366985 100644
--- a/main.c
+++ b/main.c
_AT_@ -45,8 +45,9 @@ logmsg(const struct connection *c)
inaddr_str[0] = '\0';
}
- printf("%s\t%s\t%d\t%s\t%s\n", tstmp, inaddr_str, c->res.status,
- c->req.field[REQ_HOST], c->req.uri);
+ printf("%s\t%s\t%d\t%s\t%s%s%s%s%s\n", tstmp, inaddr_str, c->res.status,
+ c->req.field[REQ_HOST], c->req.path, c->req.query[0] ? "?" : "",
+ c->req.query, c->req.fragment[0] ? "#" : "", c->req.fragment);
}
static void
Received on Wed Feb 03 2021 - 19:08:01 CET
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: Wed Feb 03 2021 - 19:12:37 CET