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8fa0a298c6
curl/lib/altsvc.c
Daniel Stenberg 5d903ce3a3
altsvc: minimize variable scope and avoid "DEAD_STORE" 
Closes #6182
2020-11-07 18:10:21 +01:00

648 lines
18 KiB
C
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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 2019 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at https://curl.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
***************************************************************************/
/*
* The Alt-Svc: header is defined in RFC 7838:
* https://tools.ietf.org/html/rfc7838
*/
#include "curl_setup.h"
#if !defined(CURL_DISABLE_HTTP) && !defined(CURL_DISABLE_ALTSVC)
#include <curl/curl.h>
#include "urldata.h"
#include "altsvc.h"
#include "curl_get_line.h"
#include "strcase.h"
#include "parsedate.h"
#include "sendf.h"
#include "warnless.h"
#include "rand.h"
#include "rename.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"
#define MAX_ALTSVC_LINE 4095
#define MAX_ALTSVC_DATELENSTR "64"
#define MAX_ALTSVC_DATELEN 64
#define MAX_ALTSVC_HOSTLENSTR "512"
#define MAX_ALTSVC_HOSTLEN 512
#define MAX_ALTSVC_ALPNLENSTR "10"
#define MAX_ALTSVC_ALPNLEN 10
#if defined(USE_QUICHE) && !defined(UNITTESTS)
#define H3VERSION "h3-29"
#elif defined(USE_NGTCP2) && !defined(UNITTESTS)
#define H3VERSION "h3-29"
#else
#define H3VERSION "h3"
#endif
static enum alpnid alpn2alpnid(char *name)
{
if(strcasecompare(name, "h1"))
return ALPN_h1;
if(strcasecompare(name, "h2"))
return ALPN_h2;
if(strcasecompare(name, H3VERSION))
return ALPN_h3;
return ALPN_none; /* unknown, probably rubbish input */
}
/* Given the ALPN ID, return the name */
const char *Curl_alpnid2str(enum alpnid id)
{
switch(id) {
case ALPN_h1:
return "h1";
case ALPN_h2:
return "h2";
case ALPN_h3:
return H3VERSION;
default:
return ""; /* bad */
}
}
static void altsvc_free(struct altsvc *as)
{
free(as->src.host);
free(as->dst.host);
free(as);
}
static struct altsvc *altsvc_createid(const char *srchost,
const char *dsthost,
enum alpnid srcalpnid,
enum alpnid dstalpnid,
unsigned int srcport,
unsigned int dstport)
{
struct altsvc *as = calloc(sizeof(struct altsvc), 1);
if(!as)
return NULL;
as->src.host = strdup(srchost);
if(!as->src.host)
goto error;
as->dst.host = strdup(dsthost);
if(!as->dst.host)
goto error;
as->src.alpnid = srcalpnid;
as->dst.alpnid = dstalpnid;
as->src.port = curlx_ultous(srcport);
as->dst.port = curlx_ultous(dstport);
return as;
error:
altsvc_free(as);
return NULL;
}
static struct altsvc *altsvc_create(char *srchost,
char *dsthost,
char *srcalpn,
char *dstalpn,
unsigned int srcport,
unsigned int dstport)
{
enum alpnid dstalpnid = alpn2alpnid(dstalpn);
enum alpnid srcalpnid = alpn2alpnid(srcalpn);
if(!srcalpnid || !dstalpnid)
return NULL;
return altsvc_createid(srchost, dsthost, srcalpnid, dstalpnid,
srcport, dstport);
}
/* only returns SERIOUS errors */
static CURLcode altsvc_add(struct altsvcinfo *asi, char *line)
{
/* Example line:
h2 example.com 443 h3 shiny.example.com 8443 "20191231 10:00:00" 1
*/
char srchost[MAX_ALTSVC_HOSTLEN + 1];
char dsthost[MAX_ALTSVC_HOSTLEN + 1];
char srcalpn[MAX_ALTSVC_ALPNLEN + 1];
char dstalpn[MAX_ALTSVC_ALPNLEN + 1];
char date[MAX_ALTSVC_DATELEN + 1];
unsigned int srcport;
unsigned int dstport;
unsigned int prio;
unsigned int persist;
int rc;
rc = sscanf(line,
"%" MAX_ALTSVC_ALPNLENSTR "s %" MAX_ALTSVC_HOSTLENSTR "s %u "
"%" MAX_ALTSVC_ALPNLENSTR "s %" MAX_ALTSVC_HOSTLENSTR "s %u "
"\"%" MAX_ALTSVC_DATELENSTR "[^\"]\" %u %u",
srcalpn, srchost, &srcport,
dstalpn, dsthost, &dstport,
date, &persist, &prio);
if(9 == rc) {
struct altsvc *as;
time_t expires = Curl_getdate_capped(date);
as = altsvc_create(srchost, dsthost, srcalpn, dstalpn, srcport, dstport);
if(as) {
as->expires = expires;
as->prio = prio;
as->persist = persist ? 1 : 0;
Curl_llist_insert_next(&asi->list, asi->list.tail, as, &as->node);
}
}
return CURLE_OK;
}
/*
* Load alt-svc entries from the given file. The text based line-oriented file
* format is documented here:
* https://github.com/curl/curl/wiki/QUIC-implementation
*
* This function only returns error on major problems that prevents alt-svc
* handling to work completely. It will ignore individual syntactical errors
* etc.
*/
static CURLcode altsvc_load(struct altsvcinfo *asi, const char *file)
{
CURLcode result = CURLE_OK;
char *line = NULL;
FILE *fp;
/* we need a private copy of the file name so that the altsvc cache file
name survives an easy handle reset */
free(asi->filename);
asi->filename = strdup(file);
if(!asi->filename)
return CURLE_OUT_OF_MEMORY;
fp = fopen(file, FOPEN_READTEXT);
if(fp) {
line = malloc(MAX_ALTSVC_LINE);
if(!line)
goto fail;
while(Curl_get_line(line, MAX_ALTSVC_LINE, fp)) {
char *lineptr = line;
while(*lineptr && ISBLANK(*lineptr))
lineptr++;
if(*lineptr == '#')
/* skip commented lines */
continue;
altsvc_add(asi, lineptr);
}
free(line); /* free the line buffer */
fclose(fp);
}
return result;
fail:
Curl_safefree(asi->filename);
free(line);
fclose(fp);
return CURLE_OUT_OF_MEMORY;
}
/*
* Write this single altsvc entry to a single output line
*/
static CURLcode altsvc_out(struct altsvc *as, FILE *fp)
{
struct tm stamp;
CURLcode result = Curl_gmtime(as->expires, &stamp);
if(result)
return result;
fprintf(fp,
"%s %s %u "
"%s %s %u "
"\"%d%02d%02d "
"%02d:%02d:%02d\" "
"%u %d\n",
Curl_alpnid2str(as->src.alpnid), as->src.host, as->src.port,
Curl_alpnid2str(as->dst.alpnid), as->dst.host, as->dst.port,
stamp.tm_year + 1900, stamp.tm_mon + 1, stamp.tm_mday,
stamp.tm_hour, stamp.tm_min, stamp.tm_sec,
as->persist, as->prio);
return CURLE_OK;
}
/* ---- library-wide functions below ---- */
/*
* Curl_altsvc_init() creates a new altsvc cache.
* It returns the new instance or NULL if something goes wrong.
*/
struct altsvcinfo *Curl_altsvc_init(void)
{
struct altsvcinfo *asi = calloc(sizeof(struct altsvcinfo), 1);
if(!asi)
return NULL;
Curl_llist_init(&asi->list, NULL);
/* set default behavior */
asi->flags = CURLALTSVC_H1
#ifdef USE_NGHTTP2
| CURLALTSVC_H2
#endif
#ifdef ENABLE_QUIC
| CURLALTSVC_H3
#endif
;
return asi;
}
/*
* Curl_altsvc_load() loads alt-svc from file.
*/
CURLcode Curl_altsvc_load(struct altsvcinfo *asi, const char *file)
{
CURLcode result;
DEBUGASSERT(asi);
result = altsvc_load(asi, file);
return result;
}
/*
* Curl_altsvc_ctrl() passes on the external bitmask.
*/
CURLcode Curl_altsvc_ctrl(struct altsvcinfo *asi, const long ctrl)
{
DEBUGASSERT(asi);
if(!ctrl)
/* unexpected */
return CURLE_BAD_FUNCTION_ARGUMENT;
asi->flags = ctrl;
return CURLE_OK;
}
/*
* Curl_altsvc_cleanup() frees an altsvc cache instance and all associated
* resources.
*/
void Curl_altsvc_cleanup(struct altsvcinfo **altsvcp)
{
struct Curl_llist_element *e;
struct Curl_llist_element *n;
if(*altsvcp) {
struct altsvcinfo *altsvc = *altsvcp;
for(e = altsvc->list.head; e; e = n) {
struct altsvc *as = e->ptr;
n = e->next;
altsvc_free(as);
}
free(altsvc->filename);
free(altsvc);
*altsvcp = NULL; /* clear the pointer */
}
}
/*
* Curl_altsvc_save() writes the altsvc cache to a file.
*/
CURLcode Curl_altsvc_save(struct Curl_easy *data,
struct altsvcinfo *altsvc, const char *file)
{
struct Curl_llist_element *e;
struct Curl_llist_element *n;
CURLcode result = CURLE_OK;
FILE *out;
char *tempstore;
unsigned char randsuffix[9];
if(!altsvc)
/* no cache activated */
return CURLE_OK;
/* if not new name is given, use the one we stored from the load */
if(!file && altsvc->filename)
file = altsvc->filename;
if((altsvc->flags & CURLALTSVC_READONLYFILE) || !file || !file[0])
/* marked as read-only, no file or zero length file name */
return CURLE_OK;
if(Curl_rand_hex(data, randsuffix, sizeof(randsuffix)))
return CURLE_FAILED_INIT;
tempstore = aprintf("%s.%s.tmp", file, randsuffix);
if(!tempstore)
return CURLE_OUT_OF_MEMORY;
out = fopen(tempstore, FOPEN_WRITETEXT);
if(!out)
result = CURLE_WRITE_ERROR;
else {
fputs("# Your alt-svc cache. https://curl.se/docs/alt-svc.html\n"
"# This file was generated by libcurl! Edit at your own risk.\n",
out);
for(e = altsvc->list.head; e; e = n) {
struct altsvc *as = e->ptr;
n = e->next;
result = altsvc_out(as, out);
if(result)
break;
}
fclose(out);
if(!result && Curl_rename(tempstore, file))
result = CURLE_WRITE_ERROR;
if(result)
unlink(tempstore);
}
free(tempstore);
return result;
}
static CURLcode getalnum(const char **ptr, char *alpnbuf, size_t buflen)
{
size_t len;
const char *protop;
const char *p = *ptr;
while(*p && ISBLANK(*p))
p++;
protop = p;
while(*p && !ISBLANK(*p) && (*p != ';') && (*p != '='))
p++;
len = p - protop;
*ptr = p;
if(!len || (len >= buflen))
return CURLE_BAD_FUNCTION_ARGUMENT;
memcpy(alpnbuf, protop, len);
alpnbuf[len] = 0;
return CURLE_OK;
}
/* altsvc_flush() removes all alternatives for this source origin from the
list */
static void altsvc_flush(struct altsvcinfo *asi, enum alpnid srcalpnid,
const char *srchost, unsigned short srcport)
{
struct Curl_llist_element *e;
struct Curl_llist_element *n;
for(e = asi->list.head; e; e = n) {
struct altsvc *as = e->ptr;
n = e->next;
if((srcalpnid == as->src.alpnid) &&
(srcport == as->src.port) &&
strcasecompare(srchost, as->src.host)) {
Curl_llist_remove(&asi->list, e, NULL);
altsvc_free(as);
}
}
}
#ifdef DEBUGBUILD
/* to play well with debug builds, we can *set* a fixed time this will
return */
static time_t debugtime(void *unused)
{
char *timestr = getenv("CURL_TIME");
(void)unused;
if(timestr) {
unsigned long val = strtol(timestr, NULL, 10);
return (time_t)val;
}
return time(NULL);
}
#define time(x) debugtime(x)
#endif
#define ISNEWLINE(x) (((x) == '\n') || (x) == '\r')
/*
* Curl_altsvc_parse() takes an incoming alt-svc response header and stores
* the data correctly in the cache.
*
* 'value' points to the header *value*. That's contents to the right of the
* header name.
*
* Currently this function rejects invalid data without returning an error.
* Invalid host name, port number will result in the specific alternative
* being rejected. Unknown protocols are skipped.
*/
CURLcode Curl_altsvc_parse(struct Curl_easy *data,
struct altsvcinfo *asi, const char *value,
enum alpnid srcalpnid, const char *srchost,
unsigned short srcport)
{
const char *p = value;
size_t len;
char namebuf[MAX_ALTSVC_HOSTLEN] = "";
char alpnbuf[MAX_ALTSVC_ALPNLEN] = "";
struct altsvc *as;
unsigned short dstport = srcport; /* the same by default */
CURLcode result = getalnum(&p, alpnbuf, sizeof(alpnbuf));
#ifdef CURL_DISABLE_VERBOSE_STRINGS
(void)data;
#endif
if(result) {
infof(data, "Excessive alt-svc header, ignoring...\n");
return CURLE_OK;
}
DEBUGASSERT(asi);
/* Flush all cached alternatives for this source origin, if any */
altsvc_flush(asi, srcalpnid, srchost, srcport);
/* "clear" is a magic keyword */
if(strcasecompare(alpnbuf, "clear")) {
return CURLE_OK;
}
do {
if(*p == '=') {
/* [protocol]="[host][:port]" */
enum alpnid dstalpnid = alpn2alpnid(alpnbuf); /* the same by default */
p++;
if(*p == '\"') {
const char *dsthost = "";
const char *value_ptr;
char option[32];
unsigned long num;
char *end_ptr;
bool quoted = FALSE;
time_t maxage = 24 * 3600; /* default is 24 hours */
bool persist = FALSE;
p++;
if(*p != ':') {
/* host name starts here */
const char *hostp = p;
while(*p && (ISALNUM(*p) || (*p == '.') || (*p == '-')))
p++;
len = p - hostp;
if(!len || (len >= MAX_ALTSVC_HOSTLEN)) {
infof(data, "Excessive alt-svc host name, ignoring...\n");
dstalpnid = ALPN_none;
}
else {
memcpy(namebuf, hostp, len);
namebuf[len] = 0;
dsthost = namebuf;
}
}
else {
/* no destination name, use source host */
dsthost = srchost;
}
if(*p == ':') {
/* a port number */
unsigned long port = strtoul(++p, &end_ptr, 10);
if(port > USHRT_MAX || end_ptr == p || *end_ptr != '\"') {
infof(data, "Unknown alt-svc port number, ignoring...\n");
dstalpnid = ALPN_none;
}
p = end_ptr;
dstport = curlx_ultous(port);
}
if(*p++ != '\"')
break;
/* Handle the optional 'ma' and 'persist' flags. Unknown flags
are skipped. */
for(;;) {
while(ISBLANK(*p))
p++;
if(*p != ';')
break;
p++; /* pass the semicolon */
if(!*p || ISNEWLINE(*p))
break;
result = getalnum(&p, option, sizeof(option));
if(result) {
/* skip option if name is too long */
option[0] = '\0';
}
while(*p && ISBLANK(*p))
p++;
if(*p != '=')
return CURLE_OK;
p++;
while(*p && ISBLANK(*p))
p++;
if(!*p)
return CURLE_OK;
if(*p == '\"') {
/* quoted value */
p++;
quoted = TRUE;
}
value_ptr = p;
if(quoted) {
while(*p && *p != '\"')
p++;
if(!*p++)
return CURLE_OK;
}
else {
while(*p && !ISBLANK(*p) && *p!= ';' && *p != ',')
p++;
}
num = strtoul(value_ptr, &end_ptr, 10);
if((end_ptr != value_ptr) && (num < ULONG_MAX)) {
if(strcasecompare("ma", option))
maxage = num;
else if(strcasecompare("persist", option) && (num == 1))
persist = TRUE;
}
}
if(dstalpnid) {
as = altsvc_createid(srchost, dsthost,
srcalpnid, dstalpnid,
srcport, dstport);
if(as) {
/* The expires time also needs to take the Age: value (if any) into
account. [See RFC 7838 section 3.1] */
as->expires = maxage + time(NULL);
as->persist = persist;
Curl_llist_insert_next(&asi->list, asi->list.tail, as, &as->node);
infof(data, "Added alt-svc: %s:%d over %s\n", dsthost, dstport,
Curl_alpnid2str(dstalpnid));
}
}
else {
infof(data, "Unknown alt-svc protocol \"%s\", skipping...\n",
alpnbuf);
}
}
else
break;
/* after the double quote there can be a comma if there's another
string or a semicolon if no more */
if(*p == ',') {
/* comma means another alternative is presented */
p++;
result = getalnum(&p, alpnbuf, sizeof(alpnbuf));
if(result)
break;
}
}
else
break;
} while(*p && (*p != ';') && (*p != '\n') && (*p != '\r'));
return CURLE_OK;
}
/*
* Return TRUE on a match
*/
bool Curl_altsvc_lookup(struct altsvcinfo *asi,
enum alpnid srcalpnid, const char *srchost,
int srcport,
struct altsvc **dstentry,
const int versions) /* one or more bits */
{
struct Curl_llist_element *e;
struct Curl_llist_element *n;
time_t now = time(NULL);
DEBUGASSERT(asi);
DEBUGASSERT(srchost);
DEBUGASSERT(dstentry);
for(e = asi->list.head; e; e = n) {
struct altsvc *as = e->ptr;
n = e->next;
if(as->expires < now) {
/* an expired entry, remove */
Curl_llist_remove(&asi->list, e, NULL);
altsvc_free(as);
continue;
}
if((as->src.alpnid == srcalpnid) &&
strcasecompare(as->src.host, srchost) &&
(as->src.port == srcport) &&
(versions & as->dst.alpnid)) {
/* match */
*dstentry = as;
return TRUE;
}
}
return FALSE;
}
#endif /* !CURL_DISABLE_HTTP && !CURL_DISABLE_ALTSVC */
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