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MINOR: payload: add new sample fetch functions to process distcc protocol

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When using haproxy in front of distccd, it's possible to provide significant
improvements by only connecting when the preprocessing is completed, and by
selecting different farms depending on the payload size. This patch provides
two new sample fetch functions :

      distcc_param(<token>[,<occ>]) : integer
      distcc_body(<token>[,<occ>]) : binary
This commit is contained in:
Willy Tarreau 2017-10-13 11:03:15 +02:00
parent ff2b7afe0b
commit d716f9bacf
2 changed files with 227 additions and 0 deletions
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26
doc/configuration.txt
View File

@ -13252,6 +13252,32 @@ date([<offset>]) : integer
# set an expires header to now+1 hour in every response
http-response set-header Expires %[date(3600),http_date]
distcc_body(<token>[,<occ>]) : binary
Parses a distcc message and returns the body associated to occurrence #<occ>
of the token <token>. Occurrences start at 1, and when unspecified, any may
match though in practice only the first one is checked for now. This can be
used to extract file names or arguments in files built using distcc through
haproxy. Please refer to distcc's protocol documentation for the complete
list of supported tokens.
distcc_param(<token>[,<occ>]) : integer
Parses a distcc message and returns the parameter associated to occurrence
#<occ> of the token <token>. Occurrences start at 1, and when unspecified,
any may match though in practice only the first one is checked for now. This
can be used to extract certain information such as the protocol version, the
file size or the argument in files built using distcc through haproxy.
Another use case consists in waiting for the start of the preprocessed file
contents before connecting to the server to avoid keeping idle connections.
Please refer to distcc's protocol documentation for the complete list of
supported tokens.
Example :
# wait up to 20s for the pre-processed file to be uploaded
tcp-request inspect-delay 20s
tcp-request content accept if { distcc_param(DOTI) -m found }
# send large files to the big farm
use_backend big_farm if { distcc_param(DOTI) gt 1000000 }
env(<name>) : string
Returns a string containing the value of environment variable <name>. As a
reminder, environment variables are per-process and are sampled when the

201
src/payload.c
View File

@ -13,6 +13,7 @@
#include <stdlib.h>
#include <string.h>
#include <common/net_helper.h>
#include <proto/acl.h>
#include <proto/arg.h>
#include <proto/channel.h>
@ -909,6 +910,204 @@ int val_payload_lv(struct arg *arg, char **err_msg)
return 1;
}
/* extracts the parameter value of a distcc token */
static int
smp_fetch_distcc_param(const struct arg *arg_p, struct sample *smp, const char *kw, void *private)
{
unsigned int match_tok = arg_p[0].data.sint;
unsigned int match_occ = arg_p[1].data.sint;
unsigned int token;
unsigned int param;
unsigned int body;
unsigned int ofs;
unsigned int occ;
struct channel *chn;
int i;
/* Format is (token[,occ]). occ starts at 1. */
if (!smp->strm)
return 0;
chn = ((smp->opt & SMP_OPT_DIR) == SMP_OPT_DIR_RES) ? &smp->strm->res : &smp->strm->req;
ofs = 0; occ = 0;
while (1) {
if (ofs + 12 > chn->buf->i) {
/* not there yet but could it at least fit ? */
if (!chn->buf->size)
goto too_short;
if (ofs + 12 <= channel_recv_limit(chn) + chn->buf->data - chn->buf->p)
goto too_short;
goto no_match;
}
token = read_n32(chn->buf->p + ofs);
ofs += 4;
for (i = param = 0; i < 8; i++) {
int c = hex2i(chn->buf->p[ofs + i]);
if (c < 0)
goto no_match;
param = (param << 4) + c;
}
ofs += 8;
/* these tokens don't have a body */
if (token != 0x41524743 /* ARGC */ && token != 0x44495354 /* DIST */ &&
token != 0x4E46494C /* NFIL */ && token != 0x53544154 /* STAT */ &&
token != 0x444F4E45 /* DONE */)
body = param;
else
body = 0;
if (token == match_tok) {
occ++;
if (!match_occ || match_occ == occ) {
/* found */
smp->data.type = SMP_T_SINT;
smp->data.u.sint = param;
smp->flags = SMP_F_VOLATILE | SMP_F_CONST;
return 1;
}
}
ofs += body;
}
too_short:
smp->flags = SMP_F_MAY_CHANGE | SMP_F_CONST;
return 0;
no_match:
/* will never match (end of buffer, or bad contents) */
smp->flags = 0;
return 0;
}
/* extracts the (possibly truncated) body of a distcc token */
static int
smp_fetch_distcc_body(const struct arg *arg_p, struct sample *smp, const char *kw, void *private)
{
unsigned int match_tok = arg_p[0].data.sint;
unsigned int match_occ = arg_p[1].data.sint;
unsigned int token;
unsigned int param;
unsigned int ofs;
unsigned int occ;
unsigned int body;
struct channel *chn;
int i;
/* Format is (token[,occ]). occ starts at 1. */
if (!smp->strm)
return 0;
chn = ((smp->opt & SMP_OPT_DIR) == SMP_OPT_DIR_RES) ? &smp->strm->res : &smp->strm->req;
ofs = 0; occ = 0;
while (1) {
if (ofs + 12 > chn->buf->i) {
if (!chn->buf->size)
goto too_short;
if (ofs + 12 <= channel_recv_limit(chn) + chn->buf->data - chn->buf->p)
goto too_short;
goto no_match;
}
token = read_n32(chn->buf->p + ofs);
ofs += 4;
for (i = param = 0; i < 8; i++) {
int c = hex2i(chn->buf->p[ofs + i]);
if (c < 0)
goto no_match;
param = (param << 4) + c;
}
ofs += 8;
/* these tokens don't have a body */
if (token != 0x41524743 /* ARGC */ && token != 0x44495354 /* DIST */ &&
token != 0x4E46494C /* NFIL */ && token != 0x53544154 /* STAT */ &&
token != 0x444F4E45 /* DONE */)
body = param;
else
body = 0;
if (token == match_tok) {
occ++;
if (!match_occ || match_occ == occ) {
/* found */
smp->data.type = SMP_T_BIN;
smp->flags = SMP_F_VOLATILE | SMP_F_CONST;
if (ofs + body > chn->buf->p - chn->buf->data + chn->buf->i) {
/* incomplete body */
if (ofs + body > channel_recv_limit(chn) + chn->buf->data - chn->buf->p) {
/* truncate it to whatever will fit */
smp->flags |= SMP_F_MAY_CHANGE;
body = channel_recv_limit(chn) + chn->buf->data - chn->buf->p - ofs;
}
}
chunk_initlen(&smp->data.u.str, chn->buf->p + ofs, 0, body);
return 1;
}
}
ofs += body;
}
too_short:
smp->flags = SMP_F_MAY_CHANGE | SMP_F_CONST;
return 0;
no_match:
/* will never match (end of buffer, or bad contents) */
smp->flags = 0;
return 0;
}
/* This function is used to validate the arguments passed to a "distcc_param" or
* "distcc_body" sample fetch keyword. They take a mandatory token name of exactly
* 4 characters, followed by an optional occurrence number starting at 1. It is
* assumed that the types are already the correct ones. Returns 0 on error, non-
* zero if OK. If <err_msg> is not NULL, it will be filled with a pointer to an
* error message in case of error, that the caller is responsible for freeing.
* The initial location must either be freeable or NULL.
*/
int val_distcc(struct arg *arg, char **err_msg)
{
unsigned int token;
if (arg[0].data.str.len != 4) {
memprintf(err_msg, "token name must be exactly 4 characters");
return 0;
}
/* convert the token name to an unsigned int (one byte per character,
* big endian format).
*/
token = (arg[0].data.str.str[0] << 24) + (arg[0].data.str.str[1] << 16) +
(arg[0].data.str.str[2] << 8) + (arg[0].data.str.str[3] << 0);
arg[0].type = ARGT_SINT;
arg[0].data.sint = token;
if (arg[1].type != ARGT_SINT) {
arg[1].type = ARGT_SINT;
arg[1].data.sint = 0;
}
return 1;
}
/************************************************************************/
/* All supported sample and ACL keywords must be declared here. */
/************************************************************************/
@ -919,6 +1118,8 @@ int val_payload_lv(struct arg *arg, char **err_msg)
* instance IPv4/IPv6 must be declared IPv4.
*/
static struct sample_fetch_kw_list smp_kws = {ILH, {
{ "distcc_body", smp_fetch_distcc_body, ARG2(1,STR,SINT), val_distcc, SMP_T_BIN, SMP_USE_L6REQ|SMP_USE_L6RES },
{ "distcc_param", smp_fetch_distcc_param, ARG2(1,STR,SINT), val_distcc, SMP_T_SINT, SMP_USE_L6REQ|SMP_USE_L6RES },
{ "payload", smp_fetch_payload, ARG2(2,SINT,SINT), NULL, SMP_T_BIN, SMP_USE_L6REQ|SMP_USE_L6RES },
{ "payload_lv", smp_fetch_payload_lv, ARG3(2,SINT,SINT,STR), val_payload_lv, SMP_T_BIN, SMP_USE_L6REQ|SMP_USE_L6RES },
{ "rdp_cookie", smp_fetch_rdp_cookie, ARG1(0,STR), NULL, SMP_T_STR, SMP_USE_L6REQ },