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Core: add RFC 5424 syslog protocol version parameter.

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Add "rfc=rfc3164|rfc5424" to the syslog directive.  The default
remains rfc3164 for backward compatibility.

Tag validation is moved from ngx_syslog_parse_args() to
ngx_syslog_process_conf() so that the character set and length
constraints can be conditioned on the chosen protocol version.
RFC 5424 (APP-NAME) allows up to 48 printable US-ASCII characters
(0x21-0x7E), while RFC 3164 (TAG) restricts to alphanumeric
characters and underscore with a 32-character limit.
This commit is contained in:
Vadim Zhestikov 2026-03-25 10:18:06 -07:00
parent b0a4d0fb82
commit 9b8add58f3
2 changed files with 82 additions and 17 deletions
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97
src/core/ngx_syslog.c
View file

@ -49,6 +49,56 @@ ngx_syslog_process_conf(ngx_conf_t *cf, ngx_syslog_peer_t *peer)
return NGX_CONF_ERROR;
}
if (peer->tag.data != NULL) {
ngx_uint_t j;
u_char ch;
if (peer->rfc5424) {
/*
* RFC 5424: APP-NAME is at most 48 printable US-ASCII
* characters (0x21-0x7E; space and controls are excluded).
*/
for (j = 0; j < peer->tag.len; j++) {
ch = peer->tag.data[j];
if (ch < '!' || ch > '~') {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"syslog \"tag\" must contain "
"printable US-ASCII characters");
return NGX_CONF_ERROR;
}
}
} else {
/*
* RFC 3164: the TAG is a string of ABNF alphanumeric
* characters that MUST NOT exceed 32 characters.
*/
if (peer->tag.len > 32) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"syslog tag length exceeds 32");
return NGX_CONF_ERROR;
}
for (j = 0; j < peer->tag.len; j++) {
ch = ngx_tolower(peer->tag.data[j]);
if (ch < '0'
|| (ch > '9' && ch < 'a' && ch != '_')
|| ch > 'z')
{
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"syslog \"tag\" only allows "
"alphanumeric characters "
"and underscore");
return NGX_CONF_ERROR;
}
}
}
}
if (peer->server.sockaddr == NULL) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"no syslog server specified");
@ -92,7 +142,7 @@ ngx_syslog_process_conf(ngx_conf_t *cf, ngx_syslog_peer_t *peer)
static char *
ngx_syslog_parse_args(ngx_conf_t *cf, ngx_syslog_peer_t *peer)
{
u_char *p, *comma, c;
u_char *p, *comma;
size_t len;
ngx_str_t *value;
ngx_url_t u;
@ -188,30 +238,43 @@ ngx_syslog_parse_args(ngx_conf_t *cf, ngx_syslog_peer_t *peer)
}
/*
* RFC 3164: the TAG is a string of ABNF alphanumeric characters
* that MUST NOT exceed 32 characters.
* Character set and maximum length depend on the syslog
* protocol version (rfc= parameter) and are validated in
* ngx_syslog_process_conf() once all parameters are known.
* RFC 5424 APP-NAME allows up to 48 printable US-ASCII
* characters; RFC 3164 TAG allows up to 32 alphanumeric
* characters. Reject anything that exceeds the larger
* of the two limits here so that the later check can rely
* on the data fitting into the statically-sized buffers.
*/
if (len - 4 > 32) {
if (len - 4 > 48) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"syslog tag length exceeds 32");
"syslog tag length exceeds 48");
return NGX_CONF_ERROR;
}
for (i = 4; i < len; i++) {
c = ngx_tolower(p[i]);
if (c < '0' || (c > '9' && c < 'a' && c != '_') || c > 'z') {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"syslog \"tag\" only allows "
"alphanumeric characters "
"and underscore");
return NGX_CONF_ERROR;
}
}
peer->tag.data = p + 4;
peer->tag.len = len - 4;
} else if (ngx_strncmp(p, "rfc=", 4) == 0) {
if (peer->rfc_set) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"duplicate syslog \"rfc\"");
return NGX_CONF_ERROR;
}
peer->rfc_set = 1;
if (ngx_strcmp(p + 4, "rfc5424") == 0) {
peer->rfc5424 = 1;
} else if (ngx_strcmp(p + 4, "rfc3164") != 0) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"unknown syslog \"rfc\" value \"%s\"",
p + 4);
return NGX_CONF_ERROR;
}
} else if (len == 10 && ngx_strncmp(p, "nohostname", 10) == 0) {
peer->nohostname = 1;

2
src/core/ngx_syslog.h
View file

@ -23,6 +23,8 @@ typedef struct {
unsigned busy:1;
unsigned nohostname:1;
unsigned rfc5424:1;
unsigned rfc_set:1;
} ngx_syslog_peer_t;