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- From f94735eb76e634d7531f9c903113f64820c4cec0 Mon Sep 17 00:00:00 2001
- From: Willy Tarreau <w@1wt.eu>
- Date: Wed, 30 Jul 2014 08:56:35 +0200
- Subject: [PATCH 3/3] BUG/MAJOR: tcp: fix a possible busy spinning loop in
- content track-sc*
-
- As a consequence of various recent changes on the sample conversion,
- a corner case has emerged where it is possible to wait forever for a
- sample in track-sc*.
-
- The issue is caused by the fact that functions relying on sample_process()
- don't all exactly work the same regarding the SMP_F_MAY_CHANGE flag and
- the output result. Here it was possible to wait forever for an output
- sample from stktable_fetch_key() without checking the SMP_OPT_FINAL flag.
- As a result, if the client connects and closes without sending the data
- and haproxy expects a sample which is capable of coming, it will ignore
- this impossible case and will continue to wait.
-
- This change adds control for SMP_OPT_FINAL before waiting for extra data.
- The various relevant functions have been better documented regarding their
- output values.
-
- This fix must be backported to 1.5 since it appeared there.
- (cherry picked from commit 6bcb0a84e7256f00793fa8ec8a0d6c19c3b22935)
- ---
- src/proto_tcp.c | 4 ++--
- src/sample.c | 23 ++++++++++++++++++++++-
- src/stick_table.c | 11 ++++++++++-
- 3 files changed, 34 insertions(+), 4 deletions(-)
-
- diff --git a/src/proto_tcp.c b/src/proto_tcp.c
- index 9778856..72dc92b 100644
- --- a/src/proto_tcp.c
- +++ b/src/proto_tcp.c
- @@ -1048,8 +1048,8 @@ int tcp_inspect_request(struct session *s, struct channel *req, int an_bit)
- t = rule->act_prm.trk_ctr.table.t;
- key = stktable_fetch_key(t, s->be, s, &s->txn, SMP_OPT_DIR_REQ | partial, rule->act_prm.trk_ctr.expr, &smp);
-
- - if (smp.flags & SMP_F_MAY_CHANGE)
- - goto missing_data;
- + if ((smp.flags & SMP_F_MAY_CHANGE) && !(partial & SMP_OPT_FINAL))
- + goto missing_data; /* key might appear later */
-
- if (key && (ts = stktable_get_entry(t, key))) {
- session_track_stkctr(&s->stkctr[tcp_trk_idx(rule->action)], t, ts);
- diff --git a/src/sample.c b/src/sample.c
- index 3a0f3fb..8e62640 100644
- --- a/src/sample.c
- +++ b/src/sample.c
- @@ -896,6 +896,18 @@ out_error:
- * Note: the fetch functions are required to properly set the return type. The
- * conversion functions must do so too. However the cast functions do not need
- * to since they're made to cast mutiple types according to what is required.
- + *
- + * The caller may indicate in <opt> if it considers the result final or not.
- + * The caller needs to check the SMP_F_MAY_CHANGE flag in p->flags to verify
- + * if the result is stable or not, according to the following table :
- + *
- + * return MAY_CHANGE FINAL Meaning for the sample
- + * NULL 0 * Not present and will never be (eg: header)
- + * NULL 1 0 Not present yet, could change (eg: POST param)
- + * NULL 1 1 Not present yet, will not change anymore
- + * smp 0 * Present and will not change (eg: header)
- + * smp 1 0 Present, may change (eg: request length)
- + * smp 1 1 Present, last known value (eg: request length)
- */
- struct sample *sample_process(struct proxy *px, struct session *l4, void *l7,
- unsigned int opt,
- @@ -1153,7 +1165,16 @@ int smp_resolve_args(struct proxy *p)
- * and <opt> does not contain SMP_OPT_FINAL, then the sample is returned as-is
- * with its SMP_F_MAY_CHANGE flag so that the caller can check it and decide to
- * take actions (eg: wait longer). If a sample could not be found or could not
- - * be converted, NULL is returned.
- + * be converted, NULL is returned. The caller MUST NOT use the sample if the
- + * SMP_F_MAY_CHANGE flag is present, as it is used only as a hint that there is
- + * still hope to get it after waiting longer, and is not converted to string.
- + * The possible output combinations are the following :
- + *
- + * return MAY_CHANGE FINAL Meaning for the sample
- + * NULL * * Not present and will never be (eg: header)
- + * smp 0 * Final value converted (eg: header)
- + * smp 1 0 Not present yet, may appear later (eg: header)
- + * smp 1 1 never happens (either flag is cleared on output)
- */
- struct sample *sample_fetch_string(struct proxy *px, struct session *l4, void *l7,
- unsigned int opt, struct sample_expr *expr)
- diff --git a/src/stick_table.c b/src/stick_table.c
- index a708d3c..d39b4ff 100644
- --- a/src/stick_table.c
- +++ b/src/stick_table.c
- @@ -603,7 +603,16 @@ static sample_to_key_fct sample_to_key[SMP_TYPES][STKTABLE_TYPES] = {
- * no key could be extracted, or a pointer to the converted result stored in
- * static_table_key in format <table_type>. If <smp> is not NULL, it will be reset
- * and its flags will be initialized so that the caller gets a copy of the input
- - * sample, and knows why it was not accepted (eg: SMP_F_MAY_CHANGE is present).
- + * sample, and knows why it was not accepted (eg: SMP_F_MAY_CHANGE is present
- + * without SMP_OPT_FINAL). The output will be usable like this :
- + *
- + * return MAY_CHANGE FINAL Meaning for the sample
- + * NULL 0 * Not present and will never be (eg: header)
- + * NULL 1 0 Not present or unstable, could change (eg: req_len)
- + * NULL 1 1 Not present, will not change anymore
- + * smp 0 * Present and will not change (eg: header)
- + * smp 1 0 not possible
- + * smp 1 1 Present, last known value (eg: request length)
- */
- struct stktable_key *stktable_fetch_key(struct stktable *t, struct proxy *px, struct session *l4, void *l7,
- unsigned int opt, struct sample_expr *expr, struct sample *smp)
- --
- 1.8.5.5
-
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