lib/connect: defer port selection until connect() time #6295
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
If supported, defer port selection until connect() time
if --interface is given and source port is 0.
Reproducer:
start fast webserver on port 80
starve system of ephemeral ports
$ sysctl net.ipv4.ip_local_port_range="60990 60999"
start a curl/libcurl "crawler"
$curl --keepalive --parallel --parallel-immediate --head --interface
127.0.0.2 "http://127.0.0.[1-254]/file[001-002].txt"
current result:
(possible some successful data)
curl: (45) bind failed with errno 98: Address already in use
result after patch:
(complete success or few connections failing, higlhy depending on load)
Fail only when all the possible 4-tuple combinations are exhausted, which is
impossible to do when port is selected at bind() time becuse the kernel
does not know if socket will be listen()'ed on or connect'ed yet.