Hello,
While experimenting with the `wasm32-wasip2` target and CPython, I
discovered an issue with the `getaddrinfo()` implementation: it fails to
resolve the provided service into a port number, causing `sin_port` to
always be set to 0. This issue leads to failures in network-related
functions that rely on `getaddrinfo()`, such as Python's `urllib3`
library, which passes the result directly to `connect()`. This results
in connection attempts using a port value of 0, which naturally fails.
### Minimal example to reproduce the problem
```c
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
int main(void) {
struct addrinfo *res = NULL;
getaddrinfo("google.com", "443", NULL, &res);
for (struct addrinfo *i = res; i != NULL; i = i->ai_next) {
char str[INET6_ADDRSTRLEN];
if (i->ai_addr->sa_family == AF_INET) {
struct sockaddr_in *p = (struct sockaddr_in *)i->ai_addr;
int port = ntohs(p->sin_port);
printf("%s: %i\n", inet_ntop(AF_INET, &p->sin_addr, str, sizeof(str)), port);
} else if (i->ai_addr->sa_family == AF_INET6) {
struct sockaddr_in6 *p = (struct sockaddr_in6 *)i->ai_addr;
int port = ntohs(p->sin6_port);
printf("%s: %i\n", inet_ntop(AF_INET6, &p->sin6_addr, str, sizeof(str)), port);
}
}
return 0;
}
```
```
$ /opt/wasi-sdk/bin/clang -target wasm32-wasip2 -o foo foo.c
$ wasmtime run -S allow-ip-name-lookup=y foo
216.58.211.238: 0
2a00:1450:4026:808::200e: 0
```
Expected output:
```
216.58.211.238: 443
2a00:1450:4026:808::200e: 443
```
### Root Cause
The root cause is that `getaddrinfo()` does not correctly translate the
provided service into a port number. As described in the `getaddrinfo()`
man [page](https://man7.org/linux/man-pages/man3/getaddrinfo.3.html),
the function should:
> service sets the port in each returned address structure. If
this argument is a service name (see
[services(5)](https://man7.org/linux/man-pages/man5/services.5.html)),
it is
translated to the corresponding port number. This argument can
also be specified as a decimal number, which is simply converted
to binary. If service is NULL, then the port number of the
returned socket addresses will be left uninitialized.
### Proposed Fix
This pull request addresses the issue by implementing the following
behavior for `getaddrinfo()`:
* If the service is `NULL`, the port number in the returned socket
addresses remains uninitialized.
* The value is converted to an integer and validated if the service is
numeric.
The PR does not currently add support for translating named services
into port numbers because `getservbyname()` has not been implemented. In
cases where a named service is provided, the `EAI_NONAME` error code is
returned.
* implement basic TCP/UDP client support
This implements `socket`, `connect`, `recv`, `send`, etc. in terms of
`wasi-sockets` for the `wasm32-wasip2` target.
I've introduced a new public header file: `__wasi_snapshot.h`, which will define
a preprocessor symbol `__wasilibc_use_wasip2` if using the `wasm32-wasip2`
version of the header, in which case we provide features only available for that
target.
Co-authored-by: Dave Bakker <github@davebakker.io>
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
* fix grammar in __wasi_snapshot.h comment
Co-authored-by: Dan Gohman <dev@sunfishcode.online>
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
---------
Signed-off-by: Joel Dice <joel.dice@fermyon.com>
Co-authored-by: Dave Bakker <github@davebakker.io>
Co-authored-by: Dan Gohman <dev@sunfishcode.online>
