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netconn_gethostbyname: Fix race reporting success

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If the DNS request is dispatched and performed very quickly,
then it can complete before tcpip_callback() actually returns,
in which case we'll destroy the actual err_t error value passed
in the message. Use a local variable for the tcpip_callback
error code so that can't happen.

Resolves #269 https://github.com/espressif/esp-idf/pull/269
This commit is contained in:
Jan Schmidt 2017-01-20 14:17:03 +11:00 committed by Angus Gratton
parent ac412feb69
commit a14f22f65b
1 changed files with 5 additions and 4 deletions
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9
components/lwip/api/api_lib.c
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@ -880,10 +880,11 @@ netconn_gethostbyname(const char *name, ip_addr_t *addr)
{ {
API_VAR_DECLARE(struct dns_api_msg, msg); API_VAR_DECLARE(struct dns_api_msg, msg);
err_t localerr;
#if !LWIP_MPU_COMPATIBLE #if !LWIP_MPU_COMPATIBLE
sys_sem_t sem; sys_sem_t sem;
#endif /* LWIP_MPU_COMPATIBLE */ #endif /* LWIP_MPU_COMPATIBLE */
err_t err; err_t err = ERR_OK;
LWIP_ERROR("netconn_gethostbyname: invalid name", (name != NULL), return ERR_ARG;); LWIP_ERROR("netconn_gethostbyname: invalid name", (name != NULL), return ERR_ARG;);
LWIP_ERROR("netconn_gethostbyname: invalid addr", (addr != NULL), return ERR_ARG;); LWIP_ERROR("netconn_gethostbyname: invalid addr", (addr != NULL), return ERR_ARG;);
@ -918,14 +919,14 @@ netconn_gethostbyname(const char *name, ip_addr_t *addr)
} }
#endif /* LWIP_NETCONN_SEM_PER_THREAD */ #endif /* LWIP_NETCONN_SEM_PER_THREAD */
err = tcpip_callback(lwip_netconn_do_gethostbyname, &API_VAR_REF(msg)); localerr = tcpip_callback(lwip_netconn_do_gethostbyname, &API_VAR_REF(msg));
if (err != ERR_OK) { if (localerr != ERR_OK) {
#if !LWIP_NETCONN_SEM_PER_THREAD #if !LWIP_NETCONN_SEM_PER_THREAD
sys_sem_free(API_EXPR_REF(API_VAR_REF(msg).sem)); sys_sem_free(API_EXPR_REF(API_VAR_REF(msg).sem));
#endif /* !LWIP_NETCONN_SEM_PER_THREAD */ #endif /* !LWIP_NETCONN_SEM_PER_THREAD */
API_VAR_FREE(MEMP_DNS_API_MSG, msg); API_VAR_FREE(MEMP_DNS_API_MSG, msg);
return err; return localerr;
} }
sys_sem_wait(API_EXPR_REF_SEM(API_VAR_REF(msg).sem)); sys_sem_wait(API_EXPR_REF_SEM(API_VAR_REF(msg).sem));