LibC: Try to recover gracefully from failed LookupServer requests
gethostbyname() and gethostbyaddr() now set h_errno (per spec) and try to recover and return (with an error) instead of choking in VERIFY() whenever an I/O or protocol error occurs in the communication with LookupServer.
This commit is contained in:
Andreas Kling
parent
083b58fd89
commit
5caeb8b747
Notes:
sideshowbarker
2024-07-17 18:43:48 +09:00
Author: https://github.com/awesomekling Commit: https://github.com/SerenityOS/serenity/commit/5caeb8b747
1 changed files with 73 additions and 52 deletions
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@ -87,6 +87,8 @@ static String gethostbyname_name_buffer;
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hostent* gethostbyname(const char* name)
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{
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h_errno = 0;
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auto ipv4_address = IPv4Address::from_string(name);
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if (ipv4_address.has_value()) {
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@ -104,14 +106,18 @@ hostent* gethostbyname(const char* name)
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}
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int fd = connect_to_lookup_server();
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if (fd < 0)
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if (fd < 0) {
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h_errno = TRY_AGAIN;
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return nullptr;
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}
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auto close_fd_on_exit = ScopeGuard([fd] {
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close(fd);
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});
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size_t name_length = strlen(name);
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size_t unsigned_name_length = strlen(name);
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VERIFY(unsigned_name_length <= NumericLimits<i32>::max());
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i32 name_length = static_cast<i32>(unsigned_name_length);
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struct [[gnu::packed]] {
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u32 message_size;
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@ -122,20 +128,23 @@ hostent* gethostbyname(const char* name)
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(u32)(sizeof(request_header) - sizeof(request_header.message_size) + name_length),
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lookup_server_endpoint_magic,
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1,
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(i32)name_length,
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name_length,
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};
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int nsent = write(fd, &request_header, sizeof(request_header));
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if (nsent < 0) {
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perror("write");
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if (auto nsent = write(fd, &request_header, sizeof(request_header)); nsent < 0) {
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h_errno = TRY_AGAIN;
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return nullptr;
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} else if (nsent != sizeof(request_header)) {
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h_errno = NO_RECOVERY;
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return nullptr;
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}
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VERIFY((size_t)nsent == sizeof(request_header));
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nsent = write(fd, name, name_length);
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if (nsent < 0) {
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perror("write");
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if (auto nsent = write(fd, name, name_length); nsent < 0) {
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h_errno = TRY_AGAIN;
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return nullptr;
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} else if (nsent != name_length) {
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h_errno = NO_RECOVERY;
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return nullptr;
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}
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VERIFY((size_t)nsent == name_length);
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struct [[gnu::packed]] {
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u32 message_size;
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@ -145,37 +154,42 @@ hostent* gethostbyname(const char* name)
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u64 addresses_count;
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} response_header;
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int nrecv = read(fd, &response_header, sizeof(response_header));
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if (nrecv < 0) {
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perror("recv");
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if (auto nreceived = read(fd, &response_header, sizeof(response_header)); nreceived < 0) {
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h_errno = TRY_AGAIN;
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return nullptr;
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} else if (nreceived != sizeof(response_header)) {
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h_errno = NO_RECOVERY;
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return nullptr;
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}
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VERIFY((size_t)nrecv == sizeof(response_header));
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if (response_header.endpoint_magic != lookup_server_endpoint_magic || response_header.message_id != 2) {
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dbgln("Received an unexpected message");
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h_errno = NO_RECOVERY;
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return nullptr;
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}
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if (response_header.code != 0) {
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// TODO: return a specific error.
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h_errno = NO_RECOVERY;
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return nullptr;
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}
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if (response_header.addresses_count == 0) {
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h_errno = HOST_NOT_FOUND;
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return nullptr;
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}
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VERIFY(response_header.addresses_count > 0);
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i32 response_length;
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nrecv = read(fd, &response_length, sizeof(response_length));
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if (nrecv < 0) {
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perror("recv");
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if (auto nreceived = read(fd, &response_length, sizeof(response_length)); nreceived < 0) {
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h_errno = TRY_AGAIN;
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return nullptr;
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} else if (nreceived != sizeof(response_length)
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|| response_length != sizeof(__gethostbyname_address)) {
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h_errno = NO_RECOVERY;
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return nullptr;
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}
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VERIFY((size_t)nrecv == sizeof(response_length));
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VERIFY(response_length == sizeof(__gethostbyname_address));
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nrecv = read(fd, &__gethostbyname_address, response_length);
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if (nrecv < 0) {
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perror("recv");
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if (auto nreceived = read(fd, &__gethostbyname_address, response_length); nreceived < 0) {
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h_errno = TRY_AGAIN;
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return nullptr;
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} else if (nreceived != response_length) {
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h_errno = NO_RECOVERY;
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return nullptr;
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}
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VERIFY(nrecv == response_length);
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gethostbyname_name_buffer = name;
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__gethostbyname_buffer.h_name = const_cast<char*>(gethostbyname_name_buffer.characters());
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@ -193,6 +207,8 @@ static String gethostbyaddr_name_buffer;
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hostent* gethostbyaddr(const void* addr, socklen_t addr_size, int type)
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{
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h_errno = 0;
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if (type != AF_INET) {
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errno = EAFNOSUPPORT;
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return nullptr;
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@ -204,8 +220,10 @@ hostent* gethostbyaddr(const void* addr, socklen_t addr_size, int type)
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}
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int fd = connect_to_lookup_server();
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if (fd < 0)
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if (fd < 0) {
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h_errno = TRY_AGAIN;
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return nullptr;
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}
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auto close_fd_on_exit = ScopeGuard([fd] {
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close(fd);
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@ -222,20 +240,22 @@ hostent* gethostbyaddr(const void* addr, socklen_t addr_size, int type)
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sizeof(request_header) - sizeof(request_header.message_size) + sizeof(in_addr),
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lookup_server_endpoint_magic,
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3,
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(i32)sizeof(in_addr),
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sizeof(in_addr),
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};
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int nsent = write(fd, &request_header, sizeof(request_header));
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if (nsent < 0) {
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perror("write");
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if (auto nsent = write(fd, &request_header, sizeof(request_header)); nsent < 0) {
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h_errno = TRY_AGAIN;
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return nullptr;
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} else if (nsent != sizeof(request_header)) {
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h_errno = NO_RECOVERY;
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return nullptr;
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}
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VERIFY((size_t)nsent == sizeof(request_header));
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nsent = write(fd, &in_addr, sizeof(in_addr));
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if (nsent < 0) {
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perror("write");
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if (auto nsent = write(fd, &in_addr, sizeof(in_addr)); nsent < 0) {
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h_errno = TRY_AGAIN;
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return nullptr;
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} else if (nsent != sizeof(in_addr)) {
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h_errno = TRY_AGAIN;
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return nullptr;
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}
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VERIFY((size_t)nsent == sizeof(in_addr));
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struct [[gnu::packed]] {
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u32 message_size;
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@ -245,29 +265,30 @@ hostent* gethostbyaddr(const void* addr, socklen_t addr_size, int type)
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i32 name_length;
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} response_header;
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int nrecv = read(fd, &response_header, sizeof(response_header));
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if (nrecv < 0) {
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perror("recv");
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if (auto nreceived = read(fd, &response_header, sizeof(response_header)); nreceived < 0) {
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h_errno = TRY_AGAIN;
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return nullptr;
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} else if (nreceived != sizeof(response_header)) {
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h_errno = NO_RECOVERY;
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return nullptr;
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}
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VERIFY((size_t)nrecv == sizeof(response_header));
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if (response_header.endpoint_magic != lookup_server_endpoint_magic || response_header.message_id != 4) {
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dbgln("Received an unexpected message");
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return nullptr;
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}
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if (response_header.code != 0) {
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// TODO: return a specific error.
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if (response_header.endpoint_magic != lookup_server_endpoint_magic
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|| response_header.message_id != 4
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|| response_header.code != 0) {
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h_errno = NO_RECOVERY;
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return nullptr;
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}
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char* buffer;
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auto string_impl = StringImpl::create_uninitialized(response_header.name_length, buffer);
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nrecv = read(fd, buffer, response_header.name_length);
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if (nrecv < 0) {
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perror("recv");
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if (auto nreceived = read(fd, buffer, response_header.name_length); nreceived < 0) {
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h_errno = TRY_AGAIN;
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return nullptr;
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} else if (nreceived != response_header.name_length) {
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h_errno = NO_RECOVERY;
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return nullptr;
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}
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VERIFY(nrecv == response_header.name_length);
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gethostbyaddr_name_buffer = move(string_impl);
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__gethostbyaddr_buffer.h_name = buffer;
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