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projects:openssh [2019/12/25 15:56] admin [Control flow] |
projects:openssh [2019/12/25 16:33] admin [On server] |
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| ====== scp ====== | ====== scp ====== | ||
| - | ===== Control flow ===== | + | |
| - | - On client | + | ==== 1) scp run on client (copy remote to local case) ==== |
| * construct ''scp'' command to be executed on the server via ssh. append ''-v -r -p -d'' flags as appropriate. Resulting command stored in ''cmd'' variable | * construct ''scp'' command to be executed on the server via ssh. append ''-v -r -p -d'' flags as appropriate. Resulting command stored in ''cmd'' variable | ||
| * call ''toremote()'' if destination is remote; ''tolocal()'' if destination is local (handles 'remote to local' and 'local to local' cases) | * call ''toremote()'' if destination is remote; ''tolocal()'' if destination is local (handles 'remote to local' and 'local to local' cases) | ||
| * for 'remote to local' case, append '''-f <src>''' to ''scp'' command to be run on the server | * for 'remote to local' case, append '''-f <src>''' to ''scp'' command to be run on the server | ||
| - | - On server | + | * call ''do_cmd()'' to run assembled ''scp'' command on the server |
| + | * ''do_cmd()'' forks a child which executes (via ''execvp()'') "''ssh -p <port> -l <remuser> --- <host> <cmd>''" scp command on the server. Connect parent and child via pipes. Parent accesses child's pipes via ''remin'' & ''remout''. ''do_cmd_pid'' contains child's PID. | ||
| + | * ''tolocal()->sink()'' receives file from child via ''remin'' & ''remout'' and stores it to the local destination | ||
| + | * finaly wait for child to finish, check for errors, close ''remin'' & ''remout'' and exit | ||
| + | ==== 3) server accepts ssh connection from client ==== | ||
| * for ''-t'' or ''-f'' private flags: ''remin = stdin''; ''remout = stdout'' | * for ''-t'' or ''-f'' private flags: ''remin = stdin''; ''remout = stdout'' | ||
